R&D Highlights 2015publications.deltares.nl/RD Highlights Deltares 2015.pdfunderstanding that due...

R&D Highlights 2015

Dear reader,It is my pleasure and honour to present the Deltares research highlights for 2015. More than 800 Deltares employees are involved in high-grade research and consultancy in the field of delta technology, the technology needed for sustainable living, work and recreation in low-lying, densely populated areas at the interface of the land and the sea: enabling delta life. It requires technical skills, as well as a thorough knowledge of the natural system and its response to human activities and environmental change. It also requires a broad interdisciplinary view of the functions of the natural system and how they can be integrated to the benefit of society, now and in the future. All of our activities, whether applied research or specialised consultancy, are intended to contribute to this body of knowledge. I hope this report shows that Deltares and its partners have made significant progress in adding to this treasury of interdisciplinary knowledge.

I am proud to present this collection of highlights, which were produced in both subsidised research programmes and commissioned contract work. If a project description stirs your interest, please don’t hesitate to get in touch.

Jaap KwadijkDeltares Science Director

Foreword

The Deltares 2015 R&D Annual ReportDeltares wants its R&D results to be more accessible to the public and the private sector. This R&D Highlights Report for

2015 is one of the means to that end. The chapters of the report follow the structure of the five social issues that are central

to the Deltares mission. To enhance interactivity, one or more contacts are listed for each project and readers interested

in more details should not hesitate to contact them.

A PDF version of these R&D Highlights 2015 can be downloaded from www.deltares.nl. The separate papers can be found

digitally at kennisonline.deltares.nl. Re-use of the knowledge and information in this publication is encouraged on the

understanding that due credit is given to the source. However, neither the publisher nor the authors can be held responsible

for any consequences resulting from such use.

Deltares | R&D Highlights 2015

ContentsWater and Subsoil Resources 68• Spatial catchment modelling: from catchment to coast 70

• Where are the rivers? 72

• River bed erodibility in the Port of Rotterdam 74

• Geological model for earthquake studies in Groningen 76

• Impacts of groundwater conservation on vegetation patterns 78

• Collaborative modelling of complex social and environmental issues 80

• Adaptation Support Tool for a climate-resilient urban environment 82

Adaptive Delta Planning 84• The smart water management table: a successful serious game 86

• Sustainable and green urban development in Utrecht 88

• Living with Dutch peat 90

• Action framework for land subsidence 92

• An eye on Deltares so�ware 94

• Greening flood protection in the Netherlands 96

Flood Risk 98• Storm impacts on gravel beaches 100

• Relations and consequences of Critical Infrastructures 102

• Del�-FIAT: A generic tool for flood impact analysis 104

• Real-time monitoring and forecasting of dike strength 106

• Ensemble Kalman Filtering for improving coastal-wave forecasts 108

• Estimating real-time predictive hydrological uncertainty 110

• GRADE method for discharge scenarios 112

• The conjunction of storm surges and high discharges 114

• Climate change e�ects on the protection of coasts by coral reefs 116

• Extreme wind-field evolution in time and space 118

• Smart Water Management on a regional scale 120

• Testing of ancient block revetment in the new Delta Flume 122

Introduction 6

Delta Infrastructure 14• Artificial islands in Jakarta Bay 16

• Impact of extreme weather on the Port of Rotterdam 18

• Physical model tests for Nordergründe o�shore wind farm 20

• Vibration and impact piling captured numerically 22

• Automated Feature Detection using Satellite Imagery 24

• Shared tools for designing coastal infrastructure 26

• Deformations of open filters in coastal structures 28

• Propelling research into scouring caused by ships 30

• Levelling in the new IJmuiden lock, the Netherlands 32

• Optical measuring technology shows complex flows in locks 34

• Modelling of soil-water interaction 36

• A solid foundation for piled embankments 38

• Bio-geotechnical corrosion protection for steel 40

• The Observational Method? Control risk, exploit opportunities! 42

Ecosystems and Environmental Quality 44• Modelling catchment water quality in New Zealand 46

• Anaerobic degradation of organic pollutants in soil and groundwater 48

• Citizen observations of water quality 50

• Chemical risks of reshaping deep lakes 52

• Lessons from full scale flow slides 54

• Litter forecasting for the Rio Olympics 56

• CleanSea 58

• The link between river hydraulics and vegetation patchiness 60

• Vegetated foreshores to protect dikes 62

• Nanoparticles – a new concern for the environment? 64

• Flexible Mesh Morphodynamic Modelling 60

outside the Netherlands. Deltares makes its contribution to the Water Top Sector and its subsector, Delta Technology. Delta Technology involves flood risk management, managing the water system, sand is feguarding adequate supplies of fresh water for all users, preserving ecosystems, and constructing reliable and sustainable infrastructure and buildings.

Our ability to carry out innovative research to support the Dutch government and private sector requires the long-term maintenance of a knowledge base with high scientific standards. We accomplish this in part with financing from the Ministry of Economic A�airs. Their subsidy amounts to about 10% of our annual turnover.

Not only does Deltares work in the Netherlands, it is also active internationally. The international dimension is imperative: the Dutch market is limited and subsidies have been decreasing, which means we need to focus on problems facing the international community. Knowledge about sustainable delta living is becoming more critical worldwide. The growth of the world’s population is leading to an increased demand for water and natural resources, and putting increasing pressure on ecosystems. Climate change and sea-level rise, together with the increasing population and economic development, will exacerbate flood risks, a development that will be accompanied by a decline in the willingness of the public and business to accept these risks. In this context, Deltares will have opportunities to make more of an impact on the international stage.

Deltares is an independent, not-for-profit organisation with an annual turnover of about €108 million, employing over 800 people at two locations in the Netherlands: Del� and Utrecht.

A large proportion of the research conducted by Deltares centres on the Netherlands, which is located in the Rhine-Meuse delta. The research is supported by the Dutch Ministry of Infrastructure and the Environment, whose operational agency, Rijkswaterstaat, is responsible for the management of water, subsurface, environment and infrastructure. Deltares is the main supplier of scientific and technological knowledge for this agency.

Deltares is also instrumental in strengthening the competitive position of the Dutch business sector with financial support from the Ministry of Foreign A�airs and the Ministry of Economic A�airs. These ministries invest in the development of innovative tools that private enterprises can use to compete in the international market. In 2012, the government identified ‘Top Sectors’ – parts of our economy it deemed crucial (like agro-food, energy, and logistics) – where it wants to see an improvement in our international position, and an increase in sources of revenue

Introduction

Deltares is an international institute located in the Netherlands that engages in

applied research in the field of water, subsurface and infrastructure. The institute’s

motto is “Enabling Delta Life”, and it strives to implement that motto by developing

and applying top-level expertise to help people live safely and sustainably in delta

areas, coastal zones and river basins. Managing these densely populated and

vulnerable areas is complex, which is why Deltares works closely with governments,

businesses, other research institutes and universities.

6 7

Deltares | R&D Highlights 2015 Introduction

To achieve the long-term goals of each programme, it is essential to have a project portfolio that is appropriately divided between strategic research, applied research, product development, knowledge transfer, and specialist consultancy. We therefore make strategic decisions about our research and marketing activities. Specifically, we redirect about 15% of our strategic research budget each year. Accordingly, we assess research requirements and current status in each programme and decide where that money can best be allocated to achieve the programme goals. The programmes have undergone extensive restructuring in response to the Knowledge Impact Audit in 2014.

In addition to the five themes described above, we also focus on So�ware Innovation. Our so�ware, which covers the full spectrum of Deltares expertise, is by far the most important vehicle for the distribution of knowledge, which we support with an Open Source so�ware policy. We also actively pursue and initiate new developments like serious gaming, map table applications and Open Earth.

Financial resources The revenue sources of a programme are intended to evolve through the lifetime of the programme. Initially, strategic research subsidy and co-funding from European and national research funds will dominate but applied research funds and market contributions will become more prominent over the course of time. However, Deltares strives to enhance market commitment in all phases of research and development so that the valorisation of the research will receive more attention from the outset.

Research at DeltaresIn general, the role of Deltares is to link academia with practice. Deltares engages in fundamental research only when necessary, mostly in collaboration with a university or an academic research institute and usually via doctorate students (who are employed either by Deltares or universities and hosted or co-financed by Deltares), part-time assistant and full professors. In the strategic and applied research phases and for the development of so�ware and models, Deltares actively collaborates with other parties from both academic backgrounds and from the private sector. Market parties will gradually take over once the resulting products have demonstrated their worth in practice.

A unique aspect of research at Deltares is that our facilities and expertise allow us to tackle problems with many tools. For example, we are able to develop numerical models and so�ware, and combine them with large-scale field tests and laboratory experiments.

Research themes and programmesDeltares has organised its research portfolio on the basis of five themes, each of which relate to social issues that are typically relevant in deltas. The themes are: Flood Risk, Ecosystems and Environmental Quality, Water and Subsoil Resources, Delta Infrastructure, and Adaptive Delta Planning. Each theme is subdivided into a number of programmes. It is at this level that long-term goals are defined for knowledge development. The structure of the themes and programmes is shown in detail in an internet application ‘The World of Deltares’, a set of mind maps that systematically sketch all aspects of the programmes.

8 9


ments, the disciplines and the relationships with the universities, Deltares has an internal Scientific Council. This council consists of a number of Deltares sta� members with international reputations, most of whom are part-time university professors.

The members of the Scientific Council are:• Professor Dick Vethaak• Professor François Clemens – Meyer• Dr Ap van Dongeren• Professor Marc Bierkens• Professor Frans Klijn• Professor Jaap Kwadijk (chair)• Professor Han Winterwerp

In 2012, Deltares established the Young Scientific Council. The Young Scientific Council gives solicited or unsolicited advice to the Scientific Council about Deltares knowledge development, particularly in the long term. The Scientific Council put forward the idea of a Young Scientific Council in order to import the knowledge and networks of these young professionals and so to keep abreast of the latest scientific developments and safeguard the high knowledge standards at Deltares. Moreover, the Scientific Council hopes to promote mutual collaboration and interdisciplinary research through this new council.

The members of the Young Scientific Council are:• Dr Karin de Bruijn• Dr Gilles Erkens• Dr Marjolijn Haasnoot• Dr Mandy Kor� (chair)• Dr Ivo Pothof• Dr Bregje van Wesenbeeck• Dr Hessel Winsemius

The strategic research subsidy granted by the Ministry of Economic A�airs plays a crucial role in the programmes. It is used as seed money to start up new research and stir enthusiasm among other parties. Moreover, it is mobilised to co-finance concerted research actions in Joint Industry Projects (JIPs), in governmental subsidy programmes (such as TKI) and in European research programmes.

Advisory CouncilTo advise the management about research and strategic positioning, Deltares has an external Advisory Council with representatives from the knowledge world and from the commercial sector. The issues addressed by the Council are long-term in nature, an example being the questions of where Deltares should invest to realise its ambitions, and of which research issues should be addressed to produce timely responses to problems expected in the future.

The members of the Advisory Council are:• Professor Jacob Fokkema (chair), Del� University of Technology• Professor Aad van der Horst, Delta Marine Consultants• Professor Marcel Stive, Del� University of Technology• Renée Bergkamp (Vewin)• Frank Goossensen (Arcadis Nederland BV, division Water)• Dr Bram de Vos (Wageningen UR, Environmental Sciences

Group)• Professor Piet Hoekstra (Chairman Faculty Geosciences,

Utrecht University)

Scientific CouncilIn order to monitor the quality of the knowledge activities at Deltares and to provide the management with advice, solicited or unsolicited, about the research programme, strategic invest-

10 11


Facts and figuresThe figure at the le� shows the distribution of revenue across the themes, and the geographical origin of the revenue.

The annual turnover of Deltares is about € 108 million, half of which is generated by R&D. This turnover is generated by about 800 employees, 538 of whom have scientific positions. Deltares is also a breeding ground for master and doctorate students. Some are Deltares employees, others are co-supervised and supported (some financially) by Deltares. About 80 bachelor and master students were co-supervised by Deltares sta�. Between 10 and 15 colleagues obtain doctorates every year. About 15% of the Strategic Research subsidy is allocated to doctorate studies.

Seventeen doctorates supported by Deltares were completed in 2015, thirteen by Deltares employees: • Marjolein Mens (University of Twente) System Robustness

Analysis in Support of Flood and Drought Risk Management• Jan Verkade (Del¤ University of Technology) Estimating

real-time predictive hydrological uncertainty• Wijb Sommer (Wageningen University and Research

Centre) Modelling and monitoring of aquifer thermal energy storage, impacts of heterogeneity, thermal interference and bioremediation

• Pieter Pauw (Wageningen University and Research Centre) Field and model investigations of freshwater lenses in coastal aquifers

• Joost Delsman (VU-University Amsterdam) Saline groundwater – surface water interaction in coastal lowlands

• Peter Vos (Utrecht University) Origin of the Dutch coastal landscape. Long-term landscape evolution of the Netherlands during the Holocene

• Suzanne van Eekelen (Del¤ University of Technology) Basal Reinforced Piled Embankments. Experiments, field studies and the development and validation of a new analytical design model

PhD-students by university

29 Del� University of Technology

15 Utrecht University

9 VU University Amsterdam

6 University Twente

7 Wageningen University and Research Center (WUR)

6 Unesco-IHE

4 Other (Netherlands)

6 Other (Abroad)

• Robert McCall (University of Plymouth, UK) Process-based modelling of storm impacts on gravel coasts

• Stephanie Janssen (Wageningen University and Research Centre) Greening flood protection in the Netherlands. A knowledge arrangement

• Anouk Blauw (University of Amsterdam) Monitoring and Prediction of Phytoplankton Dynamics in the North Sea

• Rianne van Duinen (University of Twente) Exploring farmers’ drought adaption behaviour -The role of risk perceptions, coping factors and social interactions

• Leo Sembiring (Unesco IHE/ Del¤ University of Technology) Rip Current Prediction System for Swimmer Safety: Towards operational forecasting using a process based model and nearshore bathymetry from video

• Vera van Beek (Del¤ University of Technology) Backward Erosion Piping. Initiation and Progression

The Deltares sta� include 20 part-time university professors. Other sta� are involved on a part-time basis as assistant or associate professors, or as senior researchers. Deltares values these links highly, not only because they help to define and supervise research and disseminate knowledge, but also to recruit young talent. The academics at Deltares are alumni from a variety of universities, including universities abroad. About 15% of the Deltares academic sta� are from countries outside the Netherlands.

Deltares works with universities to invest in knowledge centres at the universities of Del�, Utrecht, Twente and Wageningen. Current examples are the Geo-Engineering Knowledge Centre at Del� University of Technology, the Risk Management Knowledge Centre in conjunction with the University of Twente, and UCAD, the Utrecht Sustainable Earth Research Centre, a collaboration involving Utrecht University, TNO, Deltares, KNMI, KWR, PBL and RIVM. Deltares also has alliances with universities abroad such as the National University of Singapore (NUS).

Theme

31 Flood Risk

18 Environment

14 Water and Soul Resourches

22 Delta Infrastructure

9 Adaptive Delta Planning

6 So�ware Innovation

% %

%

12 13

Net turnover distribution 2015

37 Demand-driven research, national government

15 Dutch government authorities

15 Government authorities other countries

19 Dutch corporate sector

14 Corporate sector, other countries

Regional distribution of 2015 revenue

71 Netherlands

10 Europe

9 Asia

4 America

3 Middle East

2 Africa

1 Australia

Social and economic impactThe world’s population will increase to nine billion by 2050 and they are concentrated more and more in delta areas. These areas are increasingly threatened by climate change, rising sea levels and land subsidence. Not only the growing population but also rising prosperity are leading to more mobility and a greater interest in sustainability, including the use of natural processes. These trends will intensify demand for natural resources and renewable energy.

Our main goal is therefore to facilitate the e³cient, safe and sustainable design, construction and maintenance of infrastructure in deltas. We develop innovative, reliable and cost-e�ective solutions for delta infrastructure that have an acceptable environmental impact.

The national and international oil and gas industry, contractors and consultants can draw on our knowledge, so�ware and facilities in order to improve their competitiveness. Knowledge institutions and companies are able to link their research to the demands of society by exchanging facilities, so�ware and experts with Deltares. Governments also benefit from risk reduction and increasing cost-e�ectiveness in the construction and

maintenance of infrastructure. And public authorities can develop sustainable solutions that minimise the environmental impact, such as Green Ports. Universities strengthen their position in national and European research programmes and doctorate and master students are hosted and supervised by Deltares.

R&D HighlightsJoint Industry Projects (JIP) are well represented in the Delta Infrastructure theme. An example of a JIP is the CoDeS project, which helps engineers to design coastal engineering solutions and to communicate with clients and stakeholders. Another example of a JIP is the Open Filters Modelling project, which was conducted for dredging companies and a consultant. The results showed that considerable material reductions were possible during the design of a coastal structure.

Some projects address Dutch challenges, an example being the study of the impact of extreme weather on the Port of Rotterdam. In this project, an interactive touch-table application (CIrcle) was developed to support the risk assessment for the impact of extreme weather events and to visualise cascade e�ects. An example of an international project is the study of oblique wave attack in Jakarta. The physical scale model of planned artificial islands in Jakarta Bay made it possible to optimise the design of the sea defences of these islands.

Other highlights included projects looking at numerical models, other physical scale models, new measurement techniques, automated detection techniques and new design methodologies.

scopeBuilding on or in the so¤ soil of deltas is not without risks. The same applies to

structures o§shore, near coasts, and in harbours and river beds. Deltares research

focuses on reducing costs and risks when building in coastal regions, in so¤ ground

and at sea. Innovative solutions are designed to make existing infrastructure climate

change-proof, if possible using natural processes.

14 15

Delta Infrastructure

Contact

Deltares | R&D Highlights 2015 Delta Infrastructure

Further reading:

Van Gent (2014), Oblique wave attack

on rubble mound breakwaters,

Coastal Engineering, 88, 43-54

[email protected] T +31(0)88 335 8034



The administration of the city of Jakarta, Indonesia, has decided to construct an archipelago of artificial islands in the Jakarta Bay. The islands will house new residential areas for the city’s fast-growing population. Because they are located in the sea, sea defences are required for protection against flooding. A¤er the preliminary design phase, sea defences are usually tested and optimised on the basis of hydrodynamic performance and structural stability. Recent design guidelines based on tests by Deltares showed that considerable savings can be obtained with respect to the required rock size by taking into account oblique wave attack. However, some aspects of the design were outside the validity limits of the guidelines. The design therefore required verification in physical model tests.

Physical model tests were performed for two di�erent clients on two di�erent islands in the multidirectional Delta Basin at Deltares. The structures had two aspects in common: both were attacked by waves at a very oblique angle, and the structures were founded on very so� subsoil. The unconventional structures were adopted due to the so� subsoil and seismic activity in the area. The slopes of the sea defences were much shallower than normal. The combination of the unconventional structure and the oblique wave angle required new physical model tests. A complicating factor was that the level of the reclaimed islands is higher than the sea level. However, the very so� subsoil means that considerable settlement can be expected, resulting in considerable subsidence, taking the islands below sea level and transforming them into a polder.

A number of large 3D physical models were constructed in the Delta Basin, including a part of the seabed in front of the structure. The scales ranged from 1:40 to approximately 1:8. These models were meant to simulate various parts of the islands, including two corners and a number of straight sections with complicated transitions. The design storms were simulated with these models and calibrated wave conditions. Optical measurements were taken during the tests: both photographic analysis and 3D laser measurements were employed to determine the damage to the structure caused by the simulated storm. In addition, the amount of water flowing over the structure due to the wave action and the waves was measured. The test results showed where the damage occurred on the structure, when it occurred in the storm sequence and the amount of damage. This information allowed our clients to optimise their designs and demonstrate design stability.

Physical model of the

north-west corner of one of

the islands before testing.

During testing

Digital terrain model made

by the laser scanner

Artificial islands

in Jakarta Bay

16 17

The frequency of extreme weather events worldwide is increasing. Rainfall, sea level and storms are also expected to become more extreme in the Netherlands and to a§ect operations in the Port of Rotterdam. In addition to the port facilities themselves, the connecting transport infrastructure (road, rail, shipping, pipelines) are vital direct factors in maintaining freight transportation through the port. The whole system depends indirectly on other Critical Infrastructures (CI) such as the power supply and communication networks. If extreme weather causes these networks to fail, port operations may be disrupted by cascade e§ects, with one failure leading to another.

The EU project INTACT was launched in 2014 to improve the resilience and responsiveness of critical infrastructure to extreme weather across Europe and therefore to make it less vulnerable. The ultimate objective is to create a set of guidelines and best practices to help policy-makers, decision-makers and other stakeholders. The INTACT project is looking at five case studies, each based in a di�erent European country, to learn about di�erent regional settings and extreme weather conditions. One of these cases is the Port of Rotterdam and its transport connections to the hinterland. The R&D focus in this case is the long-term planning of adaptation strategies based on an integral risk assessment of the system, including cascade e�ects.

The main stakeholders (owners and users) in the Port of Rotterdam case were invited to a CIrcle workshop at which they discussed together for the first time the vulnerability of critical infrastructure and interdependencies.

Past studies were used as references, one example being the Blue Spot studies which investigated the vulnerability of the road and railway network to flooding. Although many owners had already made similar assessments of their infrastructure, the analyses of interdependencies and cascade e�ects was new to them. The involvement of infrastructure users (such as freight transport organisations) also gave them a di�erent perspective.

The CIrcle tool was used to support the discussion of risk assessment and to visualise cascade e�ects. CIrcle is an interactive touch-table application which combines expert knowledge with the prediction of the interdependency e�ects of the di�erent critical infrastructure networks. The largest e�ects of extreme weather events seen by stakeholders are the disruption of the port’s market position, the degradation of safety and increased costs. For example, the interruption of essential functions such as the power supply can lead to dangerous situations on bridges and in tunnels, and to the shutdown of road links. The recurrence of situations such as this could result in a loss of income, legal claims and damage to the competitive position of the Dutch port.

Contact


[email protected] +31(0)6 2244 6762

Further reading:

http://www.intact-project.eu/

18 19

Impact of extreme weather

on the Port of Rotterdam

Contact


Increasing demand for o§shore renewable energy is currently leading to the development of large numbers of o§shore wind farms. These wind farms are sometimes planned in areas with highly morphodynamic seabeds. It is essential to keep variations in the pile-fixation level within limits for wind turbine foundations so that the resonance frequencies of the structure are kept within an acceptable bandwidth, making the cost-eªcient design of the support structure possible. Scour protection is therefore o¤en used to fixate the seabed.

The Nordergründe o�shore wind farm will be built in 2016 in the Jade-Weser estuary (German Wadden Sea). This area is characterised by a complex system of migrating tidal channels and flats. Variations in the seabed level of up to 10m are predicted. Given these predictions, Deltares proposed several strategies for scour mitigation. The most promising strategy comprised of a combination of first allowing scour development to a pre-defined level and then fixating the seabed with scour protection. Physical model testing was used to develop and validate a scour protection layout for this strategy.

The physical model tests were performed in the Atlantic Basin at Deltares. The morphological scenarios were modelled in an innovative way: the drop in the level of the seabed was simulated by using an artificial island - with the scour protection situated on the top - which was eroded by a tidal current. A�er several tidal cycles, the sides of the island were fully eroded and the scour protection now covered the slopes of the island, resulting in stabilisation. This falling apron concept had never been tested for extreme seabed-level variations or in o�shore conditions with strong currents in combination with high waves. The unique characteristics of Deltares’ Atlantic Basin, where the combined e�ect of currents and waves can be modelled, were essential for the successful completion of these tests.

Stereo photography was used to determine the performance of the scour protection, resulting in very accurate pictures of the bathymetry before and a�er each test. In combination with underwater cameras and calibrated cameras inside the scale models, the observations provided a comprehensive picture of the performance of the scour protection at di�erent stages of each test. These measurements allowed for the further optimisation of the scour protection layouts.

Moreover, the physical modelling test programme proved to be a safe and cost-e³cient instrument for the development of the Nordergründe wind farm. With this project, Deltares and the o�shore wind industry have made a positive contribution to Europe’s transition to renewable energy. In addition, the scientific results of the physical modelling can be applied to other o�shore wind farms in the future.

Physical model tests for

Nordergründe o�shore

wind farm

Further reading:

Riezebos et al. (2016). Scour

protection design in highly

morphodynamic environments.

8th International Conference on

Scour and Erosion, Oxford, UK



Stereo photography was used to determine the performance of the scour protection, resulting in very accurate pictures of the bathymetry before and a�er each test. In combination with underwater cameras and calibrated cameras inside the scale

20 21

Contact


O§shore vibration piling has several advantages compared with the widely-used approach of impact piling. It produces less peak noise and can therefore be used without the need to implement expensive mitigation measures to protect marine wildlife. The piling takes less time, allowing shorter weather windows to be used. Furthermore, vibration piling involves lower peak loads on the monopiles, allowing for design optimisation in the areas of steel use and durability. More vibration piling in wind-farm installation could therefore produce crucial time and cost reductions.

Monopiles must provide accurate vertical alignment of wind turbines during decades of continuous cyclic lateral loading. High lateral system sti�ness is therefore required. It is currently not known whether vibration piling meets this requirement in arbitrary soil conditions. Certifying bodies therefore require impact piling, at least during the final stages of piling, and this significantly reduces the benefits of vibration piling.

Finding cost-e�ective solutions for wind-farm installation that involve the use of both piling techniques requires a good understanding of the mechanical processes involved. An industry-funded field experiment was performed in Germany in 2014 as part of the VIBRO project to learn more about the relationship between the piling techniques and lateral system sti�ness. Full-scale monopiles were installed using vibration and impact piling in a sandpit near Cuxhaven and then subjected to lateral loads.

Deltares performed a numerical study of this Cuxhaven field experiment in 2015 as part of the Far and Large O�shore Wind (FLOW) research programme in collaboration with the energy company RWE and Royal IHC. The numerical analysis of vibration and impact piling and the subsequent lateral-load testing is challenging: it involves a relatively complex geometry, the modelling of large deformations

Vibration and impact piling

captured numerically



Further reading:

Phuong et al. (2016).

Numerical investigation of

pile installation e�ects in

sand using material point

method, Computer and

Geotechnics, 73, 58-71

in saturated soil and the modelling of the complex soil-monopile interaction. Complexity is significantly increased in the case of vibratory piling because of the cyclic soil loading at high frequencies. In the context of the FLOW project, the Material Point Method (MPM) has been extended to include analyses of this kind. An e³cient solution in terms of computation time and the quality of the results was obtained for the numerical study of monopile installation and subsequent lateral load testing. The analysis of the Cuxhaven experiment shows the potential of the MPM for such studies. Numerical investigations of piling in arbitrary soil conditions for the assessment of lateral system sti�ness, pile drivability and design optimisations will require the further enhancement of the MPM and subsequent validation.

The potential cost savings are large. The foundations of o�shore wind turbines account for about 20% of the total costs. Cost reductions of between 1 and 2% can be achieved if the e�ects of impact and vibration piling on the soil properties are better understood. Even larger cost savings can in all probability be achieved by optimising the actual monopile structure.

Void ratio a�er pile installation – soil

loosening in vicinity of pile (yellow/red),

soil densification at distance (dark blue)

22 23

Satellite imagery is a rich source of information about the coastal system now and in the past. This information is essential to an understanding of system dynamics and to estimate the e§ects of interventions. Deltares is developing algorithms that can produce information from satellite imagery about coastal systems at basically any location in the world.

Coastal systems o�en consist of a combination of interacting morphological features such as bars, channels, shoals, coastlines and dunes. These features are dynamic in space and time and determine to a large extent the long-term behaviour of the coastal system, as well as the impact of human interventions on the coast. In most areas in the world, long-term data about the dynamics of morphological features – and therefore an understanding of the system – is inadequate or lacking. Satellite imagery is available for some decades into the past and it therefore opens up opportunities to fill in at least some of those gaps and so supplement other data sources, especially in data-poor environments.

Satellite imagery is becoming more and more freely available at increasing resolutions in time and space. In addition, technology for the processing of these images is developing rapidly. Google recently launched Earth Engine as a platform for Earth Science and data analysis. This technology opens up enormous opportunities for the detection of coastal features and the analysis of the associated trends.

Using Earth Engine, Deltares developed algorithms for the automatic detection of coastlines, shallow shoals, crescentic sand bars, flood plains and vegetation in the coastal zone. Analyses are mainly based on free satellite imagery from the

Landsat missions initiated by USGS and NASA, but they can also be performed on higher-resolution, purchased, imagery. On the basis of a user-defined spatial extent and temporal range, morphological trends can be analysed within seconds or minutes. An example of this is shown for the Sand Motor, a mega-nourishment project on the western coast of the Netherlands. The automated feature detection technique proved to be capable of detecting the temporal dynamics in this artificial sand feature. Verification based on jet-ski surveys produced very promising results regarding accuracy.

The automated feature detection technique proved to be very useful in several commercial and research projects at di�erent locations in the world such as the Netherlands, South Korea, Africa and Colombia. The Colombia project focused on building a validation dataset for long-term coastline changes with satellite images in order to identify coastal zones at risk. Since long-term survey data was limited for this location, the use of satellite imagery was essential to perform this assessment.

Future work will focus on the quantitative validation of the technique for cases where in-situ data is available alongside satellite data. Corrections for the e�ects of clouds, tide, waves and storm surge will also require further attention. We also aim to make the algorithms easily accessible to experts and end users.

[email protected] +31(0)6 4691 1209 Automated feature detection

using satellite imagery

Sand Motordetection from

satellite imagery

Sand Motor

Contact


Further reading:

https://earthengine.google.

com/

24 25

Contact


Coastal Design Support (CoDeS) tools are relatively simple so¤ware tools developed to help engineers with the design of coastal engineering solutions and communications with clients and stakeholders. The tools provide a quick picture of the orders of magnitude of environmental conditions and impacts, and help to arrive at promising solution concepts in the early stages of a project. Bringing CoDeS tools together in one so¤ware environment enables engineers to develop a knowledge base in order to improve the eªciency of projects and promote the integration of di§erent disciplines.

Royal HaskoningDHV, Witteveen+Bos and Deltares launched the Joint Industry Project CoDeS in order to create an accessible platform for the exchange and dissemination of CoDeS tools and build an active community of developers and users amongst the partners. To this end, a number of tools related to tide, currents, waves, and sediment transport in and around ports have been developed and connected to the existing Delta Shell platform for integrated modelling. A tool for breakwater design was incorporated recently.

Delta Shell proved to be a flexible platform to which engineers, even when they have a relatively limited programming experience, can add tools and General User Interface (GUI) components relatively easily. At the end of the project the developed tools were successfully implemented and disseminated within a relatively limited period of about three working weeks of programming time in total. The dissemination of the tools using a GUI means that the tools are now easily accessible to the end users.

Shared tools for designing

coastal infrastructure


Further reading:

https://publicwiki.

deltares.nl/display/TKIP/

TKI+Projects+Home,

http://oss.deltares.nl/web/

delta-shell/home

An enthusiastic team of programmers and engineers from the three partners worked together in sprint sessions at Deltares. These sessions consist of a fixed period in which the team works specifically on a part of the scope with clear priorities, roles and responsibilities. The aim of each sprint is to produce a potentially shippable product. This product is then demonstrated to the managers and end users for feedback and for the adjustment/refinement of the scope for the next session. The sprint sessions proved to be a very constructive and pleasant working method.

A�er the successful pilot project, both the development team and the management of the partners were keen to continue their collaboration and this resulted in the follow-up project JIP CoDeS 1.0, which is starting in 2016. This project will focus on an extension of the tool base, further integration of the tools and interactive GUI components, allowing the users to obtain immediate feedback about the impacts of changes in the design.

Design process from sketch to realization

26 27

Contact


A common practice to safeguard the stability of coastal structures is the use of rock layers as a filter structure. The standard design philosophy is that any movement in the sand below the filter should be prevented. The application of open filters in coastal structures is a recent design methodology that was investigated by Deltares in a number of Joint Industry Projects. Open filters can have benefits by comparison with traditional filter designs since they reduce bulk material consumption and the number of installed layers. Open filters can therefore result in substantial savings in the final design of a coastal structure without jeopardising the overall stability of the coastal structure.

An open filter is normally installed on a base of sand. The typical characteristic of open filters is that the waves acting on the coastal structure can displace the sand grains inside the rock layer. Accepting small deformations in the base material can lead to considerable savings by comparison with conservative approaches that accept no sand movement.

Until now, the design rules for open filters were based uniquely on laboratory experiments looking at the response of the base material to irregular wave loading. The design rules are therefore limited to the range of parameters studied in the laboratory. To extend applicability, a numerical model has been developed with private partners to predict deformation in the base material. The goal was to develop a numerical model that can assess the e�ectiveness of open filters without the need to conduct physical model tests. The numerical model has been validated on the basis of existing datasets from the laboratory experiments.

The numerical model has been applied to existing large-scale laboratory datasets from the Delta Flume and it was found that the

model can also reproduce experimental observations on this larger scale. These validation and additional parameter studies have shown that open filters represent a useful design method. It has been confirmed that considerable material savings (a factor of 2 at least) can be obtained by introducing accepting minor deformation levels (in the order of 1 mm at the laboratory scale) in the base material. The model will also be used to study the e�ect of geotextile on the response of coastal structures and to look at whether local reinforcement with geotextile can lead to even more cost-e�ective designs for open filters.

Deformations of open filters

in coastal structures



Further reading:

Van Gent et al. (2015).

Rock slopes on top of sand:

Modelling of open filters under

wave loading. Proc. Coastal

Structures Conf. , Boston, USA

28 29

The initial configuration in the numerical model Deformation of the sand core a�er 9 hours of

wave loading

Deformation of the sand

core below an open filter

in the laboratory tests.

The profile of the sand

core was initially straight

Contact


The main propellers and bow thrusters of ships create strong jets in the water during manoeuvring. These jets can cause serious erosion in the bed - ‘scouring’ - near quays and other structures, in extreme cases even undermining and destabilising them. The critical hydrodynamic loads on the bed (flow velocities, pressures) dictate the minimum required strength and extent of scour protection. Protection may be optimised if these critical loads can be predicted accurately and generate major cost savings on materials and installation.

Working with the Port of Rotterdam, the Port of Antwerp and Holcim (a manufacturer of scour protection), Deltares performed scale-model tests to address these issues. The project was coordinated by SBRCURnet, a national network for civil engi-neering knowledge in the Netherlands. In this first phase of the project, Deltares considered critical flow velocities when a bow thruster jet reflected o� a quay wall and the stability of bed protection subjected to a main propeller jet in open water.

The first test series used a schematic hull shape to represent the blunt blockage of the hull. This hull contained a propeller in a transparent thruster tube. The transparency allowed for the measurement of outflow velocities inside the tube with a laser without disturbing the flow field. The flow velocities of the generated jet were measured with sensors in horizontal and vertical arrays on either side of the hull, including sensors between the ship and the quay. The results were compared with existing design formulae from the literature. These formulae describe, for a given propeller outflow velocity, where the critical bed flow velocities will occur and the flow strengths. The outcome of this study indicates that the guidelines are o�en – but not always – conservative (in other words, on the safe side) for the situation of a ship in front of a quay and that they could be optimised.

The second test series focused on how a jet from a main propeller a�ects block mattresses. These mattresses consist of concrete elements on geo-textile. Protection with loose rocks was also used for reference purposes. The tests showed that the accuracy of mattress positioning is critical for the stability of the mats. The tests also indicated that the present design guidelines – which are currently a scaled version of the guidelines for loose rocks – are not consistently applicable to block mattresses.

Future work on this topic may include field tests for the full-scale verification of the findings. More accurate information about the e�ect of propeller jets on water beds and protection measures will eventually result in major savings in construction and maintenance.

Propelling research into

scouring caused by ships

Test with the main propeller and a block mattress

Propeller in transparent tube



Situation during the tests showing

the flow measurement devices (grey

boxes)

30 31

Contact


A¤er almost 100 years of service, the Noordersluis (Northern lock) in IJmuiden, the Netherlands, needs to be replaced. A new, bigger lock will provide access to the harbour of Amsterdam for larger seagoing vessels and will therefore stimulate the economy in the region. Lock construction will commence in early 2016. The new lock is expected to be available for the first vessels in 2019. With a width of 70 m, a length of 545 m, and a depth of almost 18 m, it will be the largest lock in the world.

Deltares conducted extensive hydraulic research in 2014 and 2015 on the reference design for the levelling system of the new lock. The main objective of the study was to determine feasible levelling times while keeping the forces on vessels within acceptable limits. The hydrodynamic forces on a ship must not become too large during the lock cycle because mooring line forces may then exceed operating limits, possibly resulting in unacceptable ship movement or even line breaks. The design ship for the levelling system is a bulk carrier with a length of 330 m and a beam of 52 m. The maximum dra� of vessels passing the lock will be 13.75 m in salt water due to restrictions upstream in the canal.

One of the most important boundary conditions is the density di�erence in the water since the lock is located between salt water on one side (the North Sea) and fresh water on the other side (the canal).

The hydraulic design of two levelling systems was investigated in a 1:40 scale model. The two levelling systems considered used openings in the gates or culverts in the lock heads. The complete levelling process was simulated in the scale model, including the lock exchange process a�er the opening of the gate. All the relevant physical flow phenomena were included automatically in the scale model.

More than 200 parameters were measured, including the most important ones such as water levels, forces on the ship and the density distribution of the water. Levelling tests with a density di�erence showed that the forces due to these di�erences in density were significant and could exceed allowable force criteria. As well as providing valuable insights into the process of the complete locking cycle, the measurements were also used to validate various numerical models.

Many aspects of the locking process that are important for the safe operation of the lock were considered in the study. They included the position of the vessel in the lock, di�erent li�ing programs, di�erent density distributions, and the type of design vessel (container ship or bulk carrier). In the light of the results of the scale-model study and the validated numerical simulations, the contractual requirements for levelling times were adjusted. These new requirements were included by Rijkswaterstaat in the tender for the lock construction.

Levelling in the new IJmuiden

lock, the Netherlands


One of the most important boundary conditions is the density di�erence in the water since the lock is located between salt

32 33

Contact


Navigation locks allow ship transport through the Dutch waterway network. Many of these locks, or indeed other hydraulic structures like weirs, sluices or pumping stations, will have to be enlarged and adapted in the forthcoming decades in response to economic requirements, or replaced because they have reached the end of their lifespan. Optimising designs can help to make this process smarter. Deltares develops tools which help to design and test hydraulic structures, and performs scale-model tests for research and design verification.

Detailed scale-model measurements and numerical tools help to understand the hydrodynamics of flows in navigation locks and to produce better designs. O�en, however, scale-model tests are only conducted at the end of the design process as verification. Numerical techniques are more suited to a design optimisation process but detailed 3D Computational Fluid Dynamics (CFD) models had not been validated against high-fidelity flow field data relating to a lock levelling process until now.

Deltares has long been using scale-model tests for hydraulic structures. Much more detailed measurements have recently become possible with Particle Image Velocimetry (PIV). This optical measuring technology was applied to a scale model of a lock and provided a rich picture of the complex flow patterns during levelling. PIV is a non-intrusive technique that allows the measurement of the two dimensional instantaneous velocity field based on the displacement of groups of tracer seeding particles. Using a double-pulsed laser as a light source, the flow field is illuminated at two successive instants and two frames with illuminated seeding particles are captured by a camera. These frames are split into a grid of smaller areas where a cross-

correlation function is applied, allowing the estimation of the most likely displacement of a group of particles within each area.The technique had to be adapted first so that it could be used on a 1:7 scale model of a lock gate in the Scheldt Flume where there was a highly disturbed water surface. The result is a high-quality flow field over a window of 70 cm by 70 cm with a resolution of 0.5 cm and a frequency of 25 Hz. The highly turbulent nature of the flow is captured, producing spectacular images.

Alongside the tests, detailed CFD simulations were run and validated against the measurements. The comparison gives confidence that the main hydrodynamics are captured well by the numerical model. This means that numerical simulation can be used in the future to predict flow patterns in locks or to calibrate LOCKFILL, our design tool for locks, and give designers and engineers ways to optimise their lock designs.

Optical measuring

technology shows

complex flows in locks

Experimental setup during tests

Detail of a contour plot of vorticity with instantaneous streamlines

at the edge of the jet

CFD results – Contour plot of average velocity magnitude with

a half-open door valve

PIV results - Contour plot of

velocity with instantaneous

velocity vectors

Further reading:

www.nattekunstwerkenvande-

toekomst.nl



34 35

Contact


Water a§ects the safety of houses, industrial buildings and public infrastructures located in coastal areas and on river banks, as is seen in various ways: erosion, scouring, flooding or wave attack, for example. These phenomena can seriously damage engineering structures, with catastrophic consequences. One approach to investigating soil-water interaction problems is to perform physical experiments. However, some phenomena like erosion cannot be reproduced accurately on a small scale. As an alternative, powerful computers and computational mechanics provide opportunities to simulate these problems using numerical modelling.

The modelling of soil-water interaction focuses on the numerical modelling of the complex behaviour of soils, water, and mixtures of the two when subjected to large deformation processes. The response of the soil-water mixture varies significantly depending on its state. The soil-water mixture can behave as a soil body (this is the typical assumption in classical geotechnical engineering) or as a fluidised mixture in which solid grains are transported in water and deposited as sediments. The behaviour is also a�ected by water flowing through the soil body due to the interaction of water and the solid skeleton resulting in drag forces.

Although numerical models of computational fluid dynamics (CFD) are appropriate for sediment flow and deposition, they are less suitable for the study of the mechanical response of soil during and a�er the sedimentation process. Deltares therefore developed a new numerical tool with the University of Cambridge as part of the European Project MPM-Dredge. This new tool uses the Material Point Method (MPM) and allows for the simulation of large deformation problems involving soil, water and the interaction between them. For this particular application - the simulation of the behaviour of free water, soil and the transition between fluidised and non-fluidised states - two sets of material points were introduced. The first set describes the physical

behaviour of the liquid constituent and the second set describes the response of the solid.

Several problems were successfully simulated and used as benchmarks in the present project. Situations with analytical solutions (seepage flow through a soil body, for example) and more complex examples (complete state transition) were both investigated. The free fall of coarse-grained soil under water clearly showed that the fluidisation and sedimentation processes are well described and correspond to physical expectations. In another example, the collapse of a submerged soil column was modelled using two di�erent initial soil densities. In the dense soil case, breaching was observed; in the loose soil case, full liquefaction occurred. These two cases demonstrate the importance and feasibility of taking the constitutive soil model and large deformations into account. Finally, the failure of a dike due to seepage was simulated. Not only the failure mechanism of the dike but also the subsequent sediment transport were reproduced using MPM.

In the future, this new MPM approach will facilitate the modelling of the soil-water interaction, allowing engineers to design solutions to mitigate associated risks and to improve the construction process in industry. For example, it will be possible to model the full installation process for geocontainers, during which they are subjected to large strains and cyclic deformation. Their high permeability allows the water to flow not only around the container but also through the geomaterial itself. Soil liquefaction, fluidisation and sedimentation are some of the phenomena that occur during a catastrophic failure of this kind and that can be taken into account in this new MPM approach. Finally, in the future, MPM simulations can be used as a support tool for the construction of a hydraulic-fill tailings dam in the mining industry.

Collapse of submerged sand column

Free fall of coarse-grained soil

under water

Collapse of a soil slope due to seepage


[email protected] +31(0)88 335 7351 Modelling of soil-water

interaction

Free fall of coarse-grained soil

36 37

Contact


A solid foundation for

piled embankments

Further reading:

Van Eekelen (2015). Basal

Reinforced Piled Embankments.

PhD thesis Del� UT, downloadable

from: http://repository.tudel�.nl


Eighty percent of the world’s population lives on compressive so¤ soil. Building in and on such soils is a challenge. The weight of a road construction, for example, causes compression of the so¤ soil, resulting in a bumpy and unsafe road. One of the solutions is to apply a piled embankment reinforced with geosynthetics. This doctorate research examined the design of the geosynthetic reinforcement.

The study started with a series of experiments in a test set-up with four small piles and a foam cushion in between them. This cushion was saturated with water and wrapped so that it was leak-proof. A tap was installed on this structure. When the tap was opened and pressure applied from above to the saturated foam cushion, the water was squeezed out, simulating the compression of so� soil. The next step was to put the geosynthetic reinforcement on top of the piles and the cushion, and to complete the set-up with the embankment. A water cushion on top allowed for a large top load.

On the basis of experiments in this set-up, an analytical model was developed for the mechanism active in the geosynthetic reinforcement and the soil. This analytical model is based on a set of concentric hemispheres and arches. The load first travels along the 3D hemispheres until the hemispheres intersect and then the load travels further along the 2D arches towards the baseline. The larger the arch, the more load it transports and the more load it exerts on its subsurface.

This Concentric Arches model results in a load distribution on the subsurface that matches the load distribution observed in the experiments. This distribution, however, is very di�erent from the load distribution used in older design methods. The strain in the geosynthetic reinforcement can be calculated on the basis of the load distribution.

The figure shows the improvement obtained with the new Concentric Arches model. The strains measured in twelve field and laboratory projects are shown on the horizontal axis. The le�-hand pane shows the corresponding strains calculated with an old method on the vertical axis; the right-hand pane shows the strains calculated with the new Concentric Arches model.

The result with the Concentric Arches model is much better than the result with the old method. On average, the old method calculates a strain that is 2.5 times the measured strain; the new model calculates a strain that is 1.1 times the measured strain. In other words, the new Concentric Arches model gives less extreme values and a much better match with the measurements in these twelve projects. The new Concentric Arches model has therefore been adopted in the new Dutch design guideline that will be published in 2016.

Comparison of measurements

and calculations

The test set-up

The Concentric Arches model

38 39

Contact


Steel infrastructure is present everywhere in the soil, an example being steel sheet piling to reinforce dikes. Steel in water and soil can corrode. But how quickly, and what role do environmental conditions play? Can corrosion be minimised by controlling these conditions? The BioCoPro project, a collaboration between Del¤ University of Technology, NIOO-KNAW, Utrecht University and Deltares, addressed these questions..

The research demonstrated that the corrosion of subsurface materials is a highly complex process involving physical, chemical and biological factors. In many cases, a di�usion barrier forms at the steel surface, leading to very low corrosion values. In undisturbed soils, corrosion rates can therefore become very low with time. However, dynamic conditions such as changing water levels or soil disturbance can lead to increased risks.

This project had a unique opportunity to investigate sheet piles exposed to soil for decades. Deltares and Rijkswaterstaat investigated the reduction in thickness, while other researchers focused on microbiology, biogeochemistry or the integrated modelling of the relevant processes.

Data about the corrosion of sheet piling in soil was collected in both a literature survey and practical research. Deltares and Rijkswaterstaat studied the e�ect of exposure over time to soil conditions. Both the literature and the experimental data showed that the groundwater level and the degree of disturbance of the soil are the key factors in the rate of corrosion: corrosion rates are lowest in undisturbed soil and below the groundwater level. Corrosion rates fall with increasing exposure times.

Researchers from Del� University of Technology and NIOO KNAW took a closer look at the chemistry and microbiology at the surface of the corroding steel. A grey and black deposit was observed on some sheet piles and no corrosion was detected at all. The microbial community

Bio-geotechnical Corrosion

Protection for steel



Further reading:

Jansen et al. (2014). Corrosie

van stalen damwanden in

de grond; E�ect van zout

grondwater. Deltares report

1209030. http://kennisonline.

deltares.nl

is distinctly di�erent in samples taken close to the steel surface and in samples taken farther away. This shows that there are very specific niches at the steel surface and in the attached soil. Levels of methanogens in particular are high at the steel surface.

Biogeochemical processes near corroding metal surfaces in the soil were studied in steel sheet piling and archaeological objects. Steel sheet piling was hardly corroded at all. This is probably due to the soil not being disturbed, and to the low oxygen concentrations and low soil permeability. Many parts of the sheet pilings were covered by thick crusts and the chemical composition of these crusts was analysed. It proved possible to visualise the clogging of soil by minerals formed with dissolved iron due to the corrosion of the steel surface.

A numerical model was made that describes the linked processes that control corrosion in soil. The resulting model includes the activity of multiple types of bacteria, di�usive transport, kinetic processes (dissolution/precipitation and growth of a biofilm) and equilibrium chemical reactions. Another model was made describing the most important processes occurring in bio-corrosion protection for subsurface metallic structures: the Pore-Network Multi-Physics Simulator (PNMPS). The processes modelled include solute transport in soil, biomass growth, biodegradation, and mineral precipitation and dissolution.

40 41

Contact


The traditional approach to a construction project is to determine the design before construction starts. Conservative assumptions are made about geotechnical conditions and construction behaviour to ensure the required level of safety. These are rational decisions, but opportunities will be missed with this approach. Soil conditions may prove to be more favourable than thought, meaning that less material and e§ort could have been used to achieve safe construction.

The Observational Method (OM) addresses these disadvantages. An extensive monitoring programme and the preparation of “what-if” scenarios allow less conservative assumptions to be adopted without impairing safety and also allow opportunities to be taken when they emerge. The OM is used frequently in some countries but only in specific cases in the Netherlands. The use of the OM o�en results in discussions about legality and desirability, although Eurocode 7 allows for the use of the method. Practical guidance for the use of the method is apparently lacking. The fact that the OM is not o�en used is seen as a missed opportunity since the method can lead to robust and cost-e�ective projects.

Deltares studied the OM in a working group as part of the GeoImpuls initiative with the aim of furthering the more widespread use of the OM for the design of underground and infrastructure construction. Other objectives were to establish an overview of the obstacles and conditions involved in the application, to develop practical recommendations about how to make a safe design in the context of the Eurocode 7, and to produce practical recommendations about how to organise the OM during construction. All the results were based on the evaluation of several case studies in the Netherlands. The research resulted in a Dutch guideline for the application of the OM in practice.

A number of benefits were identified on the basis of the case studies. A design can be less conservative and this can cut construction costs. Nevertheless, the benefit of a leaner design must outweigh the additional costs associated with more extensive design and monitoring during the construction phase. Designing and building with the OM is a safe approach since explicit risk management is a pre-requisite. Failure mechanisms and fall-back measures are designed and calculated beforehand. The OM therefore fits in perfectly with the trend towards using Geo-Risk Management in infrastructural projects.

Beneficial side-e�ects of the use of the OM include improved collaboration between design and construction activities, and the possibility of using the extensive monitoring results to visualise the e�ects in communications with stakeholders. Finally, the collected monitoring results teach us more about the behaviour of ground and the ground-construction interaction in general.

The Observational Method?

Control risk, exploit

opportunities!



WorkingprocessObserva1onalMethod

StartScenario1

Scenario2

Scenario3

Scenario4

Determinelimitstoswitchtootherscenario

Predesignphase Finaldesignphase

Determinesignalvalues

Constructionphase

Monitoring

Testing

Workingplan:howtoswitchtootherscenario

Detailingofthescenarios The Observational Method

Application of the Observational Method

as ‘best way out’. During the excavation

of the Rokin station in Amsterdam,

there was an unexpected upli� problem.

Construction could continue only with the

introduction of an extensive monitoring

programme and bath tubs as pre-

designed counter-measures. Photo Ge

Dubbelman/Hollandse Hoogte

Further reading:

http://www.cobportaal.nl/

Gedeelde%20documenten/

Geo-Impuls_Handreiking-

ObservationalMethod_

20150507.pdf

42 43

scopeAquatic ecosystems are vital natural resources that provide habitats for numerous species

as well as drinking water and resources for industry and society. Pressures on ecosystems

and the environment are increasing as the population and the economy grow. At the same

time, governments are becoming more ambitious about protecting natural resources

and the environment, and the sustainable use of resources, and there is increasing

demand for ecosystem services. Deltares is developing knowledge about hydrodynamic,

morphological, chemical and biological processes, and making that knowledge available

through model and information systems for policy-makers, managers and users.

Social and economic impactThere is increasing demand for nature-based solutions in order to combine the protection of natural resources with the provision of goods and services for economic sectors and society. The theme focuses on the dynamics, services and use of general systems and ecosystems for safety, health and a green economy. Key questions covered by the theme are the following: Can social and economic developments be harmonised with environmental legislation, and vice-versa? Is it possible to replace expensive rigid flood defences or to combine them with adaptive nature-based alternatives? Can the better planning and/or use of ecosystem services and functions reduce the risks for human health, and how? And how can the need for policy-relevant information about ecosystems be translated into monitoring strategies?

Our research allows governments to implement water and environmental policies more e�ectively. Dutch consulting and

dredging companies are opening up new markets worldwide and non-governmental organisations can substantiate their visions and strategies by using our expertise. Doctorate and master students from universities worldwide can develop their talents through direct access to Deltares’ knowledge and research facilities.

R&D HighlightsTwo highlights were funded by the FP7 subsidy of the European Union. In the CITCLOPS project, observations by the general public using smartphones were used to gather information about the colour of waters. These citizen observations are a valuable addition to ocean-colour data from satellite images. The other FP7 project, Cleansea, drew up guidelines for the removal of litter, in particular plastics, from our seas.

Guanabara Bay near Rio de Janeiro will be the location for sailing and windsurfing events at the 2016 Summer Olympics and Paralympics. The operational system developed by Deltares provides four-day forecasts of surface currents, winds, water levels and litter accumulations that are all available through any standard web browser.

A cooperative project between Deltares and an international partner (River Experiment Centre of KICT, South Korea) is the integrated study that connects field measurements, flume experiments and modelling to link river hydraulics and vegetation patchiness.

Other highlights include projects related to pollutants, water quality, vegetated foreshores and modelling of curvy geometries.

44 45

Ecosystems and Environmental Quality

Contact


Modelling catchment water

quality in New Zealand


The Waituna Lagoon in Southland, New Zealand is a coastal lagoon system that is periodically closed by sedimentation and reopened by human intervention. It is extremely important for ecological, cultural and recreational reasons. The large-scale development of the catchment (which covers an area of 200 km2) commenced in the 1960s, and dairy farming and other pastoral land uses now take up more than 70% of the total land area in the catchment.

The ecological health of the lagoon has declined in recent years due to increases in water nutrient concentrations and the degradation of the water flora. The risk of a regime shi� to a turbid, algae-dominated

state is considered highly probable if no further action is taken to improve water quality. A further reduction in nutrient loading from the catchment will probably be needed, involving the implementation of on- and o�-farm mitigation measures.

A better understanding of catchment nutrient loading to the lagoon is required to identify and fully evaluate di�erent management options. The assessment of the nutrient balance should take into consideration the spatial variability of individual nitrogen and phosphorus sources around the catchment, as well as seasonal variability in discharges to the lagoon.

In close collaboration with our client, DairyNZ, the dairy industry organisation representing all New Zealand dairy farmers, a framework for modelling water quality was developed to quantify total catchment nutrient loads discharging to the Waituna Lagoon. The framework integrates a distributed hydrological

Further reading:

www.krwverkenner.nl



model (WFLOW) with a seasonal loads model (OVERSEER) and the Water Framework Directive Explorer water quality model. Del�-FEWS acts as the WFLOW user-interface, together with a data management system for importing and retrieving model inputs and outputs. This battery of instruments constitutes a complete catchment management tool that can now be applied to explore possible management options for the reduction of nutrient loading on the catchment scale in consultation with landowners and water managers.

The application of hydrological and water quality modelling tools calibrated with monitoring data is an e�ective way of quantifying total catchment nutrient loads to the lagoon. Including individual farm nutrient-load information in the model framework greatly improves the spatial resolution of the load estimates and provides much greater flexibility for the investigation of di�erent management options. This approach reflects the substantial di�erences observed in nutrient loading between di�erent farms due to di�erences in intensity, wintering practice, development and location. The scenarios can target specific types of land-use, soil types, geographical locations or di�erent land-use activities on individual farms.

In 2015, a follow-up project was launched to apply and test the Water Quality Modelling Framework in a much larger catchment measuring 3500 km2. In this project, the framework will be coupled with a groundwater model (MODFLOW), as well as an interactive touch-table application that can be used in interactive stakeholder workshops.

Types of land use in the Waituna

catchment

46 47

Contact


Anaerobic degradation of

organic pollutants in soil

and groundwater

The contamination of soil and groundwater with organic pollutants is a serious problem worldwide. Biodegradation is the most important process involved in the removal and mineralisation of these contaminants. Oxygen (O2) is usually not available in groundwater in the Netherlands, and anaerobic microorganisms perform biodegradation. Deltares developed new microbiological, biochemical and molecular analyses to detect anaerobic biodegradation in soil and groundwater. These analyses are used in numerical models to predict the transport and degradation of organic pollutants in the subsurface. In addition, we are developing new concepts to enhance the anaerobic degradation of these compounds at polluted sites.

Groundwater contaminants o�en originate from crude oil: petroleum diesel, gasoline and tar, for example. These complex mixtures contain hundreds of types of organic molecules. Petroleum diesel mainly consists of alkane molecules with C8–C21 carbon chain length. Aromatic compounds such as benzene, toluene, ethylbenzene and xylenes (BTEX) are major components of gasoline. High concentrations of polycyclic aromatic hydrocarbons (PAH) are found in tar. Chlorinated solvents such as chloro-ethenes, -ethanes and -methanes form another category of groundwater pollution caused by the dry cleaning, metals and chemical industries. The transition to a bio-based economy may result in the introduction of new organic chemicals in our environment such as the gasoline additive ethyl tert-butylether (EtBE) and biodiesel.

In many cases it is not possible to determine the degradation of organic pollutants by simply measuring changes in concentrations in groundwater. We therefore use degradation intermediates and end products, and the enrichment of stable

carbon and hydrogen isotopes in organic pollutants, as additional biodegradation indicators. The conditions in soil and groundwater determine whether, how fast, and how the complete degradation of organic contaminants can occur. In the absence of O2, the availability of alternative electron acceptors such as nitrate, iron-oxides and sulphate is important for the biodegradation of alkanes, BTEX and PAH. The measurement of these electron acceptors in soil and groundwater allows us to assess whether conditions are favourable for the biodegradation of these organic contaminants. If not, we can inject electron acceptors such as nitrate and nutrients into groundwater to enhance the activity of anaerobic microorganisms that degrade alkanes, BTEX and PAH. By contrast, the anaerobic microorganisms that degrade chlorinated solvents are usually inhibited by electron acceptors. These microbes can be stimulated by introducing an electron donor substrate such as organic acids or molasses to the groundwater.

Deltares uses laboratory tests in microcosms, bioreactors and soil columns to determine the optimal conditions for the biodegradation of di�erent organic pollutants, and to identify the microorganisms involved. By designing specific DNA analyses, we can quantify these microorganisms and reveal degradation processes in the laboratory and in the field. Current research at Deltares focuses on the opportunities to augment contaminated groundwater with active laboratory cultures to enhance the anaerobic degradation of chlorinated solvents, benzene, PAH and biofuels.

With the development of these innovative monitoring and remediation methods, Deltares is helping public bodies and industry to significantly reduce remediation time and costs.

Further reading:

Van der Zaan et al. (2012)

Anaerobic benzene degradation

under denitrifying conditions:

Peptococcaceae as dominant

benzene degraders and evidence for

a syntrophic process. Environmental

Microbiology 14(5),1171-1181


Ecosystems and Environmental Quality48 49

Contact

Deltares | R&D Highlights 2015 Ecosystems and Environmental Quality

Citizen observations

of water quality

Photo M. Blaas

Further reading:

www.citclops.eu, www.eyeonwater.org



Observations made by the general public provide useful information about our environment. The resulting data are used, for example, in meteorology to learn more about spatial variations in a country. Estimates of bird populations and phenology also rely heavily on observations by volunteers. Since the introduction of smartphones, many citizens have a camera and an internet connection. This provides new opportunities for the easy collection of citizen data. The EU FP7 project CITCLOPS has led to the development of various smartphone-based citizen observation concepts for the determination of optical water quality.

Water colour is a useful source of information about water quality. The combined concentrations of phytoplankton, suspended matter and dissolved organic matter determine the water colour and transparency. The relation between water colour and coloured substances in water is commonly used in satellite remote sensing, which involves the use of sophisticated sensors. Alternatively, relatively simple smartphone cameras and even the naked eye can be used to retrieve quantitative information about water colour. At the turn of the nineteenth century, Forel and Ule developed a colour scale (the FU scale) to determine the colour of open water (from deep blue via green to brownish). Since then, a vast number of colour observations for lakes and oceans worldwide have been made using the FU scale, and they can be used to determine long-term trends and patterns.

The FU scale has been included in a smartphone app in the CITCLOPS project. This app - Eye-On-Water - allows observers to take a picture of the water and compare the colour with the FU colour scale on the screen. The app uploads the picture, the FU observation and additional information about weather and water transparency to a database. The app also contains image-processing algorithms to validate the FU values reported by the

user. The data in the database can be viewed and downloaded from the website www.eyeonwater.org. The Eye-On-Water app is available for both iPhone and Android smartphones.

The Deltares CITCLOPS team analysed how observations collected by the public with the Eye-On-Water app can be used to map variations in water quality and monitor long-term changes in the concentrations of phytoplankton, suspended matter and dissolved organic matter. One of the key questions for Deltares is how observations of this kind can contribute to monitoring and decision-making by water managers such as water authorities and Rijkswaterstaat. A typical benefit of citizen data about water colour is that they make it possible to remedy spatio-temporal gaps in standardised water-quality monitoring networks. Most traditional monitoring schemes focus on larger-scale characteristics and therefore tend to miss extreme events and local hot spots. Since the general public is usually inclined to report observations in areas where they are personally concerned about their environment, sharing their findings with local authorities in an app also provides an excellent means of communication and stakeholder involvement.

Further work in CITCLOPS has shown that the smartphone-based observations are valuable as a way of complementing ocean colour satellite imagery, in particular in nearshore and shallow waters, such as beaches and bays, fish farms and so on where satellite observations are less reliable. The CITCLOPS partners therefore developed an FU algorithm for multispectral satellite data that allows them to be compared with smartphone-based observations on the ground.

Screen view of the www.Eye-on-

Water.org data viewer

QR code for downloading the Eye-

on-Water app

Le�: The Eye-on-Water app combines both visual and camera observations

of Forel Ule colours. (Photo M. Wernand NIOZ). Right: Classical Forel-Ule

scale.(Photo NIOZ)

50 51

Contact


Chemical risks of

reshaping deep lakes

Deltares has played a crucial role in the development of a new risk assessment approach for the reshaping of deep lakes that includes the large-scale storage of soils and sediments under water. Risk assessment tools for nutrients and pollutants were developed to protect surface water and groundwater.

The management of rivers and lakes includes, by definition, restoration and redevelopment. One particular measure is the introduction of soils in water bodies such as deep lakes and ponds, o�en former sand pits. Making lakes shallower improves the ecological potential by encouraging aquatic plant growth and developing habitats for fish. In many cases, however, the soils or sediments used have elevated levels of nitrogen, phosphorus and heavy metals that may pose a risk to the environment.

The flaw in the law. To facilitate the large-scale application of soil and sediments in surface waters, a decree on soil quality (“Besluit Bodemkwaliteit”) issued in 2007 by the Dutch ministry provided generic quality standards. However, it was widely recognised that there are many gaps in our knowledge about the chemical behaviour of nutrients and pollutants. The protection of the aquatic environment, including groundwater, was therefore not guaranteed. Detailed guidance was still needed for a practical and robust risk assessment method.

Research programme. In a consortium with leading academic institutes, Deltares conducted a three-year research programme to study chemical processes during storage. This involved unique, long-term experimental simulations in realistic conditions in our test facilities. The release of compounds from soils and sediments was tested in various conditions, with the focus being on the relationship between the solid composition

and the actual chemical availability. The results were used to calibrate geochemical models and therefore to unravel the underlying chemical processes. Scientifically-based transfer functions were derived in this way, allowing the assessment of risks for soils and sediments in aerobic (surface water) and anaerobic (groundwater) conditions.

A new legal framework. A completely renewed framework was proposed in 2015 for chemical risk assessment in lakes (“Milieuhygienisch Toetsingskader Verondieping Plassen”). The method is based on the actual availability of nutrients and pollutants in the conditions in which soils and sediments are applied: in aerobic surface water, in the water-sediment transition zone and in the anaerobic groundwater compartment.

From science to policy. Scientific research has led to the development of a practical and user-friendly approach to testing soils and sediments prior to application in lakes. Actual implementation in a legal framework is scheduled for 2016.

Further reading:

Ministry of Infrastructure

and the Environment

(2015). Milieuhygienisch

Toetsingskader voor

grootschalige bodem-

toepassingen in diepe

plassen. Voorstel voor

beoordeling van partijen

grond en bagger


Pore water measurements during the

reduction of soils with state-of-the-

art techniques (www.sofie.nl)

Large-scale storage of soil in a former

gravel pit

The new risk assessment focuses on

processes in surface water (1), the

release of compounds across the

water-sediment interface (2) and

the anaerobic compartment (3)


Contact


Lessons from full scale

flow slides

A careful balance has to be maintained between flood risk management, navigation demands and ecological boundary conditions in the Western Scheldt estuary. This task has been delegated to the Flemish-Dutch Scheldt Commission (VNSC). Deltares has been responsible since 2008 for Dutch knowledge input in this commission.

Research in 2015 focused on how intertidal areas respond physically and ecologically, in the context of the long-term drivers, to sudden changes in morphology. The ultimate aim of this research is to optimise the current sediment dredging and disposal management strategy (‘Flexibel Storten’) in order to combine channel-depth maintenance and ecosystem protection on the tidal flats and shoals by means of sediment nourishment.

There was a large flow slide on the southern edge of the Walsoorden tidal flat on 22 July 2014. Flow slides are slope failures in channel or river banks, beaches or shoal margins that can have a major impact given the volumes of sediment involved.

They can damage dikes and foreshores and have been reported along the Eastern and Western Scheldt for centuries. Before the Delta Works were completed in 1987 and hard bank protection was introduced on many vulnerable foreshores, dike collapse due to flow slides represented a major flood risk.

The 2014 flow slide opened up a large gap and 850,000 m3 of sediment was deposited in the adjacent navigation channel in a short time. The navigational depth was reduced by over 7 m and additional dredging was needed. In the context of the ‘Flexibel

Storten’ strategy, monthly measurements were being performed at several disposal locations and these measurements were extended to the location of the slide. Meanwhile, the Walsoorden flat was also selected for a validation test in the IJkdijk / Flood Protection research programme. This programme included the initiation of several small flow slides by dredging, with morphological changes being continuously surveyed with three vessels. Vibrocore boreholes and bottom samples were analysed. Several steep, six-metre-high breaches developed and slowly retrogressed into the shoreline but eventually stopped. The volumes involved remained small by comparison with the flow slide on 22 July 2014.

The detailed and frequent bathymetric surveys in combination with the soil investigation have produced a unique database of the geomorphodynamic recovery of the system a�er a large sudden change in the channel-shoal interface. Measurements show that the deposited sand moves along the channel bed in the form of migrating dunes and that the original channel bed was restored a�er about one year. This unique dataset allowed us to develop and validate a Del�3D morphodynamic model that can subsequently be used to support sediment management. A detailed analysis of the sand transport patterns provided unexpected new insights. The sand transport patterns associated with migrating dunes in the channel and sand transport along the shoal margin are in opposite directions. Further analysis and modelling will help us to understand these patterns in particular and the Western Scheldt sediment dynamics in general.

Further reading:

Van Schaick (2015). Morphological

development a�er the July 2014

flow slide on the tidal flat of

Walsoorden, MSc thesis Del� UT

(via repository.tudel�.nl)



Bathymetry measurement Bocht van

Walsoorden, Westerschelde (21 August

2014), the 22 July 2014 flow slide

deposited 7 m of sand from the shoal

margin (red) into the channel (blue)

(Van Schaick, 2015)

< Tidal flat of Walsoorden, Wester-

schelde with gap of the 22 July 2014

flow slide (Photo E. Paree, aerial view

September 2014)

Walsoorden tidal flat view from the

gap made by the 22 July 2014 flow

slide to the south (Photo Deltares/

D. Mastbergen, October 2014)

54 55

Floating litter in Guanabara Bay

Forecasted floating litter distribution in

Guanabara Bay

Contact


Rio de Janeiro is hosting the 2016 Summer Olympics and Paralympics, with Guanabara Bay serving as the location for the sailing and windsurfing events. In the ‘Guanabara Limpa’ project, Deltares developed and implemented an operational system providing four-day forecasts of three-dimensional currents and concentrations of pollution in the bay (floating solid material) once a day to allow for more eªcient and cost-e§ective cleaning operations.

Rio de Janeiro is hosting the 2016 Summer Olympics and Paralympics, with Guanabara Bay serving as the location for the sailing and windsurfing events. In the ‘Guanabara Limpa’ project, Deltares developed and implemented an operational system providing four-day forecasts of three-dimensional currents and concentrations of pollution in the bay (floating solid material) once a day to allow for more e³cient and cost-e�ective cleaning operations.

Guanabara Bay is an ocean bay measuring about 380 km2 and surrounded by 15 municipalities, including the cities of Rio de Janeiro and Niterói, with a total population of 8.6 million. Located in southeast Brazil, it has become a major oil and gas hub in South America and one of the busiest bays on the continent.

Urban growth accelerated in recent decades, but solid waste handling capacity remained limited and litter is o�en dumped on the banks of some rivers around the bay. During periods of heavy rainfall, this litter is carried downriver to the bay, a�ecting water quality and navigation. This led to mitigation measures by state authorities such as the installation of eco-barriers in specific rivers and the collection of floating litter in the bay using “eco-boats”, barges equipped to scoop floating debris from the water and collect it for recycling. Given the size of the bay, the limited eco-boat speed and the limited docking options,

the e³cient and cost-e�ective removal of the litter depends on advance information about where litter accumulates in given hydrodynamic and wind conditions.

The operational system was developed in cooperation with state and local environmental authorities, and the federal meteorological centre. It was set up in the Deltares Del�-FEWS so�ware environment, a platform for collecting and processing input data and running computer simulations of water levels, currents and floating litter using the Del�3D-FLOW and PART numerical models. Meteorological data provided by the meteorological centre with a resolution of 1 km and ocean forecasts from the US Navy’s HYCOM model are processed in real-time and supplied to the local models for accurate predictions. Discharges from 18 rivers, surface heat exchange and evaporation play a role in the modelling. Amounts of litter entering the bay from the rivers were estimated on the basis of available data from the eco-barriers, literature and catchment populations.

The operational system was inaugurated on 10 March 2015 in the Guanabara Palace. Four-day forecasts displaying surface currents, winds, water levels and litter accumulations are all accessible in any standard web browser, making it easy for boat crews to plan their work and for the public to view local conditions.

Litter forecasting for

the Rio Olympics

Further reading:

http://guanabaralimpa.deltares.nl/



56 57

Contact


CleanSea

The main goal of the European FP7 CleanSea project was to produce guidelines for eliminating litter, and in particular plastics, from the seas. The technical issues included the quantification of plastic debris, determining how the debris migrates horizontally and vertically through the water column and an examination of the e§ects on marine organisms. Socio-economic aspects were also studied, including the willingness-to-pay of beach visitors for cleaning up the plastic litter, the role that voluntary schemes can play in reducing the amount of plastics in production processes and how policy and other regulatory bodies can provide support through legislation. One of the main achievements of CleanSea was to put the issue of plastics in the marine environment on the political agenda in Brussels. This was done by providing mitigation options for policy-makers in the European Commission in a road map that covered ecological, economical, sociological, and political factors.

The role of Deltares in the project was to obtain new knowledge about the transport of macro- and microplastics from estuaries to the sea, the degradation and fragmentation of plastic litter in laboratory conditions, the e�ects of plastic particles on microalgae and e�ects higher up the food chain. Deltares also contributed to the final product, the road map.

Model simulations for the North Sea showed that the lighter microplastic particles tend to stay on the surface and to follow the hydrodynamics towards the north-eastern part of the North Sea. The heavier microplastics tend to sink towards the sea floor and accumulate. The accumulation areas are mainly in the coastal zones and they vary depending on the size and type of plastic.

The breakdown of plastic items into smaller particles was quantified using a mesocosm experiment in which, for example, weight loss over time was quantified. Fragmentation rates proved to vary considerably depending on the type of plastic material.

Dynamic Energy Budget modelling was used to learn about the possible e�ects of plastics on the marine food chain. This technique is based on how an organism acquires and uses energy and how this is a�ected by environmental variables. Microalgal growth was negatively a�ected by microplastics, but only when concentrations of particles were high. The e�ects on primary production at the base of the food chain that were predicted using ecological models with high concentrations of microplastics were negligible. However, the predicted e�ects on secondary production were apparent since they were a combination of the loss of energy from algae and the direct e�ect of plastics on zooplankton.

CleanSea was the first interdisciplinary European project to look at marine litter in an integrated way. It involved seventeen partners in a consortium of universities, research institutes, SMEs, NGOs and a network of coastal municipalities. The project has greatly increased our understanding of plastic litter in Europe’s seas but, most importantly, it has resulted in new options for making and keeping our seas clean.



Relative impact of microplastics on

annual mean secondary productivity

Marine mesocosm containing an

artificial plastic soup where di¨erent

types of plastics were exposed to a

regime of UV light and mechanical

stress to simulate field conditions

Model simulation for plastic particles

showing that most of the plastic

particles travel to the north-east Further reading:

http://www.cleansea-project.eu


Contact


The link between river

hydraulics and vegetation

patchinessOverview of experimental setup at the

River Experiment Centre in Andong

(South Korea)

Vegetation plays a fundamental role in shaping streams and rivers due to its e§ects on morphodynamic processes, particularly in small streams, where vegetation can lead to significant changes in the bed morphology of the main stream by a§ecting erosion and deposition processes. Vegetation therefore acts as a system engineer: it adapts the environmental conditions by retaining and fixing the sediment, and by changing soil moisture characteristics, therefore altering hydro-morphodynamic processes. In turn, hydro-morphodynamic processes a§ect the development of floodplain vegetation.

Models are regularly used to predict the e�ect of floodplain vegetation roughness on water conveyance. The same models are also used to explore di�erent management options for floodplain vegetation. The assumptions on which they depend are, however, not always accurate. For instance, the roughness factor of vegetation is o�en considered to be constant in time and place but, in reality, vegetation roughness and therefore water conveyance are a�ected by variations over time in vegetation density and patchiness. Improving the accuracy of these models by collecting relevant data in the field or in experimental studies will therefore be tremendously valuable. In this project, Deltares and the Korean Institute of Civil Engineering and Building Technology (KICT) created a validation dataset for flows around and through patches of vegetation at the River Experiment Centre (REC) in Andong (South Korea). Two doctorate candidates from the RiverCare programme are also working on this project.

The KICT-REC facility is designed for full-scale tests with three prototype channels (600 m long and 11 m wide) and a large capacity pump facility (maximum flow rate of 10 m3/s). The natural bed allows for real vegetation to root and establish itself in a natural way, providing a unique setting for obtaining data about vegetated flows that are unscaled but completely controlled. Seven willow patches were planted in 2014 in

alternative strips 4 m long and 1.5 m wide. The density was 38 stems/m2 in four of those patches and 10 stems/m2 in three patches. Moreover, because the willows had already been planted in 2014, understory vegetation had time to develop in the patches, reproducing natural conditions more exactly than the sticks usually used in the laboratory.

Flow velocities in front, above, in and behind the patches were measured in 2015 with an Acoustic Doppler Velocity meter and an Acoustic Doppler Current Profiler. Measurements were performed in three distinct conditions: relatively low water tables (emerged vegetation), medium water tables (partially submerged vegetation) and high water tables (fully submerged vegetation). Results showed that the e�ect of vegetation on flow velocities depends on the flow velocities themselves but that the density of the vegetation patches and the level of submergence also had considerable e�ects on flow velocity. In the coming months and years, models will be calibrated and validated using the detailed dataset. Moreover, the e�ect of understory vegetation and the level of the drag force on roots (in other words, the critical flow velocity for uprooting) will be explored in more detail.


< Vertical flow profile near

a vegetation patch


The full team working on the

joint project

60 61

Contact


Vegetated foreshores

to protect dikes


Natural foreshores are increasingly seen as a valuable alternative or supplement to conventional dikes. Natural foreshores consist of shallow zones and beaches with a gradual slope and near-natural vegetation. Examples are freshwater reed beds and wetlands, willow forests, salt marshes and mangroves. They provide additional flood protection by reducing wave attack on dikes partially or even completely. In order to better understand the crucial aspects of designing, constructing and maintaining a natural, vegetated foreshore, a pilot study is being conducted on the “Houtribdijk”, the dike that separates two large Dutch freshwater bodies, the Markermeer and IJsselmeer lakes.

During the summer of 2014, a pilot section of a sandy foreshore (design slope 1:30 – 1:25) was constructed on the south-western shore halfway along the Houtribdijk. Vegetation was planted here in the spring of 2015 in several sections with di�erent soils (areas with only sand and areas with a mixture of clay and sand in the top layer). A mixture of several willow and elder species was planted on the higher and drier sections, and common reed was planted on the lower section closer to the water. Thick willow mats (16 x 100 m) were placed on the waterline to help reeds to get established. Meteorological conditions, incoming waves, changes in morphology and the soil, and the development of the vegetation (both planted vegetation and the vegetation that established itself naturally) are all being monitored.

The pilot section has undergone some striking changes during the first eighteen months, particularly near the waterline, where a rather steep 1:10 slope has formed. This could be related to the relatively coarse sand and the constant water levels. Under the water a flat plateau has formed at a depth of approximately

1 metre. The initial slope has completely disappeared and the large willow mat on the waterline has been eroded away by the incoming waves, which can be up to 1 m high during storm events. Severe wind erosion of the exposed soil has created dunes in the highest section of the pilot section, where a wind screen has captured a lot of this sand. The sand is being displaced during storms and the shoreline shi�s depending on the incoming winds. Overall, however, most sand has remained in the pilot section for now, with little being lost to the area outside the section.

The pilot section will be monitored until 2018 to establish a sound picture of the dynamics of this vegetated foreshore. The results will be used to produce guidelines for the better implementation and maintenance of these vegetated foreshores.

Bottom photo by Mennobart

van Eerden


A camera on a mast monitors the operation and development of the foreshore.

The sheet pile wall keeps the pilot section in place.

monitors the operation and development of the

A wave meter measures the impact of waves.

Vegetation enhances the stability of the foreshore and stimulates the development of nature.

No vegetation will be planted here. It will develop by itself here.

Contact


Nanoparticles –

a new concern for

the environment?


Nanotechnology brings us numerous benefits, but also a new type of contaminant to worry about: nanoparticles. Nanoparticles (particles < 100 nm) have special properties that di§er from those of larger particles of the same material. Silver nanoparticles are used in medical textile, for instance, because they kill bacteria. Titanium dioxide and zinc oxide nanoparticles are present as UV filters in sun screens. They can also play a role in water treatment because they can break down organic micropollutants under the influence of light. Unfortunately, the properties that make them useful in personal care products and water treatment may also make them harmful for organisms in the aquatic environment.

The problems we face with respect to nanoparticles are very diverse. In general, they are manufactured from ordinary substances – titanium and zinc are common elements in the

environment – and have been used for centuries. The issue is not the substance itself but the size of the particles. This also creates a legislative problem: the substances that are used have been approved for general use so regulation requires new ideas: other characteristics like the form or the surface area must be considered.

Routinely measuring the environ-mental presence of nanoparticles, as is possible for many other contaminating substances, is

Processes a¨ecting nanoparticles

cur rent ly a distant prospect. An additional approach to deter mining whether nanoparticles constitute a problem is to work with numerical models and to focus on the transport of nanoparticles as they enter a river or a lake as part of treated or untreated wastewater. This approach was followed to investigate the situation for the Rhine. Three steps were involved. First of all, information was collected about the use and subsequent emission of nanoparticles, especially the titanium dioxide, zinc oxide and silver variants, as these are among the most commonly used and most of the available information concerns these three types. The second step was to set up a mathematical model for the processes to which nanoparticles will be subjected in the aquatic environment. The model was calibrated using published laboratory experiments. The third step was to apply this knowledge to the Rhine using detailed information about the hydrology of the Rhine and possible emissions from sewage treatment plants.

Various scenarios were considered for the calculations in order to address significant uncertainties: a large fraction of the nanoparticles is retained in the sludge of wastewater treatment plants but they may enter the river system via surface run-o� if the sludge is applied as a fertiliser, for instance. The form in which the nanoparticles enter the system, as free particles or as aggregates, is also largely unknown. As zinc oxide is used in sun screens, one would expect seasonal e�ects. The calculations reveal that heteroaggregation is the most important process and that the concentrations of the three metals in nano form are still relatively low. However, as the use of nanomaterials is increasing, environmental concentrations may also rise.

Calculated average concentrations

in the Rhine


Contact


Flexible Mesh Morpho-

dynamic Modelling

Del¤3D Flexible Mesh (Del¤3D FM) was oªcially released with the framework of the Next Generation Hydro So¤ware (NGHS) project in November 2015. Deltares is continuing to integrate functionalities from the curvilinear Del¤3D 4 in Del¤3D FM. One functionality which has been adjusted to the flexible grids of Del¤3D FM is the morphology module containing a vast range of sediment transport formulations.

For optimal results, engineering applications require a grid that follows the river bank or coastline. In the previous version of the so�ware, this was not possible at, for instance, bifurcations or in sharply winding channels. This resulted in “staircase” lines along the banks or a concentration of the grid in the flood plain at inner bends. Flexible mesh modelling opens up new prospects for the engineering applications - such as more flexibility to follow the channel geometry and increased resolution in areas of interest - without impairing performance elsewhere.

The morphology module was connected to Del�3D FM and then validated. A set of 31 test cases, including validation documents, was added to the test bench which runs a�er every change to the so�ware to ensure that functionality is preserved. These benchmark cases cover di�erent sediment transport formulations, the roughness parameters for vegetation and dunes, discharge extraction and insertion, the gravitational pull due to slope e�ects, the e�ect of secondary flow on bed-load transport, sediment composition, graded sediment, fixed layers, dredging and dumping, spatially varying morphological input and output, and boundary conditions for suspended and bed-load sediment transport.


[email protected] +31(0) 88 335 8534

Further reading:

Nabi et al. (2016)

Computational modelling

of secondary flow on

unstructured grids.

International Symposium

of River Sedimentation

Stuttgart, Germany

A pilot test and the 31 test cases in the test bench showed that the morphology functions well. Simulating a flume experiment with a mobile bed showed the formation of the shallow point bar at the inner bend and the deep pool at the outer bend. The results are the same as for Del�3D 4, demonstrating that the functionality performs well. The simulation of a schematic tidal inlet model, with stationary wave forcing and the alongshore propagating tide that are typical for the Wadden Sea, clearly demonstrates the sandbar bypassing mechanism on ebb shoals. The morphology functionality will be further tested in 2016 before being released to clients by the autumn of 2016.

Point bar in Del�3D FM

Simulation of sandbar bypassing

mechanism for tidal inlet

Flexible grid on the River Waal


Social and economic impactDemand for natural resources will continue to increase as the world’s population grows to nine billion people in 2050, in the case of fresh water by 55%. Conflicts over water scarcity may increase as well.

That is why the water and subsoil resources theme aims to find solutions to reduce uncertainties in the estimates of natural resources such as water, energy and raw materials. It also wants to improve water and groundwater management to minimise risks and optimise economic returns and sustainability. The availability of data about the earth’s surface and subsurface is growing rapidly, as is the capacity of computers to process them. In addition, innovative solutions, such as the storage of fresh water in the substrate during periods of surplus water for use in dry periods, are being developed to tackle freshwater scarcity on the local and regional scales. This theme enhances our insight into relationships between water scarcity and risks of conflicts in combination with the increasing numbers of refugees.

National governments currently formulate national water and delta plans with support from Deltares. Businesses optimise their products and services using Deltares’ evaluations of new methods and techniques for data gathering, data handling and

scopeThe main aim of this theme is to understand and manage the availability of subsoil

and water resources for di§erent uses in order to solve shortages, now and in the

future. To fulfil that aim, we develop knowledge about subsoil resources and water

availability in river basins and deltas.

visualisations. Governments worldwide learn more about water risks such as scarcity or lack of quality using analyses conducted by Deltares.

R&D HighlightsSurface waters were mapped using satellite imagery in the Where are the rivers? project. The new method was tested successfully in the Murray & Darling River Basin, Australia. Another international project was the assessment of the subsurface and the potential for groundwater storage on a man-made island o� the coast of Singapore.

The relevance of subsurface composition was demonstrated for the seismic hazard and risk analysis performed by NAM for the induced earthquakes in the Groningen gas field. The geological model contributed to the reduction of uncertainties in the hazard and risk assessment. Another example of useful information about the subsurface was seen in the project for the deepening of the waterway leading to the Port of Rotterdam. Erodible layers in the subsurface were mapped and used as boundary conditions in the Del�3D hydraulic model to assess the morphodynamic e�ects of the deepening.

So�ware development supports studies in the Water and Subsoil resources theme. An example is the incorporation of the hydrological modelling platform WFlow in the free integrated modelling environment of Delta Shell.

Other highlights include a doctorate study of the e�ect of groundwater measures on vegetation patterns, a study of participatory and collaborative modelling approaches in Integrated Water Resources Management and a tool for collaborative planning (Adaptation Support Tool).

68 69

Water and Subsoil Resources

Contact

Deltares | R&D Highlights 2015 Water and Subsoil Resources

The WFlow so¤ware, which is part of the Deltares OpenStreams project, is a distributed hydrological modelling platform (or simply: model). It consists of a set of Python programs originally used from the command line and built on the PCRaster Python framework. WFlow uses the PCRaster tools to visualise the input and output data. The WFlow code is open source. In the Spatial Catchment Modelling project, WFlow has been applied to a showcase model for the Hauraki area in New Zealand.

In this project, the WFlow model was added as a plugin to the Delta Shell framework. The Delta Shell framework is a free integrated modelling environment. Its plugin architecture can be used to add models that are used to simulate water, soil and subsurface processes. This allows these models to be set up, inspected and run from the graphical user interface (GUI) of the framework. The framework also provides the building blocks for adding useful functionality to a model. The Delta Shell framework is scheduled to be released as open source soon.

By combining WFlow and the Delta Shell framework, it was possible to run the model from a GUI for the first time. This was also the first time that a model written in Python had been added as a Delta Shell plugin. The work in the project establishes the foundations for the subsequent use of Python-based so�ware in the Delta Shell framework.

The focus of the project was to allow a showcase model (for the Hauraki area in New Zealand) to be imported, investigated and run from within the Delta Shell GUI. The model computes surface runo� and evaporation on a grid consisting of 135,000 grid cells

for a period of four years using time-dependent input data like precipitation, evapotranspiration and inflow. The outcome of the project is a fully self-contained product for the client that shows the strength of the model in a graphical environment. It is the first step towards a full catchment-to-coast modelling system.

Future developments will entail coupling to other existing plugins in the framework to make it possible to integrate ecology and a more elaborate modelling of groundwater. Other ways to interact with the model, like editing the input data, or setting up a model using a ‘3 clicks to a model’ tool, are now within reach.

Spatial Catchment

Modelling: from

Catchment to Coast

Further reading:

https://github.com/openstreams/


Screenshot of the WFlow plugin in Delta Shell


70 71

Contact

Deltares | R&D Highlights 2015 Water and Subsoil Resources Theme

Detailed maps of surface water are essential for many environmental applications. Maps of surface water can be generated by combining data from LANDSAT satellite imagery, digital elevation models from the Shuttle Radar Topography Mission (SRTM) and OpenStreetMap (OSM). Accurate identification of surface water using satellite imagery remains a challenging task for remote sensing due to sensor limitations, complex land cover, topography and atmospheric conditions. An alternative in hilly landscapes is to extract drainage networks from high-resolution digital elevation models in SRTM. A third approach is to use OpenStreetMap, which provides data that are regularly digitised and validated manually using the most widely-available data sources. In this study, Deltares developed a high-resolution water mask using OSM, LANDSAT 8 imagery and SRTM.

The approach to developing a surface-water mask using Landsat 8 imagery includes drawing on methods from remote sensing, machine learning, and geospatial processing. The algorithms are applied to process petabytes of geospatial data in the Cloud using the Google Earth Engine parallel processing platform. A new method has been developed based on image-processing algorithms such as Canny edge filtering and Otsu thresholding for the accurate detection of water in flat areas. Additional steps are performed on the basis of supervised classification and Height Above the Nearest Drainage (HAND) derived from SRTM to detect surface water accurately in hilly areas.

The new method was tested successfully in the Murray & Darling River Basin, Australia. It was found that the best surface-water mask is generated by combining all three datasets. Only 32% of the total OpenStreetMap and Landsat 8 water mask match. When the drainage network derived from SRTM was used, it

was possible to confirm about 50% of the OpenStreetMap linear water features. The data are clearly complementary. As far as positional accuracy is concerned, the observed di�erences between river features derived from OSM and Landsat 8 are mostly less than 60 m, which can be considered an excellent match. The di�erences between the OSM water features and the SRTM analysis are slightly larger (110 m) for the drainage network.

The research demonstrates that using the new satellite imagery acquired by Landsat 8 mission to detect water bodies, in combination with water masks derived from other sources, has clear benefits. We have also found the SRTM to be an excellent complementary dataset that can be used to improve the water-mask detection method for hilly areas a�er its transformation into HAND. The new Landsat 8 water mask reveals many new water bodies that were previously not present in OSM or any other vector dataset we have explored. A large proportion is made up of small but plentiful agricultural reservoirs located in the northern and southern parts of the catchment.

Where are the rivers?

Further reading:

http://osm water.appspot.com/




72 73

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River bed erodibility in

the Port of Rotterdam

The Port of Rotterdam is making preparations to deepen one of the waterways leading to the port, the ‘Nieuwe Waterweg’. The plans involve lowering the Guaranteed Nautical Depth from 15 m below Dutch Ordinance Datum (NAP) to 16.3 m below NAP. One of the risks of the planned deepening is that easily erodible soil layers in the subsurface may be exposed and cause undesirable e§ects such as the formation of ever-larger scour holes. It is therefore essential to establish a picture of the subsurface below the Nieuwe Waterweg before the deepening work on the channel begins. Deltares constructed a 3D model of the subsurface below the Nieuwe Waterweg for the Port of Rotterdam.

The 3D subsurface model was built on the basis of information from boreholes and cone penetration tests (CPTs) in combination with newly acquired information from additional boreholes and CPTs by Gemeentewerken Rotterdam and a seismic geophysical survey carried out by Deltares. The advantage of a seismic survey is that, by contrast with point sampling in a drilling campaign, continuous information is acquired in a line. Boreholes at key locations in the seismic profiles allow the profile to be interpreted and for a picture to be built up of the lateral relationships between the soil layers. This is crucial information for the mapping of the subsurface.

The data assimilation revealed that there are three units that are relevant for the risk assessment prior to the deepening of the waterway. From bottom to top, these units are: coarse sand deposited by Pleistocene

rivers, followed by a sequence of sti� clay, basal peat and clayey freshwater tidal deposits, and finally estuarine deposits of layers of clay with fine sand op top.

For the purposes of the 3D subsurface model, the second unit, which is resistant to erosion, is the most important. The seismic profiles show that this unit is cut through locally by estuarine channel deposits belonging to the third, most recent, unit. The depth, extent and thickness of the erosion-resistant unit were mapped using a combination of the boreholes, CPTs and seismic profiles. Locally, this unit is exposed on the bed of the Nieuwe Waterweg but the top of the unit is always deeper than 16.3 m below NAP. This indicates that the e�ects of the deepening of the Nieuwe Waterweg will probably be limited since dredging will be limited to the sediments in third, most recent, unit.

The 3D subsurface model of the Nieuwe Waterweg is being used as the boundary condition for the subsurface in the Del�3D hydraulic model to assess the morphodynamic e�ects of the deepening operation. In addition, the model is being used for a study of the e�ects on groundwater of the deepening, and to estimate the amount and composition of the dredged material.

Example of a seismic

profile (upper panel) and its

interpretation (lower panel)

Further reading:

Wiersma & Hijma (2015).

Ondergrondopbouw van de

Nieuwe Waterweg. Deltares

report 1210219-001-BGS-0001



Example of output from the 3D subsurface model. The colours indicate the

thickness of Unit 3 on top of Unit 2

Water and Subsoil Resources Theme

East

Unit III: Clay and fine sand, layered

Unit II: Sti� clay and peat

Unit I: Coarse sand

0 km

0 km

1 km

1 km

2 km

2 km

West

74 75

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Geological model for

earthquake studies in

Groningen

The province of Groningen in the Netherlands is experiencing earthquakes induced by the exploitation of a large gas field. The largest induced earthquake to date had a magnitude of 3.6. It led to an extensive study programme to determine the seismic hazard and the risk associated with the exploitation of the gas field. Deltares collaborated with international experts, KNMI, TNO, NAM and Shell in a study programme for NAM. Deltares created the geological subsurface model, conducted field measurements at KNMI earthquake recording stations, calculated site amplification and determined the liquefaction potential.

All these items will be used for the seismic hazard and risk analysis that is being carried out by NAM and Shell for the next exploitation permit. The analysis has to be specific for the Groningen situation, and so one cannot rely on global databases of tectonic earthquakes. The analysis is therefore tailored to the specific so�-soil conditions in Groningen, the measured and expected magnitudes, and the characteristics of induced earthquakes for the Groningen reservoir.

When an earthquake occurs, the seismic waves travel through the earth. When the waves encounter so� soil such as peat or so� clay in the shallow subsurface, the ground motion can be amplified. This results in turn in the amplified shaking of buildings on the surface. In seismic hazard and risk analyses in the past, the so�ness of the soil and the amplification have been characterised by VS30, the average shear wave velocity in the top 30 m. The analysis assumed a single constant value of VS30 = 200 m/s for the entire Groningen field. However, the formation history of Groningen, which includes loading by ice sheets in recent ice ages and infill with deltaic deposits, means that the subsurface is notably heterogeneous.

Deltares and TNO Geological Survey of the Netherlands constructed a geological model of the subsurface to a depth of 350 m that reflects this heterogeneity. Several sources of subsurface information were used, one of these being the TNO state-of-the-art high-resolution geological model GeoTOP. The Groningen field was divided into zones with similar geological structures. The characteristic site amplification for each zone was calculated on the basis of the geological model. These calculations form one of the inputs for the Groningen seismic hazard and risk analysis conducted by NAM.

In addition, the new geological zones and the GeoTOP model facilitated the calculation of a new VS30 map. A database of seismic cone penetration tests provided information about representative shear-wave velocities in the geological units. The new map shows that the average VS30 is around 200 m/s indeed. However, there are large regional di�erences that can be linked to the geology. For example, channel structures with low VS30 and the Hondsrug, where the VS30 is high, can be seen in the map. In addition, lower VS30 values show that there is also a Holocene layer of so� sediments to the north that is much thicker than in the south. The new, site-specific information about VS30 and site amplification helps to reduce the uncertainties in the seismic hazard analysis for the region.



mandy.kor�@deltares.nl T +31(0)6 5136 9569

Geological zonation

VS30 ranging from 150 m/s (dark

green) to 275 m/s (red)

Further reading:

Kruiver et al (2015), Geological

schematisation of the shallow

subsurface of Groningen (http://

kennisonline.deltares.nl)

Water and Subsoil Resources Theme76 77

Contact


Impacts of groundwater

conservation on

vegetation patterns

It therefore led to an improvement in model performance. The model demonstrated that di�erent climate-change scenarios a�ect groundwater flow patterns in di�erent ways, reducing the regional flow in one location and increasing it elsewhere.

An evaluation was made of the e�ects of climate and socio-economic change, climate adaptation measures and policy legislation on changes in the use of agricultural land and the subsequent e�ects on hydrology, vegetation distribution and communities. Changes in land use triggered the largest e�ects, followed by the climate adaptation measures and climate change. The results stress the importance of an interdisciplinary model approach if vegetation responses are to be evaluated successfully.

Further reading:

Van der Knaap (2016). Stream valley

catchments in times of climate

change: an ecohydrological approach,

PhD thesis, VU-University Amsterdam

Example of model results

One of the tasks of regional water managers is to configure the spatial arrangement of landscape elements in stream valley catchments while optimising biodiversity in the context of a range of scenarios involving climate change and climate adaptation measures. To help them perform this task, a range of e§ects of groundwater conservation measures were determined by combining greenhouse experiments, database analyses, field work and a new hydrology-vegetation model-ling approach. The doctorate research was part of Climate Adaptation for Rural Areas (CARE), a part of the Knowledge for Climate research programme. The project focused on a stream valley catchment in the south-east of the Netherlands, the Tungelroyse Beek.

The responses of plant species to extreme drought and inundation events were recorded in the greenhouse experiments by observing plant performance and plant trait plasticity, in other words the ability of plants to adjust their characteristics. The results showed that the sequence of extreme hydrological events of droughts and floods determines plant response. Three plant traits (root porosity, specific leaf area and leaf phosphorus content) were identified as potential predictors of how plant species respond to these events.

The database analysis looked at di�erences in the traits of species at recharge or discharge sites. Di�erences were found in five traits, although the explained variance was low.

A new model tool was used to di�erentiate between local and regional groundwater discharge sites. The model results were compared with field data and the new model tool was found to provide a better match with the data collected in the field than the model output based on modelled head di�erences alone.



Water and Subsoil Resources Theme

<

<

Reference

Climate change + measures

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Collaborative modelling

of complex social and

environmental issues

Population growth and socio-economic developments are the main causes of the growing pressure on water systems. However, the allocation of water resources to competing organisations and flood risk management make planning for water resources complex. Informed decision-making and participatory planning have therefore become widely recognised as a pre-requisite for sustainability in Integrated Water Resources Management (IWRM).

Against this background, much research has focused on engaging stakeholders in planning and decision-making. There has been much less scientific research exploring the use of conventional computer-based models in these participatory planning and decision-making processes. The development of Decision Support Systems (DSSs) emerged to address this gap. However, in many cases, DSSs were not used by stakeholders and decision-makers for a variety of reasons, most of which were associated with the di�erent knowledge and expertises of the developers of such systems and the diversity of the stakeholders who were the intended users.

“Participatory modelling” and later on “collaborative modelling” emerged as possible solutions to address the challenges encountered with DSSs. At the core level, both generic approaches emphasise the importance of involving stakeholders in a modelling process. Specific types of participatory and collaborative modelling have emerged in the last few decades: some are used extensively for Water Resources Management while others are emerging approaches. Participatory modelling for IWRM integrates four key components to support decision-making: water-resource planning, informed decision-making using computer-based models, stakeholder participation and, finally, negotiation. Stakeholder involvement in collaborative modelling will generally be more intensive than in participatory modelling, resulting in an increase in the importance of negotiation during the process. These interlinked aspects are considered to be the basis for e�ective and sustainable IWRM.

Deltares has been working since 2013 on an extensive study of the existing participatory and collaborative modelling approaches that are used worldwide for IWRM and that can be applied to the collaborative or participatory use of our computer-based models. The collaborative modelling approach - Group Model Building - has been used in several innovation projects in the Netherlands (STORM, for example). This approach has also been followed in several IWRM projects such as the WISMP2-BWRMP World Bank project in Indonesia where the Group Model Building approach was used to construct the water balance model RIBASIM, as well as to formulate measures. In another World Bank project in the Philippines, the Group Model Building approach was deployed to identify problems based on the water security framework. A participatory modelling approach based on the Companion Modelling approach was applied to water quality and ecology using the Water Framework Basin Explorer (also called River Basin Explorer) in Turkey for river-basin planning. A similar approach is being followed in the ongoing World Bank project in the Ganga basin. Collaborative or participatory modelling are also suitable for groundwater management such as the MIPWA or AZURE projects in the Netherlands, where an approach of this kind was applied to improve and unify all the regional groundwater models in a unique iMOD model. Finally, a web-based participatory modelling approach involving a set of building blocks (a “Blokkendoos”) was included in the Rivers Delta Programme for strategy design in collaboration with key stakeholder groups.



Ranked list of measures

Map window Total score of measures

Legend of implementedmeasures

Adaptation Support Tool

Contact


Adaptation Support Tool

for a climate-resilient

urban environmentClimate change and socio-economic developments make urban areas vulnerable to flooding, drought and heat stress. Adaptation measures have to be retrofitted to make our environment more resilient to the hazards of extreme weather. An Adaptation Support Tool (AST) has been developed to support collaborative planning for adaptation measures of this kind.

Urban planners, landscape architects, water managers, civil engineers, local stakeholders and other experts can use the AST in their design workshops to create conceptual designs for a more resilient and attractive environment. Participants can use the AST, which is a touch-table-based system for planning support, to select adaptation interventions, situate them in their project area and immediately assess e�ectiveness and cost. The AST consists of a panel on the le� for input, a centre panel for design - a map of the project area - and a panel on the right for AST dashboard output.

The AST includes 62 blue, green and grey measures for ecosystem-based adaptation. Examples of “blue-green” solutions are green roofs, bioswales, porous pavements and water squares. The AST also contains a selection assistant for ranking applicability and an assessment tool to estimate the e�ectiveness of adaptation measures. Ranking is determined on the basis of the characteristics of the area, such as adaptation targets, existing type of land use, surface characteristics and availability of subsurface space. The le�-hand panel shows a ranked list of potential adaptation measures.

Di�erent map layers can be shown in the central panel. The default layers use Google Earth or OpenStreetMap. Layers such as surface elevation, land ownership, flood-risk maps or heat-stress maps can be added. Participants at design workshops can select a measure from the le�-hand panel and drag it to the map in the project area. For example, the user can move an extensive or

AST session in Beira, Mozambique

AST application for

Utrecht Centre-West

area, the Netherlands

Detail of AST application for

Decoy Brook, London


Further reading:

Voskamp & Van de Ven,

(2015) Planning support

system for climate

adaptation: Composing

e�ective sets of blue-green

measures to reduce urban

vulnerability to extreme

weather events. Building and

Environment 83, p 159-167.

http://dx.doi.org/10.1016/j.

buildenv.2014.07.018

intensive green roof to a large flat roof, install permeable pavements at street level, or locate an artificial wetland near the outlet of a tributary drain.

The AST then provides an assessment of the e�ects of the measures using a number of key metrics such as additional storage capacity, the reduction in the frequency of the normative runo�, the reduction of heat stress, extra groundwater recharge, the e�ects on water quality, the cost and additional benefits. These results are shown on the AST dashboard in the right-hand panel. The e�ects are determined not only for each adaptation measure separately but also for the total package of measures.

The Adaptation Support Tool was developed in close cooperation with Alterra Wageningen UR and Bosch Slabbers Landscape Architects as part of the Climate KIC project Blue Green Dream. The AST was applied in Beira, Mozambique, to facilitate collaborative planning of solutions for flooding and heat stress in the Chota district of Beira. This led to the spatial reservation of water-retention areas in the Chota district and a plan to provide the area with a second drainage outlet. Other examples are the co-creation of attractive, climate-resilient alternatives for the reconstruction of part of the city centre of Utrecht in the Netherlands and the application of AST to Decoy Brook, London, U.K.


Social and economic impactDelta areas are becoming increasingly urbanised, leading to challenges in the areas of sustainable planning and pressures on natural resources. Climate change is a�ecting flood risks and the distribution of water, and therefore land use and spatial planning. Demand for integrated solutions is constantly increasing.

That is why the adaptive delta planning theme develops integrated methods and instruments to accelerate design, improve quality and reduce the costs of spatial planning. The costs and benefits of climate adaptation strategies need to be assessed over time and for di�erent possible pathways. Integrated instruments will help to develop integrated solutions and apply them to urbanisation issues in deltas.

Government organisations involved in water management, subsurface and spatial planning are already integrating and applying Deltares knowledge to address adaptive planning issues. Businesses also advise governments by using Deltares tools for consulting services. Doctorate and master students from universities worldwide are developing their talents through direct access to Deltares knowledge.

R&D HighlightsOne of the tools being developed for Adaptive Delta Planning is the action framework for land subsidence. This framework helps local and regional governments to better understand how they currently address land subsidence and how they can shi� towards other strategies that may reduce the level of land subsidence in the future.

Another field where cooperation between parties is required is water management. The smart water management table is a simulation tool (or serious game) that was used to give sixty water managers a hands-on introduction to the smart water concept by asking them to manage the combination of a heavy rainfall event, the failure of a pumping station and a change in wind direction.

The Adaptation Support Tool is a planning support system that is developed and used in various projects. The City of Utrecht and the local Fair and Exhibition centre used the tool to develop plans for a greener, more comfortable, attractive and climate-resilient neighbourhood in the centre of the city.

Other highlights include projects looking at so�ware, living with peat and the greening of flood protection.

scopeThe main aim of the Adaptive Delta Planning theme is to integrate our technical

knowledge about water, subsurface and infrastructure with governance and policy-

making to solve problems in highly complex systems in dynamic deltas. The primary

focus is therefore on developing and testing concepts, methods and instruments to

achieve this goal. The theme naturally requires strong ties with all the other Deltares

themes.

84 85

Adaptive Delta Planning

Contact

Deltares | R&D Highlights 2015 Adaptive Delta Planning

Smart water management is an operational concept for water management that focuses on the early anticipation of weather events to prevent flooding, and water shortages during drought spells. Smart water management is becoming an increasingly important issue for the Dutch national and regional water authorities. Smart water management depends crucially on cooperation between the regional and national water authorities, who need to share real-time data, link hydrological decision support models and establish formal agreements. Against the background of advances in ICT (processor speed, so¤ware, interconnectedness), smart water management is about employing these advantages to optimise operational water management and to limit water-related damage.

The concept of smart water management is alluring but implementation is challenging. To further implementation, Deltares developed a serious game, the smart water management table, that provides a picture of what smart water management means in practice. The smart water management table was tested with approximately 60 water managers at a regional conference in the north of the Netherlands looking at the implementation of smart water management. The conference was attended by four regional water authorities and Rijkswaterstaat, the national water authority.

The participants were divided into five groups. Each group was asked to manage increasing water levels in some parts of the system due to a sequence of a heavy rainfall event, the failure of an important pumping station and a change in wind direction. The discussion at the tables resembled the discussions that would take place in reality: discussions about the problems, the measures to be taken and negotiations between the water

authorities about helping each other. The selected measures were implemented in a rapid assessment model that showed the e�ects of the measures immediately. In addition to the real-life experience, the simulation proved useful as an analytical tool to identify what is needed to implement smart water management in terms of critical scenarios, open data, system knowledge, model requirements and political agreement.

The smart water management table is now serving as a pilot project for the actual implementation of smart water management at the water authorities. Users are experimenting with new elements in the game and then implementing those elements that work.

We will be continuing to develop the table in 2016 by adding new scenarios. A drought scenario will be developed, the underlying rapid assessment model will be further refined and a cost-damage module will be added to the simulation. The smart water management table can be used for other regions, both in the Netherlands and abroad.

The smart water

management table: a

successful serious game


86 87

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The City of Utrecht and the Jaarbeurs Fair & Exhibition Centre are developing plans for a greener, and more comfortable, attractive and climate-resilient Centre-West area in the city. A Climate-KIC project team - with experts from Deltares, TNO and the Utrecht Sustainability Institute - provided assistance by quantifying climate vulnerability in the area, and by formulating the adaptation requirements for flooding due to extreme rainfall, for drought and for heat stress reduction. Furthermore, Deltares has helped the local stakeholders to create three e§ective and attractive alternative packages of blue-green adaptation measures. On the basis of the available data for the project area, best practices were identified to reduce the vulnerability of the area and inspire potential developers.

Blue-green adaptation measures such as green roofs, bioswales, porous pavements and water squares can enhance the climate resilience of an area and also make the area more comfortable and attractive. Services, benefits and opportunities for a number of blue-green measures were therefore identified, as were the water quantity and water quality required to harvest those benefits. Particular attention was paid to the opportunities a�orded by a roo�op greenhouse since the active use of the large roo�op area of the Jaarbeurs for food production and accommodation would be a welcome development.

Working with the local stakeholders and the Adaptation Support Tool (page 82) as a planning support system, we investigated to what extent the adaptation assignments can be met by

implementing blue-green adaptation measures in the project area. Representatives of the city, the Jaarbeurs and the project team co-created three alternatives that not only meet the adaptation objectives but also produce interesting services and benefits: a Green Development alternative with a focus on green solutions, a High Urban Density alternative that emphasises the large numbers of residents and visitors, and a Maximising Benefits alternative combining the best of both worlds.

Results show that the water storage, the water retention and the peak flow reduction requirements can be met, albeit only a�er substantial investments. Reduction objectives for heat stress will be achieved at the most vulnerable sites if extra water is supplied to the adaptation features during hot dry spells. Other benefits of the proposed adaptation measures were assessed in a qualitative way because the uncertainties about preferences, size and construction do not allow for a quantification of the benefits at this early stage in the planning process. Most of the proposed adaptation solutions can be combined with adaptation measures that were brought forward in the field of tra³c management and measures for closing energy cycles and electric power generation. The City of Utrecht and Jaarbeurs have started on the further elaboration of these initial conceptual plans to see how they can best harvest the economic, social, environmental and health benefits of the projected adaptation measures.

Sustainable and green

urban development in

Utrecht

Further reading:

Van de Ven et al. (2016) Green,

comfortable, attractive and climate

resilient Utrecht Centre-West area.

Deltares report 1220357-001


88 89

Contact


Careful water management enables the Dutch to live in a coastal plain, large parts of which are below sea level. The engineering of the Dutch water management system has o¤en been rightfully praised but much less attention is paid to why the Dutch coastal plain is so low-lying. Healthy natural deltas and coastal plains are formed at or above sea level, and it is the human cultivation of these areas that causes them to subside. Indeed, the Dutch have a long record of draining coastal peatlands to create arable land. This has not been without consequences: the physical compaction of peat and its degradation by oxidation lead to subsidence, and oxidation also leads to emissions of carbon dioxide (CO2). In addition, the Dutch started to mine the highly calorific peat in mediaeval times, becoming one of the first fossil-fuel-based economies.

A joint study conducted by Deltares, TNO and Utrecht University quantified total land subsidence and associated CO2 respiration over the past millennium in the Dutch coastal peatlands. The aim was to show the consequences of cultivation over longer periods of time. The results show that the peat volume loss was 19.8 km3, lowering the Dutch coastal plain by 1.9 metres on average and taking most of it below sea level. At least 66% of the volume reduction is the result of drainage, and 34% was caused by the excavation and subsequent combustion of peat. Since mediaeval times, an estimated 3.07 Gton of CO2 was released as a result of the oxidation and combustion of peat in the Netherlands, the equivalent of an atmospheric concentration of about 0.39 ppmv. Interestingly, the estimated emission peak of 3 Mton a year in the seventeenth century caused by large-scale peat combustion is considerably lower than the current annual drainage-related release of 4.0 to 8.0 Mton CO2 in the Netherlands. This shows that drained

peatlands have now become a larger source of CO2 than peat mining ever was.

The cultivation of coastal peatlands can turn a carbon sink into a carbon source. The Dutch situation is not unique: coastal plains are increasingly drained to create arable land in other deltas around the world. This implies double trouble: globally significant carbon emissions and increased flood risks in a globally important human habitat. The e�ects could be more far-reaching than the historical impact reconstructed in this study: most of the cumulative Dutch subsidence and peat loss was accomplished with much less e³cient techniques than those available now.

Even today, living on peat in the Netherlands poses challenges. Subsidence in the peatlands is still one of the most significant subsidence components. Many urban areas are increasingly a�ected by damage to the public space, infrastructure and even buildings. The estimated damage and extra maintenance involves a cost of hundreds of millions of euros a year. There are no easy solutions, but increased awareness of both the historical and current processes causing the subsidence will support more carefully considered policies for subsidence.

Living with Dutch peat

Further reading:

Erkens et al (2016). Double trouble:

subsidence and CO2 respiration

due to 1000 years of Dutch coastal

peatlands cultivation. Hydrogeology

Journal, DOI 10.1007/s10040-016-

1380-4


Subsidence of a street in Kanis.

Photo © Sam Rentmeester

A former peat bog to the

south of Amsterdam.

Background image created

with ArcGIS® so�ware

Subsidence of the peat landscape

since 1000 AD

Legend

Subsidence (m)

1

4

8

90 91

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Action framework for land

subsidence


More and more politicians and civil servants realise that subsidence in the Netherlands is increasingly a§ecting the quality of life in urban and rural areas. The damage caused by subsidence is increasing every year: flood damage, damage to railways and roads, dikes, pipelines and buildings. Although it is clear that measures need to be taken, it is o¤en less clear who should intervene, and when. Deltares has developed an action framework that helps local and regional governments to reflect on their current attitude to land subsidence. The framework helps them to obtain a better understanding of strategies and governance changes that are needed to address land subsidence di§erently in the future.

The action framework method for subsidence based on governance goes beyond an exploration of the technical measures. It makes governance concrete by discussing various options with stakeholders: who will do what, and when. The method helps governments to explore measures and action styles for land subsidence. At present, a sense of responsibility for land subsidence is lacking. Organisations try to pass the buck because they expect the intervention costs to be high. The frameworks can guide discussions about what to do and help government authorities to change their management approaches to subsidence, identifying promising measures as a result.

The method was primarily developed in Gouda, the Netherlands, which is an exemplary case of a sinking delta city. The old city centre was built in the middle of a swampy peat area. Since the 11th century, the peatland has been reclaimed for agriculture. Over time, a city rose out of the first settlements. Nowadays, the picturesque old city centre is at particular risk because it is on a peat layer 9 metres thick. No accurate information is available about local subsidence rates but the Dutch land subsidence map shows that Gouda may drop another 50 cm between 2002 and 2050. Given the huge costs and impact of subsidence on quality

of life, the municipality is trying – in collaboration with other parties – to address land subsidence so that Gouda is preserved as a beautiful city in the western Netherlands.

Civil servants and various experts in the fields of water, subsurface and foundations discussed di�erent future perspectives for addressing land subsidence between now and 2060. The action framework showed whether measures were pro-active (in other words, whether they tackled the causes of land subsidence) or reactive (addressing the impact of subsidence) and whether responsibility resides with public or private bodies. This resulted in a list of measures that fit in di�erent action frameworks. All the participants then selected three measures and assessed them on the basis of criteria that included administrative support, technical and financial feasibility, the level of adaptation and the timing of implementation (2016-2050).

By using the action framework, participants obtained a better understanding of how they currently address land subsidence (mostly in reactive ways), and what kind of measures are needed to maintain the current management style or shi� to other strategies that may reduce the level of land subsidence in the future. The action framework has been applied to the city of Almere as well as Gouda. The framework can be used by regional and national authorities who are looking for ways of addressing the causes and consequences of land subsidence.

Two strategies, two types of organi-

sations give four perspectives to

overcome water problems

92 93

Contact


Deltares research on user-centred design in 2014 showed that the way users interact with so¤ware is more important than is currently acknowledged. To enhance and improve user interaction, it is crucial to develop this field.

Eye movements enable us to see and interpret our world. The eye movements of so�ware users show how they scan the interface and therefore how they work with the so�ware. Innovative eye-tracking techniques can be used to show what attracts users’ interest and whether users can e³ciently find what they seek in the user interface.

In a unique collaboration between Deltares and the Erasmus MC Rotterdam, Department of Neurosciences, eye-tracking techniques and usability testing were combined to evaluate the Deltares so�ware applications Del�-FEWS, SOBEK and Levee Patroller. Del�-FEWS is an open data handling platform initially developed as a flood forecasting and warning system, SOBEK is a modelling suite for surface water quantity and quality studies, and Levee Patroller is a serious game for training dike inspectors.

Users were asked to perform a given task in each of the so�ware packages. The eye movements made while performing these tasks, as well as the frequency of mouse clicks, were analysed, allowing for an evaluation of whether the expected sequences of actions in the user interface were actually executed. This helps us to understand whether user interfaces are designed optimally to accommodate user actions. The SOBEK interface, for example, was designed on the assumption that the default setting is optimal for most applications. It was now possible to test this assumption.

The eye-tracking equipment consists of infrared LEDs and an infrared camera. The infrared light emitted by the eye tracker

is reflected by the user’s pupils. The infrared camera captures these reflections and the system uses this information to calculate where a user is looking on the screen without the user having to wear special goggles. It is also important to note that the user can work with the so�ware in a normal way without being disturbed by the – invisible – infrared beams. The eye-tracking equipment records where the user looks, and for how long. The areas in the user interface that attract most attention while a task is being performed can be visualised using heat maps and gaze plots. Recordings can be played back in real time, showing the sequence of eye movements in combination with the user’s actions (such as mouse clicks or keyboard strokes). These analyses provide quantitative data to measure and compare di�erent locations on a screen. This provides a more objective impression of how our so�ware is used and how users interact with di�erent areas of interest in the interface.



.

An eye on Deltares so�ware

The red line shows eye movements

tracking in practice

94 95

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The dominant paradigm of ‘building hard structures’ in flood risk management is being challenged by approaches that integrate ecosystem dynamics and are ‘nature-based’. In Greening Flood Protection (GFP) approaches of this kind, natural dynamics contribute to flood risk management, the ecosystem is enhanced, and nature and flood protection are combined. Knowledge development and policy ambitions for GFP are advancing rapidly but actual full-scale implementation continues to lag behind. The knowledge gaps represent a key barrier to implementation because GFP involves technologies that are still unproven, works with knowledge uncertainties, and integrates knowledge from di§erent disciplines and policy domains. The central focus of this doctorate research is on how knowledge about GFP decision-making enables and constrains GFP.

By contrast with conventional research and models looking at knowledge in decision-making - where the need to bridge the gap between knowledge and policy is central - this research assumes a strong connection between knowledge and policy in specific policy domains. This connection is conceptualised as a “knowledge arrangement” that shows how domain-specific actors, rules, resources and discourses structure knowledge and knowledge processes. GFP involves domains relating to nature and flood protection policy and therefore an interaction between knowledge arrangements. In three Dutch case studies, we showed how this interaction evolved and what is required to achieve GFP implementation. These case studies were the Sand Motor, the Afsluitdijk barrier dam and the Markermeer dikes.

We distinguish four levels of interaction in knowledge arrange-ments: separation, cooperation, integration or unification. In the Markermeer dikes project, the nature and flood protection knowledge arrangements remained separate: a flood protection project and an ecology project developed knowledge that did not overlap. The result was the development of two di�erent and discordant knowledge bases, with only flood protection knowledge being considered in decision-making. By contrast, the Sand Motor was organised as a multi-functional project with integrated nature and flood protection knowledge arrangements. This led to integrated design development and the implementation of a multi-functional GFP solution.

This research shows that the structure of a policy domain has a direct impact on knowledge and knowledge processes. When design solutions are multi-functional (as is the case with GFP) and require cross-domain cooperation, there is a serious threat of multiple and discordant knowledge bases being developed and inhibiting implementation. The implementation of GFP depends on transcending the gaps between policy domains and knowledge arrangements should be integrated to produce integrated knowledge and knowledge processes. The research identified some critical factors, one of which is the balance between knowledge arrangements. The flood protection domain took precedence over the nature field to a significant degree in two of the case studies and paved the way to monofunctional approaches. Another crucial factor supporting integration in the Sand Motor project was the fact that it was organised as a pilot project. This allowed for the acceptance of uncertainties, ample design space and less need for trade-o�s between functions.

Further reading:

Janssen (2015). Greening Flood

Protection in the Netherlands: a

knowledge arrangement approach,

PhD thesis WUR, http://edepot.

wur.nl/352709


Greening flood protection

in the Netherlands

Interaction modes between

knowledge arrangements

Interacting knowledge arrangements

96 97

Social and economic impactDeltares helps governments, businesses, civil society and knowledge institutions with innovative and e�ective solutions in flood risk management. For example, the world benefits from experiments in our high-quality wave facilities, such as the Delta Flume, where we simulate wave attacks and loads on flood defences.

Using our expertise and practical tools and models, governments throughout the world can respond better to flood risks. For example, 41 countries are currently using ‘FEWS’, the Deltares flood forecasting and warning system. Dutch consultants in the private sector are strengthening their international competitive position by drawing on our knowledge and international recognition. In society as a whole, the public trusts Deltares’ expertise and judgement as an independent top research institute. And finally, we have an impact in the scientific world through our combined research initiatives with universities, the support of professors and the supervision of doctorate and master students. In addition, scientists can use our open-source so�ware.

R&D HighlightsThe new Delta Flume was o³cially opened on 5 October 2015. This unique test facility will be home to full-scale experiments looking at the e�ect of extreme waves on dikes, dunes, breakwaters and o�shore structures. One of the first projects was the testing of older block revetments.

Highlights covered by the Flood Risk theme related to real-time monitoring and forecasting, modelling, data analysis from monitoring datasets, uncertainty and tools. Two real-time monitoring examples are the real-time monitoring and forecasting of dike strength and estimating real-time predictive hydrological uncertainty. The first example involved fitting out a pilot dike with sensors. The resulting data were used to determine the real-time stability of the dike. The second example combined uncertainty in weather forecasts and hydrological conditions to assess uncertainties in hydrological forecasts.

The tools developed as part of the Flood Risk theme were Del�-FIAT for flood impact analysis, GRADE for discharge scenarios for the Rhine and Meuse, and CIrcle for the analysis by stakeholders of the cascade e�ects of natural hazards on critical infrastructure. Modelling studies looked at storm impacts on gravel beaches and the impact of extreme wind fields over open water on dikes.

scopeRising sea levels, population growth and economic activity are driving an increase in

demand for flood risk forecasting and possible protective measures.

The research conducted by Deltares improves the precision of our assessments of dike

strength, water-level predictions, wave heights and erosion, and allows for better risk

assessments. Our expertise covers the full scope of flood risk management: from risk

calculations to practical support for making policy decisions. The result is seen in flood

prevention measures that are more e§ective, more cost-eªcient and socially acceptable.

98 99

Flood Risk

Contact

Deltares | R&D Highlights 2015 Flood Risk

Gravel beaches and barriers are found on many high-latitude, wave-dominated coasts across the world. Due to their natural ability to dissipate large amounts of wave energy, gravel coasts are widely regarded as an e§ective and sustainable form of coastal defence. However, during extreme events, waves may overtop, overwash, and even lower, the crest of the gravel beach, flooding the hinterland. Despite the obvious public importance of gravel beaches and barriers, beach managers currently have few operational management tools to predict how gravel beaches will respond to storms. Deltares worked in partnership with lead partner Plymouth University, the Channel Coastal Observatory, the Environment Agency, HR Wallingford and UNESCO-IHE to address this shortfall by developing a predictive modelling capability for storm impact on gravel coasts.

The numerical model developed for this purpose is based on the open-source XBeach model for sandy coasts, and is called XBeach-G. The model simulates the morphological response of gravel beaches and barriers to storms by solving the hydrodynamics of individual waves in the nearshore and swash zone, overtopping flows, groundwater processes, and gravel sediment transport. The model was developed using insights gained from a unique dataset of storm processes on gravel beaches measured at Chesil Beach (Dorset, England) by Plymouth University, as well as from detailed data collected in physical model experiments. The coupled approach of data collection and model development allowed for the rapid and focused development of the numerical model, and a robust analysis of the model’s strengths and weaknesses.

Model validation was carried out using hydrodynamic and morphodynamic data collected at five gravel beaches in the UK during multiple storm events over a three-year period.

Validation simulations showed that the model can simulate the hydrodynamics in the coastal zone (wave transformation, wave run-up and wave overtopping) well, and predict the storm-driven morphological change on a wide range of gravel beaches with universal model calibration coe³cients. The XBeach-G model can also predict the key indicator of coastal flooding - the potential for waves to overtop the beach crest - much more accurately than the empirical models currently used for this purpose. Crucially, this analysis identified the possibility of flood risks on many gravel coasts being significantly under-estimated using existing empirical relations, and highlighted the value of process-based models in improving existing methods for flood risk analysis.

In order to ensure the easy uptake of the XBeach-G model by coastal managers and local engineering firms, the project has developed a simple graphical user interface (GUI) for the XBeach-G model and has organised a training workshop on the application of the model for over twenty public and private parties.

Further reading:

McCall et al (2015). Modelling

the morphodynamics of gravel

beaches during storms with

XBeach-G, Coastal Engineering,

103, 52-66, ISSN 0378-3839,

http://dx.doi.org/10.1016/

j.coastaleng.2015.06.002


Storm impacts on

gravel beaches

< Example of the XBeach-G GUI

showing storm wave run-up and

groundwater response in a gravel

barrier

Storm waves hit Chesil Beach (Dorset,

England). Photograph courtesy of

T. Poate (Plymouth University)

Comparison of measured beach

change and beach change predicted

by the XBeach-G model in front of

the sea wall at Chesil Beach

100 101

Contact


The direct impacts of natural hazards may lead to indirect consequences via cascades of causes and e§ects passing through di§erent critical infrastructure networks. CIrcle is a touch-table application for working with stakeholders on these cascade e§ects, that Deltares developed as a way to collect expert knowledge.

The application can be used at workshops where grid operators and other stakeholders in a particular area contribute their expertise and identify cascade e�ects without having to supply that information in an accurate GIS map. Important information emerges during the dialogues. For example, 25 to 50 centimetres of water will cause short-circuits in network control cabinets and result in the failure of the electricity supply. Without back-up facilities, complete industrial areas may collapse. These

relationships are known as ‘causal links’. The database supporting CIrcle is used to collect these links and combine them with flood models (or other natural hazard models) and with public data to visualise the cascade e�ects. These results can then be presented immediately and assessed by the participants.

Deltares hosted an extensive CIrcle workshop in 2015 for the Waterland area to the north of Amsterdam. This region su�ered severe flooding in 1916 and the Hollands Noorderkwartier water authority wanted to commemorate the event 100 years later with a flood simulation and an analysis of cascade e�ects: were we better o� 100 years ago when we were less dependent on networks than we are now? A large group of stakeholders from the Waterland area attended the workshop. Looking at the flood maps, they

exchanged thoughts and knowledge about the performance and weaknesses of their own networks, and discussed dependencies between the networks. The CIrcle tool collected a total of four A4 pages of dependencies and other important facts. A film showing the cascade analysis in GIS was made on the basis of these data.

The ongoing development of CIrcle will involve an interactive, 3D model environment for visualising the cascade e�ects even more convincingly. This model environment allows for switching to a tsunami model, a rain model or an earthquake model running in the background to see what happens to critical infrastructures in the case of such an event. The dependencies collected during CIrcle workshops are used to visualise the e�ects. Moreover, the interactivity of the model environment facilitates the exploration of protective measures. For instance: “This particular transformer station is extremely important for this region. Would cascade e�ects be diminished if we were to protect this station by building a dike around it?” At a CIrcle workshop, it is possible to immediately visualise the results of the shared knowledge of the stakeholders, to try out measures interactively and to discuss the possibilities a�orded by certain measures.

Still from the Waterland cascading

e¨ects animation

CIrcle tool

CIrcle workshop for the Port of

Rotterdam at the iD Lab

Further reading:

www.deltares.nl/circle


[email protected] T +31(0)6 5209 1231 Relations and consequences

of Critical Infrastructures

Flood Risk

Inundation depth

102 103

Contact


Flood risk management draws increasingly on information about the damage and casualties caused by floods. The information helps policy-makers decide which measures will reduce impacts most e§ectively and how much investment is justified. Deltares has developed a tool - Del¤-FIAT - that can estimate impacts by converting inundation maps into figures and maps that show projected damage and casualties. Deltares recently used this tool in several flood risk studies around the world for both data-poor and data-rich areas.

Del�-FIAT acts as a generic map overlay calculator. Hazard maps (usually showing water depth), object maps or land-use maps are used as input. Input also includes the relationship between the hazard and the specific flood e�ect (the depth-damage function, for example) for each object or land-use category. This generic setup provides the flexibility that allows the tool to be used in di�erent regions and on very di�erent spatial scales for di�erent types of input data and, potentially, even in fields other than Flood Risk Management.

The core of Del�-FIAT is an open-source Python script. This script has been optimised by the Del� So�ware Centre to complete large-scale calculations extremely quickly and it can therefore run large numbers of high-resolution scenarios in a short amount of time. The script can be controlled from an Excel file, making it easy to use for people without scripting experience. The core Python script can also be decoupled from the Excel interface and serve as a module in other tools or computations. For example, it is used as the calculation engine behind the new standard Dutch flood damage model so�ware, SSM2015.

Because of its simplicity and flexibility, Del�-FIAT has enhanced flood impact analyses in several projects. An example is the application of Del�-FIAT to estimate flood risk in the C4 Basin in

Miami (Florida). This project was carried out as part of a research grant for NOAA. The aim was to identify an optimal flood risk management strategy for extreme rainfall. The optimisation model required damage calculations for approximately one hundred di�erent water levels. Local data on land-use and buildings was processed with a Python script, and used to set up a damage model in Del�-FIAT. Del�-FIAT speeded up this process significantly by comparison with traditional GIS solutions and allowed for straightforward modifications in input data or export formats

With Del�-FIAT, flood-impact modellers can focus on the data and impact information rather than the calculation technology. The tool has been used in the Netherlands, the United States, China, Turkey, Bangladesh, Afghanistan, Malawi, Vietnam, for the whole of Europe and for a global study. The spatial scales in these studies varied from just a few metres to kilometres. Del�-FIAT and Del�-FEWS are now being linked with the aim of transforming flood forecasts into impact forecasts.

Del�-FIAT: A generic tool for

flood impact analysis

Further reading:

https://publicwiki.deltares.nl/

display/DFIAT/Del�-FIAT+Home




Example of a high-resolution map

from Del�-FIAT showing flood damage

projected onto an aerial photograph

<Overview of the process for

calculating flood impact

104 105

Contact


LiveDijken (‘live dikes’) are dikes equipped with sensor systems to deliver real-time information about things like water levels inside the dike. The aim is to assess the actual strength of the dike and to provide additional information before and a¤er improvements are made. Forecasting dike strength provides useful information in early warning situations to guide emergency responses: a specific flood warning is converted into specific measures such as dike reinforcements with sand bags, temporary protection of specific structures or evacuation.

In the Noorderzijlvest pilot project in the province of Groningen (NL), continuous monitoring and forecasting have been established for the strength of the dike system. This system consists of a combination of real-time data, information about the dike structure and behaviour, and calculations based on stability models. Water levels inside the dike are obtained with multiple pressure sensors distributed in several cross-sections of the pilot dike, the Ommelanderzeedijk. Dike stability is calculated on the basis of the phreatic line derived from the water levels and on the schematisation of the subsoil profiles. The resulting safety factor is a direct measure for the dike strength. Fragility curves are derived from the geometry and material properties of the dike profiles. The total fragility curve is calculated with a model-based probabilistic analysis for each failure mechanism considered: overflow, wave run-up, waterside erosion by waves, wave impact, piping, micro- and macro-stability. Total fragility represents a compact summary of the reliability of a dike section in relation to the water level outside the dike. In this way, forecasts of water levels make it possible to determine the probability of dike failure over time.

The two work flows of real-time monitoring and the forecasting of dike strength are being integrated in the FEWS-DAM Live so�ware system. FEWS-DAM Live provides modules for managing the data monitoring and forecasting processes. It is therefore possible to visualise, for each dike section, the real-time and historical water levels measured by each sensor and the safety factor resulting from the stability calculations. The water levels forecast for the next 48 hours are transformed, on the basis of the fragility curve for each dike section, into a forecast time series of failure probability. Both the total probability of failure and the probability for individual mechanisms can be visualised for each section in FEWS-DAM Live. The results generated provide precise information for the purposes of the emergency response about the location, timing and probability of failure of defined sections of the flood defence line. On the basis of this information, emergency measures that apply to the flood defence line (such as more frequent inspections or temporary dike reinforcements) can be operationally planned, adapted to the situation and triggered.

Real-time monitoring and

forecasting of dike strength

Further reading:

Bachmann et al. (2015): http://www.

slideshare.net/Del�_So�ware_Days/

dsd-int-2015-fewsrisk-a-step-

towards-riskbased-flood-forecasting-

daniel-bachmann-54944078



Time series showing the safety factor

for dike stability and failure probabilities

for an historical event

Fragility curve with total failure

probability and partial fragility curves

for di¨erent failure mechanisms

stability

standby level

measurement

106 107

Contact


The aim of the European MyWave project was to improve the accuracy and dissemination of wave forecasts in general and coastal-wave forecasts in particular. The project ran from 2012 to 2015 and was coordinated by the Norwegian Meteorological Institute. It brought together several major institutes responsible for ocean-wave forecasting, research and observation in Europe, including the ECMWF (a European institute located in the United Kingdom) and the Met Oªce (United Kingdom), Météo-France (France), Helmholtz Zentrum (Germany), Puertos del Estado (Spain), ISMAR (Italy), Deltares and KNMI (Netherlands) and HRG (Greece). The Deltares contribution to the project was the application of an innovative data-assimilation technique, Ensemble Kalman Filtering (EnKF), with the aim of improving the operational Dutch coastal-wave forecasts.

The model used for the operational wave forecasts in Dutch North Sea waters is SWAN (http://www.swan.tudel�.nl/), a state-of-the-art third-generation shallow-water phase-averaging wave model. OpenDA (http://www.openda.org) is a generic toolbox for data assimilation, with Ensemble Kalman Filtering being one of the tools available for data assimilation. Furthermore, a connection with SWAN is available in OpenDA. OpenDA is therefore the ideal toolbox for EnKF data assimilation in SWAN models.

In the first stage of the project, a number of experiments with EnKF data assimilation in SWAN were conducted using small SWAN wave models for the North Sea. The small models were computationally inexpensive. The experiments were twin experiments, meaning that the same model is used to create the observations: the model results and the di�erences between the observations and the model results are solely due to di�erences in the model input or parameters. These twin experiments for the North Sea led to the determination of the appropriate settings

for EnKF data assimilation in SWAN and an understanding of the sensitivities. The resulting recommendations and OpenDA adjustments enhanced the reliability of EnKF multi-variate data assimilation in SWAN.

In the second stage of the project, a number of experiments were conducted with EnKF data assimilation in the operational SWAN model for Dutch coastal waters. The experiments focused on improving the forcing winds. The results exceeded expectations. Not only did the experiments with the EnKF assimilation of o�shore wave measurements lead to improvements in error statistics for the assimilated variables, but also for variables that were not assimilated and at locations other than those covered by the observations used. Furthermore, the EnKF data assimilation in SWAN showed more accurate results than those obtained by increasing the resolution of the atmospheric model that was used to compute the forcing winds from tens of kilometres to a few kilometres and by assimilating high-resolution scatterometer wind fields in the high-resolution atmospheric model.

Ensemble Kalman Filtering

for improving coastal-wave

forecasts

Further reading:

http://cordis.europa.eu/result/

rcn/58601_en.html



Comparisons at a coastal location

between the buoy observations of

significant wave height, model results

with no data assimilation (First

Guess) and model results with EnKF

assimilation of data for o¨shore wave

heights

Schematic diagram showing the

connection between SWAN and

OpenDA

108 109

Contact


Real-time hydrological forecasts can reduce but not eliminate uncertainty about future hydrological conditions such as future streamflow rates or water levels. The uncertainty can be caused by many factors such as imperfect hydrological models for streamflow generation and streamflow propa-gation and weather forecasts. These models and weather forecasts themselves are inherently uncertain and so hydro-logical forecasts may be ‘wrong’ in that events (such as floods) may not be noticed in time or in that a forecast event may not materialise.

Uncertainty can be managed in multiple ways. In the long term, it may be reduced through research. Indeed, improvements to hydrological and meteorological forecasts have achieved just this: forecasting skills have gradually improved over the years. A more immediate approach involves the assessment of the remaining uncertainties in order to produce probabilistic forecasts. Although probabilistic forecasts cannot prevent missed events or false alarms, the probability will be known in advance, allowing for risk-based decision-making. The research has provided evidence that allows for larger reductions of flood risk than would be the case with single-valued, deterministic forecasts.

The hydro-meteorological sciences have multiple approaches for estimating predictive uncertainty. Many are based on either ensemble techniques (the implementation of the Monte Carlo principle) or on statistical post-processing techniques. The aim of the first approach is to produce multiple forecasts by using multiple inputs that vary from one another while remaining plausible. Post-processing techniques modify forecasts on the basis of prior performance. The study described here explored variations on existing techniques. These included the application of post-processing techniques to both weather forecasts and hydrological forecasts, the combination of ensemble techniques with statistical post-processing techniques, and improvements to statistical post-processing techniques. Many of these experiments were conducted with the Del�-FEWS forecasting system and its inherent facilities for ‘hind-casting’ or reforecasting.

Estimating real-time

predictive hydrological

uncertainty

Further reading:

Verkade (2015), Estimating Real

Time Predictive Hydrological

Uncertainty, PhD thesis Del� UT,

via http://repository.tudel�.nl


‘Ensemble dressing’ forecast for Meuse at St Pieter

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2000

1500

1000

500

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0,8

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0,4

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now

Prediction

Thresholds

110 111

Contact


In 2014, the Netherlands Meteorological Institute KNMI presented four new climate scenarios for the Netherlands and for the river basins of the Rhine and Meuse for the time horizons 2050 and 2085. Deltares estimated the impact of these climate scenarios on the extreme discharges (both high and low) of the Rhine and Meuse

In 2014, the Netherlands Meteorological Institute KNMI presented four new climate scenarios for the Netherlands and for the river basins of the Rhine and Meuse for the time horizons 2050 and 2085. Deltares estimated the impact of these climate scenarios on the extreme discharges (both high and low) of the Rhine and Meuse.

The GRADE Generator of Rainfall and Discharge Extremes was used to calculate the distribution of high discharges in the Rhine at Lobith and the Meuse at Borgharen. GRADE was developed by Deltares and KNMI as an improvement to the current extrapolation method on observed discharge series. GRADE consists of three components: very long, synthetic, rainfall series are produced by a stochastic weather generator, hydrological models of the Rhine and Meuse basins calculate the flow contribution into the main rivers, and hydrodynamic models simulate the flood propagation in the main rivers. In the case of the Rhine, the method also includes the e�ect of flooding upstream from Lobith.

Changes in both high and low flow statistics were calculated. The resulting discharge projections were compared with existing ones, in other words those based on KNMI’06 scenarios and the results from the international AMICE (Meuse) and RheinBlick2050 (Rhine) projects. The comparison focused on the annual cycle of the mean monthly discharge, the mean annual minimum 7-day

flow, the mean annual maximum flow and extreme flows with long return periods. The e�ects of the KNMI’14 scenarios on both rivers show a general tendency towards rising discharges in winter and spring, and falling discharges in - usually late - summer. In most scenarios, the mean annual discharge clearly falls as well. The range of the change in extremely high discharges for all KNMI’14 scenarios is relatively small for 2050 but becomes larger in 2085. These ranges are consistent with the ranges for extreme multi-day precipitation in the KNMI’14 scenarios.

The e�ect of upstream flooding is taken into account for the Rhine. This includes the e�ect of the potential flood areas between Wesel and Lobith, which are taken into account by correcting the discharges calculated by the SOBEK 1-D model above 16,000 m3/s (start of flooding around Emmerich) for the potential flooding volumes and considering the maximum flow over the dikes between Wesel and Lobith. The result is that, with very long return periods (above ~1250 years), the di�erences between the scenarios become small, largely due to the limited discharge capacity of the Rhine between Wesel and Lobith. These state-of-the-art results confirm once more that the maximum discharge at Lobith will be between 17,500 and 18,000 m3/s.

Further reading:

Sperna Weiland et al (2015).

Implications of the KNMI’14 climate

scenarios for the discharge of the

Rhine and Meuse, Deltares report

1220042

(http://kennisonline.deltares.nl)


[email protected] T +31(0)88 335 8230 GRADE method for

discharge scenarios

Flood Risk

Upper panel: current method,

lower panel: GRADE method

Photo: Beeldbank Rijkswaterstaat

112 113

The conjunction of storm

surges and high discharges

Gouwe aquaduct, A12

(RWS beeldbank)

Contact


The need to better understand the interactions of the various processes that contribute to high levels in the IJsselmeer lake is becoming increasingly pressing. Typical issues requiring answers are the pump capacity needed at the Afsluitdijk barrier dam in 2020 to compensate for sea-level rise, the feasibility of raising the lake level in early spring within the current safety standards in order to generate a better environment for birds, and the impact of a structural failure of pumping and discharge resources on the flood frequency curve for the lake level.

Information about the correlations between, and time shi�s in, the most important stochastic variables contributing to high lake levels is needed to set up a probabilistic model. This research is investigating these correlations and time shi�s using measured time series. As this information will be used for situations that occur less frequently, an understanding of the underlying meteorological processes is required to make it clearer whether these processes also hold for more unusual situations that have never occurred before.

The IJsselmeer lake is fed by the river IJssel, a branch of the river Rhine, and by “local” runo� from a number of relatively small drains, rivers and surrounding polders. The water is discharged from the lake through the locks at Den Oever and Kornwerderzand into the Wadden Sea under gravity during low tide.

These processes and mutual interactions have been explored on the basis of five historical events and statistical analysis using a thirty-year time series. The analyses show there is a

certain regularity in the occurrence of the processes causing high lake levels. First, the water level in the lake rises as increased seawater levels reduce discharge capacity and heavy precipitation causes a large ‘local’ supply. The small local drains respond quickly to the precipitation brought by low-pressure areas (in other words, meteorological depressions) and add to the increased level. The discharge from the IJssel then increases, prevent the lake dropping back to normal levels. This sequence is explained by the arrival of low-pressure areas from the north-west moving in the upstream direction in the catchment of the Rhine. The response from the Rhine/IJssel river system arrives a�er a delay of about 5-7 days.

Some of the historical events analysed involved multiple successive depressions with concurrent rainfall. In these events the process repeats itself, resulting in higher and higher lake levels. The main contribution of the current study is the identification of the importance of local runo� for lake levels, which has been underestimated to some extent in the past. The study therefore provides crucial information for probabilistic analyses of flood risk and flood risk management for the IJsselmeer lake.


Discharge into and out of the IJsselmeer

lake in the early months of 2002

1

2

Stevin locks in the Afsluitdijk barrier

dam at Kornwerderzand discharge IJsel at Olst

discharge into the Wadden sea

discharge local rivers and region

level IJsselmeer lake

Rainfall events

114 115

Contact


Climate change e�ects

on the protection of

coasts by coral reefs

Coral reefs under pressure from climate change and direct human activity may provide tropical islands with less protection from wave attack, erosion and the salinisation of the drinking water resources that help to sustain life on those islands. Deltares collaborated with the U.S. Geological Survey to assess how climate change will a§ect the potential mitigation of coastal hazards by coral reefs.

Inhabitants of low-lying coral islands and atolls depend on coral reefs for protection. At present, some of these islands are flooded a few times a decade due to wave events. It is expected that the frequency of flooding will increase due to sea-level rise and the decay of coral reefs because the smoother structure of the dead coral dissipates wave energy less e�ectively. The loss of coral cover not only causes increased shoreline erosion but also degrades the sparse drinking water resources on these islands, and this may eventually make these islands uninhabitable. In order to prevent or mitigate these impacts, coastal managers need to know the extent of the degradation of the protective function of their reefs so they can take action. The present study provides an indication of local reefs’ sensitivity to change.

We used the open-source wave model XBeach to understand the e�ects of changing conditions on coral reefs. The model was first validated using field measurements obtained on the Kwajalein Atoll in the Marshall Islands in the Pacific Ocean. It was then used to investigate the e�ects of changing reef properties on water levels, waves, and wave-driven run-up. Reef roughness, steepness, width and the total water level on the reef platform are all important factors for coastal managers to consider when planning mitigating measures.

The results of the model runs suggest that coasts fronted by relatively narrow reefs with steep faces and deeper, smoother reef flats are expected to experience the highest wave run-up and therefore to be at more risk of flooding. Wave run-up increases with higher water levels (which are to be expected with sea-level rise), higher waves, and lower bed roughness (as coral degrades and becomes smoother), all of which are expected as a result of climate change. Rising sea levels and climate change will have a significant negative impact on the capacity of coral reefs to mitigate the e�ects of coastal hazards in the future.

Further reading:

Quataert et al (2015). The

influence of coral reefs and climate

change on wave-driven flooding

of tropical coastlines, Geophys.

Res. Lett., 42, 6407– 6415,

doi:10.1002/2015GL064861



Flood Risk

Reef flat width [m] Fore reef slope

116 117

Contact


Extreme wind-field

evolution in time and space

The Dutch Water Act requires the periodical assessment of the strength of the Dutch primary water defences. In order to improve the accuracy of this assessment, Deltares and the KNMI (Royal Netherlands Meteorological Institute) launched a wind-modelling project in 2011 to determine wind strength above open water and to incorporate the dimensions “time” and “space” in the hydraulic boundary conditions used in the assessment.

The project calibrated and validated the high-resolution atmospheric model HARMONIE before using it to produce accurate wind velocities above open water for all Dutch water systems. One of the primary results of the project is a unique time series of wind fields covering the period from 1979 to 2013 with a time resolution of 1 hour on a grid with a 2.5 km resolution. The HARMONIE resolution is significantly finer than the resolutions of models used so far, enabling better modelling of strong gradients in atmospheric variables due to factors such as roughness variations at land-water transitions.

In parallel with this activity, the statistical Combined Max-Stable (CMS) li�ing method was developed to determine extremes in evolution over space and time. Roughly speaking, the method uses time series with the variables of interest and location-specific distributions of extreme values in order to “li�” observed extreme events into yet unobserved and even more extreme events. The li�ed events provide descriptions of what could happen in time and space in a future extreme event with a very small probability of occurrence.

The 1979-2013 dataset was used to determine directional distributions of extreme wind speeds on open water. These distributions complete our knowledge about winds on open

water since the distributions used at present are based on wind velocity measurements at land stations, which require a parametric, error-prone, transformation to open water. The CMS li�ing method was then applied using the distributions of extreme wind speeds and the original fields to determine the evolution of extreme winds in space and time in all Dutch water systems. The extreme storm winds can be used as input for hydrodynamic and wave models to determine temporal and spatial variations in the hydraulic boundary conditions used to assess Dutch primary water defences.

As well as being useful in the assessment of primary water defences, the data and knowledge gained in this study can be applied more broadly. The li�ing method developed is generic and can be used to li� other data, such as water levels and the associated hydraulic loads, elsewhere in the world. The HARMONIE data and li�ing methods can be used to explore a number of storm scenarios in the Dutch waters, such as the consequences for safety of increasingly severe classical storms due to climate change. Furthermore, the extreme wind statistics and li�ed winds can be used as standards for the assessment and design of Dutch o�shore platforms, wind farms and piles, and for structures and floating bodies in lakes, rivers and estuaries.


[email protected] T.+31(0)6 4691 1161

Further reading:

Van Nieuwkoop et al (2015).

Towards time- and space-evolving

extreme wind fields, 36th IAHR

World Congress, The Hague

< Original (HARMONIE) and li�ed

time series showing wind speeds

at a reference location

10,000-year return values

for wind speed from western

direction (arrow)

56

36

16

Flood Risk

< Snapshot of a li�ed wind field

Woodcut from the book of W. Scheidig:

Die Holzschnitte des Petrarca

118 119

Contact


Smart Water Management

on a regional scale

The regional water systems in the Dutch province of Noord-Brabant are managed and maintained by three regional water authorities. These water systems are intersected by a canal system managed by the national water authority (Rijkswaterstaat). During long periods of intense rainfall, high flows can threaten cities and villages. The situation may become particularly serious when the water levels in the downstream water bodies are also high. Fortunately, the water authorities have several ways of controlling the water flows. The available options require close collaboration between the authorities.

With encouragement from the “Smart Water Management” programme, the water authorities decided to engage in the joint development of a decision-support system for use during crises of the kind described here. Working with consultant Witteveen + Bos, Deltares developed an operational forecasting system based on Del�-FEWS that contains innovative components such as ensemble forecasting and the optimisation of control structures.

The FEWS system contains several types of model: rainfall runo�, low- and high-resolution flow models and optimisation models. The models are forced with high-resolution precipitation radar images, numerical weather forecasts, flow forecasts from the Flanders Environment Agency and water level forecasts from Rijkswaterstaat. One innovative aspect of this system is that data from the European Centre for Medium-Range Weather Forecasts (ECMWF) in Reading are used four times a day to simulate an ensemble of fi�y forecasts with the rainfall-runo� model and the low-resolution flow models. These forecast ensembles provide water managers with a picture of uncertainties in the weather forecasts. The high-resolution

models provide a detailed insight into the forecasted water flows and levels, and also calculate detailed flood-extent maps. The simulated water levels are corrected using observed water levels collected from the monitoring systems of the water authorities.

Another unique aspect of FEWS Brabant is that it contains optimisation models that advise on the best distribution of surplus water between the intersecting canal systems. When no other control options are available, it also suggests how to use the water-retention areas. The control of the structures is based on Model Predictive Control (MPC), which uses a system of goals and penalties to generate the best solution. The optimal structure settings are visualised alongside the regular settings to support the decision-maker.

Using the native Del�-FEWS client, decision-makers have access to all observations and model forecasts. This client also gives them access to the scenario functionality. The generated forecasts are disseminated via the shared web portal of the collaborating water authorities.

Further reading:

http://www.vakbladh2o.nl/

index.php/h2o-online/recente-

artikelen/entry/noord-brabantse-

waterbeheerders-anticiperen-

samen-op-hoogwater



Ensemble simulations provide an understanding of

uncertainties in the weather forecast

Flood Risk120 121

Contact


Testing of ancient

block revetment in

the new Delta Flume

A¤er a period of three years, the construction of the new Delta Flume on the Deltares campus in Del¤ was completed in 2015. The new flume is 300 metres long, 9.5 metres deep and 5 metres wide and it replaces the 35-year-old flume in Marknesse. The length means gradually rising coasts can be modelled, the depth makes it possible to generate waves up to 4.5 metres high. This major advance requires a 10-metre-high wave board that is moved to and fro using hydraulic cylinders.

A�er the grand opening of the flume in October in the presence of ministers and other dignitaries, the first project involved studying the stability of a specific type of block revetment under wave attack: grouted boulders. Particularly in the north of the Netherlands, a number of dikes have been protected with this type of revetment, which is made from round natural stones (boulders) transported to our region by the glaciers in the last Ice Age. The stones used on Dutch dikes range in size from 30 cm to 90 cm and are o�en grouted with concrete. Cra�smen used to position these stones on a gravel bed of crushed bricks, forming a relatively smooth revetment.

The need to know more about the stability of boulder revetments of this kind became urgent because a lack of knowledge made it impossible to assess the stability of the dike between Eemshaven and Delfzijl as required by the mandatory periodic safety assessment for Dutch dikes. This particular dike is approximately 11 km long, and 9 km is protected with grouted boulders. Old documents show that this revetment was already in place in the 19th century. Due to positive experience with the block revetment on this dike, the water authority was convinced that stability was adequate and decided to perform a model experiment to prove it.

The block revetment was built in the Delta Flume on a dike with an outer slope of 1:3.6 and with a height of 11 m. Experienced cra�smen were hired to make a realistic model revetment. The tests were carried out on almost prototype scale (1:1.3). The wave height was increased step by step to find the maximum wave conditions in which it was stable. The test showed that the block revetment is stable enough for the dike Eemshaven - Delfzijl and that the safety margin is more than adequate. This result saved the water board approximately €10 million that had been earmarked for the renovation of this revetment.

Further reading:

Mourik et al (2015). Stabiliteit van

met beton ingegoten Noorse steen,

Deltares report 1220204

Flood Risk


122 123

EditorsPauline Kruiver

Jurjen van Deen

English Text AdvicePete Thomas, Alkmaar

Layout Welmoed Jilderda

PrintingDrukkerij van Deventer bv

Photo coverDesmond Lee, Field measurements during a

project in the Water and subsoil resources theme

Colofon

PO Box 1772600 MH Del�The NetherlandsT+31 (0)88 335 82 [email protected]

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