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Burns Beach near Brighton, Western AustraliaRPS has won a series of awards from the Urban Development Institute of Australia - including the Water Sensitive Urban Development Category for the Brighton Estate near Perth.

Eastern CFRAM Study(Catchment Flood Risk

Assessment & Management)

Stakeholders’ BriefingPoddle & Camac

Watercourses Mapping

Grace Glasgow

July 2013

What are we modelling ?

� CFRAMS -Flooding from fluvial and coastal sources

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Types of Models

• Physical• Computational

Objectives of hydraulic models

� Use appropriate methodology and level of detail to meet the objectives of the CFRAM studies:

– Identification, assessment and mapping of existing and potential future flood hazard and flood risk

– Development and appraisal of flood risk management measures

– Preparation of flood risk management plan

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Model extents - ECFRAM

� High Priority Watercourse (HPW)– Watercourses through AFAs (Area for Further Assessment)– Catchment area >1km2

– Extend a short distance upstream and downstream of the development boundary, depending on:

– If watercourse outside AFA could flood the AFA– If model accuracy could influence flooding in the AFA

� Medium Priority Watercourses (MPW)– Watercourses between AFAs– Watercourses from most d/s AFA to the sea

Unit of Management

Number of AFA's HPW (km) MPW (km) UoM Totals (km)

07 10 122.4 97.9 220.3

09 21 341.9 78.9 420.8

10 12 146.8 15.5 162.3

Total 43 611.1 192.3 803.4

Model extents - ECFRAM

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Producing Flood Maps

� Historical flood maps

• Predictive flood maps

Data Collection:-Eye witness accounts

-Video, photographs

- Wrack marks survey

Modelling

GIS

GIS

Overview of Mapping Process

Model runs

Post modelling processing of outputs

Display of outputs

Final Mapping Outputs

Model outputs (Checked)

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Types of Hazard Maps

� Flood Extent � Flood Depth� Flood Zone � Flood Velocity� Flood Hazard Function Maps

Flood Extent

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Flood Depth

Flood Zone

Zone AFlood Zone A – High probability of flooding – Where the average probability of flooding from rivers and sea is highest (greater than 1% annually or more frequent than 1 in 100 for river flooding or 0.5% or 1 in 200 respectively for coastal flooding)

Zone B Flood Zone B – Moderate probability of flooding – (Risk between 0.1% or 1 in 1000 and 1 % or 1 in 100 for river

Zone C Flood Zone C – Low probability of flooding – (Risk is less than 0.1% or 1 in 1000 for both rivers and coastal flooding)

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Flood Velocity

Flood Hazard Function

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Flood Hazard

CFRAMs Hazard Mapping Requirements

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Scenarios - Allowances� Current� Mid-Range Future Scenario (MRFS) : Likely future scenario –

allowances for increased flow/sea level rise� High-End Future Scenario (HEFS): Extreme future scenario -

allowances for significant increased flow/sea level rise

Mapping uncertainty

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Degrees of confidence

• Used to account for uncertainties in outputs

Mapping and Assessing Flood Risk

• Assessment of flood risk requires consideration of probability and consequence of flooding

• Source – Pathway – Receptor model of flooding

• 'Flood receptors' are people, places, objects or activities that would suffer harm or damage in the event of a flood

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Key Receptors

� Define four groups of flood receptors:– Society (including risk to people)– The Environment– Cultural Heritage– The Economy

� Also consider measure of vulnerability to aid visualisation of consequences of flooding

Social

• Flooding can impact human health and community infrastructure

• Impacts could include personal injury, anxiety, relocation, death, loss of services (education, emergency services, health services etc)

• Consider four types of social receptors:– Residential properties– High vulnerability sites (e.g. residential homes)– Social infrastructure assets (e.g. emergency

services, hospitals etc)– Social amenity sites (e.g. parks, leisure centres)

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Social

Environment

� Flooding can impact the environment through the depth and duration of flooding, as well as the quality of the water (i.e. pollution)

� Consider three types of environmental receptors:– Integrated Pollution Prevention and Control (IPPC)

sites (e.g. refineries, mineral and chemical processing plants, landfills)

– Water abstraction for human consumption, recreational water bodies and designated habitats where water is an important factor in their protection

– Other environmentally valuable sites

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Environment

Cultural Heritage

� Flooding can impact world heritage sites, architecturally important sites, national monuments, museums etc

� Impacts could include direct damage due to depth, duration and quality of flood water, as well as indirect financial loss due to closure and repair

� Consider one type of cultural receptor:– Sites or assets of cultural value (e.g. museums,

historical monuments)

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Cultural Heritage

The Economy

� Flooding can impact residential and commercial properties, transport infrastructure and utility infrastructure (e.g. water, electricity)

� Impacts could include loss or reduction of commercial services, revenue, mobility and utilities

� Consider four types of economic receptors/indicators:– Residential and commercial properties– Density of annual average damage per unit area– Transport infrastructure (e.g. roads, rail, airports)– Utility infrastructure assets (e.g. water treatment works,

electricity sub-stations)

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The Economy

Economic Map Series

� General Flood Risk Maps

� Numbers of Inhabitant Maps

� Types of Economic Activity Maps

� Economic Risk Density Maps

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Economic Risk Density

Key Mapping Considerations

� Uncertainty – Accuracy – limitations (Need to be stated up front to avoid misinterpretation)

� Audience (who will view these maps and how will they be interpreted)

� Ensure level of detail is sufficient for the purpose and use of the maps

� Output quality (such as flood maps) are linked to quality of:� input data to modelling� modelling approach� past flooding information

� Maps allow for visual interpretation of complex modeling approaches and techniques and allow for easy consumption by stakeholders and the public