Water

Abstracts from the 38th Flood and Coastal Management Conference, July 2003

Please see the main Conference page for details of ordering Conference proceedings or individual papers. Please note that the views expressed in Conference papers are those of the speaker and do not necessarily represent Defra views or Government policy.

Session 1: Sustainable Estuary Management

01-1 Saltmarsh and mudflat development after managed realignment

By: Angus Garbutt, Centre for Ecology and Hydrology (CEH), Chris Reading, CEH, Mineke Wolters, University of Groningen, Sue Brown, CEH and Alan Gray, CEH.

Abstract: During the past decade managed realignment, the setting back of sea defences to allow tidal inundation of reclaimed land, has become increasingly used in coastal management. The technique has significant economic and nature conservation benefits.

It is widely accepted that saltmarshes play an important part in ameliorating the effect of wave action on sea defences. By setting back defences and creating saltmarsh in the intervening area considerably savings could be made. Around the UK the annual loss of saltmarsh is estimated at 100ha per year. The UK Biodiversity Action Plan (BAP) commits the Government to develop strategies to conserve and, where possible, enhance biodiversity. Managed realignment has become the main technique used to meet BAP objectives for the creation of intertidal habitats.

In 1993 the Ministry of Agriculture, Fisheries and Food commissioned research, led by CEH (formally Institute of Terrestrial Ecology), to remove some of the uncertainties about returning agricultural land to intertidal habitat by managed realignment, specifically - will natural re-colonisation recreate saltmarsh within the realignment site and, if so, over what time scale; will there be any deleterious effects to the existing saltmarsh; and is it possible to aid the processes of natural colonisation directly or indirectly? The project was focused on the realignment site at Tollesbury, Essex. In this presentation we present the findings of monitoring and experimental studies and discuss the implications for other managed realignment schemes in the UK.

01-2 Making Room for Realism

By: Joanna Cooper and Helen Shardlow, Environment Agency and Ben Hamer, Halcrow Group Ltd.

Abstract: Flood defence works in the coastal environment principally fall into two main categories; capital schemes and maintenance works. The route through the Habitats Regulations for capital schemes is reasonably clear and has been for some time.

However, it is more difficult to justify "over-riding public interest" for maintenance works, especially for small, routine works. All works are required to be compliant with the Habitats Regulations and any works that perpetuate the current line of defence, in areas suffering from coastal squeeze are significant.

A revision of the guidance on applying the Habitats Regulations to maintenance works in Essex was undertaken in 2002. This resulted in some significant new policy and funding procedures for maintenance works for the next five years, prior to delivery of the CHaMP. It has been established that approximately 250 hectares of saltmarsh creation will be required over the next five years as a result of maintenance works in Essex.

Issues covered will be: Environment Agency guidance on revised policy; implications for maintenance programme; acquisition of land and integration into work of Essex Estuarine Strategies; public education and consultation process.

01-3 Developing a Coastal Strategy for the Steart Peninsula

By: Iain Blackwell, C.Eng, MCIWEM (KBR), and Daniel J. Leggett, MCIWEM (Babtie Group), Nick Moore, C.Eng, MICE (Environment Agency)

Abstract: The Stolford to Combwich Strategy combines the needs of Flood Management with over 25 other objectives, used as evaluation criteria for a range of options, to provide an integrated management plan for the Steart Peninsula. A wide range of investigations have been undertaken to provide detailed data and information on which to develop the Stolford to Combwich Strategy.

Session 2: Strategic Approaches to Estuary Management

02-1 Equilibria between Estuarine Bathymetries and Tides, River Flow and Sediment Supply

By: David Prandle and Andrew Lane, Proudman Oceanographic Laboratory

02-2 Estuary Process Research Project Linking Hydrodynamics, Sediments and Biology (ESTPROC)

By: Richard Whitehouse, HR Wallingford Ltd in association with The Estuary Process Consortium

Abstract: This paper discusses a major research project on estuarine processes within the Defra/EA R&D framework of Fluvial, Estuarine and Coastal Processes. The EstProc project brings together a multi-disciplinary team to undertake innovative research on estuarine hydrodynamics, sediments and biology and their interactions. The 3 year research project is being undertaken by a project team comprising 11 partners drawn from the UK and Netherlands. The paper describes the objectives and the agreed approach to the research and summarises some of the thinking at the mid-point of the project. More information about the project is available from the web site http://www.estproc.net/.

02-3 A Tale of Two Estuaries

By: Sarah Lavery, CEng MICE and Philip Winn, CEng MICE, Environment Agency

Abstract: The Humber and Thames - major East Coast estuaries flowing into the North Sea and subject to its coastal processes, tidal surges and sea level rise. Both estuaries provide the flood defences to major areas of population and urban regeneration as well as providing important wildlife habitats.

The Environment Agency is planning long-term flood risk management strategies for both estuaries. Work started on the Humber 7 years ago and plans are starting to take shape. The Thames strategy is in its early stages. The two projects have marked similarities but also significant differences. A small part of the Thames estuary is designated under the Habitats Directive unlike the Humber's anticipated estuary-wide designation. Regeneration initiatives provide opportunities and constraints for creative flood risk management in both the Humber and Thames estuaries. The Humber Trade Zone is looking to capitalise on the Humber ports for economic development, and the Thames Gateway initiative includes proposals for construction of additional housing for a population equivalent to that of Leeds to the east of London. Extensive modelling work will underpin the projects. There are significant opportunities for partnership working and developing creative flood risk management options.

This paper describes the Agency's approach to long-term flood risk management of these estuaries, and how the two projects will collaborate to develop sustainable solutions.

Session 3: Coastal Design and Management

03-1 Cliff Behaviour Assessment: A Quantitative Approach Using Digital Photogrammetry and GIS

By: Roger Moore, PhD CGeol, Paul Fish, PhD and Mark Glennerster, Halcrow Group Ltd, and Andrew Bradbury, PhD, New Forest District Council

Abstract: Further to Defra's FutureCoast study and the recently published Investigation and Management of Soft Rock Cliffs, there is a need to make robust projections of coastal change over the next 50 to 100 years to support coastal management strategies and decision-making. Projection of coastal change is not new, but until recently, the historical and baseline data on which they were based were largely qualitative and incorporated unknown errors. Probabilistic methods have been advocated in such cases to account for the errors with data and the wider uncertainties associated with the prediction of coastal change.

A quantitative approach for evaluating historical and future cliff behaviour is desirable given the nature of coastal geohazards and risk and the consequences of making decisions on high levels of uncertainty. With recent advances in technology and computer software, it is now possible to make use of spatially referenced (i.e. map-accurate) historical aerial photographs and compare these with digital historical mapping using desktop and laptop computers.

The UK archive of aerial photography dates back to the late 1930s, which provides a 60 year historical record of change of value to coastal studies. When used in a geomorphological context, quantification of the spatial and temporal pattern of coastal change provides a fundamental basis for making projections of coastal change for at least a comparable future period, all factors considered. The quantitative approach is primarily focused on establishing the errors with data so that account can be made of these in the projections. The approach is ideally suited for relatively simple coastal cliffs that have maintained an equilibrium form and behaviour in historical times that is set to continue during the life of the strategy.

The paper demonstrates the benefits of digital photogrammetry and the use of geographic information systems (GIS) by illustration of a quantitative cliff behaviour assessment of the Barton-on-Sea frontage carried out to inform the Christchurch Bay Coastal Defence Strategy.

03-2 Low Cost Rock Structures for Beach Control and Coast Protection

By: Matt Crossman (Defra, formerly HR Wallingford), Andrew Bradbury (New Forest District Council), William Allsop and Silvia Segura-Dominguez (HR Wallingford)

Abstract: Rock structures are used in coastal engineering for a wide variety of purposes, including controlling the morphological development of beaches and providing protection against coastal erosion. Strict adherence to existing design guidance has resulted in many of these structures being built using multiple layers of different rock sizes, high quality imported rock and carefully prepared foundations. Some innovative schemes have, however, used locally available rock with simpler cross-sections placed on unprepared foundations, apparently without significant reduction to the overall performance of the defence scheme.

This paper summarises practical guidance relating to the design and assessment of low cost rock structures for beach control and coast protection. It is hoped that the information presented will give greater confidence in the use of simplified rock structures, and encourage their wider adoption for beach control or coast protection purposes, particularly in situations where conventional structures would be uneconomic.

A more comprehensive practical guidance document has recently been published (Crossman et al., 2003) describing the applicability, performance requirements, design details and procedures in more detail. Through the inclusion of case studies the document also provides practical examples and the project has also identified some further research that could help to advance the design and assessment process.

03-3 Mixed Beaches (Sand/Gravel): Process Understanding and Implications for Management

By: Belén López De San Román-Blanco and Dr. Richard Whitehouse, HR Wallingford, Prof. Pat Holmes, Imperial College and Dr. Suzie Clarke, HR Wallingford

Abstract: A description of the main findings and implications of the 3-year research programme undertaken by HR Wallingford into mixed beaches (sand/gravel) is presented in this paper. The previously low level of understanding about the processes and behaviour of mixed beaches has been improved upon in the research, which has encompassed theoretical, laboratory and field data collection and numerical modelling. Gaps in knowledge have been identified in order to guide the future research in this area and suggestions made for the way in which further integration of the research into beach management practice can be achieved.

03-4 Responsible Use of Timber in Coastal and River Engineering

By: Matt Crossman1, Jonathan Simm2, Rod Nelson3, Richard Copas4, John Roach5 and Jeremy Purseglove6
1Defra (formerly employed by HR Wallingford), 2HR Wallingford, 3Ecosylva, 4Environment Agency, 5Babtie Group, 6Mott MacDonald

Abstract: Timber has long been used in coastal and river engineering and has many technical and environmental advantages over materials such as steel and concrete. However, recently there have been concerns regarding the environmental responsibility of using tropical hardwoods; these have been addressed as part of a recent project led by HR Wallingford to produce a 'Manual on the use of timber in coastal and river engineering'.

This paper provides an introduction to the issues associated with the use of timber and the specification and procurement framework developed for the manual which, building on the existing Environment Agency 'Timber information note', provides engineers and other professionals with a pragmatic decision pathway. This encourages the use of responsibly produced and certified timber whilst providing scope for the continued use of traditional hardwood species (both tropical and non-tropical) in appropriate situations. Examples of environmental benefits associated with the use of timber are illustrated through a case study of the Deptford Creek frontage improvements, which included extensive use of timber in an environmentally sensitive location.

Session 4: Shoreline Management Plans - Guidance

04-1 Shoreline Management Plans - The First Review

By: Jim Hutchison, BSc(Hons), MSc, CEng, MICE, MCIWEM (Department for Environment, Food and Rural Affairs (Defra))

Abstract: Shoreline Management Plans [SMPs] provide a large scale assessment of the risks associated with coastal processes and present a policy framework to reduce these risks to people and the developed, historic and natural environment in a sustainable manner. As such, they are important high level policy documents for the shoreline, developed, monitored and updated by the coastal operating authorities.

First generation SMPs covering the entire coastline of England and Wales have been completed and some in place for 6 or 7 years are now due for review. This paper sets out the background to the first generation of plans and explains what additional guidance has been developed to assist in the production of the second round of SMPs to ensure they are transparent and more consistent than the first round and that outputs are meaningful and clear.

04-2 Development of New Procedural Guidance for SMPs

By: Kevin Burgess and Adam Hosking (Halcrow Group Ltd), Jim Hutchison, BSc(Hons), MSc, CEng, MICE, MCIWEM (Department for Environment, Food and Rural Affairs)

Abstract: The document 'Shoreline Management Plans, A guide for coastal defence authorities', Defra, June 2001, (hereafter termed the '2001 SMP Guidance') identifies the requirements for developing future SMPs. It provides the aims and aspirations for future SMPs, but does not elaborate upon the mechanisms to achieve them. The new SMP Procedural Guidance document has been developed using industry-wide expertise to establish the most appropriate, best practice methodologies to deliver the SMPs in accordance with the 2001 SMP Guidance.

This is the first of 2 papers that are to be presented at the conference to convey the findings of the PG project. These provide a brief synopsis of the main developments from the PG and the tools and approaches to be used in developing future SMPs. The content of this paper is intentionally brief, with the draft PG document now available to all for scrutiny, containing the details.

04-3 Policy Definition in SMPs

By: Adam Hosking, Alison Atkinson and Helen Jay (Halcrow Group Limited), Gregor Guthrie (Posford Haskoning), Daniel Leggett (Babtie Group), Jonathan McCue(Atkins) and Jeremy Richardson (Scott Wilson Kirkpatrick)

Abstract: The document 'Shoreline Management Plans: A Guide for Coastal Defence Authorities' (Defra, June 2001; hereafter termed the '2001 SMP Guidance') identifies the requirements for developing future SMPs. It provides the aims and aspirations for future SMPs, but does not elaborate upon the mechanisms to achieve them. To address this, the new SMP Interim Procedural Guidance (PG) document has been developed using industry-wide expertise to establish the most appropriate, best practice methodologies to deliver the SMPs in accordance with the 2001 SMP Guidance.

This is the second of two papers presented at the conference. This paper discusses the approaches promoted for the definition of policies in SMPs, using the understanding of coastal processes to achieve policies that best achieve the shoreline management objectives for an area. These approaches include the clear definition and ranking of the objectives, and their subsequent use in the testing of generic options.

04-4 Identifying Biodiversity Opportunities to Inform the Review of Shoreline Management Plans

By: Christopher Pater (English Nature), Helen Dalton and Francesca Ravaioli (Posford Haskoning)

Abstract: The Identifying Biodiversity Opportunities study was commissioned by English Nature and undertaken by Posford Haskoning Ltd to identify enhancement opportunities that might be realised through the coastal defence policies adopted by the second generation of Shoreline Management Plans. The study used facilitated workshops to identify potential opportunities for restoration and improvement, but also where effort could be directed at expanding existing habitats or modifying habitat management to benefit biodiversity. The study used English Nature's 'Natural Areas' framework to break down the targets for the UK Habitat Action Plans with attention directed to the Shoreline Management Plan areas where review is underway in Kent, Norfolk and East and West Sussex. If repeated around England, this study will enable coastal defence Operating Authorities to make progress towards the High Level Target for biodiversity set by the Department for Environment, Food and Rural Affairs (Defra).

04-5 CHaMPs - Past, Present and Future: Lessons Learnt and use with SMPs

By: Stephen Worrall, IEng (Living with the Sea LIFE Nature Project)

Abstract: The paper outlines the challenges facing the United Kingdom in managing its coastal habitats designated under European legislation. It looks at how the United Kingdom can fulfil its obligations under the Habitats Directive and continue to provide protection to the important urban and developed coastal areas. This must be considered against the habitats response to the increasing pressures of sea level rise and climate change.

The paper sumarises lessons learnt from the 'Living with the Sea' LIFE Nature project that has been piloting 'Coastal Habitat Management Plans' (CHaMPs). The seven pilots are summarised and the link with SMPs considered.

Session 5: Managing Flood Risks

05-1 Maximising the Synergy of Emergency Response and Flood Warning Target Lead Times

By: Martin Whiting, B.SC CENG MICE MCIWEM ( Posford Haskoning Ltd), Rahman Khatibi, B.Sc M.Sc Ph.D ( Environment Agency) Fola Ogunyoye, B.Sc M.Sc CEng MCIWEM ( Posford Haskoning Ltd) and Dave Jackson, B.Sc CEng MICE ( Environment Agency)

Abstract: The recognition of the inter-connection of the activities involved in flood risk reduction during extreme events could reap significant benefits in future integrated flood risk management. Two of these activities are flood forecasting and warning, and emergency response. The current management of these two activities tends to predominantly be a transfer of information between two relatively discrete activities without maximising their synergies.

The Environment Agency currently provides a flood warning service in England and Wales, with target lead-times to flooding of two hours and one hour respectively. While this deterministic approach has served as a rule of thumb to provide a consistent service since 1995, the significant advances in forecasting, modelling, and temporary protection systems provides the opportunity to move towards a more probabilistic system. Such a system needs to be targeted to provide better service to areas with higher flood risk, and be better integrated with temporary flood protection and other emergency response activities.

This paper will review the feasibility of improving the integration of flood warning services with the planning and operation of emergency response; in particular temporary and demountable systems. The effect on flood risk reduction and other related issues like property insurance will also be considered.

05-2 Risk Assessment for Strategic Planning (RASP) - A National Scale Application and a Look Forward to More Detailed Methods

By: Paul Sayers1 CEng MICE, Jim Hall2 PhD CEng MICE, Richard Dawson2 MEng, Corina Rosu1 PhD, John Chatterton3 PhD, Rob Deakin BSc4 , Mike Panzeri BSc1
1Engineering Systems and Management, HR Wallingford
2Department of Civil Engineering, University of Bristol
3John Chatterton and Associates
4Halcrow Group Ltd

Abstract: This paper builds upon the paper presented at Defra 2002, outlining the RASP High Level Methodology, to provide more detailed level analysis within the context of a consistent and tiered analysis framework. In particular, the paper provides an insight into the Intermediate and Detailed Level analysis proposed under RASP, with the following distinction:

  • The Intermediate Level of the RASP methodology aims to support Shoreline Management Plans, Catchment Flood Management Plans and more detailed aspects of fluvial and coastal strategy plans. The results could also be used to improve and verify studies such as the National Flood Risk Assessment 2002 for defined areas, and will support decision-makers in the prioritisation of expenditure, regional and strategic planning, planning of flood warning, regulation of development and maintenance management.
  • The Detailed Level of the RASP methodology supports scheme design and optimisation. The level of analysis and associated costs mean that for detailed level methodology it is feasible to undertake data collection and analysis that may be considered infeasible on the scale of a catchment or coastal cell.

In addition to outlining the methodologies, the paper will demonstrate the vision of data and information flow between levels and the concept of increasing detail and reducing uncertainty.

The Intermediate and Detailed Level analysis are currently under development and due for completion by December 2003. This paper is therefore timely in outlining best practice approaches, raising awareness as to the applicability of the methods and looking forward to better, more risk-based, decision-making.

05-3 Flood Safety and Spatial Quality: Towards Integrated Coastal Zone Management in the Netherlands

By: Hans Balfoort, Aline Arends and Hermine Erenstein, National Institute for Coastal and Marine Management/RIKZ - Ministry for Transport, Public Works and Water Management, Netherlands

Abstract: The Netherlands coast is an attractive living, working and recreational environment, with substantial economic and environmental value. In the future, however, coastal defences will face a heavy battering from rising sea levels and an expected higher frequency of storms. The ability to combat these challenges requires space in the coastal zone, which space is being claimed by other functions. Moreover, the national government is undertaking the duty to guarantee the safety of the hinterland and maintain - and where necessary enhance - the spatial quality of the coastal zone.

The Dutch government resolved to publish a policy line for the coast in 2003. The policy line will cover subjects of imminent importance, giving priority to safety policy. Nonetheless, it intentionally defines the scope of coastal policy as broadly as possible, particularly in the chapters addressing the weak links in the coastal defence, the management of risks in coastal towns, and a coastal foundation zone for long term coastal protection. In addition, the policy line will represent the next step towards a more integrated coastal zone policy.

The process leading up to the policy line includes the publication of a policy agenda and discussion sessions with all relevant authorities and stakeholders. The paper will cover the outcome and the process leading up to this new coastal policy development in the Netherlands.

05-4 Community and Public Participation: Risk Communication and Improving Decision Making in Flood and Coastal Defence

By: Jeremy Richardson (Scott Wilson), Joanne Reilly ( Flood Defence, Environment Agency), Dr P. J. S Jones (Environment and Society Research Unit (ESRU), Dept of Geography, UCL)

Abstract: This paper will examine the role of 'social research' and 'communications' in the flood warning and response process.

We know that the 'at flood risk' population is not a homogenous group. To deliver a flood warning service which elicits an effective response from the at risk population, the service development must be informed by and able to respond to the diverse needs of the recipient group.

This presentation will focus on the following:

  • A programme of research and communications which underpins the Agency's Multi Media Warning Dissemination project in partnership with the Met Office. This will examine the role of social research in informing the development of new channels for the dissemination of flood and severe weather warnings. It will also look at the communications challenge posed by this project (encouraging people to sign up for a flood warning service etc) and how these are to be met.
  • Results from Defra & Agency funded research to identify those groups most vulnerable to flooding and how the warning service should be tailored to address their specific needs. It will introduce recommendations for methods of delivering flood warnings to those least able to receive warnings, those least able to understand the warning those least able to act upon the information.
  • The Agency's relationship with the National Flood Forum, a network of community groups in areas at risk of flooding. It will focus on how the Agency involves the Forum in providing grass roots level input to the development of both the flood warning service and the supporting communications programme.
05-5 Climate change and flood frequency in the UK: An appraisal of the 20% sensitivity allowance in the light of the UKCIP02 scenarios

By: Nick Reynard1, Simon Brown2, Sue Crooks1 and Alison Kay1
1CEH-Wallingford
2Hadley Centre for Climate Prediction and Research

Abstract: Global warming is predicted to cause significant changes to the world's climate, but uncertainties remain about the precise nature of these changes. This is particularly true with regard to possible changes at a regional level and to extremes, such as short duration, high intensity rainfall. This means that the climate statistics of the past might not provide an adequate description of the future. To address this, Defra guidance on scheme appraisal suggests sensitivity allowances for climate change, for example a 20% increase in peak flows over the next 50 years.

The need to further develop this policy and guidance on climate change impacts is being informed by improved modelling capabilities and climate change scenarios. The new UKCIP02 scenarios are available at a finer resolution than were previously available and they also provide more information on possible changes to extreme events. CEH-Wallingford has been commissioned by Defra and the Environment Agency to assess the climate change impacts on flood flows under these UKCIP02 scenarios. This paper provides a first appraisal of the appropriateness of the 20% allowance under the UKCIP02 scenarios by presenting the flood frequency results for the Thames and Severn catchments.

Session 6: Catchment Flood Management Issues

06-1 The Impact of Floodplain Restoration on Flood Hydrology

By: Mike Acreman, Centre for Ecology and Hydrology

Abstract: This study was part of the Wise Use of Floodplains initiative funded partly by the EU LIFE programme, Defra, the Environment Agency, Thames Water and the Centre for Ecology and Hydrology. Its overall aim was to demonstrate how floodplains can contribute to the sustainable management of water within river basins and thus play a role in effective implementation of the EU Water Framework Directive.

This paper reports on computer modelling of the River Cherwell in Oxfordshire, to show the impacts on floods of changes to river channel geometry and construction/removal of embankments that prevent water spreading onto the floodplain at high flows. Using hypothetical changes to the River Cherwell between Oxford and Banbury, embanking the river increases the peak flows downstream by up to 150%. Restoring the river channel through the floodplain to pre-engineered dimensions reduces peak flow by around 10-15% and increases peak water levels within the floodplain by 0.5-1.6 m. These results suggest that floodplain restoration, in terms of embankment removal or reducing channel dimensions to pre-engineered dimensions, can be part of a catchment's flood management strategy. Both measures lead to increased inundation of the floodplain, which can have positive benefits for ecological restoration.

06-2 River Habitat Objectives: Guiding River Management And Engineering

By: Jim Walker, Marc Naura, Mark Diamond and Paul Raven
Conservation and Ecology, Environment Agency, England and Wales.

Abstract: The current approaches to setting objectives for river restoration at a catchment and national scale in the UK are described.

  • The development of a national framework to set River Habitat Objectives (RHOs) for the benefit of wildlife, landscape and society is discussed.
  • A national strategy for River Habitat Objectives is defined, including the development of a typology of natural rivers and mechanisms for setting simple habitat improvement targets for different river types.
  • The pilot application of this strategy at a catchment scale and the importance of Flood Defence and other forms of river management in the implementation of RHOs are discussed.
  • A provisional timetable for the development of the national RHO strategy is presented.
06-3 The Integration of Wetland Habitat Re-Creation and Flood Defence - The Severn & Avon Vales Wetlands Partnership

By: Brian Smith, The Severn & Avon Vales Wetlands Partnership

Abstract: The loss of natural floodplains through urban development, flood defence, land drainage and agricultural improvements has led to a dramatic decline in habitats and wildlife. Once common wetland birds, such as Lapwing, are now uncommon or rare breeding species and many historic features have disappeared from our river landscapes.

Changes over the past ten - fifteen years in agricultural economics, increasing public awareness of environmental issues and access to the countryside for recreation have, however, created new pressures and incentives for the development of sympathetic and sustainable land management practices. Recent major flooding events have raised awareness of the need to restore and manage our floodplains for a broad spectrum of socio-economic and environmental objectives, which are now reflected in changes in government policy for flood defence and agriculture.

This paper sets out the structure and achievements of the Severn and Avon Vales Wetlands Partnership (SAVWP) and demonstrates how, as a major cross-sectoral initiative; SAVWP can contribute to the integration of economically viable farming and the re-creation of wildlife habitats into the development of sustainable floodplain management.

06-4 Update of Research on Land Use and Runoff

By: E P Evans1, P E O'Connell2, P F Quinn2, K Beven3, J N Carney4, R O Clements5, G L Harris6, J M Hollis7, J C Packman8
1Project Manager, Defra, 2University of Newcastle upon Tyne, 3University of Lancaster, 4British Geological Survey, 5Inst. of Grassland and Environmental Research, 6ADAS, 7Cranfield University, 8Centre for Ecology and Hydrology

Abstract: An interdisciplinary consortium is conducting a review on behalf of Defra of the current state of knowledge on the impacts of rural land use and management on flood generation. The review will cover a range of impacts associated with afforestation/deforestation, field drainage and agricultural land management practices, and will be delivered in the form of an Impact Study Report. A short-term method for assessing impacts within Catchment Flood Management Plans (CFMPs) is being developed which also incorporates decision support on the mitigation of adverse impacts. Gaps in knowledge will be identified and a Research Plan prepared which will map out the research projects needed to make reliable predictions of impacts across a range of catchment scales. This will include an integrated programme of experimentation and modelling which will link with existing national catchment research programmes (CHASM and LOCAR). A modelling framework will be proposed which can incorporate alternative model structures and the quantification of predictive uncertainty. A framework for decision making under uncertainty will be developed which will enable appropriate courses of action to be identified to mitigate flooding.

06-5 Integrated Washland Management for Flood Defence and Biodiversity

By: Morris J1, Hess T M1, Gowing D J1, Leeds-Harrison P B1, Bannister N1, Vivash R M N2 and Wade M.
1Cranfield University at Silsoe
2River Restoration Centre, Silsoe, Ecoscope, St Ives, Cambs

Abstract: A combination of reform of agricultural policy, changing priorities in the countryside, growing commitment to protect and enhance biodiversity, and concerns about increased flood risk in lowlands have drawn attention to the potential contribution that managed washlands can make to deliver benefits to biodiversity and flood management. In this context, and with funding from Defra and English Nature, the study reported here set out to determine the scope for simultaneously achieving flood management and biodiversity objectives, and how this might be achieved in practice. The broad purpose is to inform policy on washland creation and management, including mechanisms for implementation if deemed appropriate.

Session 7: Planning Delivery and Appraisal

07-1 Top Teams Test the Water

By: Lloyd Marlow ( Environment Agency) and George Whetman (Mowlem Plc)

Abstract: In 2000, the Environment Agency launched a strategy designed to improve the procurement of its £150mpa civil engineering programme to provide better flood defences. The strategy was designed to

  • Deliver best value for money
  • Place the Agency at the leading edge of technology, innovation and business best practice
  • Champion environmental best practice

This paper traces the development of the strategy, the targets that were set and how the Agency selected its future partners, before highlighting the initial results and lessons learned from the projects delivered so far.

07-2 The Extreme Flood Outline

By: Simon Waller, BEng CEng MICE and Kate Bradbrook, MA PhD CEng MCIWEM (JBA Consulting), Marc Huband, BA MSc and George Mitchell BEng MEng Sc MBCS (Atkins) and Peter Gilkes BSc CEng FICE MCIWEM MIM (Environment Agency)

Abstract: Flooding has now assumed high profile, becoming a lively, nationally debated topic; Government has recognised the need for better-informed decision making with regard to flooding and development within the floodplain and published PPG25 to give guidance to Planning Authorities. PPG 25 anticipated the Agency's intention to produce the EFO although, at the time of publication, no defined method for producing the EFO had been developed.

The Agency has worked in Partnership with its framework consultants to develop the techniques and methods to produce a nationally consistent and robust EFO. This will both assist in the operation of PPG25 planning guidance and improve the general understanding of flood plains and the sensitivity of their mapped extent in extreme events.

This paper sets out the methods to be used in mapping both fluvial and tidal envelopes of extreme flooding and summarises the validation checks that have been undertaken.

07-3 Accommodating Growth in the South East: The Implications of Water Issues and Flood Risk

By: Hugh R Howes, B.Sc. (Econ), M.R.T.P.I. Regional Strategic Planner, Environment Agency-Thames Region

Abstract: Pressures on local planning authorities to allocate land in floodplains for development are at their greatest in the South East of England. They have experienced difficulties in interpreting floodplain policies in terms of relative risk from a flooding event and are not always best informed when deciding to allocate land for development or not. Recent research has highlighted these problems and has proposed a refinement to policy formulation to overcome them.

07-4 PPG 25 - Is It Working?

By: David Brook, Cgeol FGS, Jonathan Chapman, CEng MI AgrE MCIWEM and Dave Crowson C Eng MICE MCIWEM
Office of the Deputy Prime Minister and the Environment Agency

Abstract: PPG 25 was published in July 2001 with a commitment to review it 3 years after publication. Monitoring of its implementation and effectiveness is carried out principally through high-level target 12 and land-use change statistics supplied to ODPM by the Ordnance Survey. The information available from before and after publication suggests that PPG 25 is beginning to have an effect in raising the profile of flooding in the planning system. Most local authorities now have flood-risk policies and most decisions in flood-risk areas follow Agency advice. Some elements of PPG 25 have not yet been fully implemented.

07-5 The Appraisal of Human-Related Intangible Impacts of Flooding

By: Peter Floyd and Carolyn George (Risk & Policy Analysts Ltd.), Sylvia Tunstall, Sue Tapsell and Colin Green (Flood Hazard Research Centre, Middlesex University), Michael Jones-Lee and Hugh Metcalf (University of Newcastle)

Abstract: This paper provides an overview of a major study to assess the health impacts of flooding and the development of a methodology to account for such impacts in the economic appraisal of flood and coastal defence projects. The study involved the development of questionnaires that were used in a survey of 1,500 respondents in 30 locations across England and Wales, which had experienced flooding in the last few years. The results demonstrate that flooding causes adverse health impacts, particularly psychological, and these were measured using various scales. The impacts are associated with a wide range of factors, covering not only flood attributes and socio-economic factors but also those relating to post-flood difficulties such as problems with insurers and builders. Respondents were also asked to express a willingness to pay (WTP) to avoid such impacts. Nearly two-thirds of respondents expressed a WTP and, after allowing for zero bids, the overall mean WTP was estimated to be about £200 per household per year. A methodology for incorporating this value into economic appraisal is being developed and will be presented at the conference.

Session 8: Policy Forum

08-1 Current Policy Issues

By: Flood Management Division, Defra

Abstract: Conference Session 8 provided the opportunity for delegates to discuss progress with current policy developments.

Session 9: River Modelling and Design

09-1 Testing and Benchmarking 1D Hydraulic River Modelling Packages

By: Richard Crowder, BSc, PhD, CEng, MCIWEM ( Halcrow Group Ltd, UK)
Andrew Pepper, BSc, CEng, MICE, FCIWEM ( ATPEC River Engineering Consultancy, UK)
Chris Whitlow, BSc, PhD, MIAHR ( Eden Vale Modelling Services, UK)

Abstract: The past 20 years has seen the proliferation of hydraulic river modelling software for studying many different river problems. Their origins were usually undergraduate project work, doctoral research, one-off consultancy commissions or in-house project solutions. By 1996 this approach saw eleven different software packages used by the Environment Agency for 1D hydraulic river modelling, leading to significant technical and business delivery issues. Therefore a series of benchmarking tests was undertaken [1],[2] to identify and assist selection of the most appropriate software packages. Subsequently new and more advanced features were added to some of these packages, although the most appropriate package for a given problem may not be the most advanced software package. Testing and Benchmarking provides a vital role in identifying the appropriate use of hydraulic river modelling software packages as they are developed or improved.

As part of the Environment Agency/Defra R&D Programme, a new generic test dataset and specification [3], which has built upon the strengths of the previous work, has been devised to enable river modelling software packages (1D, 2D or 3D) to be benchmarked. The tests have identified [4] some of the fundamental differences and constraints of three widely used 1D hydraulic river modelling software packages (ISIS, MIKE 11 and HEC-RAS).

09-2 Selection of Appropriate Methods for Flood Modelling

By: Jon Wicks and Richard Mocke (Halcrow Group Ltd) Paul Bates (University of Bristol), David Ramsbottom (HR Wallingford Ltd), Edward Evans (Consultant), Carl Green (Wyre Borough Council)

Abstract: The use of computer modelling to predict flood extents now forms a key element of many coastal and fluvial flood management studies. In order to minimise the cost of this element it is important to select the most appropriate modelling method (ie that giving sufficient accuracy at least cost). For coastal flood studies this paper recommends dynamic storage cell based approaches such as ISIS flood cell representations and raster routing. Based on the experience of the Wyre coastal flood study described in the paper, the raster routing approach is considered to have benefits in terms of minimal set up time and making best use of digital terrain data. For Catchment Flood Management Plans, the paper discusses the conditions under which flood modelling is required and recommends the use of 'enhanced' routing and sparse hydrodynamic models.

09-3 Revitalising The FSR/FEH Rainfall-Runoff Method

By: E J Stewart, J C Packman and A C Bayliss (CEH Wallingford)

Abstract: The paper discusses recent progress within a two-year project jointly funded by Defra and the Environment Agency to revitalise the FSR/FEH rainfall-runoff method, taking advantage of new data, updated analytical techniques and advances in computation since the original method was developed. A revised form of the unit hydrograph model is proposed, which includes new procedures for soil moisture accounting and baseflow separation. An example of the first results of applying the model is given and the likely direction of future research is discussed.

09-4 The Flood Estimation Handbook Statistical Procedures: Automation, Appraisal and Future Development

By: D G Morris, A C Bayliss and E J Stewart (CEH Wallingford)

Abstract: The Flood Estimation Handbook statistical procedures for estimating the magnitude of the T-year flood peak at any river location in the UK have been automated and applied nationally for a range of return periods. The lessons learned during automation and in analysing the automatically produced network-wide estimates have led to numerous recommendations for improving the procedures. This paper describes the procedures, their automation, their performance and anticipated future development. It also describes how the resultant datasets of UK-wide flood peak estimates are being used and how they could be further developed.

Session 10: Best Practice in River Engineering

10-1 Weirs - Best Practice Guidance

By: Charles Rickard1, Dr Rodney Day2 and Jeremy Purseglove1
1Mott MacDonald and 2The University of Hertfordshire

Abstract: This paper presents a brief overview of the EA/Defra funded Best Practice Guide on Weirs. The intention of the paper is to make delegates attending the 2003 Defra Conference aware of the new Guide. Inspiration for the Guide came out of an MSc thesis by Paul Wyse (EA Thames) - "Considerations to be taken into account when constructing or decommissioning a weir or sluice".

The Authors are grateful for the considerable assistance provided by a large number of EA personnel and other interested parties. Particular thanks are due to Andy Pepper (ATPEC) and Samantha Godfrey (EA), who provided support, advice and guidance.

10-2 Operations and Maintenance of Flood and Coastal Defences - A Framework for Performance-Based Management

By: Fola Ogunyoye, CEng MCIWEM, Posford Haskoning, Dr Mervyn Bramley, CEng FICE FCIWEM, Environment Agency and Gregor Guthrie, CEng MICE, Posford Haskoning

Abstract: Operations and Maintenance (O&M) tends to be an under-supported area within the overall flood and coastal defence business. A Concerted Action on O&M was carried out within the Defra / Environment Agency joint R&D programme to review current practice and developments, and to identify how best R&D might support the improved delivery of O&M benefits. Recommendations for future O&M development and a performance-based management framework for its delivery have been developed as part of this study. The proposed framework provides a logical process for asset management that allows decisions on management intervention to be based on their effect on the ability of the individual asset or defence system as a whole to meet its performance objectives. The broad nature of the framework will enable O&M to be planned on a similar risk-reduction basis as other forms of intervention such as major improvement schemes.

The development is in line with the general shift in the approach to flood and coastal management in the UK from a deterministic approach focused on the design standard towards a risk-based approach that considers performance over a wider range of flood or storm events (ICE, 2001). It also allows the most appropriate form of management to be carried out on flood and coastal defence systems, based on whole life analyses of river catchments or coastal cells.

An important aspect of the delivery of the framework is the development and trialling of a performance based asset management system (PAMS). R&D to provide improved knowledge on the performance and management of key parts of the flood and coastal defence systems should support this. This paper is relevant to all Flood and Coastal defence operating authorities. It discusses the O&M framework, the development of PAMS, and ongoing and proposed R&D and pilot studies on the management of embankments, river channel conveyance and defence structures. All these embrace the principles of an improved focus on performance and the practitioner needs.

10-3 River Eastern Rother - Robertsbridge Flood Alleviation Scheme: Reacting Quickly to Manage Flooding Through Partnering

By: Andrew Pearce, Andrew Davies and Paul Sedgwick (Environment Agency) Roland Grzybek and John Palmer (Halcrow Group Ltd) and John Garland (Edmund Nuttall Ltd.)

Abstract: Robertsbridge was one of the worst affected townships in East Sussex during the flooding in the autumn/winter 2000, and over that period some properties were flooded up to eight times. The most serious flood on 12 October 2000 affected over 80 commercial and residential properties. Following those events, the Agency targeted this high risk township as one of the key, high priority, projects in its National Capital Programme.

In January 2001, studies started to propose solutions that could be justified within technical, economic and environmental assessment criteria. The recommended outcome was a stand-alone scheme reducing the risk to the village against the 1% probability flood, supported by the Environment Agency and DEFRA. The studies progressed to detailed design and the preparation of drawings and documents for construction, and the contractor embarked on a programme that will see completion of the works in summer 2003.

This paper describes the use of the Agency's new procurement strategy, based on the principles of Egan and Latham, to "fast-track" a flood defence scheme through the myriad of obstacles that often beset a project. It illustrates how obstacles can be overcome if a dedicated and committed team create the drive and desire for success. The paper covers the scheme development on a stand-alone basis, and then looks at the procedural aspects and the approach that enabled the challenging programme to be met.

10-4 Perth Flood Prevention Scheme: Operational Issues And Environmental Considerations

By: G A McInally (Babtie Group) and A Olejnik (Perth & Kinross Council)

Abstract: In every scheme there is the need to balance engineering, operational requirements and financial considerations against environmental impact. Increasingly recognition is given to the existing environment and greater efforts being made to produce schemes that, whilst meeting the needs of the end user, are also environmentally sustainable. The recognition and embracing of this approach has led to the completion of a major flood prevention scheme that enhances the local environment and gives the required level of flood protection. In achieving this balance there has been a financial consequence arising from the inclusion of comprehensive environmental mitigation measures. However, perhaps the greatest impact has been the increase in operational and maintenance requirements due to the retention of existing access to the river and the commitment to accommodate business requirements within the flood defences.


Page published: 16 August 2004
Page modified: 16 August 2004

Department for Environment, Food and Rural Affairs