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A SUSTAINABLE APPROACH TO FLOOD MANAGEMENT FOR THE UK

KAREN THOMAS

To fully appreciate why we have the flood defences we have around our coasts and estuaries today we need to go back to the Roman occupation of Britain to ascertain how flood defence began. Over 2000 years ago the occupying Romans drained huge areas of wetland in the Fenland areas to create new, fertile agricultural lands. The Romans, after investing a lot of time and money in draining such lands needed to ensure it was then not flooded from tides in the Wash. Small earth walls were built to keep out the larger tides and this was really the humble beginnings of flood defence. After the Romans left Britain landowners maintained the systems of low walls which in many low-lying areas became known as ‘wicks’ or ‘wichs’, and were used as footpaths and walkways for people and livestock particularly during times of flood. Many places in East Anglia today have the suffix ‘wich’, such as Norwich, Ipswich and Harwich for example.

Moving on in history the next big change in drainage and defence occurred under the reign of King Charles I. He saw the lowland marsh areas of East Anglia as potential prime agricultural land and set about employing his Dutch counterparts (renowned for their drainage expertise) to come to England and drain the marshes. They were incentivised with the promise that they could keep half the land that they managed to drain. This may not have been an issue if the marshes were not already being used by local people for various activities such as fishing, reed cutting and wild-fowling which formed the basis of many trades and livelihoods locally. Whole communities lived among the marshes and moved seasonally with the freshwater and tidal floods. These people had traditionally had a common-law right to use the lands and effectively King Charles I was removing their livelihood and their homes through his drainage of the marshes. So the widescale en-wallment and drainage of East Anglia began.

At this time Oliver Cromwell was becoming a representative of ordinary people of Britain in opposition to the King and the removal of common lands from the people throughout the UK was one of the reasons that Cromwell and his followers, rose up against the King and had him executed. Unfortunately for him, Cromwell did not last in power long before he too was executed and replaced by Charles II.

The new heir’s mind was not really focussed on the subject of sea defence as he was more interested in the finer things in life, so the Dutch continued draining and en-walling land. The landscape began to assume the appearance of low-lying agricultural fields with complex drainage patterns that we see today throughout Norfolk, Suffolk and Essex.

During the 17th Century the UK went through a period of very cold climate. The winters were exceptionally cold and the Thames would regularly freeze over. At this time sea level around the UK was at a much lower level. By the late 1800s the cold spell diminished as a result of the sudden warming, sea levels rose. This factor coupled with some severe storms caused many of

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the low earth embankment walls around the coast to be overtopped and breached causing significant losses to the agricultural communities now living and working in East Anglia.

In 1901 a Royal Commission looked into the issue of sea defence and concluded that if landowners wanted improved defences then they should pay for it themselves. As a result levies were introduced to collect funds for the building and improvement of defences and drainage systems and more land was reclaimed from the marshes to supply the nation with food. During the First and Second World Wars it became important that Britain was not ‘starved into submission’ and consequently our reliance on fresh and salt water reclamation to provide us with additional agricultural land increased.

In 1953 however, the largest natural disaster to affect Britain occurred along the most of the North Sea coast. A sea surge, fuelled by bad weather conditions and winds from the North began its progression south in early February 1953. As the surge reached The Wash it coincided with the spring high tide and consequently raised water levels to 1 m above the expected high tide level. To make matters worse the tide and surge were happening during the night and as a result few were aware of its occurrence. As a result very few people could be warned of the impending flood. The surge tide flooded vast areas of Norfolk, Suffolk and Essex and as a result killed over 300 people, thousands of livestock and ruined crops and agricultural land for many months to come. Consequently, the reaction was to repair breached defences, improve, strengthen and build higher and stronger than before. It is the defences that were created as a response to this natural catastrophe that the Environment Agency has inherited today. Some of the walls were built to such high standards of defence that they have only required minimum levels of maintenance since 1953.

However, over the past few decades many of the walls have required significant financial investment to repair damage. In most cases the level of investment has increased where the adjacent saltmarsh has been lost. In the last 25 years over 1000 ha of saltmarsh have been lost in Essex alone and this is largely due to coastal squeeze, a phenomenon caused by changing sea level and hard defences on the coast. Climate change is causing an increase in sea level rise and changes to our weather patterns. Reports by the UKCIPS programme show that in future, as a result of climate change, there will be dryer, hotter summers and colder wetter winters. The changing weather will also bring different wind patterns and increased storminess in the North Sea. The storminess is of concern as this will affect the size and direction of waves and coupled with a background rate of relative sea level rise in the order of about 6 mm per year, has significant implications for future coastal and estuarine management. Information regarding overtopping rates being collected by our Dutch colleagues shows that there is a definite increase in wave overtopping rates and this is an issue which they are particularly concerned about as it may not be physically, or economically possible to keep raising defences long term.

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East Anglia is experiencing the remnant effects of the last ice age in the UK over 10,000 years ago. The weight of the ice on the northern half of the country depressed the rocks and land lying below. As the ice melted at the end of the Ice Age the land covered by ice sprang back, a process called isostatic rebound. East Anglia, which was not affected by the ice sheets is currently being thrust downwards at a rate of several mm/yr in response to the northern UK rising up. This sinking effect coupled with global eustatic sea level rise creates a combined relative sea level rise which is greatest in the South East and Anglian regions. Saltmarsh, mudflats and beaches respond to rising sea level by moving upwards (through accretion) and rolling inland to maintain there position within the tidal frame. Effectively, the supra tidal areas move inland (high marsh, dunes etc) and the intertidal zones accrete to keep pace with the changing level if sediment supply permits. This ‘rollover’ of the coast allows the habitats to stay within their tidal zone, maintaining the same beach or marsh width overall. However, the presence of hard defences along much of the coast prevents the habitats from rolling back and consequently increases the rate of erosion, either through steepening and narrowing (beach) or through direct erosion of the habitat as a result of increased energy (marsh).

The effect of previous reclamation of thousands of hectares of freshwater and salt water marshland areas and the impacts of coastal squeeze has resulted in a significant reduction in the natural floodplains around the East Anglian Coast. As a result when large tides, storms and significant fluvial events occur the defences around the estuaries and coast come under increasing pressure. The advancement of Mean Sea Level landward is apparent around the coast (Futurecoast 2002) and where the coast is backed by hard defences the beaches and marshes are becoming trapped between the two. This results in over-steepening of shore profiles and increased erosion of intertidal zones. The significant changes going on around the coast are of concern to coastal managers. As erosion rates increase valuable habitats are lost or threatened and at the same time flood risk increases. Saltmarsh and shingle are both Biodiversity Action Plan habitats and East Anglia has some of the best and greatest expanses of such habitats in the UK. Rapid losses due to coastal squeeze are significant nationally both in terms of the loss of important habitat and natural flood defences. The rest of the paper focuses on the loss of saltmarsh habitats in particular.

Where sea defences are fronted by wide expanses of saltmarsh the maintenance costs on the walls is minimal. In fact many such walls are under so little stress that they are populated by plants and grasses on the seaward face. This is in stark contrast to walls where there is little or no salting fronting the wall as the defences can be prone to wave attack and strong tidal currents. Saltings are a natural flood defence and are capable of removing wave energy as the plants protrude into the water column causing friction and slowing the advancing waves down. Similarly, the convoluted creek systems help minimise tidal currents so that little energy from waves and tides reaches the defences.

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Where the saltings have eroded away, maintenance costs can be excessive. Overtopping by waves is more frequent as there is no secondary natural barrier between the waves and the sea. Waves can cause severe damage to the back face of a wall and this is often a primary cause of wall failure and breaching. As waves reflect off the hard vertical surfaces of the defence backwash undermines the sediments at the base of the wall and can undermine the toe of the defence, again leading to weakening and eventual failure of the defence. The power of breaking waves on defences can force concrete structures apart as the hydraulic pressure of the dissipating wave get between joints and a common maintenance requirement is the replacement of areas of block-work after storm events.

The loss of saltmarsh and intertidal areas through coastal squeeze is not the only problem that the coastal manager is faced with. Behind sea defences around our coast are numerous legacies of past decision making that make the management of flood risk more complicated still. The coast of East Anglia is relatively low lying and apart for some large seaside towns and ports, the coast is relatively rural. Certain land use decisions have been made in the past that limit the options we now have for relieving pressure around our coast. The reclamation of saltmarsh was not just from agricultural purposes, in many places around the coast such areas are now heavily populated with people. At one time, before the Dutch drained the marshes, the people of East Anglia lived in these low lying areas but were able to move away when flood events were expected. The people who lived and worked on the marshes were very aware of their watery environment and consequently were better prepared to evacuate the marshes if flooding was imminent.

In the present day people are not so nomadic but enjoy living in close proximity to the coast, choosing permanent homes which cannot be moved out of flood risk zones. Similarly, people choose to locate temporary structures like caravans close to the sea and again such development is hard to move once permanent buildings and investment are in place to serve the tourist population. New Planning and Policy Guidance (PPG25) should help to minimise such scenarios happening in future but with increasing pressure to build outside of London (Thames gateway proposals) and the desirability of homes near the coast and estuaries there will always be significant pressure on this zone for development. Investment as a result of past decisions can be extensive, for example, there are 3 nuclear powers stations in Essex and Suffolk, Bradwell and Sizewell A and B respectively. Bradwell is currently being decommissioned and Sizewell will be at some point in the future. The consequences of not maintaining a flood defence at such locations is not an option for many tens of years if not hundreds to come and therefore long term plans to maintain the right standard of protection are being put in place. However, there must therefore also be a commitment to invest funds for the future of these defences and this will mean funds cannot be spent elsewhere as a result.

Large expanses of rural agricultural land sit behind many flood defences and are frequently flooded by saltwater as even good quality seawalls are overtopped more frequently. Areas which once flooded tidally, twice a day,

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everyday are now highly populated and as sea level has risen since the land was en-walled and built on, the marsh and water levels outside the seawall are often higher than the land behind the walls. Outside of the seawalls on the coasts and estuaries there are marinas, yacht moorings, fisheries to name but a few of the coastal industries that take an income from the sea. All need consideration when planning for the future flood management of the coast.

The rural nature of the coast has led to the designation of much of the coast as nationally or internationally important habitats, many of which require protection in situ. The wealth of habitat types and important species around East Anglia makes conservation a very high priority when looking at the future of the coast. The difficulty is that the coast is a very dynamic environment that is currently constrained by many of the defences we have put in place. It is not able to adapt freely to coastal change and as a result saline habitats are under pressure. One way of dealing with this issue is to re-align the coast, set back defences to high land or build a retired defence. This, however, presents difficulties as many important freshwater habitats exist directly behind the defences as result of, in some cases, hundreds of years of drainage and water level management. In re-aligning the coast we can loose important freshwater areas which in turn, under EU legislation, also need to then be replaced elsewhere. This is not an easy task given the relatively low availability of surplus freshwater and suitable sites for such recreations, an issue which under climate change predictions for the area is likely to be even more difficult in future. One solution might be to replace freshwater habitats in a huge wetland scheme around the Fens, the area first reclaimed from the sea and defended by the Romans over 2000 years ago!

All these factors need to be balanced when considering future coastal management and all these factors are potentially going to be very expensive to maintain as they are ad infinitum. The budgets for flood management are not limitless and funding for flood defence is dependant on other pressures on the national purse such as Health and Education. Changes to the way Flood Management will be funded in future are coming into place in 2004 with the new Block Grant system. This effectively means that in future the money received for Flood Management in East Anglia will be determined by the needs everywhere else in the country. Consequently, places like London, which have a high economic status, are considered a serious flood risk in terms of economics, although likelihood of flooding is low due to the high standards of defence on the Thames. As a result rural estuaries and coasts like those in Essex, Suffolk and Norfolk (which have a potentially higher likelihood of flooding but a lower economic risk) may receive less Flood Management funds in future as nationally money will need to be spent in areas of greatest population and infrastructure.

Consequently, there is a need for effective flood management that encompasses many of the inherited responsibilities from previous decisions made on the coast. This must be coupled with a reduction in expenditure on uneconomic seawalls (those which are perceived to protect little economically) so that expenditure can be focussed on where it will be needed most in the future. In Eastern Area the Agency and our partners have already begun taking steps to the secure the long term management of the coast in the future. This is happening at both a strategic level through Shoreline Management Plans

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(SMPs) and Estuarine Flood Management Strategies (EFMSs) and at an experimental level with schemes such as managed re-alignment and foreshore recharge. Managed realignment has been successful at Orplands (EA), Hullbridge (EA) and Tollesbury (EN) and foreshore recharge in the Blackwater, Stour, Orwell and Hamford estuaries in partnership with Harwich Haven Authority.

Managed realignment, foreshore recharge and regulated tidal exchange techniques are now described in more detail, followed by local examples of the techniques in practice.

Foreshore recharge This is a technique which allows the foreshore in front of a defence or cliff to be replaced by means of importing material from elsewhere and pumping or spraying onto the frontage. The material can range from beach sands (Jaywick, Essex), to shingles (Tollesbury and Old Hall defences, Blackwater, Essex) to fine muds and silts (Shotley, Orwell, Suffolk). Locally the sediments are supplied by Harwich Haven Authority (HHA) as part of their dredging of the ports of Felixstowe and Harwich in the mouth of the Stour and Orwell estuary. The ports generate material whenever they do capital works i.e. a new scheme and when they do annual maintenance and dredging campaigns. This tends to generate sands and shingles and fine muds and silts respectively. The ports are under pressure to use dredged material beneficially whenever they can and consequently the Agency is working with HHA to identify potential sites for foreshore recharge. The sediments, if not used in this beneficial way, would be lost to offshore dump sites where water depths and currents will preclude the sediments returning to the coastal zone. This could then enhance erosion rates within our estuaries and coastal zones as sediments are lost to the open coast instead of nourishing mudflats and saltmarshes This is an issue which greatly concerns coastal managers as the potential for increased water depth in the future due to sea level rise, means that the interaction between the seabed and wave activity will decrease, this reducing sediment transport rates from deep water areas back to the coast. . By returning sediments from the ports to the estuaries the material can be recycled. Sediments placed in vulnerable areas to protect defences and recreate habitat are not a permanent solution, however, as they degrade the sediments are re-cycled within the estuary system and should nourish an adjacent intertidal area undergoing accretion at that time. The aim of recharge using silts and muds is that the ports remove material on an ongoing basis, so it should be utilised on an ongoing basis. This is a short-medium term solution to recreating habitat and reducing flood defence maintenance costs.

Managed re-alignment Managed re-alignment is the process of removing sections (breaching) or whole lengths (bank removal) of flood defences to allow tidal inundation onto the land. The principal is designed to allow the estuary or coast back onto the areas that were once floodplain. The technique can help us manage flooding because during surges re-aligned sites allow water to move sideways onto the

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land instead of moving up estuaries where properties and infrastructure are usually at their greatest. Effectively the surge is ‘stored’ in the re-aligned areas and this reduces increased water levels upstream. A network of re-aligned sites in estuaries at strategic locations can help reduce flood risk significantly. This approach has other benefits too. The removal of sections of defence means that those sections of defence need no longer be maintained so funds for maintenance can be diverted elsewhere in the estuary where there is a greater need for protection. Equally, managed re-alignment creates habitats that are currently being lost at an alarming rate, habitats such as saltmarsh and mudflat can be recreated at re-alignment sites and help restore the local environment and meet national and international biodiversity targets. Such habitats support fish and bird communities which may be of importance locally for example, tourism, wild-fowling and commercial and recreational fishing. Finally the schemes help to restore the landscape, introduce new footpaths and recreational areas and recreate the marshland areas that East Anglia is famous for. This is a long term solution that has immediate benefits as soon as a scheme is in place. The most recent Agency schemes are now discussed in more detail.

Regulated Tidal Exchange This is the process of allowing saltwater onto the land by a controlled means. This could be a very simple process of reversing a freshwater drainage sluice so that instead of freshwater draining off the land into ditches and exiting through the seawall, instead the seawater comes in through the pipe and onto the land. The techniques is used in other parts of the world (Holland, USA) with far greater technology involving tidal gates, hydraulics and pumping to get the right amount of seawater into and out of the site. The technique is employed in southern France to allow oysters to be grown effectively ‘on land’ with RTE providing the seawater environment. The control of seawater allows different water levels to be achieved and therefore allows different habitats to become established. In the UK, the technique can be employed to create a new habitat in an area where breaching the defences would be detrimental to the adjacent estuary. The technique can be used to prepare a site prior to breaching in terms of the soil chemistry and seed bank so that a new managed re-alignment gets off to a good start. The method can also be used to warp up a site that is lower than the outside estuary or coast as a result of drainage and settlement. This allows marine sediments to enter the site and build up again perhaps prior to a realignment.

Foreshore recharge at Horsey Island, Hamford Water in Essex. Horsey Island is the largest island in Hamford water an embayed estuary on the Essex coast. The island is of key flood management interest to the Agency as it serves strategically to protect a significant area of mudflat and saltmarsh as well as many kilometres of Agency flood defences particularly from Northerly, Northeasterly and Easterly storm conditions. During the early 1990s the island’s defences were becoming badly affected as a result of significant saltmarsh losses on the north east and northern areas of the island.

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In a bid to restore the marshes and beach areas in front of the defences the agency in partnership with HHA and English nature put a scheme in place to recharge the foreshore areas in front of the defences at Horsey. HHA provided shingles and muds and English Nature assessed ecological change. The RSPB also assisted by monitoring bird numbers and CEFAS examined the recovery of invertebrate populations.

The Horsey Recharge scheme comprised the placement of redundant Thames Lighter barges along the foreshore to provide an instant wave break. This was couple with recharge of sands and shingles to create a new beach area. The shingles were placed to a height that exceeded the MHWS so that the beach would act as naturally as possible and could roll back over time with changing tidal conditions. Behind the sand bund fine silts and muds were pumped ashore to create a new muddy backshore. Brushwood polder fencing was used along the back of the shingle placement to allow the beach to build up naturally to a height above MHWS and the polders were also used to contain the fine muds within the site. Within a year the mud had become colonised with pioneer saltmarsh species and was performing as an intertidal habitat. Subsequent recharges have placed more muds onto the saltmarsh in an attempt to raise the levels of the saltmarsh for the future. Early in 2003 the scheme was extended further along the exposed frontage to create a new area of intertidal in front of the seawall. The scheme has performed well at both creating valuable intertidal habitat and reducing flood defence maintenance costs at the site. The success of the trials has meant that a new scheme will go ahead late 2004/early 2005 to place fine muds onto an area of existing saltmarsh which is highly degraded. This is part of the Interreg funded Comcoast project which aims to look at multifunctional coasts and long term flood management.

Abbotts Hall Managed Re-alignment Scheme This project is a good example of a multi-functional flood management scheme involving varied partners. The site is at Abbotts Hall Farm, near Great Wigborough in Essex. The farm is on the north bank of Salcott Creek which is a tributary of the Blackwater estuary. The scheme began in the mid-1990s as a Regulated Tidal Exchange scheme which allowed areas of the site to develop into intertidal habitats prior to the managed re-alignment scheme coming into being simply by reversing a couple of the freshwater drainage sluices. This allowed controlled tidal inundation onto the site (see Plate 6).

The managed re-alignment schemes followed on from the RTE scheme and comprises an 80 hectare wetland recreation scheme The farm was bought by the Essex Wildlife Trust in 2000 with funding from WWF-UK and the Heritage Lottery Fund. The intention of EWT and The Wildlife Trust nationally was to use the site as the new Essex Headquarters and to create a ‘wild-life’ friendly farm. The farm had to incorporate conservation values but also had to be an economic business. The Agency’s involvement was to design a flood management scheme at the site. The managed re-alignment scheme was needed to create much needed compensatory habitat, reduce the need for expenditure on 3·5 km length of uneconomic seawall, and also test the latest

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hydrodynamic modelling techniques to increase confidence in modelling as a useful tool to predict hydrodynamic change in future re-alignment schemes. English Nature set up ecological monitoring at the site and used it as an opportunity to revise their monitoring protocols for such schemes.

HR Wallingford were contracted by the Agency to monitor the hydrodynamics and geomorphology of the creek prior to any breaching and to model the likely effects of the scheme on the adjacent estuary and its users. The monitoring programme was largely conducted during the autumn equinox period each year to get conditions similar to those found on surge events. Lidar (Light detection and range) proved a very effective tool in assessing the local topography and tied in well with surveyed transects on the ground. Posfords Haskoning were contracted to write the Environmental Impact Assesment which was used to consult the stakeholders locally. The scheme proposed to create 50–60 ha of intertidal mudflats, saline lagoons and saltmarsh by means of 5 breaches through the existing seawall. The largest breach was originally designed at 80 m wide. The scheme also incorporated the replacement and creation of nearly 20 ha of freshwater, brackish water and grazing marsh habitats. Due to the naturally rising land on the site there was no requirement for secondary flood embankments other than 2 small spur walls at the fringes of the site to protect neighbouring land from saline intrusion on high tides. The tidal range on the site ranges from 1·5 MHWN–2·7MHWS. This means that the site can be fully transitional with saltwater habitats extending inland and areas of brackish and then freshwater further inland again.

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Due the concerns of local stakeholders the main breach was widened and moved downstream slightly to avoid any impacts on the adjacent south bank of the creek where the flood defence protects the RSPB Old Hall bird reserve which is a designated SPA and an important freshwater site. Also additional monitoring was carried out and the 5th breach phased to a later date as there is an oyster fishery downstream of the site and their concerns ranged from increased sedimentation at the oyster layings to increased tidal velocities which could erode the layings. The modelling work concluded that some changes would take place in the creek, most notably that there would be an increase in tidal velocities on the peak of spring tides of up to 30%.

The monitoring and modelling was carried out between September 2000–2002. In October 2002 the site was breached at 4 of the breaches. The largest breach was taken down to 1·65 m ODN so that it would act as a cill at the end of the receding tide. This was to reduce the level of sediments stirred up at near low water on the adjacent mudflat as water exited the site. The cill was designed to reduce increased suspended sediment loads arriving at the oyster laying downstream. The 5th breach was carried out in the spring of 2003. In the spring of 2003 the site had become colonised by the pioneer saltmarsh species, Salicornia and by the autumn several species of saltmarsh plant were living on the site. Water voles and Great Crested newts (some of which had to be relocated as a result of the tidal inundation) were found in the new freshwater lakes that had been constructed further inland. Thames fisheries staff surveyed the site and ongoing work shows that the site is being used by over 10 species of fish and 2 of those are Bass and the Blackwater Herring both of which are commercially fished.

The site is an excellent example of multi-functional coastal management. The site performs a flood management function, is a working farm which encompasses environmental best practice. The EWT receive payments through DEFRA’s stewardship schemes for the habitats that have been created on site in the same way that a farmer can receive a subsidy for crops that are grown. These payments are currently being reviewed and it is hoped that the amount and length of time the payments cover will be increased in 2005 so that more landowners may be encouraged to undertake such projects in conjunction with EA and other coastal authorities and NGO’s. Also under the Comcoast project the EWT are aiming to build an education centre to deal with the huge volume of people wishing to visit the site. Abbotts Hall has become a great educational tool in helping the partners involved illustrate to the public, stakeholders, landowners and other partners how such schemes can work in practise. The site is a great example of how the coast could be farmed in future whilst accommodating the environment and helping to reduce flood risk.

Summary Whilst managed re-alignment and foreshore recharge are not a panacea for all our future flood management problems, such techniques used in the appropriate places on the coast will allow the Agency to both manage flooding and reduce maintenance costs at uneconomic sites. These techniques also allow us to recreate some of our most vulnerable habitats nationally and

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internationally. A strategic approach to managing the coast will incorporate these techniques to compliment wall strengthening and improvement schemes at other coastal frontages. The aim is to use these techniques where they are strategically needed to create a coastline that is meets our long term socio-economic, environmental and technical needs over the next 100 years. Many people often ask why we simply don’t lobby for more funds and then build defences higher to keep the sea out. Even if funding were to be found, the technical ability to engineer such walls has limits. The Dutch (mentioned earlier regarding overtopping) have invested heavily in defences because a huge area of the Netherlands is below sea level. Their recent overtopping findings have alerted their engineers to the problems of building higher. To do so means to build defences wider at the base and this is not necessarily possible on certain ground types, equally significant amounts of infrastructure lie immediately behind such defences making widening impossible without removing homes, businesses etc. The Dutch are also part of the ComCoast project because they now realise that they may have to build a secondary line of defence along some areas of the coast and allow for some degree of overtopping in future. This would then allow funds to be channelled into the areas where overtopping would create the greatest risk to people and property.

Unlike the Netherlands large areas of low-lying coastal land in East Anglia rises to high ground fairly quickly. There is therefore greater flexibility for change. The issue of replacing freshwater areas currently behind sea walls is not necessarily desirable but effectively possible by finding more sustainable sites inland and up estuaries. There is the issue of freshwater supply, which is low in East Anglia and likely to diminish under present climate change scenarios for the region, however, as mentioned earlier a national freshwater wetland in the Fens could be a possible solution?

After inheriting the flood defence decisions of our predecessors spanning nearly 2000 years since the Romans first began draining the Fens, the emphasis for coastal agencies today is moving away from flood defence towards flood management. The coast is a dynamic environment that we must work with rather than try to defend against. The number if options open to us in the future regarding coastal management will dramatically reduce over time. To recreate saltmarshes and mudflats there needs to be sediments in place to nourish the habitats, there need to be plants to provide seeds to new sites and there needs to be organisms for re-population to be possible. If the rate of erosion of such environments continues then the recreation of such environments becomes increasingly difficult. Even if the funds were available, and it was technically possible to build really high walls, by the time one had climbed to the top of the defence there wouldn’t be much to see on the other side. In time the marshes and mudflats, beaches and dunes would be eroded away as sea level rises. In turn this would increase the vulnerability of the defences and increased investment would be necessary.

If instead we can start to employ managed re-alignment, foreshore recharge and regulated tidal exchange techniques now then we can keep abreast of climate change and sea level rise before the opportunities for change are reduced. The coast needs to change so it can adapt to future sea level

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changes. Adopting a proactive approach to flood management and habitat creation now means that coastal change can be accommodated and managed for the next 100 years. At this point in time we can manage that change to encompass environmental and socio-economic gains whilst reducing flood risk for the greatest number of people.

Karen Thomas Coastal Processes Engineer Environment Agency Cobham Road Ipswich

Plate 6: Managed retreat site at Abbots Hall, Little Wigborough, Essex (p. 50).

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