Quantitative Analysis of Urban Pluvial Flood Alleviation ...
Real-time optimal urban & natural flood control …...1 Real-time optimal urban & natural flood...
2
1 Real-time optimal urban & natural flood control –putting in 4 weirs to save Leeds from flooding Academic supervisors: Prof Onno Bokhove and Dr Mark Trigg, Schools of Mathematics and Civil Engineering, University of Leeds. Information: [email protected] and [email protected] Industrial advisors: Lindsay McMillan (Mott MacDonald); Doug Whitfield and Simon Stokes (Environment Agency). Project Outline: Motivated by the Boxing Day 2015 floods, we aim to improve flood mitigation using active flood control given rainfall and river level data as well as rainfall predictions. The effects of creating more water storage capacity in upstream tributaries using natural flood management will also be explored in combination with active control. Mathematical control for transient and nonlinear phenomena such as flooding goes beyond established control techniques for linear time-invariant systems. We will explore the application of optimal control techniques for strongly nonlinear flooding events: Pontryagin’s theory of optimal control as gold standard, which requires adjoint modeling, as well as fast (linear) approximations thereof, such as State-Dependent Ricatti Equation –SDRE– control and Model Predictive Control [2,3]. All these techniques have shortcomings in their current form in flood alleviation applications that need to be overcome. Our aim is to establish optimal flood control theory for generic use in mitigating (urban) flooding. Flood control options include: (i) the use of moveable weirs for hydraulic control, (ii) the (de-)activitation of bypass channels or canals, and (iii) the use of moveable weirs and underpass dams to create temporary reservoirs by hydraulic constriction, as controls. The desired project outcome is to inform Mott MacDonald and the Environment Agency about options for optimal flood control measures for Phase 2 of Leeds’ Flood Alleviation Scheme and in general to demonstrate the power of real-time flood control. To reach this outcome we will apply our modelling to a) an adaptation of the table- top flood demonstrator Wetropolis [1] and b) a conceptual model of Leeds’ Aire River and its catchment [4], see Figs. 1 and 2. The former will inspire the redesign of Wetropolis to bring relevance to the current challenges in exploring flood mitigation options for Leeds City. Wetropolis allows accessible model testing in a laboratory environment using control and data acquisition features operated by Arduino technology. To facilitate a step-by-step investigation, we aim to use a model hierarchy including one-dimensional kinematic river and ground-water level models, as well as more advanced two-dimensional shallow water models. Rainfall will be modeled either in a probabilistic way or generated using a simple chaotic dynamical model representing uncertainty. Alignment with UK industrial hierarchy: The Boxing Day Flood of 2015 in Leeds had an estimated excess volume of at least a body of water of 1 mile by 1 mile in horizontal extent by 2 metres high (see [1] and [4]), to avoid levels going over 3.9m in Armley. The hypothesis to be investigated is whether multiple strategically placed and adjustable weirs, normally open but closing on average 1:50 to 1:100 years, could have prevented all or the worst flooding in the middle Aire catchment including Bradford and Leeds. The principle of natural-flood-management or nature-based solutions is applied because the weirs will be placed at naturally suitable locations,
Transcript of Real-time optimal urban & natural flood control …...1 Real-time optimal urban & natural flood...
1
Real-time optimal urban & natural flood control –putting in 4 weirs to save Leeds from flooding Academic supervisors: Prof Onno Bokhove and Dr Mark Trigg, Schools of Mathematics and Civil Engineering, University of Leeds. Information: [email protected] and [email protected] Industrial advisors: Lindsay McMillan (Mott MacDonald); Doug Whitfield and Simon Stokes (Environment Agency). Project Outline: Motivated by the Boxing Day 2015 floods, we aim to improve flood mitigation using active flood control given rainfall and river level data as well as rainfall predictions. The effects of creating more water storage capacity in upstream tributaries using natural flood management will also be explored in combination with active control. Mathematical control for transient and nonlinear phenomena such as flooding goes beyond established control techniques for linear time-invariant systems. We will explore the application of optimal control techniques for strongly nonlinear flooding events: Pontryagin’s theory of optimal control as gold standard, which requires adjoint modeling, as well as fast (linear) approximations thereof, such as State-Dependent Ricatti Equation –SDRE– control and Model Predictive Control [2,3]. All these techniques have shortcomings in their current form in flood alleviation applications that need to be overcome.
Our aim is to establish optimal flood control theory for generic use in mitigating (urban) flooding. Flood control options include: (i) the use of moveable weirs for hydraulic control, (ii) the (de-)activitation of bypass channels or canals, and (iii) the use of moveable weirs and underpass dams to create temporary reservoirs by hydraulic constriction, as controls. The desired project outcome is to inform Mott MacDonald and the Environment Agency about options for optimal flood control measures for Phase 2 of Leeds’ Flood Alleviation Scheme and in general to demonstrate the power of real-time flood control.
To reach this outcome we will apply our modelling to a) an adaptation of the table-top flood demonstrator Wetropolis [1] and b) a conceptual model of Leeds’ Aire River and its catchment [4], see Figs. 1 and 2. The former will inspire the redesign of Wetropolis to bring relevance to the current challenges in exploring flood mitigation options for Leeds City. Wetropolis allows accessible model testing in a laboratory environment using control and data acquisition features operated by Arduino technology. To facilitate a step-by-step investigation, we aim to use a model hierarchy including one-dimensional kinematic river and ground-water level models, as well as more advanced two-dimensional shallow water models. Rainfall will be modeled either in a probabilistic way or generated using a simple chaotic dynamical model representing uncertainty. Alignment with UK industrial hierarchy: The Boxing Day Flood of 2015 in Leeds had an estimated excess volume of at least a body of water of 1 mile by 1 mile in horizontal extent by 2 metres high (see [1] and [4]), to avoid levels going over 3.9m in Armley. The hypothesis to be investigated is whether multiple strategically placed and adjustable weirs, normally open but closing on average 1:50 to 1:100 years, could have prevented all or the worst flooding in the middle Aire catchment including Bradford and Leeds. The principle of natural-flood-management or nature-based solutions is applied because the weirs will be placed at naturally suitable locations,
2
creating “space for water” of which some potential locations have already been identified in the Aire middle catchment between Gargrave and Leeds.
The ultimate goal is the design of a practical, realistic and modern flood defense system, ready for implementation in the Aire River system and any generic river system. Minimising flood damage has direct economical benefits, with initial estimates suggesting that damage of 500M pounds due to the Boxing Day Flood in Leeds could have been largely avoided with suitable flood defense investments of 240M, see [4]. References [1] Bokhove, Zweers 2016: https://www.facebook.com/resurging.flows [2] Breckpot 2013: PhD Thesis KU Leuven, Belgium. [3] Ding, Wang 2012: Adv. Water Res. 44, 30. [4] Bokhove 2017: http://www.turing-gateway.cam.ac.uk/event/tgmw41/programme
Figure 1: Overview sketch of Wetropolis flood demonstrator (photo: Luke Barber).
Figure 2: Leeds’ Aire River 2015 flooding: in Kirkstall (left) and under Leeds’ railroad
station (right), where we notice the high-water mark on the wall (photos: O.B.).
