West Somerset Catchment Flood Management Plan Summary Report June 2012 Managing Flood Risk We Are the Environment Agency

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West Somerset Catchment Flood Management Plan Summary Report June 2012 managing flood risk We are the Environment Agency. It’s our job to look after your environment and make it a better place – for you, and for future generations. Your environment is the air you breathe, the water you drink and the ground you walk on. Working with business, Government and society as a whole, we are making your environment cleaner and healthier. The Environment Agency. Out there, making your environment a better place.

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Environment Agency Manley House Kestrel Way Exeter EX2 7LQ Tel: 0870 8506506 Email: [email protected] www.environment-agency.gov.uk

I am pleased to introduce our summary of the West Somerset Catchment Flood Management Plan (CFMP). This CFMP gives an overview of the flood risk in the West Somerset catchment and sets out our preferred plan for sustainable flood risk management over the next 50 to 100 years.

The West Somerset CFMP is one of 77 CFMPs for The West Somerset catchment has a history of flood England and Wales. Through the CFMPs, we have risk. Over the last 50 years engineering schemes have assessed inland flood risk across all of England and been implemented to reduce flood risk in the Wales for the first time. The CFMP considers all types of catchment. At present 1,600 properties are at risk in inland flooding, from rivers, ground water, surface the catchment in a 1% event (taking into account flood water and tidal flooding, but not flooding directly from defences). This will increase to over 2,040 properties in the sea (coastal flooding), which is covered by the future. Shoreline Management Plans (SMPs). Our coverage of We cannot reduce flood risk on our own, we will surface and ground water is however limited due to a therefore work closely with all our partners to improve lack of available information. the co-ordination of flood risk activities and agree the The role of CFMPs is to establish flood risk management most effective way to manage flood risk in the future. policies which will deliver sustainable flood risk We have worked with others including: Somerset management for the long term. This is essential if we County Council, Natural England, Wessex Water and the are to make the right investment decisions for the National Farmers Union to develop this plan. future and to help prepare ourselves effectively for the This is a summary of the main CFMP document, if you impact of climate change. We will use CFMPs to help us need to see the full document an electronic version can target our limited resources where the risks are be obtained by emailing greatest. [email protected] This CFMP identifies flood risk management policies to or alternatively paper copies can be viewed at any of assist all key decision makers in the catchment. It was our offices in South West Region. produced through a wide consultation and appraisal process, however it is only the first step towards an integrated approach to Flood Risk Management. As we all work together to achieve our objectives, we must monitor and listen to each others progress, discuss what has been achieved and consider where we may Richard Cresswell need to review parts of the CFMP. South West Regional Director

Environment Agency West Somerset Catchment Flood Management Plan 1 Contents

The purpose of a CFMP in managing flood risk 3

Catchment overview 4

Current and future flood risk 6

Future direction for flood risk management 10

Sub-areas

1 Lower River Aller sub-area 12

2 Exmoor Plateau sub-area 13

3 Middle Catchments sub-area 14

4 Lower River Avill sub-area 16

5 Minehead sub-area 17

6 Watchet sub-area 18

7 Williton sub-area 19

8 Hills and Cliffs sub-area 20

Map of CFMP policies 21

2 Environment Agency West Somerset Catchment Flood Management Plan The purpose of a CFMP in managing flood risk

CFMPs help us to understand the • Internal Drainage Boards (IDB), CFMPs aim to promote more scale and extent of flooding now and water companies and other sustainable approaches to in the future, and set policies for utilities to help plan their managing flood risk. The policies managing flood risk within the activities in the wider context of identified in the CFMP will be catchment. CFMPs should be used to the catchment; delivered through a combination of inform planning and decision different approaches. Together with • transportation planners; making by key stakeholders such as: our partners, we will implement • land owners, farmers and land these approaches through a range • the Environment Agency, who will managers that manage and of delivery plans, projects and use the plan to guide decisions operate land for agriculture, actions. on investment in further plans, conservation and amenity projects or actions; The relationship between the CFMP, purposes; delivery plans, strategies, projects • Regional Assemblies and local • the public and businesses to and actions is shown in Figure 1. authorities who can use the plan enhance their understanding of to inform spatial planning flood risk and how it will be activities and emergency managed. planning;

Figure 1. The relationship between CFMPs, delivery plans, projects and actions

Policy planning • CFMPs and Shoreline Management Plans. • Action plans define requirement for delivery plans, projects and actions.

Policy delivery plans (see note) Projects and actions • Influence spatial planning to reduce risk and • Make sure our spending delivers the best restore floodplains. possible outcomes. • Prepare for and manage floods (including local • Focus on risk based targets, for example numbers Flood Warning plans). of households at risk. • Managing assets. • Water level management plans. • Land management and habitat creation. Note: Some plans may not be led by us – we may identify the • Surface water management plans. need and encourage their development.

Environment Agency West Somerset Catchment Flood Management Plan 3 Catchment overview

The catchment of the rivers in the The overall catchment area is about The catchment contains a number of West Somerset CFMP are located in 320 square kilometres and has a designated sites of national and the south west of England. population of around 31,000. It’s a international importance. These rural catchment, with urban areas include Exmoor National Park, which The rivers drain from Exmoor and the making up only four per cent of the is also an Environmentally Sensitive Quantocks, flowing north to the total. Its main urban areas, generally Area and a Special Area of Bristol Channel. Map 1 shows the located on the coastal plain, include Conservation (SAC); the Quantocks location and extent of the West Minehead, Watchet and Williton. which is an Area of Outstanding Somerset CFMP area. It includes the Natural Beauty that includes the River Avill, Pill River, Washford River, The rivers and streams flow from Quantocks Oakwood’s SAC; Horner Monksilver Stream, Doniford Stream, their sources on Exmoor and the Wood National Nature Reserve, 12 Hawkcombe Stream, Horner Water Quantock Hills, in the south and east Sites of Special Scientific Interest and River Aller. The downstream of the catchment respectively. They (SSSI); nine National Nature limits of the CFMP area meets with are steep in nature and flow towards Reserves and 135 Scheduled the upstream boundary of the North the Bristol Channel in the north. Monuments. Devon and Somerset Shoreline Geology has a significant influence Management Plan (SMP) boundary at on the response to rainfall. The the Bristol Channel coast. geology of West Somerset has low The North Devon and Somerset, and permeability, this contributes to the Severn Estuary Shoreline high level of overland flow and the Management Plans deal with coastal rapid response of the rivers to flood management, while the CFMP rainfall. considers the risk from tidal flooding.

4 Environment Agency West Somerset Catchment Flood Management Plan Map 1. Location and extent of the West Somerset CFMP area

Legend

West Somerset CFMP Urban areas

Main rivers

Railway

Motorway Minehead

Porlock Watchet

Williton

Taunton

0 3 6 9 12 Kilometres

➜ Flooding from the River Avill at Dunster in November 1963

Environment Agency West Somerset Catchment Flood Management Plan 5 Current and future flood risk

Overview of the current flood risk What is at risk?

Flood risk has two components: the Currently the main sources of flood At present there are around 2,700 chance (probability) of a particular risk for people, property, people and 1,600 commercial and flood and the impact (or infrastructure and the land are: residential properties at risk in the consequence) that the flood would whole catchment from a 1% annual • river flooding from the River Aller have if it happened. The probability probability river flood taking into in Allerford and Bossington, of a flood relates to the likelihood of account current flood defences. Washford River in Washford, a flood of that size occurring within a Monksilver Stream in Williton and This means that 8.5% of the total one year period. It is expressed as a Doniford Stream in Doniford; population living in the catchment percentage. For example, a 1% flood are currently at risk from flooding. has a 1% chance or 0.01 probability • tidal flooding in Minehead, of occurring in any one year, and a Porlock and Blue Anchor; It is difficult to assess the current 0.5% flood has a 0.5% chance or impact of flooding to environmental • surface water drainage flooding, 0.005 probability of occurring in any features. Many designated sites at which has occurred in Minehead, one year. The flood risks quoted in risk would not actually be damaged Williton and Washford. Other this report are those that take by the inundation. account of flood defences already in towns have the potential to be at place. risk from surface water flooding. Four Scheduled Monuments are at risk of flooding, but again, the actual This catchment has a long history of risk of damage from flooding is flooding. The most significant event limited. in recent years occurred in Williton in December 2000 when 50 properties were affected by surface water and river flooding after periods of heavy rainfall.

➜ Flooding from the Washford River at Roadwater in December 1965

6 Environment Agency West Somerset Catchment Flood Management Plan Map 2. Flood risk to property in a 1% annual probability river flood, taking into account current flood defences

Legend

Properties with a 1% chance of flooding 50 - 100 101 - 200 201 - 400

401 - 600 Minehead 601 - 1,200 Porlock Blue Anchor Watchet Dunster & West Somerset Marsh Street CFMP Williton Main rivers

0 4 8 12 16 Kilometres

Table 1. Locations of towns and villages with 25 or more properties at risk in a 1% annual probability river flood

Number of properties at risk Locations

>1,000 Minehead

500 to 1,000 None

100 to 500 Watchet

50 to 100 Porlock, Williton, Blue Anchor, Dunster, Marsh Street

25 to 50 Allerford & Bossington

Table 2. Critical infrastructure at risk:

3 electricity substations, 1 water treatment works, 1 care home, 2.4 km of main roads, and 3 schools

Environment Agency West Somerset Catchment Flood Management Plan 7 Where is the risk? How we currently manage the risk

More than two thirds of the people The catchment has a history of flood • maintenance of road drainage and properties that are at risk within risk, generally due to the high and sewers. the catchment from a 1% annual rainfall that can lead to extensive Activities that reduce the probability river flood are located in flooding of the river valleys. Over the consequences of flooding include: Minehead. A further 8% are located last 50 years, engineering schemes in Watchet. have been implemented to reduce • understanding where flooding is flood risk in the catchment, likely by using flood risk mapping; The distribution of properties at risk including: • providing flood forecasting and from a 1% annual probability river warning services; flood is illustrated in Map 2. Table 1 • building a flood relief channel on • promoting awareness of flooding summarises where there is flood risk the River Avill at Dunster; so that organisations, to more than 25 properties. We • widening and straightening of communities and individuals are recognise that there is also a channels including the Washford aware of the risk and are prepared potential risk from surface water and River at Roadford, Hungerford and in case they need to take action in groundwater flooding. Watchet. time of flood; However, further studies following These measures have all reduced • promoting resilience and on from the CFMP are needed by us flood risk. resistance measures for those and our partners to quantify this properties already in the In addition to these engineering potential risk. floodplain. schemes, other flood risk • working with local authorities to management activities are carried influence the location, layout and out in the catchment. These include design of new and redeveloped activities which help to reduce the property and ensuring that only probability of flooding and those appropriate development is that address the consequences of allowed on the floodplain through flooding. the application of Planning Policy Activities that reduce the probability Statement 25 (PPS25). of flooding include:

• maintaining and improving existing flood defences and structures, including a new culvert and screen at Pill River outfall; • maintaining river channels, especially debris clearance to reduce risk of blockage;

8 Environment Agency West Somerset Catchment Flood Management Plan The impact of climate change and future flood risk

In the future, flooding will be Using river models we estimate that Figure 2 shows the difference influenced by climate change, by 2100, around 3,500 people and between current and future flood changes in land use (for example 2,040 properties across the risks from a 1% annual probability urban development) and rural land catchment may be at risk from a 1% river flood at key locations in the management. In the West Somerset annual probability flood. Flood risk catchment. Following on from the catchment, climate change will have from rivers increases mainly in CFMP, organisations need to work the greatest impact on flood risk. The Minehead, Watchet and Dunster. together to investigate flood risk from following future scenario for climate other sources (e.g. surface water and The sensitivity testing undertaken change was used in the CFMP: ground water flooding) in more detail. showed that river flooding in the • 20% increase in peak flow in all catchment is not sensitive to changes In general, it is unlikely that the watercourses. This will increase to the predicted urban development, impact of flooding on environmental the probability of large-scale flood but is very sensitive to climate sites will change significantly in the events; change, as flood depths and extents future. • a total sea level rise of 500 mm by increased, land use changes was also the year 2100. This will increase found to have a widespread affect on the risk of flooding at Minehead, the CFMP area. Porlock and Watchet.

Figure 2. Current and future (2100) flood risk to property from a 1% annual probability river flood, taking into account current flood defences

1600

1400

1200

1000

800

600

400

200 Number of Properties at Flood Risk at Properties Number of

0 Minehead Watchet Porlock Marsh Street Dunster Williton Blue Anchor Allerford & Bossington

Current Future

Environment Agency West Somerset Catchment Flood Management Plan 9 Future direction for flood risk management

Approaches in each sub-area

We have divided the West Somerset catchment into eight distinct sub-areas which have similar physical characteristics, sources of flooding and level of risk. We have identified the most appropriate approach to managing flood risk for each of the sub-areas and allocated one of six generic flood risk management policies, shown in Table 3.

To select the most appropriate policy, the plan has considered how social, economic and environmental objectives are affected by flood risk management activities under each policy option.

➜ A shingle trap on the Hawkcombe Stream at Hawkcombe Map 3. West Somerset sub-areas Legend

West Somerset CFMP Sub-area

1 Lower River Aller (Policy 3)

2 Exmoor Plateau (Policy 6)

3 Middle Catchments (Policy 4)

4 Lower River Avill (Policy 4)

5 Minehead (Policy 5) Porlock Minehead 6 Watchet (Policy 4) 7 Williton (Policy 5)

8 Hills and Cliffs (Policy 1) Williton 9

Taunton South Molton

0481216 Wellington Kilometres

10 Environment Agency West Somerset Catchment Flood Management Plan Table 3. Policy options Policy 1 Areas of little or no flood risk where we will continue to monitor and advise This policy will tend to be applied in those areas where there are very few properties at risk of flooding. It reflects a commitment to work with the natural flood processes as far as possible.

Policy 2 Areas of low to moderate flood risk where we can generally reduce existing flood risk management actions This policy will tend to be applied where the overall level of risk to people and property is low to moderate. It may no longer be value for money to focus on continuing current levels of maintenance of existing defences if we can use resources to reduce risk where there are more people at higher risk. We would therefore review the flood risk management actions being taken so that they are proportionate to the level of risk.

Policy 3 Areas of low to moderate flood risk where we are generally managing existing flood risk effectively This policy will tend to be applied where the risks are currently appropriately managed and where the risk of flooding is not expected to increase significantly in the future. However, we keep our approach under review, looking for improvements and responding to new challenges or information as they emerge. We may review our approach to managing flood defences and other flood risk management actions, to ensure that we are managing efficiently and taking the best approach to managing flood risk in the longer term.

Policy 4 Areas of low, moderate or high flood risk where we are already managing the flood risk effectively but where we may need to take further actions to keep pace with climate change This policy will tend to be applied where the risks are currently deemed to be appropriately-managed, but where the risk of flooding is expected to significantly rise in the future. In this case we would need to do more in the future to contain what would otherwise be increasing risk. Taking further action to reduce risk will require further appraisal to assess whether there are socially and environmentally sustainable, technically viable and economically justified options.

Policy 5 Areas of moderate to high flood risk where we can generally take further action to reduce flood risk This policy will tend to be applied to those areas where the case for further action to reduce flood risk is most compelling, for example where there are many people at high risk, or where changes in the environment have already increased risk. Taking further action to reduce risk will require additional appraisal to assess whether there are socially and environmentally sustainable, technically viable and economically justified options.

Policy 6 Areas of low to moderate flood risk where we will take action with others to store water or manage run-off in locations that provide overall flood risk reduction or environmental benefits This policy will tend to be applied where there may be opportunities in some locations to reduce flood risk locally or more widely in a catchment by storing water or managing run-off. The policy has been applied to an area (where the potential to apply the policy exists), but would only be implemented in specific locations within the area, after more detailed appraisal and consultation.

Environment Agency West Somerset Catchment Flood Management Plan 11 Sub-area 1

Lower River Aller

Our key partners are: Currently 32 properties are in the Proposed actions 1% annual probability flood extent to implement the West Somerset District Council and the number is expected to increase to 43 in the future 1% preferred policy Somerset County Council annual probability flood extent. Carry out contingency planning for Natural England The A39 road at Allerford is emergency response, improve flood susceptible to flooding during the National Farmers Union warning lead times by telemetry 1% annual probability river flood. improvement and improve response Farming Wildlife Advisory Group to warnings through raising awareness in Allerford and Country Land and Business Bossington. Association The vision and preferred policy Continue to work with landowners Land managers and representative organisations to Policy Option 3 - we are generally promote uptake of sustainable land managing existing flood risk management techniques that will The issues in this effectively. reduce surface water run-off. sub-area This policy would prevent a Whilst the contingency plans are significant increase in the number being prepared, continue with This sub-area covers the lower, of people susceptible to flooding existing flood risk management more urbanised reaches of the River along with preventing a significant activities in the Lower River Aller. Aller and Horner Water. The sub- increase in the number of This includes: area includes Allerford, Bossington, infrastructure and key services Lynch, Brandish Street and adversely affected by the 1% • siren based automatic alarm Holnicote. annual probability river flood. system; and, Flooding in this sub-area has • maintenance of watercourses, historically been associated with removal of vegetation, shingle out of channel flow. Due to the and debris, and erosion control. relatively impermeable geology and the very steep gradient of the upstream catchment, watercourses respond quickly to rainfall on Exmoor. This makes the nature of flooding in this sub-area very hazardous. Flooding is also caused by under capacity or blocked structures. Many of these structures are bridges that are designated as Scheduled Monuments (SMs), which often have limited conveyance capacity.

12 Environment Agency West Somerset Catchment Flood Management Plan Sub-area 2

Exmoor Plateau

Our key partners are: rapidly draining off the steep hills of Proposed actions Exmoor. The future would see a to implement the Exmoor National Park negligible increase to the number of properties affected. The extent of preferred policy Natural England the river floodplain is very narrow due to the topography and geology, Continue to work with land owners South West Water therefore sheet run-off processes and representative organisations to Wessex Water and surface water flooding are promote the uptake of sustainable relatively more important. land management techniques that National Farmers Union will reduce surface water run-off. This sub-area is very Farming Wildlife Advisory Group environmentally rich, with several Identify potential areas for restoration projects on the Country Land and Business designated areas and historic sites. headwaters of rivers and streams in Association Exmoor to attenuate flood water Land managers and contribute to the healthy The vision and condition of habitats. Measure the preferred policy cost effectiveness of such projects and make recommendations The issues in this Policy Option 6 - we will take action towards implementing necessary sub-area with others to store water or changes. manage run-off in locations that This sub-area covers the steep provide overall flood risk reduction upland area of Exmoor National or environmental benefits. Park. It includes the headwaters of This chosen policy would reduce the the principal watercourses of the number of people and properties Hawkcombe Stream, Horner water affected by surface water flooding and River Aller. by improving flow attenuation. This sub-area has historically Increased attenuation will reduce experienced little flood risk. flood risk downstream in the Middle Flooding occurs on roads and to Catchment and the Lower River Aller isolated properties as the result of sub-areas. river overtopping but also surface This policy will also help to sustain water flooding in the form of and enhance habitats on the overland flow, from the water Exmoor plateau.

Environment Agency West Somerset Catchment Flood Management Plan 13 Sub-area 3

Middle Catchments

Our key partners are: around 270 in the future 1% annual The vision and probability flood extent. preferred policy West Somerset District Council All principal watercourses in the Somerset County Council sub-area have experienced river Policy Option 4 - we are already flooding. River flooding has been managing the flood risk effectively Natural England reported at confluences such as but we may need to take further that at Monksilver, and other National Farmers Union actions to keep pace with climate locations in the immediate change. Farming Wildlife Advisory Group floodplain of the watercourse. The Hawkcombe Stream and especially This policy sustains the number of Country Land and Business the Horner Water and River Aller people affected by flooding at the Association system are susceptible to flash current level, prevents an increase in the length of A road affected by Land managers flooding as their geology and topography lend them to respond flooding and prevents an increase rapidly to rainfall. River flooding in the amount of infrastructure linked to tide locking situations is affected by flooding, and prevents The issues in this also an issue. an increase in damages. Flood risk sub-area from tidally influenced fluvial flood For many areas on the steeper events will be further investigated catchments, surface water flooding This sub-area covers most of the under this approach and based on is highly problematic. Several mid, upland and lowland reaches of this work, actions will be taken to locations have suffered surface the principal watercourses of the ensure the risk does not increase in water flooding due to run-off from CFMP area. This sub-area extends the future. the steep hills of Exmoor and the from the Hawcombe Stream Quantocks. Other locations, such as catchment, including the majority of at Carhampton, have also the mid and lowland reaches of the experienced surface water flooding watercourse catchment to the east, specifically as the result of run-off to the Holford Stream catchment in from agricultural land. the west. The watercourses transport a Flooding in this sub-area has significant amount of shingle. The historically been associated with a deposition of shingle upstream of variety of source. This includes out culverts can reduce the capacity of channel flow, tidally influenced and increase the likelihood of river flooding, and surface water flooding. Shingle traps are currently flooding, as well as fluvial flooding emptied on a regular basis. There which is exacerbated by under are also many bridges which are capacity or blocked structures. designated for their historical There are currently around 250 importance, which exacerbate properties in the 1% annual flooding in some locations. probability flood extent and the Flooding due to blocked structures number is expected to increase to can be very hazardous.

14 Environment Agency West Somerset Catchment Flood Management Plan Proposed actions to implement the preferred policy

Continue work with land owners and representative organisations to promote the uptake of sustainable land management techniques that will reduce surface water run-off.

Use awareness campaigns to ensure people are aware of their own flood risk responsibilities and to increase uptake of the flood warning service in Doniford, Porlock, Washford and Roadwater.

Carry out more detailed investigation of future flood risks and identify changes in sources, pathways and receptors in Porlock, Doniford and Washford, including tidelocking and tidal risks.

Until detailed investigation of future risks is completed, continue with existing flood risk management in the Middle Catchments sub-areas, including:

• general channel maintenance being undertaken on the Hawkcombe Stream at Porlock, the Washford River at Roadwater and Washford, the Monksilver Stream at Williton, the Doniford Stream at Doniford and the Pill River at Blue Anchor. • a flood warning service being provided on the Hawkcombe Stream, Washford River, Monksilver and Doniford Streams. • defences being maintained on the Washford River, Timberscombe Stream, Wootton Courtenay Stream and at Porlock. • shingle traps and erosion control measures remaining in place on the Hawkcombe Stream, Timberscombe and Wootton Courtenay Streams.

Encourage re-siting of critical amenities and caravan parks away from flood risk locations.

➜ Roadwater flooded by the Washford River in December 1965

Environment Agency West Somerset Catchment Flood Management Plan 15 Sub-area 4

Lower River Avill

Our key partners are: The vision and Proposed actions preferred policy to implement the West Somerset District Council preferred policy Policy Option 4 - we are already managing the flood risk effectively Review the current and future The issues in this but we may need to take further standard of protection offered by sub-area actions to keep pace with climate the River Avill flood relief channel change. and improve as required. The sub-area covers the lower By continuing with maintenance of Until detailed review of current and reaches of the River Avill. It includes the flood relief channel and making future standard of protection is part of the Dunster and Marsh improvements as required to ensure completed, continue with existing Street. it is able to withstand increases in flood risk management in the Lower flood risk as a result of climate Currently around 60 properties are River Avill, including: change, this policy sustains the in the 1% annual probability flood number of people affected by • general channel maintenance extent and the number is expected flooding at the current level, being undertaken on the River to increase to around 100 properties prevents an increase in the length of Avill at Dunster. in the future 1% annual probability A road affected by flooding, prevents • maintenance of the flood relief flood extent. an increase in damages, and channel Flooding in this sub-area has been sustains the water environments on Investigate the feasibility of a flood historically associated with out of which the Special Area of warning service by considering channel flow. A flood relief channel Conservation and Dunster Marsh possible telemetry and other data was constructed following the County Wildlife Site rely. In addition, requirements. severe 1960s floods to alleviate the introduction of a flood warning some of the risk to this sub-area and system under this approach would to locations in the upstream Middle further reduce the risk to people. Catchments sub-area. This scheme significantly reduced flood risk and no river flooding has been reported since its completion.

Surface water flooding from overland flow down fields and roads

is problematic in this sub-area. The River Avill at Dunster in spate ➜ in November 1963, before the flood relief channel was built

16 Environment Agency West Somerset Catchment Flood Management Plan Sub-area 5

Minehead

Our key partners are: Given the impermeable, hard Proposed actions standing nature of this sub-area, to implement the West Somerset District Council surface water run-off is also problematic. preferred policy Somerset County Council Highways Division Implement the recommendations of the Minehead pre-feasibility study. Wessex Water The vision and This recommends maintaining the preferred policy streams and culverts in order to maximise their hydraulic capacities The issues in this Policy Option 5 - we can generally and to reduce the likelihood of sub-area take further action to reduce flood blockages, review the maintenance risk. programme periodically to ensure that the correct activities are being This sub-area covers the urban area Minehead is the CFMP’s primary undertaken at the right time of Minehead. urban centre and as such contains a intervals, and monitor the costs of Minehead is situated within the significant amount of key services, these maintenance activities. floodplain of the Bratton Stream and commercial properties and Provide development control advice its tributaries. Minehead is a dense infrastructure. Minehead is also an and promote Sustainable Drainage urban area and as such the important employment centre and Systems to ensure that there is no watercourses have been culverted, tourist destination. Flooding in this increase in surface water run-off modified and largely encroached sub-area would significantly impact from new developments in upon by development. Currently the local economy and even the Minehead. Monitor the 1,000 properties are in the 1% economy of the County. A large implementation of advice/planning annual probability event flood number of people with high social conditions. outline. vulnerability are exposed to flooding. Flood risk in Butlins Promote the provision of a Surface The number is expectedt to increase Holiday World needs to be Water Management Plan to around 1,400 properties in the addressed through a flood warning future 1% annual probability event service, based on telemetry installed Investigate the feasibility of a flood flood outline. in the headwaters. warning service for Minehead by considering possible telemetry and Flooding has historically been other data requirements. associated with out of channel flow as a result of under capacity or Review emergency contingency blocked structures. The Bratton planning in the light of climate Stream discharges into the Bristol change, especially for Butlins. Channel via a flapped outfall. During times of very high tides, this outfall Encourage re-siting of critical can become tide locked and amenities and caravan parks exacerbate river flooding. outside flood risk locations.

Environment Agency West Somerset Catchment Flood Management Plan 17 Sub-area 6

Watchet

Our key partners are: The vision and Proposed actions preferred policy to implement the West Somerset District Council preferred policy Policy Option 4 - we are already managing the flood risk effectively Improve flood warning lead times by The issues in this but we may need to take further telemetry improvement and improve sub-area actions to keep pace with climate response to warnings through change. raising awareness in Watchet. This sub-area covers the urban area Watchet is considered an important Progress the recommendation for of Watchet and surrounding urban centre and as such contains a improved defences which arose agricultural land, which is situated significant amount of key services, from the Washford River and on the Washford River. commercial properties and Watchet pre feasibility study. Flooding in Watchet has historically infrastructure. In addition to this, a been associated with out of channel number of people of high social flow and river flooding as a result of vulnerability are exposed to under capacity or blocked flooding. Increased flooding would structures. Watercourses respond significantly impact the local quickly due to the relatively economy. impermeable geology and the steep Flood risk is currently managed to an gradient of the upstream acceptable level. Continuing with catchment. Watchet is an urban this in the future, and enhancing area and as such the watercourses certain elements to sustain the have been modified, culverted and current level of risk through in places encroached upon by increased checking of structures for development. Currently around 180 blockages, increasing embankment properties are at risk during the 1% heights and improving the flood annual probability river flood. This warning service. The chosen policy is expected to increase to 220 in the would prevent a significant increase future. in the number of people affected The Washford River discharges into and the cost of flood damage to the Bristol Channel via an properties and agricultural land. unflapped outfall. During times of very high tides, this outfall can become tide locked and hence exacerbate river flooding.

18 Environment Agency West Somerset Catchment Flood Management Plan Sub-area 7

Williton

Our key partners are: Currently around 80 properties are Proposed actions at risk during the 1% annual to implement the West Somerset District Council probability river flood. This figure is expected to remain the same in the preferred policy Somerset County Council future. • Review emergency contingency Wessex Water Given the impermeable, hard planning for Williton standing nature of this sub-area, Local land managers surface water flooding from • Promote the provision of a overland flow down fields, roads Surface Water Management Plan and railway line is also problematic. The issues in this • Improve flood warning lead times by telemetry improvement and sub-area improve response to warnings The vision and through raising awareness This sub-area covers the urban area preferred policy of Williton. • Investigate flood defence schemes for Williton. Flooding in Williton has historically Policy Option 5 - we can generally been associated with out of channel take further action to reduce flood flow and under capacity or blocked risk. structures. River flooding is also Williton is an important urban centre exacerbated by the confluence of and as such contains a significant the Monksilver Stream with the amount of key services, commercial Doniford Stream immediately properties and infrastructure. downstream of Williton. When water Williton is also an important levels in the Doniford Stream are employment centre. Flooding would high, the flow in the Monksilver significantly impact the local Stream cannot discharge easily and economy and even the economy of therefore backs up, creating higher the County. In addition to this, a water levels upstream. Williton is a large number of people with a high dense urban area and as such the social vulnerability are exposed to watercourses in the sub-area have flooding. Selecting this policy would been constricted, modified and significantly reduce the number of largely encroached upon by people affected by frequent development. flooding.

Environment Agency West Somerset Catchment Flood Management Plan 19 Sub-area 8

Hills and Cliffs

Our key partners are: The vision and Proposed actions preferred policy to implement the West Somerset District Council preferred policy Policy Option 1 - we will continue to monitor and advise. No specific actions have been The issues in this This policy has been selected identified for this sub-area. sub-area because opportunities to manage Continue to monitor and advise. surface water flooding, or reduce it, This sub-area Includes the areas of are limited due to the steep West of Porlock Bay, the Area topography of these sub-areas, the behind Minehead, the Quantock steepness of the watercourses and Hills and Kilve and Hinkley. the rapid responses to rainfall. No flood management is undertaken in Due to the steep topography, this these sub-areas currently, and the sub-group responds very quickly to number of people affected by rainfall. These sub-areas have surface water flooding is low and historically experienced little fluvial does not increase significantly in flooding. Instead, flood risk is the future. significantly from surface water processes, such as sheet run-off.

Currently two properties are at risk during the 1% annual probability flood event. This figure is not expected to change in the future.

At risk from surface water flooding are agricultural land, recreational accesses and nationally and internationally designated sites. Local roads may be also affected. Flood risk from surface water flooding is likely to increase in the future as a result of climate change.

20 Environment Agency West Somerset Catchment Flood Management Plan Map of CFMP policies

Map of the policies in the West Somerset catchment Legend

West Somerset CFMP Sub Area Main rivers Railway Motorway Porlock Urban areas 8 8 Minehead Preferred approach 1 5 4 Policy 1 Policy 2 3 6 Williton Policy 3 7 8 Policy 4 2 Policy 5 Policy 6 N

Wellington

0 3 6 9 12 Kilometres

The sub-areas

1 Lower River Aller 2 Exmoor Plateau 3 Middle Catchments 4 Lower River Avill 5 Minehead 6 Watchet 7 Williton 8 Hills and Cliffs

Environment Agency West Somerset Catchment Flood Management Plan 21 Would you like to find out more about us, or about your environment?

Then call us on 08708 506 506* (Mon-Fri 8-6) email [email protected] or visit our website www.environment-agency.gov.uk incident hotline 0800 80 70 60 (24hrs) floodline 0845 988 1188

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