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Introduction to Flooding. by Environment Agency, Halcrow and Universities of Cardiff, Heriot Watt and Cambridge. General Background to Flooding. Background. Up to 5m people in U.K. are at risk from river and coastal flooding Annual average damage estimated at £0.7 bn

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Introduction to flooding

Introduction to Flooding

by

Environment Agency, Halcrow and

Universities of Cardiff, Heriot Watt

and Cambridge


General background to flooding

General Backgroundto Flooding


Background
Background

  • Up to 5m people in U.K. are at risk from river and coastal flooding

  • Annual average damage estimated at £0.7 bn

  • Recent floods have been more frequent

  • Damage extent exacerbated by:

    • Extensive building on flood plains

    • Alterations to riverine channels

    • Changes in recorded rainfall patterns

    • Changes in land management use

  • Climate change expected to increase flooding


Background1
Background

  • River flooding essentially a natural process that helps shape landscape

  • Flooding generally caused by high rainfall and inability of land to drain water effectively - aggravated further when ground saturated

  • Flooding frequently leads to serious water pollution and epidemiological problems

  • Flood damage extent often exacerbated by:

    • Inadequate flood warning systems

    • Use of crude hydroinformatics tools

    • Inadequately trained model users














River taff some typical challenges

River TaffSome Typical Challenges












Hurricane katrina august 2005

Hurricane KatrinaAugust 2005












Floodguards international
Floodguards International

  • State-of-art flood guards designed to protect homes and properties from flooding

  • Accessories designed to complement guards e.g. brick sealant and one-way toilet valves

  • Based on principle of arch dam design with pressure force used to enhance seal

  • Simple glass reinforced plastic (GRP) guards:

    • Permanent and unobtrusive narrow frame fixed around doors and air vents

    • Removable curved lightweight guards readily clipped in place before flooding


Arch dam principle
Arch Dam Principle

Mountain

Mountain

Arch Dam

Water Pressure

  • Water pressure transmitted to dam

  • Forces then transmitted to mountain


Flood guard principle
Flood Guard Principle

House Wall

Door

House Wall

Flood Guards

Water Pressure

  • Water pressure transmitted to flood guard

  • Force then used to increase seal efficiency


Without guards

Protection of Patio Doors

With guards



Model of seepage through brickwork
Model of Seepage through Brickwork

Aim:- Predict protection times and seepage for extended flooding

  • Research Centre’s model HEMAT used to predict seepage rates through brickwork and under wall foundations

  • Finite volume method solves flow equations

  • Irregular triangular mesh used to fit domain




Summary of floodguards
Summary of Floodguards

Benefits

  • Based on state-of-the-art technology

  • Relatively inexpensive and lightweight

  • Frame can be fitted easily and concealed

  • Prevents flooding of properties through doors, windows, air vents etc

  • Prevents silt and sewage contamination



Who are they
Who Are They?

  • Have over 10,000 staff - mainly scientists, engineers, planners - responsible for environmental protection

  • Have an annual operating budget of over £0.5 billion

  • Work in following areas:

    • Air Quality – regulate release of pollutants

    • Conservation – important role, especially along rivers

    • Fish – monitor and study fish habits and ecology

    • Flood – warn public about flood risk and build defences etc

    • Land Quality – seek to prevent land from becoming polluted

    • Navigation – responsible for rivers, estuaries and harbours

    • Recreation – managing use of inland and coastal waters

    • Waste – regulate waste management through licencing

    • Water Quality – ensure quality of surface and ground water

    • Water Resources – monitor and issue abstraction licences






Flood details
Flood Details

  • Spring 1998:-

    • Floods lasted 6 days and affected large parts of central and eastern England

    • More than 1,500 people were evacuated and 5 people died (questionably from floods)

    • Damage caused was approximately £0.75 billion

  • Autumn 2000:-

    • Floods were wettest in U.K. since records began

    • Rainfall in October was four times mean for month

    • More than 10,000 properties were flooded

    • Insurance claims totalled some £0.7 billion damage


Lessons from floods
Lessons from Floods

  • Flooding impact and damage to property etc was often much worse where defences were breached

  • Flooding in parts of catchments often made much worse by construction on floodplain or elsewhere along river, e.g. flood defences or realignment etc

  • Flooding impact exacerbated by responsibility being unclear between local and national authorities

  • Government reviews through various bodies have particularly highlighted need for a more strategic and catchment wide approach to flood risk management

  • Catchment Flood Management Plans (CFMPs) being prepared for all 80 catchments in England and Wales



What are they
What Are They?

  • Three year programme introduced by DEFRA and Environment Agency to develop Flood Management Plans for all catchments in England and Wales

  • Aim is to identify long-term sustainable policies to manage flood risk throughout catchment

  • Wide range of issues affect flood risk management:

    • Land use changes

    • Development planning

    • Flood defence works

    • Flood warning and emergency response

  • Consideration of flood risks and management solutions at catchment wide scale


Summary of main steps
Summary of Main Steps

  • Three year programme introduced by DEFRA and Environment Agency to develop Flood Management Plans for all catchments in England and Wales

  • Aim is to identify long-term sustainable policies to manage flood risk throughout catchment

  • Wide range of issues affect flood risk management:

    • Land use changes

    • Development planning

    • Flood defence works

    • Flood warning and emergency response

    • Consideration of flood risks and management solutions at catchment wide scale


Summary continued
Summary (Continued)

  • Determine existing and future flood risks and problem areas within catchment

  • Appraise all potential policies and future scenarios for flood risk management - also examine risks upstream and downstream

  • Determine preferred management policies by considering range of alternative scenarios against their relative impact on flood risk

  • Consult on and disseminate preferred CFMP

  • Regularly monitor, review and update CFMP


Catchment Flood Management Plan Process as Defined in Guidelines

Define catchment

Periodic review of plan

Scoping study

Collect catchment data and consult with stakeholders

Identify future scenarios

climate change / land use change

Understand catchment processes

Determine existing and future flood risks and problem areas

Identify opportunities and constraints

Identify future change in catchment processes

Appraise plan policies for each scenario

New or modified plan

Assess effect on catchment responses and flood risks

Define proposals and determine preferred plan (and residual risks)

Feedback Loop

Preferred plan consultation

Plan dissemination


Catchment data types
Catchment Data Types Guidelines

  • Flood management, e.g. flood defences, flood warning, existing flood maps, historical data

  • Catchment processes, e.g. climate, hydrology, hydraulics, hydro-geology, morphology

  • Economics, e.g. flood damage estimates, capital investment, maintenance of defences

  • Environment, e.g. nature conservation, landscape, recreation, archaeology, habitat

  • Land use and planning, e.g. national and municipal plans, and local plans (e.g. farmland changes)

  • Social aspects, e.g. population profiles at risk, sites of high risk facilities such as hospitals


Broad scale modelling
Broad Scale Modelling Guidelines

  • DEFRA and Environment Agency have introduced Broad Scale Modelling (BSM) initiative which includes following models:

    • Distributed rainfall-runoff processes

    • River flow routing throughout river basin

    • Effect of all potential flood risk management options on flood flows

    • Hydro-geological processes where applicable

    • Probability distribution predictions for different drivers of flooding risk

    • Effects of new developments and land use change

    • Effects of climate change and sea level rise


Outputs from cfmps
Outputs from CFMPs Guidelines

  • Assessment of current position across catchment

  • Clear statement of flood risk management objectives

  • Preferred long-term and sustainable policies for catchment wide flood management

  • Assessment of risks and uncertainties associated with preferred catchment flood management plan

  • Timetable for reviews of and revisions to CFMPs

  • Up to date list of references and related studies

  • Prioritised programme for future monitoring and modelling, and production of strategic plans



Development Team Guidelines


Basic tools
Basic Tools Guidelines

  • MDSF includes flood spreading tools based on ArcView GIS






Water some challenges
Water – Some Challenges Guidelines

  • 1.2 b people on this earth have no access to safe drinking water > 3 mpa die of diarrhoea

  • 2.4 b people on this earth do not have basic water sanitation > 1 mpa die from hepatitis A

  • A child dies in Africa every 30s due to Malaria  a disease related to stagnant water

  • Flooding often causes many deaths world- wide  over 250,000 in Indonesia tsunami

  • More than half hospital beds in world filled by people with water related diseases (BMJ 04)


Water is infinitely more critical to life on earth than oil
“Water is infinitely more critical to life Guidelines on earth than oil”

HRH The Princess Royal

Bradford University, 1989


Thank you
Thank You Guidelines


Presentation produced by
Presentation Produced by Guidelines

Professor Roger Falconer (Cardiff University)

Professor Garry Pender (Heriot Watt University)

Professor Binliang Lin (Cardiff University)

Dr Dongfang Liang (University of Cambridge)

Dr Jon Wicks (Halcrow)


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