41st conference abstracts
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Session 1: Environmental challenges
01.1 Broad scale ecosystem assessment (BSEA)
Dr Kieran Conlan MCIWEM CBiol
Steve Dangerfield CEnv MCIWEM
Trevor Wade
Cascade Consulting
Key Words: ecosystem, ecology, flood risk, broad-scale, fluvial, coastal/estuarine, cfmp, smp, sea
Abstract: BSEA was commissioned to develop good practice procedures (guidance and methods) for the assessment of catchment or coastal cell ecosystem effects that may result from river and coastal cell management policies/options (assessed within the Catchment Flood Management Plans and Shoreline Management Plans frameworks). The work supports the joint Defra/Environment Agency flood and coastal erosion risk management R&D programme.
BSEA uses nationally consistent, broad-scale data to define ecosystem function and status in a GIS-based framework. Catchments are described in terms of channel condition, floodplain connectivity and channel continuity. Coastal cells are characterised by shoreline migration, tidal inundation and coastal flooding, and mobile sediment availability. Catchment or coastal-cell protection or enhancement objectives (termed Broad-scale Ecosystem Criteria, BEC) are generated and spatially mapped. The objectives are used to inform and/or assess management policies and are in a format that allows integration with Strategic Environmental Assessment and the Water Framework Directive procedures.
The BSEA guidance and toolbox has been developed by a consortium led by Cascade Consulting. They have been tested on three case studies (Rivers Derwent and Ribble, and South Foreland to Beachy Head). This paper introduces the concept of BSEA and sets out the approach to fluvial catchments, illustrated with examples from the River Derwent case study. The final report will be available soon on the Defra website.
01.2 South-east strategic regional coastal-ecology monitoring programme
Helen Dalton
Kate Potter
Environment Agency
Sam Cope
Channel Coastal Observatory
Chris Blair-Myers
Peter Brett Associates
Andrew Bradbury
Channel Coastal Observatory
Key Words: bap monitoring, aerial photography interpretation
Abstract: The Environment Agency Southern Region are partners in a region-wide coastal monitoring programme called the South-East Strategic Regional Coastal Monitoring Programme (SRCMP). The SRCMP monitors coastal process data between Portland Bill, Dorset and the Isle of Grain, Kent in partnership with 30 Local Authorities. Ecological monitoring has recently been incorporated into the programme to identify the location of coastal Biodiversity Action Plan (BAP) habitats and to integrate this information with the coastal process data. This has followed the recommendations of a Scoping Report produced for English Nature and the Environment Agency by the Channel Coastal Observatory.
Operating authorities dealing with flood risk and coastal protection are increasingly required to take account of and report on their impacts on BAP habitats. With sea level rise exacerbating issues such as coastal squeeze, it is pertinent that these habitats are monitored in a strategic manner. Results from this cutting edge project will feed into Shoreline Management Plans (SMPs), coastal strategies, coastal defence schemes and Defra High Level Target reporting.
A baseline coastal BAP habitat map is being produced using aerial photography interpretation so that future surveys can monitor change (every 6 years). The habitats are classified using the Integrated Habitat System (IHS) created by Somerset Environmental Records Centre. The classification integrates UK BAP priority habitat and Annex 1 (Habitats Directive) classes within a hierarchical structure and relates to the National Vegetation Classification system (NVC).
The IHS has been substantially expanded and modified for use in coastal habitats as part of the Environment Agency Thames Estuary 2100 Project. The SRCMP has adopted the same methodology to ensure consistency between the neighbouring Environment Agency regions and the same approach may be extended into South-West Region.
The production of this baseline is being part-funded by the European Interreg IIIb project, BRANCH , led by English Nature. This is looking at the need for biodiversity to adapt to the impacts of climate change and the project is developing spatial planning tools to inform policy and future site management.
01.3 Regional habitat creation programmes: delivering environmental objectives
Duncan Huggett
Paul Miller
Environment Agency
Nathan Richardson
Atkins
Key Words: strategic, habitat, creation
Abstract: Delivering environmentally acceptable flood risk management solutions is challenging where internationally important wildlife sites are involved. This is particularly the case where these are coastal sites affected by rising sea levels. Often, for schemes to proceed, new habitats have to be created to compensate for those damaged or lost. Furthermore, the Environment Agency has habitat creation targets agreed with Defra. These include ensuring no net loss of Biodiversity Action Plan habitats as well as creating a minimum of 200 hectares of new habitat a year.
Current Defra policy encourages us to take a strategic approach to providing compensation habitat and promotes anticipatory land acquisition where appropriate. The Anglian Region of the Environment Agency has developed a habitat creation programme, which identifies likely habitat compensation requirements, and enables the purchase of land and creation of habitats in advance of them being needed. This approach has a range of important benefits. In particular, it facilitates the delivery of environmentally acceptable flood risk management schemes in a cost-effective and timely manner.
01.4 Challenges in meeting the WFD and achieving sustainable flood risk management in urban rivers
Valerie Bain
Roger Bettess
HR Wallingford Ltd
Matthew Hardwick
Steve Vernon
Royal Haskoning
Key words: wfd, river rehabilitation
Abstract: The improvement of urban rivers to reach good ecological status or good ecological potential represents a significant component of the work to meet the Water Framework Directive (WFD), given that the ecology of urban rivers is frequently highly degraded and that many of the rivers in the UK flow through urban centres. Likewise, the degradation of urban rivers has an impact on the hydrology and sediment regime of the catchment which can result in channels with low conveyance for flood flows.
The URBEM European research project that was completed in October 2005, has provided extensive information on urban river rehabilitation schemes throughout Europe and North America. This paper draws on the lessons learnt from these international experiences of urban river rehabilitation, including information on the effectiveness of rehabilitation schemes in improving the ecological status of a river and on the timescales required for such improvement.
Having explored the wide range of international examples, the paper then discusses in more detail the use of best practice geomorphological techniques in river rehabilitation for the Rothes Catchment case study in Scotland. Techniques such as Fluvial Audits and Conservation Baseline Assessments complement a multi-disciplinary approach to meeting the WFD and achieving sustainable flood risk management.
In addition to the scientific aspects of rehabilitation, consideration will be given to the legislative framework for urban river rehabilitation schemes and will emphasise the importance of assigning organisational powers, time and budget to this task. The range of issues discussed in this paper highlight the growing challenges in implementing the WFD as the time to meet the requirements ticks by.
Session 2: Good practice - delivery
02.1 Implementing rural flood alleviation schemes in Aberdeenshire
Kenneth MacDougall
EnviroCentre
Alasdair Smith
Aberdeenshire Council
Tricia McGregor
EnviroCentre
Key words: sustainable solutions, rural flooding, partnerships
Abstract: Following extensive flooding in 2002, Aberdeenshire Council has developed a number of flood alleviation schemes in close partnership with local communities affected, landowners, NGOs and other statutory agencies. These schemes are characterised by their partnership approach and integration of multi agency representations, allowing the promotion of sustainable approaches to flood risk management.
Rural communities across Aberdeenshire were affected by the 2002 floods, with incidents reported at over 80 locations. Many of these were on smaller watercourses near villages where traditional flood defences would be expensive, inappropriate and have the potential to cause disruption to the local community. The challenges facing the Council were to develop sustainable flood alleviation schemes, while preserving the character of the villages to be protected.
The involvement of the local community and landowners/tenant farmers as part of that community has been crucial to the successful development of the schemes to date. Consultation been used to scope local opinion and gain feedback on proposed schemes. Innovative techniques such as the use of 3D visualisation techniques have been adopted to illustrate the extent of proposed schemes.
This iterative design process has enhanced the functionality of schemes, leading to increased biodiversity benefit, continued agricultural use, increased recreational potential and improvements to watercourse morphology as well as providing flood prevention. These wider benefits help ensure buy-in for the schemes being taken forward.
In parallel with the scheme development, education and maintaining the awareness of flood risk following the 2002 floods is seen as a key action in managing future flood risk. This is being achieved through the use of community meetings and creating a greater role for active involvement within the community, an example being community flood wardens. This approach has proved a success with local residents appreciating the work being undertaken and having the satisfaction of having contributed to the schemes being implemented.
02.2 Managing flood risk on railway infrastructure
John Dora BSc CEng MICE
Network Rail
Dr Jonathan Rogers MEng PhD CEng MICE
Halcrow Group Ltd, formerly of Mouchel Parkman
Bairbre O’Breasail BEng
Mouchel Parkman
Key Words: scour, coastal, management, risk
Abstract: Network Rail is the operator of Britain's rail infrastructure. Its mission is to maintain, improve and upgrade the railway fit for the 21st century. The company relies upon management processes based on good practice to ensure the safety and integrity of its 10,000 mile network. Within its ownership are 40,000 bridges, 200 miles of culverted watercourse and 300 coastal and estuarine defences.
This paper explains the strategic approach Network Rail is adopting towards developing medium to long-term plans for managing assets at the coastline, and how scour risk at bridges and earthworks is managed in the short-term.
Good Practice Guidance has been produced for the development of Coastal Defence Management Strategies. The resulting Territory and Frontage Management Strategy documents are “off the shelf” publications providing Territory Civil Engineers with essential sources of information and guidance for managing their coastal defences.
Some history relating to the requirement for scour risk assessments is presented and the management processes are explained. The Western Territory Flood Plan, is shown as an example of how this translates into practice; Environment Agency Flood Warnings are key to controlling rail traffic during floods.
The paper ends with details of current Network Rail initiatives.
02.3 15 years of coastal management in the Netherlands; policy, implementation and knowledge framework
Marcel Taal
Jan Mulder
Jelmer Cleveringa
Daan Dunsbergen
Rijkswaterstaat, National Institute for Coastal and Marine Management / RIKZ
Key Words: coastal policy, coastline management, sand nourishment
Abstract: The Netherlands are managing their sandy frontyard. A necessity, with a country that is for 2/3 below sea-level and with pressure on space constantly growing (for living, working, nature, recreation). The paper discusses coastal characteristics as well as coastal policy and management to realise sustainable safety. It can be concluded that, as result of the success of the focus on nourishments in the last 15 years, coastal management in the Netherlands is developing into sand management. The Dutch will need to continue the nourishments to allow their coast to grow with sea level rise, but have a seemingly unlimited amount of sand in the North Sea. This fact is the source for recent innovations like channel-slope nourishments. With the present shift from a small scale to a large scale approach there are new opportunities, for instance by using the long term required sand for purposes on the short term.
02.4 Making space for water in an urban environment on the Quaggy River
Joanna Gray CENG MICE
Jennifer Hawkes ALI
Halcrow
Phil Stephens CENG MICE
Environment Agency
Graeme Howard
Alfred Mcalpine
Keith Scarff MRICS
JBreheny
Key Words: urban, multifunctionality, river restoration
Abstract: The Quaggy River in South East London has a history of major flooding problems caused by urban development in the river valley and on the natural flood plain. The Quaggy River Flood Alleviation Scheme is an outstanding example of an integrated multifunctional design which will help manage future flood risk to 600 homes and businesses, and protect over 2500 people living and working in the London Boroughs of Greenwich and Lewisham. The scheme comprises the creation of upstream wetland flood storage areas and downstream channel improvements. The first of three phases, Sutcliffe Park, involved the construction of a flood storage area designed as a multifunctional open space. It not only provides crucial flood risk benefits, but has restored the river and river valley to the original 19th century alignment in the centre of Sutcliffe Park. The park has incorporated a series of lakes and ponds, thereby making space for water while maximising the potential for wildlife and improving opportunities for recreation. When in use as a flood retention area, the park will hold up to 85,000m3 of flood water. The second phase, Weigall Road, provides a flood storage area of 65,000m3 in an area currently used as a sports field, allowing dual use of an open space. These storage areas have reduced the flood risk and the need for major works downstream.
The final phase of the scheme involves improvements to the flood defences and river environment in sections of the river running through rear gardens, beneath roads and along open spaces in an urban part of the catchment. A major success of the scheme involved gaining agreement from land owners in appropriate stretches of the river to allow their rear gardens to act as flood storage areas during high flows. Along these stretches, flood defences have been turned into garden decking and wall features, improving many people's gardens and increasing their access to the river corridor. Soft defences have replaced hard defences along some stretches of the river. Where hard defences have been necessary, they incorporate bird nesting boxes and flora planting boxes designed and installed to encourage some of the Quaggy River's rarest and most valuable species.
Each of these sections were significantly different in terms of the existing situation and opportunities for flood risk management, yet each one has achieved flood defence, recreation and ecological wins.
Session 3a: Dealing with flooding inland
03a.1 Recent advances in modelling flood water levels at bridges and culverts
Robert Lamb
Peter Mantz
Serter Atabay
Jeremy Benn
JBA Consulting
Andrew Pepper
ATPEC
Key Words: afflux, bridges, culverts
Abstract: Afflux at bridges and culverts can be a significant source of flood risk by causing elevated flood water levels. A wide range of methods are currently used to model afflux, but a review of current practice found that these are not always well understood and can be applied inappropriately. Some of the underlying assumptions and calibration data are not the most relevant for typical situations in the British Isles. This paper presents a summary of recent research to develop more consistent, efficient methods and software for calculating water levels at structures.
03a.2 Urban watercourse management and trash screens: getting it right!!
Steve Magenis BSc MPhil CEng MICE FCIWEM FConsE
Martin Whiting BSc (Hons) CEng MICE FCIWEM MIEM
Royal Haskoning
Key Words: trash screen; debris removal; telemetry; urban watercourse; screen blockage; screen design.
Abstract: It has been five years since the Environment Agency issued the “Trash Screens - Design and Operations Manual”. This paper is written by one of the authors of that Manual and the then Environment Agency R&D Project Manager. It examines the key design principles of the Manual including the decision process to be followed for screening or not screening.
The paper uses examples to illustrate some of the common pitfalls encountered by the designer and propose areas which require further research in light of recent experience.
With the ever increasing impacts of heavy short duration rainfall, attributed in part to climate change, and the resultant increased runoff, together with the call for more effective use of flood risk management resources, it is vital that trash screen installation and subsequent maintenance is of the highest order.
The paper challenges the industry to raise its awareness of the design and operating issues and to raise the quality of decision making and product in this key field.
03a.3 - Two dimensional variable geometry modelling of flood defence breaches - assisting in the delivery of cost-effective flood management
Matthew Roberts PhD
Michael Turnley BEng (Civil)
Key Words: flood defence breach, variable geometry, tuflow
Abstract: To maximise the benefits of future investment in flood and coastal defences the cost of maintenance must not exceed the benefits of the defence. Breach analysis can be used to determine the consequences associated with withdrawing defence maintenance. Limited guidelines exist for undertaking fluvial flood defence breach analysis. The breach formation is often represented by an instantaneous removal of a fixed geometry, which is simplistic and can overestimate the associated flood extent and/or levels. This can lead to unnecessary reinvestment in defences and constraints on floodplain land-use and development. To assess the benefits of hydraulically modelling variable geometry breaches, in which the dimensions of the breach vary with time, several fixed and variable geometry fluvial defence breach scenarios were undertaken using TUFLOW, a two-dimensional, finite-difference model. A risk-based approach is proposed that considers flood hazard as a means of quantifying the consequences of defence failure.
03a.4 A multi-agency approach to delivering a sustainable flood alleviation scheme for Carlisle
Jonathan Griffin
Celia McNally
Glyn Vaughan
Environment Agency
Key Words: sustainable flood risk management, flood alleviation, urban flooding, making space for water, collaboration
Abstract: The city of Carlisle suffered extensive flooding in January 2005. During the emergency response the Environment Agency, City and County Councils, water company (United Utilities) and emergency services worked together under difficult circumstances.
This co-operative approach has been maintained since the flood as the separate organisations have developed their proposals for reducing the flood risk and regenerating the city. Carlisle City and Cumbria County Councils have developed a “Renaissance” vision for the city that aims to create economic growth, improve pedestrian and traffic movement and highlight the historic and natural environments. United Utilities have assessed the urban flood risks and improved the flood resilience of the city's electricity substation and wastewater treatment works. The Environment Agency has promoted a strategy for reducing the fluvial flood risk in Carlisle through the delivery of three flood alleviation schemes.
The Renaissance and United Utilities' proposals are reliant on the Environment Agency delivering reduced fluvial flood risk within the tight timeframe agreed immediately following the 2005 flooding. Close co-operation between the partner organisations is therefore crucial and has been ensured through the creation of a Carlisle and Cumbria Project Board with high-level representation from each of the partners and other agencies such as English Nature.
The experience in Carlisle gives an insight into how the objectives of Making space for water will need to be delivered. However, even with the level of collaboration that has been achieved in Carlisle, there are fundamental barriers to delivering the joint outcomes. These have been identified in this paper and opportunities for addressing them are discussed.
Session 3b: Informing the management of coastal erosion risk
03b.1 Toe scour at seawalls: monitoring, prediction and mitigation
James Sutherland
Alan Brampton
Richard Whitehouse
HR Wallingford Ltd
Key Words: scour, seawalls, mitigation
Abstract: This paper summarises the main results from the Defra/EA R&D project Understanding the Lowering of Beaches in front of Coastal Defence Structures, Stage 2 (FD1927). Evidence has been presented showing beach lowering and recovery happening over a range of timescales. In particular, beach levels have been shown to drop and recover close to their original levels within a tidal cycle. This behaviour cannot be detected from beach profiles alone. A large set of toe scour data from medium- to large-scale laboratory and field experiments has been analysed to produce a new equation for the maximum scour depth.
Beach profiles have been analysed to show that the annual rate of beach lowering in front of a coastal structure varies considerably from one decade to the next. The residual beach levels about the long-term trend were found to have a probability distribution close to Gaussian, providing there were no significant changes in beach management. A list of monitoring methods has been compiled and an indication of the suitable timescale for deployment has been given. The use of remote sensing is becoming more common and is likely to lead to the greatest changes to the type and quantity of data available for monitoring.
A review has also been carried out of the mitigation methods that have been, or could be used to delay or to reduce the severity of problems arising from the lowering of beach levels in front of a seawall or a similar coastal structure. These measures include ones that reduce the hazard without removing the lowering. Mitigation methods include filling in scour holes with rock, encouraging deposition of sediment using, for example, groynes, beach recharge and the underpinning of seawalls so that they remain structurally sound when beach levels drop.
03b.2 Using ‘Futurecoast’ predictions to inform shoreline management in Morecambe Bay
Alun Williams
ABP Marine Environmental Research Ltd
Nick Cooper
Royal Haskoning
Phil Barber
Shoreline Management Partnership
Nigel Cross
Lancaster City Council
Key Words: shoreline management; morecambe bay; coastal evolution
Abstract: The Defra-funded futurecoast study provided a broad scale assessment of future coastal evolution to inform the development of shoreline management policies. The objective of this paper is to provide a discussion of how the Futurecoast methodology can be further developed, with the predictions refined and enhanced at a local level. These predictions can then be applied in practice to assist in policy development at the strategic level. This is illustrated through reference to Strategy Scoping Studies that have been undertaken in Morecambe Bay, northwest England.
This paper illustrates how Futurecoast predictions provide the scientific baseline that can be developed and used to allow a consistent approach to local level shoreline management in the UK. In doing so, a best practice example of applying an understanding of shoreline evolution to shoreline management is provided. The benefits of the approach described are highlighted in terms of informing local shoreline management issues, allowing uncertainty to be identified and focusing data collection and monitoring programmes. The qualitative approach that is suggested and discussed is highlighted as being appropriate and beneficial in areas where a high degree of uncertainty exists regarding future shoreline change.
03b.3 Coastal retreat: the role of eroding cohesive shore platforms
Peter S Balson
British Geological Survey
David S Brew
Haskoning UK Ltd
Richard Charman
University of Sussex
Peter Hobbs
British Geological Survey
Cherith Moses
University of Sussex
Mike Walkden
University of Newcastle
Rendel Williams
University of Sussex
Key Words: coast erosion, shore platforms
Abstract: The irreversible erosion of cohesive intertidal and subtidal shore platforms plays a large part in controlling the functioning of the wider coastal system and poses significant problems for management. Cohesive platforms typically lie along the most rapidly eroding cliffed coastlines in the country, where sand and gravel beaches overlie cohesive clay materials. These platforms make an important contribution to the local sediment budget, providing large quantities of silt and clay for deposition on tidal flats and salt marshes which form important and, increasingly protected, habitats. However on retreating coastlines where beaches have decreased in volume the platform may become exposed which can be an unwanted side effect of the erosion process on some popular tourist beaches. Mitigation of coastal retreat usually consists of engineered toe protection at the foot of the cliff. Such interventions however do not protect the intertidal and subtidal parts of the profile and can in some cases actually exacerbate platform erosion.
This project is examining two UK east coast sites at Warden Point, Sheppey, Kent [TR 021 725] (London Clay) and Easington, East Yorkshire [TA 398 208] (glacial till) which have contrasting geology, geomorphology and oceanographic settings to better understand the controls and drivers of platform erosion. Summer and winter field measurements have obtained data on geomorphology, geotechnical properties and biological impacts on platform erodibility. These factors are seen to have a degree of influence which differs strongly between the two sites. The findings will assist in the development of models to assess the impacts of future environmental changes to enhance prediction of coastal retreat on cohesive shorelines.
03b.4 Design and management implications for the use of modelled wave data in the south-east - a comparison between modelled and measured conditions
Prof. Andrew Bradbury PhD
Travis Mason PhD
Channel Coastal Observatory
Martin Holt PhD
Met Office
Key Words: wave climate, extremes, wave modelling
Abstract: The design and management of coastal engineering- and operational flood forecasting- programmes, within the UK, is reliant upon hindcast or forecast synthetic wave-data and numerical models of wave transformations to provide wave climate data. Data sets are occasionally supplemented with short time series of localized measured wave-data, but hitherto there has been no systematic shallow water wave measurement or validation programme off the UK coast.
The network of directional wave buoys provided by the southeast regional coastal monitoring programme provides an opportunity to validate numerical modelling methods in operational use. The review is a collaborative initiative between model end users (Channel Coastal Observatory) and the developers (UK Met Office). The buoy network also provides a number of operational advantages. Significant findings have been highlighted by the comparisons of the buoy and modelled data that may have region-wide design and flood forecasting implications. Each of the key model output parameters shows significant variability under extreme conditions:
- Under prediction of significant wave height in extreme events
- Over prediction of wave period
- Low frequency resolution and wide scatter of wave period
- Under-prediction of wave steepness
- Poor resolution of wave direction
Implications of each variable are discussed in design and operational terms and recommendations made for future development.
Session 4: Understanding and managing change in estuaries
04.1 One hundred years of morphological change in the Thames Estuary. Impacts on tide levels and implications for flood risk management to 2100
Graham Siggers MSc DIC CSci MCIWEM
Jeremy Spearman MA MSc DIC PhD
Mervyn Littlewood
HR Wallingford Ltd
Bill Donovan MSc
Environment Agency
Key Words: thames estuary, morphology, tides
Abstract: An analysis of one hundred years of morphological changes has been undertaken in the Thames Estuary. The cumulative effect of these changes is seen to have led to an increase in the tide range from Tower Pier upstream to Richmond, with mean spring tide range under low fluvial flow conditions predicted to have increased by up to 1.1m (25%) at Richmond.
High water levels in the Thames Estuary have been relatively insensitive to changes in morphology of the Outer Estuary.
The effect of morphology changes on the propagation of extreme tide/surge events has been tested and found to be similar in location (increased high water levels in the Upper Estuary) but smaller in magnitude than for a mean spring tide. Finally, the implications of these findings for flood risk management in the future are considered.
04.2 Sources of flooding on floodplains of the tidal Thames
David Ramsbottom
HR Wallingford Ltd
Owen Tarrant
Environment Agency
Alan Cooper
HR Wallingford Ltd
Key Words: flooding, tidal, fluvial
Abstract: The Thames Estuary 2100 (TE2100) project requires an assessment of flood risk for present day and future scenarios for the tidal Thames floodplains, to provide a basis for planning flood risk management over the next 100 years and beyond.
To do this it is first necessary to understand the causes of flooding. The main potential sources of flooding include the surge tides on the tidal Thames, and fluvial flooding from the Thames, tributaries, land drainage systems and urban drainage systems. Flooding is affected by the operation of moveable gates including the Thames Barrier and barriers on other tributaries.
The paper describes the sources of flooding, the ways in which they interact and the effects that they have on flood levels. The flood management system on the tidal Thames is described, and the impacts of failure of elements of the system are considered.
Extreme sea levels and fluvial flows are expected to increase in the future, and the main implications for flood management on the Thames are summarised.
04.3 Predicting intertidal change in estuaries
Adrian Wright
Ian Townend
ABP Marine Environmental Research Ltd
Key Words: regime theory, hybrid modelling, morphological updating, numerical model, sea level rise
Abstract: There is an increasing need to better predict possible future morphological behaviour of estuaries, over timescales of decades to centuries to improve and support the development of sustainable shoreline management polices. Whist models to examine short-term, site specific, changes are well developed, the ability to make predictions over time-scales of 10-100 years is less well advanced. Therefore, this has formed a primary focus of the Estuary Research Programme funded partly by Defra and the Environment Agency (EA). One approach to this problem entails combining the level of detail available from the well established hydrodynamic process based models (bottom-up methods), with some system goals, determined from various equilibrium relationships (often referred to as top-down methods). This hybrid modelling approach has recently been applied to good effect to support the SMP geomorphological studies on the Humber (Keiller & Young, 2005) and is currently being used as part of the assessment for the Severn Coastal Habitat Management Plan’s (CHaMP).
The approach of hybrid models to these two estuaries, in conjunction with detailed analysis of the historic data, has revealed how much of the variation in intertidal area is due to the nodal tidal cycle (an 18.6 year cyclic variation in the tidal range). This means that a reduction in area over a 10-year period is part of a cycle that will restore the area during the next 10 years. Such changes must, however, be superimposed on the underlying response to sea level rise.
04.4 Thames Barrier gates - 100 Year Life Project
Robert Hall AMNI MRICS
Environment Agency (NCPMS)
Martin Earlam CEng MIMechE
Environment Agency (Improvements)
Roland Grzybek CEng FICE MCIWEM MIOSH
Halcrow Group Ltd
Ian Padgett CEng FICE MCIWEM
Atkins
Dick Tappin MA(Oxon) CEng FICE
High Point Rendel
Windsor Young CEng MICE
Volker Stevin
Key words: gates, appraisal, barrier
Abstract: This paper describes the approach to the appraisal and design for extending the life of the Thames Barrier Gates into the future. The barrier is part of the integrated tidal and fluvial flood defences that protect London. In summer 2005 the first major condition survey was undertaken on the barrier steel gates. This was to appraise the options for determining the optimum solution to extend their design life from 2030 to 2100 (including “do-nothing”). The paper explains the approach to the investigations and includes themes on innovative approaches to long-term working in confined spaces, incorporating health and safety improvements, working as a “high performance” integrated team, maintaining the reliability of the defences during the works and incorporating the project into other high level plans that are being developed at the same time, i.e. the Thames Estuary 2100 project and the Thames Barrier and Associated Gates strategy. The paper concludes with the future potential of the barrier to perform as an improved flood risk management structure into the future.
Session 5a: Public and industry engagement
05A.1 Stakeholder and community engagement - examples of good practice
John Colvin
Ruth Johnston
Environment Agency
Key words: none
Abstract: The aim of Making space for water is to provide greater clarity for both communities at risk of flooding and professional bodies involved in flood and coastal erosion risk management. Its aims are to manage risks through an integrated portfolio of approaches that reflect both national and local priorities so that the threat to people and property is reduced. Making space for water proposes implementing stakeholder involvement at all levels of risk management to provide more informed dialogue with stakeholders, leading to better ownership and more effective solutions.
05A.2 Telling good stories: engaging in dialogue with communities about flood and coastal erosion risk management in a post-modern society
Jonathan Simm CEng FICE MCIWEM
HR Wallingford
Mary Samuels
Oxford Brookes University
Key Words: community, storytelling, dialogue
Abstract: This paper suggests that new approaches are required to communicate with communities affected by flooding and coastal erosion. In post-modern society, communities question the validity of the message. They have expectations of the medium of the message. They receive the message through the frameworks of their multiple stories and identities. The personal narratives and experiences within a local community seek recognition and voice alongside the official statements and claims of the engineering and scientific community. Objectivity and reliability are challenged.
The authority of the formal written word, communicating at a cognitive and rational level, takes its place alongside new oral and visual traditions. Technology allows individual stories to reach a wider and more immediate audience. A single, general story is replaced by a multiplicity of particular stories from local communities and individuals. NGOs have followed the media in becoming adept at using all these aspects of communication.
Effective approaches to communication acknowledge the different cultures of the professional and citizen communities (e.g. residential, fishing, farming, sailing) involved in interacting with FCERM. The paper will examine the way in which stories and storytelling can be used as a bridge between different cultures, creating communities of practice in which knowledge may be shared and sense made of common problems. It suggests some devices which can be used in effective storytelling to help us put our own messages across. Drawing on recent experiences (for example during recent major disasters such as Boscastle), the paper also explains how stories can work for us as we uncover the information buried in the stories of others.
Story telling may also be important in establishing shared fields of experience with communities. This needs to be in the context of effective dialogue that seeks to hear and understand what each community is trying to communicate, based on mutual respect or humility. This humility recognises the value of both the practical knowledge, lodged in the experiences and stories within communities, and the analysis and judgement of professionals as they reflect on and contextualise that experience for future decision making.
05A.3 Delivering sustainable development on the coast
Adam Hosking
Halcrow Group Limited
Jane Taussik
Independent Researcher
Kevin Burgess
Halcrow Group Limited
Key Words: spatial planning, social justice, adaptation
Abstract: Awaiting paper
05A.4 Improving the industry's performance contribution to flood risk management
John Horne BSc CEng MICE
Department for Environment, Food and Rural Affairs
Steve Magenis BSc CEng MICE CIWEM
Royal Haskoning
John Lawson MA FREng FICE FCIWEM
Halcrow Group Ltd
Richard Nunn BSc CEng MICE CIWEM
Environment Agency
Key Words: none
Abstract: Against an ever changing background of increasing flood risk and variable funding certainty, the Chief Engineer of Defra Flood Management Division challenged delegates at the 2004 conference to respond by improving the vision of responses to flood reduction and improve the cost efficiency of decision making. The response was an Industry Action Plan entitled “Improving Your Contribution to Flood Risk Management” which was launched at the 2005 Defra conference. This paper reports on how the industry has responded and the benefits that have been derived.
05A.5 Floodscape - sustainable flood risk management: a decision-making tool
Katie Bunting
Alastair Dale
Mark Skelton
Capita Symonds Ltd.
Key Words: floodscape, consultation, stakeholder, engagement, sustainable flood risk management, decision-making
Abstract: The Floodscape project was initiated to consider the impact of sustainable flood risk management policies for the Thames Estuary on the North Kent and Aveley & Rainham marshes. In particular stakeholder acceptability of a range of possible flood risk management measures was investigated. Central to this was the use of a range of stakeholder engagement techniques, including the development of a decision-making tool. This tool sought to capture and highlight some of the complexities involved in flood risk management as well as the issues that must be negotiated when considering a sustainable flood risk management strategy.
Early stages of the project and consultation were concerned with developing an understanding of the sites in terms of their ecological and environmental baseline, flood risk situation and community value. Information was gathered through a variety of consultation methods including public meetings, questionnaires and a guided walk. This information informed the development of a range of possible flood risk management measures for the sites.
The decision-making tool developed encouraged stakeholders to consider five key themes for each of the sites. The tool guided stakeholders through a series of yes/no questions relating to each of the key themes so as to reach a preferred flood risk management measure or group of measures. In North Kent the tool was used by an invited group of stakeholders brought together at an independently facilitated workshop. In Aveley & Rainham it is proposed that an online version of the tool will be developed and used.
This innovative method of shared decision-making proved very successful in encouraging stakeholders to consider the range of issues involved in identifying an acceptable and appropriate flood risk management measure, including taking account of differing views to their own. The decision-making tool also revealed interesting stances and helped identify inconsistencies in preconceived positions and values.
In presenting the results of this pilot study the paper explores the techniques used, evaluates the consultation methods employed and describes stakeholder preferences for flood risk management, which through subsequent initiatives will feed into the Thames Estuary 2100 project.
Session 5B: Tools and approaches underpinning risk management decisions
05B.1 Development of an objective-led approach to the management of flood and coastal erosion risk data
Fola Ogunyoye
Andrew Robinson
Royal Haskoning
Suresh Surendran
Environment Agency
Claire Brown
ABPmer
John Chatterton
J B Chatterton & Associates
Key Words: objective-led data management, data sharing, information management
Abstract: The success of integrated flood and coastal erosion risk management (FCERM) is dependent on the use of good data, information and knowledge management. A few years ago, a scoping study within the Joint Defra/Environment Agency R&D Programme, which reviewed data and information issues within FCERM, confirmed the need for significant improvement in the management of the data life-cycle.
A recently completed project within the same programme (Ref FD2323) supports this view, but concludes further that data life-cycle management will only achieve effective data and knowledge management where it is underpinned by an objective-led approach. Here, business objectives and the information required to provide knowledge for their management identify the need for data and its required attributes and management. In order to achieve a shift from the currently data-centred focus to one that is led by business objectives, a culture change is required.
This paper presents the development of a framework for objective led data management and the structures to assist with its delivery, through an understanding of the relationships between the key roles/objectives within FCERM and the information exchange network involved with linking the data and information sources to the users. It also describes the complementary tools that were developed to support the collection, management, access and exchange of relevant information, as well as a methodology for appraising the need for data. This paper aims to support users, managers and suppliers of FCERM data and information with the ability to access and manage FCERM data in such a way that it is efficient, avoids repetition and redundancies, and maximises the use of appropriate supporting tools and technology.
05B.2 Thames Estuary - establishing a robust flood system model to support engineering investment decisions
Eur Ing Paul Sayers BEng CEng MICE
HR Wallingford Ltd
Owen Tarrant BSc
Environment Agency
Ben Gouldby BSc
HR Wallingford Ltd
David Kavanagh BEng CEng MICE
Anser Project Managers
Mike Panzeri BSc MSc
HR Wallingford Ltd
Key Words: flood risk, thames estuary, system modelling
Abstract: The Environment Agency is currently planning its long-term approach to Flood Risk Management within the Thames Estuary. This is a significant and multi-dimensional challenge. Adapting and managing existing defences, barriers, gates and pumps as well as building new ones are likely to have a significant role as part of this future. This paper explores the initial development and first application of a system model capable of supporting a risk-based targeting of investment.
The paper demonstrates how a regional system analysis tool – based on the RASP High Level analysis framework - can be used to provide an assessment of both flood risk and the performance of different response strategies under future scenarios. The practical issues explored in this paper include:
- Data gathering – including hierarchical approaches to the use of data and the attribution of data uncertainties.
- Defence performance analysis – how national scale and local analysis of defence failure can be integrated.
- Quantifying the individual defence contribution to risk (within the context of over 480km of defences within the tidal Thames).
The paper concludes with a practical insight to the use and utility of system models in the context of an active and complex decision making process.
05B.3 Capturing and abstracting flood defence data from low level LIDAR surveys
David Scott
Sun Yan Evans
Alison Stuck
Mott MacDonald
Trevor Burton
BKS Surveys Ltd
David Kavanagh
Patrick Butcher
Environment Agency
Key Words: lidar, flood defence, flood risk mapping
Abstract: Flood risk management assets, particularly embankments and vertical walls, in the South East of England and elsewhere in Britain protect thousands of homes from the risk of coastal and fluvial flooding. Accurate survey information on these assets is vital to the Environment Agency's (EA) approach both to day to day asset management, and to the decision-making process for their improvement or replacement. This paper discusses the development of the EA's new Low-level LiDAR Flood Defence Survey Specification to identifying defence form (shape and crest levels) over a large area, without the need for the extensive field visits associated with land-based survey techniques. The paper presents results from a pilot survey of over 500 km of flood defences along the Medway/ Swale and Thames estuaries and Hampshire coastline conducted in 2005. It shows that remotely-sensed LiDAR data taken from a helicopter platform is capable of gathering accurate and detailed information on soft and hard defences, not previously possible.
The data has been used to extract defence longitudinal sections and cross sections, providing high density information for the benefit of 2D modelling of the Medway Estuary and strategic planning tools and related asset surveys being developed by the EA's TE2100 project. The high resolution images were capable of identifying defence type and provide important background data on the condition of a defence before field inspections were carried out. Post inspection assessment of field observations could also be made using the combined information of field and remote survey. The paper discusses the benefits and difficulties of using dense point cloud data (>12 points/m2) to extract defence data, within urban and rural environments. It compares the LiDAR survey techniques against conventional surveys in terms of vertical accuracy, the speed of obtaining results and cost.
The paper illustrates that the technique of extracting defence data from high density helicopter LiDAR is a quick and accurate method of improving defence assets information, and, in combination with flood modelling and risk assessment, can improve the flood risk management process. It concludes that the Low Level LiDAR techniques have a national importance for volume survey of defence crest elevations, the video and photo images are invaluable for office use in support of inspections and assessment. The use of LiDAR has a major potential to bring asset condition assessment onto a common footing as flood risk mapping. It will contribute immensely to the effective implementation of the EA asset management strategy and flood risk mapping policy.
05B.4 Scottish Flood Defence Asset Database
David Bassett
JBA Consulting
David Seaman
Scottish Executive
Angus Pettit
Caroline Anderton
Paul Grace
JBA Consulting
Key Words: standard of protection, condition assessment, cost benefit analysis
Abstract: The Scottish Executive is investing in improving understanding of flooding in Scotland. Recommendations made in reports on climate change identified a need for a register of fluvial and coastal defences containing detailed records of the assets, the defended areas and number and value of properties protected. SEPA flood maps will be made available to the public in early 2006 showing a range of flood outlines, but without account being made for the presence of flood defences. The new flood map may therefore show locations that currently benefit from flood prevention schemes as being at risk from flooding, whereas the database will allow a determination of the true level of risk in these locations. The database will allow planners to readily determine whether a site benefits from flood defences and the standard of protection afforded under SPP7 (Planning and Flooding) which would allow determination of whether a site is suitable for development.
The review of costs and benefits allows an assessment of the value of defending properties and has implications for national planning, expenditure and the financial sustainability of flood management. Of the 72 Flood Prevention Schemes (FPS) 39 were reviewed in detail. In total the schemes provide 90km of defences. Present day costs of £82 million were found for 54 FPS with present day damage avoided for 39 schemes in the order of £240 million pounds. Of assets surveyed 87% are in good and very good condition.
At present an FPS can only be promoted if it will defend to at least the 100 year flood and the research shows that many of the schemes providing defence against frequent flooding are economically viable at their current standard of protection which is often much lower than 100 years. In a number of locations Councils have made or are planning improvements identified as part of this research. The database is web enabled and is currently available to the Executive, Local Authorities and SEPA, although this could be made available to the public.
05b.5 Never a day without risk (the Dutch approach to flood protection)
Pieter Janssen MSc
Alex Roos MSc
Cees-jan van Westen MSc
Ministry of Transport Public Works and Water Management Road and Hydraulic Engineering Division
Key Words: risk-based approach, knowledge development, continuous policy improvement
Abstract: This paper covers recent developments in the Dutch approach to flood protection, including the intermediate results of a study to derive nation-wide flood risks (the project Floris, meaning Flood Risks and Safety in the Netherlands).
The Dutch have been fighting the water for centuries in a quite structural way. But only after the storm surge disaster of 1953, steps were taken to rigorously modernise the flood protection system. The 1953 disaster and other smaller calamities also stressed the need to organise knowledge management and development. To that end the Technical Advisory Committee on Flood Defences was established in 1965, and was itself succeeded by the Expertise Network on Flood Protection (ENW) in 2005. Members of ENW are employees of all relevant parties in flood protection, both from the public and private sectors. This paper elaborates on the value of such an expertise platform for all parties involved, focussing on the example of the Floris project mentioned above.
The intermediate results of the Floris project provide a lot of meaningful new information on the present state of the Dutch flood protection system. Important results include an improved insight into a number of failure mechanisms for flood defence works, and also into the possible consequences of flooding. This paper summarises the most relevant results of the project to date and identifies areas of work to be taken forward in future.
Nowadays, the Dutch do realise that adequate flood protection is a matter of continuous development. Therefore, a broad discussion has recently been started with stakeholders from society and experts, to investigate the possibilities for further improving the present policy. The steps to be taken in this process are also summarised in this paper.
Session 6: Holistic approach to managing flood and coastal erosion risk
06.1 Integrated catchment & urban modelling for flood management
Richard Crowder PhD CEng MICE MCIWEM
Daniel van der Leer PhD
Halcrow Group Limited
Key Words: urban flooding, integrated modelling, flood mapping
Abstract: Making space for water (July 2004), the Government strategy for flood and coastal erosion risk management, promotes the adoption of “whole catchment” and “more holistic” approaches to managing flood risks. It specifically stresses the need to take into account all sources of flooding and thence be consistent with, and contribute to the implementation of, the Water Framework Directive.
Taking an appropriately joined-up approach has the potential to provide integrated catchment benefits for urban areas. It will not only provide a better understanding of catchment processes but it will enable the management of flood risk by all stakeholders, specifically local authorities, water companies, the Highways Agency and the Environment Agency. It will also lead to improved water quality and water resources management.
An overview of the latest methods and tools for undertaking Integrated Catchment & Urban Modelling and details on some of the latest research and development work being undertaken in this rapidly developing technological area are presented. It is demonstrated how separate 1-D hydrodynamic models of the river and sewer/culvert surface water network can be dynamically linked with a 2-D hydrodynamic model of the overland (surface) flow and be used to understand flood risk and develop flood risk management approaches. Outputs from “Integrated Catchment and Urban Modelling” studies are presented showing how detailed flood hazard maps can be developed for fluvial, sewer and pluvial flooding.
06.2 Setting policies for the management of groundwater flooding
Pete Campbell
Marc Pinnell
Capita Symonds
Key Words: groundwater, flooding, policy, cfmp
Abstract: Historically flood management policy in the UK has focused on fluvial and tidal flooding at the expense of other flood mechanisms such as groundwater and sewer flooding. Previous Government policy has made little mention of groundwater flood events.
Catchment Flood Management Plans (CFMPs) aim to aim to identify long term sustainable policies for managing flood risk from rivers (and sewers, groundwater and the sea) and its impact on people, property and the natural and built environment. This paper reviews why groundwater flood events are often ignored in policy and legislation and asks whether this is appropriate – is it worth setting policies or are groundwater events inherently unmanageable? The paper looks to answer why groundwater events are excluded, if this situation should be reversed, and if so what new work and analysis will be required. Do groundwater flooding mechanisms make it too difficult to predict risk areas with a suitable degree of confidence to set policy, or are these types of events inconsequential and undeserving of resources when compared to the much more visible problem caused by fluvial flooding?
This question is examined with reference to catchment scale hydrological studies undertaken to assist in setting flood risk management policies for groundwater flooding during the production of a CFMP. This work identified risk areas using a simple multi-criteria analysis. Results highlighted the difficulty in applying standard risk analysis methodologies to groundwater flooding.
06.3 Opportunity mapping: benefits for complex decision making in flood risk management
Drs. Marnix Cyriel de Vriend
Royal Haskoning, Nijmegen, The Netherlands
Key Words: decision-support-tool, opportunity-mapping, dutch experiences applied to thames estuary 2100
Abstract: Building bridges between science and decision makers is necessary and urgent in order to arrive at sustainable solutions to tackle major issues of flood risk management. Multi-criteria- and cost benefit analysis prove to be useful tools. Opportunity mapping, as developed and applied in a number of projects in the Netherlands may provide an additional and powerful tool. It is especially useful in screening, evaluating and ranking options in complex multi-criteria integrated decision making processes. It does not take a lot of extra time. Once integrated in the process from the start it might even save time.
The author developed the methodology and gained his experience with applying this tool primarily in three different Dutch projects on comparing strategic flood defence options in the Arnhem-Nijmegen region, the EIA on the dyke replacement Lent/Nijmegen and inland and coastal measures in the weak link ICZM project of West Zeeuwsch-Vlaanderen. This will allow him to effectively evaluate the Early Conceptual Options in the Thames Estuary 2100 project.
06.4 Developing East London: how do we deal with flood risk?
Fabio Spaliviero
Entec
Jonathan Cooper
JBA Consulting
Rachael Hill
Environment Agency
Andrew Tucker
Thames Gateway London Partnership
Key Words: sfra, pps25, flood defences
Abstract: East London is the nexus of two growth areas and a national and regional regeneration priority. A large proportion of the brownfield development land in East London is situated in the floodplain or “areas benefiting from flood defences”. This paper shows how flood risk can be taken into account to inform the future strategic planning of East London, ensuring that flood risk is considered in determining the type, location and design of development at a strategic scale in accordance with the PPG25 sequential test.
Flood Zone maps published by the Environment Agency do not describe the variation of flood risk within large low-lying areas of East London. This is because they do not take into account the moderating effect of the Thames Tidal Defences. A Residual Flood Risk map based on a source-pathway-receptor model analysis is used in addition to influence both the allocation of land for development, and the management of flood risk through the adoption of mitigation measures.
The SFRA delivers a strong and transparent application of the sequential test which is translated in an innovative web based approach aiming at increasing the level of awareness of flood risk and improve dialogue between Developers, Local Councils and Environment Agency as highlighted in the Defra Strategy - Making space for water.
The paper concludes by debating the wider socio-economic issues arising from the dual and often conflicting dialogue between the prosecution of the sequential test to remove future allocations from high flood risk areas and the need for regeneration or housing renewal through flood risk mitigation. RFRAs and CFMPs are the ideal platform to inform and influence this dialogue by exposing the spatial distribution of risk, the community impacts of that risk, and how society and the regional economy should respond.
Session 7: Making space for water – Making it happen
07.1 Identifying the barriers and incentives to the delivery of better environmental and social outcomes
John Ash
Teresa Fenn
Beatriz Lucas
Risk & Policy Analysts Ltd
Paul Murby
Department for Environment, Food and Rural Affairs (Defra)
Brian Empson
Environment Agency
Key words: environment, social issues, appraisal
Abstract: This paper describes the study undertaken for Defra and the Environment Agency “Identifying the Barriers and Incentives to the Delivery of Better Environmental and Social Outcomes” which forms one of the projects in the Delivery Plan for Making space for water under the Achieving Sustainable Development Theme. In the consultation phase for Making space for water, stakeholders identified shortcomings in addressing environmental and social impacts in flood risk management. The objective of the overall project was to ensure that any obstacles to delivery of the greatest environmental and social benefits were identified with a view to considering how they could be removed. The study comprised two main approaches to assist in meeting this objective:
- Identifying what barriers or obstacles there are to the delivery of better environmental and social outcomes through consultation; and
- Assessing the importance/significance of barriers or obstacles and suggesting possible solutions.
This information is to be used to develop and agree action plans with relevant partners to remove barriers where possible.
07.2 A discussion of the challenges of delivering flood risk management using the probabilistic approach
John Goudie BSc CEng MICE
Karl Hardy BEng CEng MICE
Department for Environment, Food and Rural Affairs
Keywords: policy, risk management, appraisal
Abstract: This paper proposes for the Source-Pathway-Receptor model in Flood and Coastal Erosion Risk Management (FCERM) to be used to analyse the envelope of probabilities of failure across the full range of events, taking account of the fragility of any defences that are in place, and assessing a given probabilistic performance at a reference location/receptor. This should form the basis of new approaches to design and appraisal of FCERM activity (e.g. maintenance), and should take into account the defence fragility to better understand performance.
This paper also explores the facets that need to be taken into account in the management of the overall delivery process, including design, operation and maintenance. Particular aspects are explored including; Outcome Measures, performance based asset management systems, climate change, design maintenance interface, whole life costs, probabilistic approach, along with a perspective on multi criteria analysis for use in investment decision making and how this might link with disaggregated appraisal techniques.
Possible future policy development could involve probabilistic approaches, and how the Source-Pathway-Receptor model can be used in appraisal and decision making, pulling together the themes listed above, to better reflect sustainability in decision making.
07.3 How we determine where to invest - the current position and the future
John Parker
Environment Agency
Key Words: investment, outcome measures
Abstract: This paper attempts to summarise the many factors which will over the next two or three years bring major change in the way investment decisions are made by the Environment Agency in relation to Flood Risk Management activities. Many of these changes are complicated in nature, and are often interdependent, but the aim of this short paper is to explain these changes clearly.
07.4 Risk assessment of coastal erosion
Kevin Burgess
Adam Hosking
Frances Loran
Roger Moore
Halcrow Group Limited
Mark Lee
Geohazard Risk Consultant
Dominic Reeve
Adrián Pedrozo-Acuña
University of Plymouth
Key Words: erosion, defence, risk
Abstract: Successful management of the coast requires a clear understanding of the risks of coastal erosion and instability. The importance of understanding and managing these risks is recognised in Defra’s High Level Targets (Output Measures), which require Local Authorities to assess coastal erosion risks and reflect these in their development plans. In recognition of this a Defra/EA Research & Development project (FD2324) was commissioned to establish a robust and consistent probabilistic approach to assess coastal erosion risk.
This research set out to provide methods suitable for application at a range of scales commensurate with different end user requirements. A key driver for the research was the need to provide coastal authorities with the means to better understand appraise and quantify the coastal erosion risks they manage. As such the tools developed are appropriate for application without requiring expert inputs. Consistent erosion risk evaluation at a local level, fused with ‘high level’ methods, will also benefit National Government in its assessment of coastal erosion risk in the context of the scale and prioritisation of funding.
Session 8: Policy forum
Session 9: Short papers
09.1 COMCOAST: A smart concept for strengthening dikes and levees against wave overtopping
Gert Jan Akkerman
Royal Haskoning, The Netherlands
Jentsje van der Meer
Infram, The Netherlands
Joop Koenis
CUR, The Netherlands
Patrizia Bernardini
Directorate-General for Public Works and Water Management, The Netherlands
Key Words: flooding safety, dikes, strength improvement
Abstract: In this paper an alternative concept for strengthening of earthen sea defences, like dikes and levees, is presented, developed within the European ComCoast project. After an introduction, a short review of wave overtopping and strength of grass revetments, the paper addresses the potential improvements that can be made to the grass revetments of sea dikes in coping with increased amounts of wave overtopping. Detailed engineering on the improvement concepts, indicated here as Smart Grass Reinforcement (SGR), yet needs to be done and field tests will be carried out within the ComCoast project. However, the concepts as developed thus far, seem very promising, as regards economy and feasibility for placement, and also as regards the limited time required for recovery of the grass cover.
09.2 Practical guidance on modifying beach recycling practices to optimise beach performance
Jonathan Clarke BSc (Hons) MSc
Canterbury City Council
Simon Brooks BSc (Hons) MSc
Shepway District Council
Key Words: beach recycling/replenishment, mixed beach permeability, tankerton, folkestone
Abstract: This paper provides an insight into the ongoing Defra funded research projects at two locations in Kent, namely Tankerton and Folkestone, the primary objective of which is to provide practical guidance for beach management practices. Utilising extensive post-replenishment monitoring of beach morphology, sediment composition and inter-tidal beach groundwater levels, it was possible to assess the long-term efficiency of different materials/methodologies in order to define the most cost effective beach management practices.
09.3 Delivering SDA 27: the national priority programme
Brian Francis
Environment Agency
Key Words: sda 27; capital expenditure panel; national priority programme
Abstract: The paper charts how the Environment Agency supported the achievement of Defra’s Service Delivery Agreement (SDA) 27 target. The Paper considers the workings of the National Capital Expenditure Panel and the processes and protocols established to manage the National Priority Programme and reflects on the lessons learned.
09.4 Measuring changes in ground level at tide gauges, using continuous GPS and absolute gravimetry to improve estimates of changes in sea level around Britain
Richard Bingley
Norman Teferle
Alan Dodson
IESSG, University of Nottingham
Simon Williams
Trevor Baker
Proudman Oceanographic Laboratory
Key words: tide gauge, continuous gps, absolute gravimetry, sea level, britain
Abstract: Researchers studying climate change have used historical tide gauge measurements from all over the world to investigate the changes in sea level that have occurred over the last century or so. However, such estimates are a combination of any true sea level variations and any changes in ground level at the specific tide gauge. For a tide gauge record to be used to determine the climate related component of changes in sea level it is necessary to correct for any changes in ground level. The development of geodetic techniques for monitoring changes in ground level at British tide gauges has been on-going at the IESSG and POL since 1990, based on research funded by both Defra and the Environment Agency. Since 1996, this research has focused on the establishment of continuous GPS (CGPS) stations and the use of absolute gravimetry (AG), as independent geodetic techniques for measuring changes in ground level. This paper details the results of Defra/EA R&D project FD2319, which is part of the Risk Evaluation and Understanding of Uncertainty Theme. The paper shows how CGPS and AG have been used on a national scale to monitor changes in ground level at tide gauges and obtain estimates of changes in sea level, decoupled from changes in ground level.
09.5 National river flood frequencies using continuous simulation
Ann Calver BSc PhD CEng FICE
CEH Wallingford
Howard Wheater MA PhD CEng FREng FICE
Imperial College London
Key Words: flood frequency; continuous simulation; rainfall modelling; runoff modelling
Abstract: This paper describes recent research on a next-generation approach to river flood frequency which is based on the continuous time-base modelling of rainfall and catchment hydrological response. Specifically, the results of two Joint Defra / Environment Agency Flood and Coastal Erosion Risk Management R&D Programme projects, FD2105 and FD2106, are reported. A suite of tools has been developed for simulation of long sequences of single site and spatial-temporal rainfall based on observed raingauge or radar data. Catchment runoff models have been spatially generalised to enable use at ungauged as well as gauged sites and measures of uncertainty have been derived for flood frequency curves.
09.6 Managing the coastal historic environment
Peter Murphy BSc MPhil MIFA
Maritime Archaeology Team, English Heritage
Key words: coastal archaeology historic
Abstract: The role of English Heritage in managing and conserving the coastal historic environment is presented. Coastal historic assets and relevant legislation and planning guidance are outlined. Approaches to protection and/or mitigation in relation to shoreline management are reviewed. The problem of mitigating adverse impacts attributable to natural processes of coastal change is considered.
09.7 Short term ensemble prediction system (STEPS): a stochastic precipitation nowcast scheme for flood forecasting and warning
Clive Pierce
Joint Centre for Hydro-Meteorological Research
Alan Seed
Bureau of Meteorology, Cooperative Research Centre for Catchment Hydrology
Neill Bowler
Met Office, Ensemble Forecasting Research Group
Robert Moore
Bureau of Meteorology, Cooperative Research Centre for Catchment Hydrology
David Jones
Bureau of Meteorology, Cooperative Research Centre for Catchment Hydrology
Key Words: precipitation, very short range forecasting, uncertainty
Abstract: In collaboration with the Australian Bureau of Meteorology, the Met Office (Joint Centre for Hydro-Meteorological Research) has developed an ensemble-based, stochastic precipitation forecast scheme, designed to model and predict the probability density function (pdf) of surface rain rate and rain accumulation in time and space. The uncertainties in the motion and evolution of the radar-inferred precipitation fields are quantified, and the evolutionary uncertainty is shown to be the more important. The use of ensembles allows the scheme to be used for applications that require forecasts of the pdf of areal and temporal averages of precipitation, such as fluvial flow and flood forecasting – a capability that has not been provided by previous, very short range precipitation forecast models.
09.8 Integrating the Floodsite Project into UK practice
Paul Samuels
HR Wallingford
Peter Allen-Williams
Department for Environment, Food and Rural Affairs (Defra)
Craig Elliott
Environment Agency
Key Words: flood risk management, research, implementation and uptake
Abstract: The FLOODsite project is the largest single project ever funded by the European Commission on flood risk management and has substantial support from the joint Flood and Coastal Erosion Risk Management (FCERM) R&D programme of Defra and the Environment Agency. The research team and the funders are aware that the benefits from investment in research are only achieved when the research outputs are taken up by the flood management profession and implemented in practice. This paper discusses how the current and projected outcomes of the FLOODsite project map onto national needs in the UK and planning for uptake and implementation of the project results. The paper also discusses the challenges posed by establishing and running a multi-partner, multi-national team with funding from several sources.
09.9 Cliffing of mixed sand-gravel beaches - causes and possible solutions
Kaiming She
University of Brighton
Diane Horn
Birkbeck College, University of London
Paul Canning
Atkins Water
Key Words: cliffing, permeability, bimodal
Abstract: Many of the beaches on the UK coast that constitute the main defence against erosion and flooding are composed of highly permeable sediments, usually a mixture of sand and gravel. Recharge material dredged from offshore is increasingly used to replenish these mixed sand and gravel beaches. Because beach recharge materials may contain a larger proportion of fine sediment than the natural beach, sediment size distributions, sorting and hydraulic conductivity can be significantly altered, as is beach profile response. Even when the size distributions of the natural sediment and the recharge sediment are quite similar, the standard recovery technique produces an increased proportion of sand on the upper foreshore, which is normally composed of coarse sediment. The higher amount of fine sediment leads to the development of cliffing around the high water mark, which results in enhanced loss of recharge material due to undercutting by wave action. Such cliffs, sometimes approaching 2m height, are highly unstable and potentially hazardous to the public. They have to be removed at the first opportunity.
This study investigates the cliffing problem by carrying out a theoretical analysis of the hydraulic conductivity of the bimodal mixed sand-gravel sediment with the support of laboratory and field data. The percentage of sand is shown to be a critical factor in the formation of cliffing. Severe cliffing is likely to occur when the sand percentage exceeds 30~40%. Centrally managed use of available sediment resources and improved on-site sediment placement techniques seem to hold the key to the solution of the cliffing problem.
09.10 Developing a performance-based management system tool for flood and coastal defence assets
Eur Ing Jonathan Simm MEng C Eng FICE MCIWEM
HR Wallingford
Michael Wallis MSc AIEMA
HR Wallingford
Eur Ing Paul Sayers BEng C Eng MICE
HR Wallingford
Ben Gouldby BSc
HR Wallingford
Foekje Buijs
HR Wallingford and University of Newcastle
Jaap-Jeroen Flikweert
Royal Haskoning
Ben Hamer BSc CEng MICE
Halcrow
Key Words: flood, risk, management
Abstract: This paper provides an update on the on-going research and development to develop new methods and tools to support asset management. The new approaches aim to support the attribution of risk to particular assets within the flood system and quantify how this may change over time and how alternative whole life strategies of capital and maintenance interventions can be best directed to manage the changing risk. The research includes development of a revised methodology for asset inspection and ongoing studies into how the probability of defence failures can be modelled and represented in a scientifically robust way.
09.11 2D or not 2D? – an Australian perspective
Bill Syme
WBM Pty Ltd
Key Words: 2d flood modelling, tuflow, isis
Abstract: Australia, like elsewhere, suffers socially and economically from flooding, with an annual average direct damages bill in excess of $300million. Federal, state and local government policies and guidelines address this issue through a framework of objectives on how to assess, quantify and mitigate flood risks. Accurately predicting flood hazards to help identify the risks, within the array of uncertainties the practitioner deals with, is often a challenge.
2D and 2D/1D flood-modelling software has been researched, developed and embraced within Australia since the early 1990s, and is today, for many flood investigations, mandatory. Compared with 1D solutions, 2D or the combination of 1D and 2D, considerably improves the quality and accuracy in quantifying flood hazards. The primary benefits from 2D are: more accurate solution of the governing equations; two or three orders of magnitude higher resolution output; flowpaths do not have to be pre-defined; vastly more accurate mapping of flood inundation, flood levels and flood hazard; and importantly, the modelling is more easily understood and accepted by stakeholders. The primary disadvantage is the longer simulation times compared with 1D solutions. The pros and cons of 2D and 2D/1D flood modelling are discussed and illustrated through several examples.
09.12 The impact of upland land management on flooding, preliminary results from a multi-scale experimental programme
Howard Wheater
Miles Marshall
Imperial College London
Zoe Frogbrook
Centre for Ecology and Hydrology, Bangor
Oliver Francis
Imperial College London
Brian Reynolds
Centre for Ecology and Hydrology, Bangor
Neil McIntyre
Imperial College London
Key Words: land use; land management; runoff processes; flooding
Abstract: This paper describes ongoing field and modelling research at Pontbren in the Upper Severn catchment, investigating the effects of upland land management and flood risk. The multi-scale programme aims to bridge the gap between plot scale experiments and catchment scale responses. It focuses on soil properties and runoff processes, using plot and hillslope scale measurements nested within instrumented 1st order catchments. Initial tensiometer and groundwater data from an instrumented hillslope with heavy textured, clay-rich soils under improved grassland production have revealed a saturated upper soil horizon for most of the winter, resulting in extensive saturation excess surface runoff. However, dye tracing experiments have illustrated the importance of preferential flow paths in the movement of water through these soils, and a significant amount of water is rapidly transported through land drains which are often present in these land use systems. Preliminary results from wooded buffer strips suggest that soils tend to be drier, infiltration capacities are increased and overland flow reduced due to the presence of trees and/or absence of sheep. The effects on hillslope runoff are currently being explored using a 3D physically-based model which forms part of a new multi-scale modelling methodology.
Session 10: Best practice in river engineering
10.1 Tsunamis - assessing the hazard for the UK and Irish Coast
Dr Stephen Richardson
HR Wallingford
Dr Roger Musson
British Geological Survey
Dr Kevin Horsburgh
Proudman Oceanographic Laboratory
Key Words: tsunami, hazard, coastline
Abstract: Following completion of the 2005 Defra commissioned study “The threat posed by tsunamis to the UK”, this study was undertaken to investigate more specific questions raised from the previous report. The original Defra study identifies four potential tsunami sources origins, and provided first estimates for wave conditions at the UK coast for tsunamigenic events of very high, high and moderate likelihood.
This second study reviewed two of these source origins in more depth, the North Sea event and a Lisbon-type event, with their consequence impact compared with regard to hazard. Previously proposed source terms for a 1755 Lisbon event was assessed and three simple models considered that could be used to study the impact of a tsunamigenic earthquake of a similar size, and in a similar region to the 1755 source, on the UK and Irish coastline. The resulting sea level displacements were used as initial conditions in a numerical model to propagate the initial disturbance to nearshore. A further numerical model propagated the tsunami to the shoreline and provided estimated of water level elevations on the Southern Irish coast, the Cornish coast and in the Bristol Channel. Information regarding the tsunami magnitude at the coast was then used to assess hazard.
This paper focuses on one of the hypothesised Lisbon type events, the propagation of the tsunami from source to shoreline and the consequence of an impact on the coastlines of south-west England and southern Ireland.
10.2 Flood forecasting using real time hydraulic and other models: lessons from the Carlisle flood in January 2005
Peter Spencer
Dan Boswell
Ian Davison
Ben Lukey
Environment Agency
Key Words: flood forecasting; hydrodynamic models; carlisle
Abstract: In January 2005 more than 1800 properties were flooded in Carlisle by an event more than one metre higher than any other in the previous two hundred years. Under these exceptional conditions some well-tried flood forecasting models, whether simple or complex, performed poorly. This paper describes the background, the performance of the models, reasons for the poor performance during the event, and subsequent improvements. It suggests lessons which will apply to flood forecasting modelling elsewhere.
10.3 Residual risk revisited - flood incident management in the Netherlands
Ir Lisette Heuer
Ir Jaap-Jeroen Flikweert
Royal Haskoning
Ir Dianne Hoogendoorn
Province of Overijssel
Drs Nils Ligthard
Ministery of the Interior and Kingdom Relations
Key words: flood incident management, operational response, international good practice
Abstract: In Dutch flood risk management, the role of incident management is quite different from the UK. The existing Dutch system of flood defences reduces the probability to an unimaginably low level, down to 1/10,000 per year for most people. However, as the consequences of flooding could be disastrous, residual flood risk is still significant. Recent years have seen a rising awareness of this residual risk, first among practitioners, then among the public and among politicians. Dutch flood risk management is still strongly focused on flood defences, but the Government has initiated the development of a balanced strategy to manage residual flood risk from the main rivers, the Rhine and Meuse. Main elements of this strategy are: cross-border cooperation, organisational measures, emergency inundation areas, compartmentalisation and further increase of standards.
This paper focuses on one element of the strategy: organisational measures. Work thus far has led to the following main conclusions for the Dutch context:
- Flood incident management is essential as there is always a residual risk, even with Dutch standards of protection.
- The authorities have limited resources so there must be a focus on the capability of the public to help themselves. This is a challenge given the existing public perception of absolute safety against flooding.
- Flood response procedures are getting better, but must be further improved and integrated in existing emergency response structures.
- Decision makers, usually politicians, must learn how to deal with uncertainty.
- Contingency plans must be based on the reality of limited resources.
- Available resources in a large flood would be insufficient.
Some interesting comparisons with the UK:
- Despite the much longer Dutch tradition of flood risk management, flood incident management appears to be at a similar level of development, so mutual lessons can be learned. Public flood warning is certainly better developed in the UK.
- In the Netherlands flood incident management hardly needs justification, while the UK always balances costs and benefits.
- Strategic decisions during emergencies are made by politicians in the Netherlands (at all levels), while in the UK politicians seem to come into the picture only at higher levels.
- Last year’s Defra conference contained a paper on Exercise Triton (session 6B, paper 4). Many of the lessons identified there are comparable to the conclusions for the Netherlands, despite the physical and organisational differences: multi-agency working, uncertainty about the need for evacuation, resource management.
10.4 Risk based design of telemetry networks for flood warning applications
Kevin Sene CEng MICE PhD
Esther Ainsworth
Geoff Graham BSc(Hons) MCIWEM
Atkins Water and Environment
Keywords: telemetry network, flood warning, risk based
Abstract: River level and raingauge telemetry sites provide the basic information required for issuing flood warnings and for supporting the operation of flood forecasting models. Following a major expansion of the telemetry network in England and Wales after the Easter 1998 and October 2000 floods, the installation of new instruments is currently being driven by the introduction of a more targeted approach to issuing flood warnings, and the target set out by the Environment Agency’s corporate strategy to extend the coverage of the flood warning service to 77% by 2007. The decision to install new gauges can be taken at a site specific, river reach, catchment or regional scale, with potential cost savings from an integrated catchment approach. This paper discusses a range of approaches to prioritisation of telemetry network improvements, including issues of scale, technical feasibility, flood forecasting requirements, and flood warning needs. In particular, the traditional cost-benefit approaches to prioritisation are compared with a more risk-based multicriteria approach. The methods are illustrated with various case studies at a regional and catchment scale.
10.5 A new approach to flood estimation using flood peak and duration - a case study informing incident management plans for Exeter
Sun Yan Evans
Mott MacDonald Ltd
Duncan Riches
Mark Russell
Tim Wood
Environment Agency
Key Words: flood estimation, flood incident duration, flood incident management
Abstract: Flood events are dynamic and present major challenges to organisations responsible for flood incident management. Informed and effective flood incident management plans are essential, helping to guide actions before, during and after flood events.
Following the completion of a flood risk mapping project, an innovative approach was developed to better inform flood incident management plans for Exeter. This paper describes how historical flood data can be used to account for both flood peak and duration, allowing flood volume to be estimated for a range of scenarios. Key indices were developed from that data to define short, median and long duration flood events. The results of the study were used to produce inundation maps of urban flooding from the River Exe through Exeter under various scenarios.
The paper concludes that the innovative approach presented could be applied to flood incident management plans for a wide range of catchments and flood event scenarios.
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modified: 13 February 2008
Page published: 13 February 2008