Planning for our Coasts
Over the last few years several studies and consultations have taken place on and around the Exe in order to understand the coastal processes taking place in this very changeable estuary.
At the highest level, Shoreline Management Plans (SMP) set high level policy for very large areas and are based on large scale coastal processes. The Exe forms part of the South Devon and Dorset SMP, more information about which can be found here.
Below the SMPs come Strategies. These are more detailed documents that cover areas where there are several interconnected issues, such as in the Exe Estuary.
The Strategy will identify a range of projects required to actually deliver the work required. Ideally, we would produce these documents following the Strategy, but in reality some projects are already underway, such as the Exe Estuary Coastal Management Study and Lower Clyst Project, so information from these has been used to inform the higher level studies.
Exe Estuary Strategy
The Environment Agency have developed a strategy to manage tidal flood and erosion risk around the Exe Estuary for the next 100 years. They are carrying it out in partnership with the local authorities of Teignbridge, East Devon, Exeter City and Devon County.
This is being done to work out the best way to protect communities and the environment into the future as sea levels rise.
For more information download the full report.
If you want to find out more information please contact the project team by email at:
The Lower Clyst Valley is one of the areas being studied in more detail. A project has been running here since 1999 and a new study has recently been completed by consultants Halcrow. The study, which has been carried out on behalf of the majority of valley landowners, considers the effects of breaching (creating holes in) the banks alongside the river between Clyst St Mary and Topsham, allowing water to spill into the adjacent low lying land (known as the floodplain) both during high tides and flood events.
The river banks were built many years ago, offering protection to the agricultural land behind. As sea levels rise, water will increasingly overtop the embankments making them ineffective. Most of the houses and other properties lie at the edge of the floodplain, where they will only be affected by the biggest flood events.
Breaching floodbanks could:
Help in adapting to climate change. Sea level rise means that the standard of protection offered by the banks is reducing and will continue to do so. Breaching the banks would allow this to be a managed process rather than an unplanned failure.
Provide income for landowners and enable agricultural use to continue, albeit in a different way. Landowners could enter into agreements to receive payments for delivering environmental enhancements.
Use the floodplain to reduce water levels, helping to prevent flooding elsewhere.
Reduce the cost to the taxpayer of ongoing maintenance.
Increase the extent of wetland habitat benefiting the estuary's wildlife.
Produce recreation opportunities for local people and visitors alike.
Some key findings of the study are that:
Breaching banks would increase the frequency of flooding but not the size of the area of land flooded.
There is little change in flood risk to property and no residences are likely to be affected in the 1 in 200 year flood scenario.
Breaching banks would be likely to increase bank erosion in some locations.
Two copies of the report are available for viewing at Darts Farm.
Inevitably there will be concerns about loss of agricultural land, property and infrastructure, notably the old Clyst Bridge and road. The report doesn't provide all the answers; there are still outstanding uncertainties and gaps in knowledge, and work is underway to address these. The Environment Agency is commissioning further studies to investigate the possible amount of erosion, investigate options for future management of the road and model the effects of breaches on smaller areas of land.
However, no project to breach the banks will happen without both the agreement of the relevant landowner and detailed assessment of the effect on others' properties and infrastructure.
A Growing Trend
The Lower Clyst is just one location where these issues are likely to occur as sea level rise requires us to rethink our flood defence management. In the longer term, it's likely that we'll need to find a way to allow landowners to adapt to change without having to sell their land; this project might be a model for others to follow.
East Devon District Council and landowners are working to create a new 200 hectare wetland on the Axe Estuary. A mosaic of wet grassland, saltmarsh and brackish pools have not only attracted more wildlife to the area but also provided new opportunities for people to enjoy the spectacle, with new facilities for walking and cycling
Latest Climate Change Predictions
As with all our river and estuarine systems, the Exe estuary and Clyst valley will evolve as a result of climate change. The UK Climate Projections 2009 is the most comprehensive package of climate information for the UK to date, and its central estimate (50% probability) suggests that, for SW England, winter precipitation will increase by almost a quarter by 2080 and that sea levels will rise by 20-25 cms by 2050 and 40cms by 2080 (based on thermal expansion of oceans only, not including glacial melt). The way in which we include these latest estimates in our calculations is being decided by Government.
If you have any questions please contact: Mike Williams, Environment Agency
The Coastal Management Study and Shoreline Management Plan Technically Feasible Options for the Exe Estuary have been published and are available at www.sdadcag.org/
Why is the Coastal Management Study needed?
The long sandy beaches of Exmouth and Dawlish Warren are among the most popular holiday destinations in south Devon, attracting thousands of visitors and holidaymakers every year. As well as providing excellent amenity and recreational facilities, both beaches help protect Exmouth and the Exe Estuary by absorbing the energy of waves and currents during storms. The Warren is also a Site of Special Scientific Interest (SSSI),
Special Area of Conservation (cSAC), National Nature Reserve (NNR) and Local Nature Reserve (LNR), and lies within Exe Estuary SSSI, Special Protected Area (SPA) and Ramsar Site. However, due to these conflicting pressures, the sand dunes and associated plant life on Dawlish Warren SSSI are considered to be in an ‘unfavourable and declining condition'.
At Exmouth, the beach reduces the risk of the seawall being overtopped. This is particularly important because the town centre is lower than the seawall and homes and local businesses are at risk of flooding..
The sand spit at Dawlish Warren is a natural barrier that prevents waves penetrating the estuary during storms and may help to protect waterside properties from flooding. It is also thought that the spit provides essential protection to the two railway lines that run along each side of the estuary shore. In recent years, the level and extent of the beaches at Exmouth has changed considerably. In 2004, part of the sea wall collapsed and the foundations of other sections have been undermined. There is now a need to increase beach levels to improve its effectiveness as a coastal defence.
The beach at Dawlish Warren has also suffered from erosion. Considerable quantities of sand have gone from the foreshore at the western end of the beach - the area of the Warren most popular with holidaymakers. An initial inspection suggests that this sand has been transported by waves and currents to the eastern end of the spit. The loss of this sand reduces the amenity value of the beach and raises concerns about a possible breach of the sand spit and possibly increasing the risk of flooding to properties around the estuary. Network Rail are also concerned that any breach of the Warren, or narrowing of this spit at the western end, could jeopardise the safe operation of the railway.
Due to these concerns, the Environment Agency are currently drawing up emergency plans that will help reduce the impacts of a sudden breach.
With sea levels forecast to rise over the coming decades, these flood risks could increase significantly.
What will the study tell us?
We are working to obtain a better understanding of the changes occurring at Exmouth and Dawlish Warren and how best to manage these important coastal defences. The Exe Estuary Coastal Management Study is supported by the Environment Agency, East Devon District Council,
Natural England and Teignbridge District Council. The study will investigate the causes of these changes and suggest strategies to best manage these local defences in the long term.
The study is being carried out by the Halcrow Group, a leading firm of Civil Engineering Consultants, with a local presence in Exeter. Initial stages include the collection of data on the wind, waves and currents, topographic and bathymetric surveys, historical maps and photographs, aerial photographs and records of previous storms. This data will enable Halcrow to prepare reports on the height, direction and frequency of waves and water levels along the coastline. In addition, a draft report has also been prepared on previous changes to the coastline at Exmouth and Dawlish over the last 300 years.
An understanding of the historic evolution of this area gives a valuable insight into the factors that have influenced the
changes and will provide the Consultants with a basis for forecasting how the estuary may evolve in the future.
A Strategic Environmental Assessment (SEA) has been prepared to report on the baseline information that has been gathered. This will serve to identify and develop the environmental objectives of any proposed management plan to address the long-term coastal defence and environmental management issues at the site. This SEA can be downloaded here (Strategic Environmental Assessment).
What Happens Next?
The Study is essentially a technical process which will be used to inform the locally relevant policies of the wider South Devon and Dorset Shoreline Management Plan (SMP) as they apply to the Exe. Members of the public have been able to give their views on the policies put forward by the Coastal Management Study as part of the SMP consultation process.
The SMP provides a large-scale assessment of the risks associated with coastal evolution and presents a policy framework to address these risks to people and the developed, historic and natural environment in a sustainable manner.
The coast is a dynamic environment, perhaps few places more so than at the mouth of the Exe, and by better understanding the wider technical aspects we can refine our local responses in terms of both policies and practical management options. The Study is doing this for the Exe area of the SMP process
If you need further information please contact Graeme Smith
Tel: 01626 215748
or in writing to: Teignbridge District Council, Forde House, Brunel Rd, Newton Abbot, TQ12 4XX