Thames Valley Flood Scheme - What is the Thames Valley Flood Scheme?

Closed 20 Aug 2021

Opened 26 May 2021

Overview

  1. Welcome
  2. Why do we need the Thames Valley Flood Scheme?
  3. What is the Thames Valley Flood Scheme?
  4. Project ambitions and working together
  5. Strategic Environmental Assessment
  6. Timeline
  7. Frequently asked questions
  8. Other consultations and engagement

On this page you can find out what approaches are being considered by the Thames Valley Flood Scheme. At this stage there are a long list of approaches. It is important to remember that for these approaches to be taken forward they will need to be applied at a catchment scale.

What approaches are being considered?

A diagram of the River Thames Catchment. The green area shows us the catchment for the central river.  All rain falling in this catchment will eventually flow into the central river or seep into the ground. The 17 approaches to reduce flood risk are listed here.

 

 

The 3 layered approach to reducing floods

Layer 1: Homes and businesses

The first layer is at the home, it can include measures like putting flood gates on your property and using flood resilient materials in the home like tiles instead of carpets.

Thames catchment diagram showing images of flood gates.

Thames catchment diagram showing images of flood gates. These are examples of the home and business layer.

It also includes signing up to flood warnings and making a flood plan, so you know what to do if a flood is forecast.

the Environment Agency’s flood warning system, which consists three stages - prepare, act and survive.

You can use the Environment Agency website to check if you live in a flood risk area by putting in your postcode.

You can sign up for flood warnings, this is a free service and you will receive a text or email when flooding is expected and how severe that expected flooding is likely to be.

To help make quick decisions when you receive a flood warning it can help to make a flood plan.

For some people this can be as simple as taking some time to think about what they would do if flooding was expected. For others it could be writing down a detailed plan. This might include making sure important phone numbers are stored and having a flood bag with essentials like a first aid kit, fresh water and medication ready in case it is needed.

Layer 2: Community

The second layer in reducing flood risk is to look at the community where flooding is happening. There are a number of ways to reduce flooding to a community, some of these are schemes that are in place all the time, like flood walls and embankments or bypass channels.

Other community level approaches are only put up when flooding is expected. These include temporary flood barriers or demountable flood barriers, often combined with pumps.

Thames catchment diagram showing temporary (demountable) flood barriers, a flood wall and a flood relief channel. These are examples of the second layer out of three in reducing flood risk, the second being community level.

Thames catchment diagram showing temporary or removable flood barriers, a flood wall and a flood relief channel. These are examples of the community layer.

Layer 3: Catchment

The diagram here shows a river and its catchment. The catchment is the whole of the valley, from the hills to the floodplain.

The green area, the river’s catchment, is where rain falls, this water then drains towards the rivers. Some rainfall seeps into the ground while some runs across ground into the streams which in turn feed into the central river.

A diagram of the River Thames Catchment. The green area in the diagram shows us the catchment for the central river.  All rain falling in this catchment will eventually flow into the central river or seep into the ground.

The catchment scale for the whole of the non-tidal part of the River Thames – which is everything upstream of its tidal limit in West London - is the scale of the area we are looking at for the Thames Valley Flood Scheme.

Map of Thames catchment area

Map of the Thames Valley catchment along with the key towns and tributaries that run into the River Thames.

The Thames Valley Flood Scheme is looking to complement the community and household level approaches. It will act as an ‘overlay’ across the catchment, looking at what can be done to make a big difference to flood risk over a large geographical area and providing climate resilience.

The Thames Valley Flood Scheme is considering all these approaches, but will be looking at which ones have the most potential to contribute to managing flood risk at a catchment (or large geographical) scale.

As part of this consultation we will be asking you whether you think there is another approach that we should be considering that isn’t on the list.

How will we decide which of these approaches to managing flood risk will be taken forward?

We do not yet know which of these approaches to managing flood risk the scheme will include. We are at the early stage of the project where we look at all options to make sure we are considering everything. There may be some we haven’t thought of yet, that will come up through the consultation process.

As the project develops we will need to decide which of these ways of managing flood risk are the most effective or appropriate for the Thames Valley.

The decision on which approaches to take forward will depend on a large number of factors including:

  • Technical feasibility - can it physically be built?
  • The cost of the project relative to the flood risk benefits it will bring
  • Other benefits associated with delivery including improvement to the natural environment
  • Environmental constraints, for example heritage buildings 
  • Technical sustainability - will it stand the test of time?
  • Information provided through engagement and consultation

The 17 approaches to reduce flood risk

These images are designed to illustrate what the different approaches are. Any change in flood risk would vary depending on the scale and location of the approach.

More Information

Offline flood storage is where water is diverted from the river in times of a flood. The water is stored in a separate area, which may or may not be part of the floodplain, and then released back to the river after the flood.
To manage flood risk across the Thames Valley and deliver the objectives of this project on its own, this approach would need to store millions of cubic metres of flood water.  
If carried out at a smaller scale, this approach would need to be delivered in combination with other approaches.
There is a river that flows from the top right to the bottom left of the image. There are buildings on the right side of the river and an offline flood storage area on the left side of the river. At the top section of the river there is a channel built redirecting water to the top edge of the offline storage area. At the bottom edge of the offline storage area, there is channel controlling flow of water back to the river.

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Joint water resource and flood storage is where a reservoir is designed to store water for both use in homes and businesses (including drinking water), as well as managing flood risk.
To manage flood risk across the Thames Valley and deliver the objectives of this project on its own, this approach would need to store millions of cubic metres of flood water, ​​in addition to the water stored for use in homes and businesses. ​​
If carried out at a smaller scale, this approach would need to be delivered in combination with other approaches.​
There is a river running from left to right of the image. At the top section of the river, water is diverted away from the river to a large reservoir nearby. At the bottom of the reservoir there is a water outflow for use in businesses and homes and a flood outflow to control water back to the river

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Runoff attenuation features are where small to medium sized storage areas are created, similar to ponds, that intercept water runoff. This reduces the amount of water reaching the river following rainfall. They may be dry most of the time. This option can also help to clean water before it enters rivers. 
To manage flood risk across the Thames Valley and deliver the objectives of this project on its own, hundreds or thousands of these features would be needed. ​
If carried out at a smaller scale, this approach would need to be delivered in combination with other approaches.
The before image shows how flooding happens without runoff attenuation. There is a large area of land with a river that flows from the top right to the bottom left of the image. To the left of the river there is a large area of open land showing that rainfall quickly runs off to the river. Along the river the image shows houses which represent communities at risk of flooding and the extent the flooding might reach. The after image shows how runoff attenuation features. There is a large area of land with a river that flows from the top right to the bottom left of the image. To the left of the river there is a large area of open land containing small to medium sized storage areas such as ponds.  Along the river there are houses which represent communities at risk of flooding and the extent the flooding might reach.

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Improving urban drainage is where  water runoff is slowed in cities, towns and villages (for example with rain gardens and storage) to slow water reaching the rivers. This option can also help to clean water before it enters rivers. 
To manage flood risk across the Thames Valley and deliver the objectives of this project on its own, this approach would need to be applied across many cities, towns and villages. ​
If carried out at a smaller scale, this approach would need to be delivered in combination with other approaches.
The before image shows how flooding happens before improving urban drainage. At the top of the image is a built-up area with buildings and hard surfaces such as paving and concrete, preventing water from soaking into the ground. The flow of water is shown to runoff quickly from the built-up area to a river. The after image shows how flooding happens once urban drainage has been introduced. At the top of the image is a built-up area with permeable paving allowing water to drain into the ground. New green areas and pond have been created between the buildings to help capture rainwater. Increased tree and vegetation cover gives greater evaporation. The amount of rainwater run off to the river is reduced.

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Changes to management of agricultural land can include a wide range of soil and crop management measures such as:
  • conservation tillage, where planting, developing and harvesting plants is done with minimal disturbance to the soil
  • sowing crops early 
  • planting cover crops 
  • reducing the number of farm animals in one area
  • planting more hedgerows
  • leaving a strip of land around a field that is left wild
These changes reduce and slow the flow of water runoff to rivers. 
This option can also help to clean water before it enters rivers. 
To manage flood risk across the Thames Valley and deliver the objectives of this project on its own, this approach would need to be applied across many hundreds or thousands of hectares within the Thames Valley.
If carried out at a smaller scale, this approach would need to be delivered in combination with other approaches.
This before image shows the flow of water before changes in soil and crop management. The image shows farmed land with limited hedgerows and suggests some farming practices can compress soil, increasing rainwater runoff. The image shows all the water runoff heading straight for the river across the bottom of the picture. This after image shows the flow of water with changes in soil and crop management. The image shows farmed land influenced by different measures such as increased hedgerows, wild strips of land, regular rotation of differing crops and cover crops which help give greater evaporation and allows more water to soak into the ground reducing the rain water run-off to the river.

More Information

Managed aquifer recharge is where water is directed into the ground by creating areas for it to soak in, possibly by pumping, during wet periods. This reduces the amount of water reaching the rivers. 
To manage flood risk across the Thames Valley and deliver the objectives of this project on its own, this approach would need to increase infiltration by millions of cubic metres. 
​If carried out at a smaller scale, this approach would need to be delivered in combination with other approaches.
In the top part of the image there is a built-up area on a hard surface with drainage. The left of the image, below the built-up area is a rainwater storage tank which collects the water from the drains and pump. The image shows different levels in the ground and where rainwater collected in the storage tank may be redirected including an underground layer of water-bearing permeable rock known as aquifer. The rainwater runoff is shown by arrows from the built-up area toward the river which flows across the lower part of the image from left to right indicating a reduced runoff and reduced risk of flooding from the river.

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River restoration is where the natural shape of a river is restored. This can include putting back meanders or bends, changing the width of the channel. Water enters the floodplain sooner, reducing flow and the risk of flooding downstream.
To manage flood risk across the Thames Valley and deliver the objectives of this project on its own, this approach would need to be applied to tens or hundreds of kilometres of river. 
​If carried out at a smaller scale, this approach would need to be delivered in combination with other approaches.
The before image shows a fast-flowing river travelling across from the top middle to the bottom middle of the picture. On the left side of the river is farmland with limited space between the river the farmland. On the right side of the river there are limited trees and vegetation. The after image shows a meandering river with varying depths travelling from the top middle to the bottom middle of the picture. On the left side of the river some farmland has been removed from the floodplain allowing for new trees and vegetation to be planted on both sides of the river.

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Woodland planting is where woods are created or enlarged by planting new trees. This can stop, slow and store water before it reaches the rivers.  This option can also help to clean the water before it enters rivers. 
To manage flood risk across the Thames Valley and deliver the objectives of this project on its own, many hundreds or thousands of hectares of trees would need to be planted.  ​
​If carried out at a smaller scale, this approach would need to be delivered in combination with other approaches.
The before image show a large area of land with limited vegetation. The flow of rainwater runoff show most rainwater heads straight for the river that flows across the bottom of the picture. The after image shows a large area of land with new woodland to capture rain and increase evaporation. The rainwater runoff is slowed down and more water soaks into the ground.

More Information

Property Level Resilience, also known as Property Level Protection (PLP) is where products are used to reduce flood risk to an individual property or help a property to recover more quickly after a flood. This can include flood gates, water resistant mortars and non return valves on drains. It can also include using tiles instead of carpets and raising electrics above the predicted flood level.
To manage flood risk across the Thames Valley and deliver the objectives of this project on its own, this approach would need to be applied to tens of thousands of properties.  ​​
​If carried out at a smaller scale, this approach would need to be delivered in combination with other approaches.​
This image shows a property with measures in place to help manage flooding. The house is built from water resistant building materials. There is a door guard at the front of the house, anti-flood air brick and a flood door to the side of the house. The flood door opens on to a permeable paving in the driveway.

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Deeping or widening a river can increase the amount of water that can pass along that section. 
To manage flood risk across the Thames Valley and deliver the objectives of this project on its own, this approach would need to be applied to tens or hundreds of kilometres of river. ​ ​​​
If carried out at a smaller scale, this would need to be delivered in combination with other approaches.​​
The before image shows a river with limited width or depth flowing across from the left to the right of the picture. Above the river are buildings representing communities at risk of flooding. The extent of the flood plain is shown to reach beyond the built-up areas. The after image shows a river flowing across from the left to the right of the picture that has been increased in depth and width. The increased size of the river means more space for water to flow through it making the area at risk of flooding smaller.

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Flood relief channels are built to divert flow away from a community during a flood. The water then rejoins the river further downstream. 
To manage flood risk across the Thames Valley and deliver the objectives of this project on its own, flood relief channels would need to be built around many cities, towns and villages.  ​​
If carried out at a smaller scale, this would need to be delivered in combination with other approaches.​​
The before image shows an area of land with a river running from the top right corner to the bottom left corner of the picture. Along either side of the river are buildings representing communities. The area at risk of flooding is shown to reach beyond these communities. the after image shows an area of land with a river running from the top right corner to the bottom left corner of the picture. Along either side of the river are buildings representing communities. In the top section of the river a flood relief channel has been created that flows in parallel to the river to divert river water away from the floodplain. This helps to reduce the risk of flooding to the communities along the river. There is a structure to control the flow of water entering the flood relief channel at the point where it begins

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Washlands or washes are where land next to rivers are designed to be deliberately flooded. Flooding of the washlands can be controlled. This reduces flooding in other areas. 
To manage flood risk across the Thames Valley and deliver the objectives of this project on its own, millions of cubic metres of flood water would need to be stored across hundreds of hectares.  ​​​​
If carried out at a smaller scale, this would need to be delivered in combination with other approaches.​​
The before image shows a large area of land. At the top of the picture are houses representing communities. Along the bottom of the picture, there is a river flowing from one side to the other. The after image shows a large area of land. At the top of the picture are houses representing communities. Along the bottom of the picture, there is a river flowing from one side to the other. The houses are protected by an embankment which separates them from a new washland. On the other side of the washland, along the river, there is another embankment containing a structure to control the amount of water flowing both into and out of the washland from the river.

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Temporary or removable flood barriers are used to keep flood water away from properties. They are only put in place when flooding is expected and are removed after the flood. Some have fixings that are in place all the time, others just need a flat area of land to be put up on.
To manage flood risk across the Thames Valley and deliver the objectives of this project on its own, tens or hundreds of kilometres of temporary flood barrier would be needed.​​​​​​
If carried out at a smaller scale, this would need to be delivered in combination with other approaches.​​
The non flooding conditions image shows a property on land near a flood risk area. There is a flat area between the flood plain and the property for temporary flood barriers with permanent fixings for removable barriers to attach to. The flooding conditions image shows a property on land near a flood risk area. There is a temporary flood barrier in place on a flat area between the flood plain and the property which is protecting it against high-water levels.

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Online flood storage is where water is temporarily stored within the floodplain. This is done by building an embankment across the floodplain and a control structure in the river. This reduces the amount of water in the river downstream during a flood. The water is slowly released after the flood. 
To manage flood risk across the Thames Valley and deliver the objectives of this project on its own, millions of cubic metres of flood water would need to be stored across hundreds of hectares. ​​​​​
If carried out at a smaller scale, this would need to be delivered in combination with other approaches.​​
The before image shows an area of land with a river flowing through the middle of the picture from the top to the bottom. Near the lower part of the river in the picture there are buildings representing communities at risk of flooding on both sides of the river. The after image shows an area of land with a river flowing through the middle of the picture from the top to the bottom. Near the lower part of the river in the picture there are buildings representing communities at risk of flooding on both sides of the river. In the open land between the top of the picture and the communities an online flood storage area has been created. An embankment is in place between the online flood storage and the communities at risk of flooding. This embankment contain a structure to control the amount of water flowing out of the online storage area.

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Wetland creation is where new wetlands are constructed or existing ones extended. This slows and stores water within the plants and pools of the wetland, reducing the amount of water reaching the river during a flood. This approach can also help to clean the water before it enters rivers. 
To manage flood risk across the Thames Valley and deliver the objectives of this project on its own, hundreds or thousands of hectares of wetland would need to be created.  ​​​​​​ ​
If carried out at a smaller scale, this would need to be delivered in combination with other approaches.​​
The before image shows a large area at risk of flooding from a river that runs from the top right to the bottom left of the picture. There are houses representing communities along both sides of the river. The image shows the area at risk of river flooding affects many of the communities. The after image shows a large area at risk of flooding from a river that runs from the top right to the bottom left of the picture. There are houses representing communities along both sides of the river. The image shows that by introducing new wetland upstream of the communities, the risk of flooding for the communities will reduce.

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Flood water transfer is where water from one river catchment is moved to another or to the sea. This is done using pipes or channels. This reduces the amount of water in the river during a flood. 
To manage flood risk across the Thames Valley and deliver the objectives of this project on its own, tens or hundreds of cubic meters of water would need to be transferred every second during a large flood.  ​​​​​
If carried out at a smaller scale, this would need to be delivered in combination with other approaches.​​
The before image shows a large area of land at risk of flooding. There is a river that flows from the top right to the bottom left of the picture. On either side of the river at the bottom of the picture are houses representing communities. These communities are at risk of flooding. The after image shows a large area of land at risk of flooding. There is a river that flows from the top right to the bottom left of the picture. On either side of the river at the bottom of the picture are houses representing communities. At the top of the picture there is a new river or pipeline shown flowing from the river. This is connected with a structure to help control the amount of water allowed to flow into a different river catchment.

More Information

Permanent flood barriers are where floodwalls or embankments are used to keep flood water away from properties. This reduces the likelihood of water reaching properties during a flood.
To manage flood risk across the Thames Valley and deliver the objectives of this project on its own, tens or hundreds of kilometres of permanent flood barrier would be needed. ​ ​​​​​​​ ​
If carried out at a smaller scale, this would need to be delivered in combination with other approaches.​​
This image shows an area of land with houses representing communities. The communities are situated along the top of the picture. At the bottom of the image is a flood area. Between the flooded area and the communities there is a new flood embankment and a new flood wall. These are examples of permanent flood barriers which are help to reduce flooding to the communities.

Next: Project ambitions and working together

Previous: Why do we need the scheme?

Audiences

  • Recreational and commercial river users
  • Fishing clubs and representative associations
  • Members of the public with an interest in the river, the species and conservation
  • Businesses
  • Charities
  • Statutory organisations
  • NGOs
  • Members of the public
  • Elected representatives, including MPs
  • Local councils
  • Academics
  • Environment Agency customers
  • Local authorities
  • District and parish councils
  • Environmental bodies
  • Land owners
  • Farming associations
  • RFCCs
  • Elected representatives, including MPs
  • Water companies
  • Members of the public
  • Recreational and commercial river users
  • Community groups
  • Flood action groups
  • Environment Agency colleagues
  • Lead Local Flood Authorities
  • Flood Resilience Forums
  • Members of the public
  • Town and parish councils
  • Regional Flood and Coastal Committees

Interests

  • Flood management
  • Water resources
  • Habitats and wildlife