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What is Flood Resilience?
Flood resilience can be defined in two ways: with hard engineering flood defences (Thames barrier, river walls, etc.) and without. Flood defences typically work against nature and can cause problems themselves. For example, if the now outdated Thames barrier stops working high tides will surge upstream. If water breaches flood walls it will be trapped on land for much longer that if it was allowed to return to the river without a wall.
Definitions of flood resilience without hard engineering can be described as:
Here at BCL our focus is to work with nature and as such, we tend to steer away from flood defences.
Flood Risk:
The Beverley Brook rises in Worcester Park, flows through Barnes and enters the Thames on the Barnes/Putney border at Ashlone Wharf.
The catchment of the brook is somewhat in reverse, with the upper half, south of Richmond Park and the A3 being heavily urbanised and concreted over and the lower half being more verdant and open. This can lead to pluvial and fluvial flood risk.
Pluvial flooding comes from the rain and is exacerbated by poor surface water drainage (SWD). If an area is concreted over the water cannot go anywhere, causing flooding.
When this enters a watercourse it become fluvial flooding – flooding from a watercourse, where there is too much water for the river channel to hold.
As the Beverley Brook joins the tidal Thames it is affected by the tides. When high tide goes upstream it effectively acts as a wall for water coming downstream. This is called tide lock and can cause fluvial flooding as the water has nowhere to go apart from out of bank. When all three of these events happen at the same time, as in July 2021, devastating flooding can result.
It is important to remember that floodplains and floods are natural habitats and processes that benefit river ecosystems and the land around them. However, as populations have grown flood plains have been built upon and altered, resulting in more dangerous and damaging floods than would otherwise have occurred. BCL aims to develop community recognition of flood plains as a vital and necessary ecosystem in natural river management and flood resilience.
State of the Beverley Brook:
It used to be believed that the best way to deal with rivers and flooding was to get it out to a larger waterbody or the sea as quickly as possible. This was done by straightening, widening and deepening the channel and removing any obstacles/natural features from it. Either that or it was placed in culverts and buried underground to be forgotten about, as with the Rythe, a secondary channel of the Beverley Brook. In actual fact, as we now know, all this does is increase the risk of flooding downstream and destroy any biodiversity or natural processes that once existed in the area. As such, the Environment Agency (EA) believe that due to the lack of in-channel features and vegetation the fry (juvenile fish) retention of the Beverley Brook is extraordinarily low: high levels and heavy rainfall washing them out to the Thames.
Since the Beverley Brook was altered as above, the floodplain has been built on, in some cases with the walls of houses making up the riverbank. What we are left with is very little room to fix the brook. In addition to this urbanisation, it was once the mindset that rivers were good places to get rid of rubbish. Once washed away, one did not have to think about it again. Unfortunately, this is still the attitude by some as sewer pipes are sometimes ‘misconnected’ into the river rather than into the sewage system, towards treatment plants.
The natural source of the Beverley Brook is the Surrey Hills above Epsom, however, the aquifer supplying the water has been completely abstracted (drained), meaning that it runs dry. Today, the Beverley Brook’s water comes from treated water from the Hogsmill Sewage Treatment Works.
Why does this matter?
Barnes and the surrounding areas are very low lying – the highest point in Barnes is only 8m above sea level. Naturally and before creation of the flood wall, the inside meander of the Thames that Barnes sits on would be flooded regularly. However, due to hard engineering this process is no longer allowed to occur. As such, the tide and high river levels will try to find ways behind the flood wall wherever possible. This pressure, combined with the pluvial and fluvial flood risks, tide lock, modification of the natural channel and pressures from urbanisation, encroachment and development on the floodplain mean that Barnes is very prone to flooding. Additionally, Barnes sits in Flood Zones 2 and 3 and is shown as being at risk if the Thames Barrier fails.
We cannot tear Barnes down and start again elsewhere. Nor can we change the natural processes that are currently occurring due to our previous activities by enhancing those activities. Instead, we must work with nature to make sure that we, our properties and possessions, as well as the land around us, can cope with these flooding events in the future. We must enhance our flood resilience by ensuring capacity and attenuation of water entering the appropriate drainage channels and remember that what is happening is inevitably because of human activity.
What is Flood Resilience?
Flood resilience can be defined in two ways: with hard engineering flood defences (Thames barrier, river walls, etc.) and without. Flood defences typically work against nature and can cause problems themselves. For example, if the now outdated Thames barrier stops working high tides will surge upstream. If water breaches flood walls it will be trapped on land for much longer that if it was allowed to return to the river without a wall.
Definitions of flood resilience without hard engineering can be described as:
Here at BCL our focus is to work with nature and as such, we tend to steer away from flood defences.
Flood Risk:
The Beverley Brook rises in Worcester Park, flows through Barnes and enters the Thames on the Barnes/Putney border at Ashlone Wharf.
The catchment of the brook is somewhat in reverse, with the upper half, south of Richmond Park and the A3 being heavily urbanised and concreted over and the lower half being more verdant and open. This can lead to pluvial and fluvial flood risk.
Pluvial flooding comes from the rain and is exacerbated by poor surface water drainage (SWD). If an area is concreted over the water cannot go anywhere, causing flooding.
When this enters a watercourse it become fluvial flooding – flooding from a watercourse, where there is too much water for the river channel to hold.
As the Beverley Brook joins the tidal Thames it is affected by the tides. When high tide goes upstream it effectively acts as a wall for water coming downstream. This is called tide lock and can cause fluvial flooding as the water has nowhere to go apart from out of bank. When all three of these events happen at the same time, as in July 2021, devastating flooding can result.
It is important to remember that floodplains and floods are natural habitats and processes that benefit river ecosystems and the land around them. However, as populations have grown flood plains have been built upon and altered, resulting in more dangerous and damaging floods than would otherwise have occurred. BCL aims to develop community recognition of flood plains as a vital and necessary ecosystem in natural river management and flood resilience.
State of the Beverley Brook:
It used to be believed that the best way to deal with rivers and flooding was to get it out to a larger waterbody or the sea as quickly as possible. This was done by straightening, widening and deepening the channel and removing any obstacles/natural features from it. Either that or it was placed in culverts and buried underground to be forgotten about, as with the Rythe, a secondary channel of the Beverley Brook. In actual fact, as we now know, all this does is increase the risk of flooding downstream and destroy any biodiversity or natural processes that once existed in the area. As such, the Environment Agency (EA) believe that due to the lack of in-channel features and vegetation the fry (juvenile fish) retention of the Beverley Brook is extraordinarily low: high levels and heavy rainfall washing them out to the Thames.
Since the Beverley Brook was altered as above, the floodplain has been built on, in some cases with the walls of houses making up the riverbank. What we are left with is very little room to fix the brook. In addition to this urbanisation, it was once the mindset that rivers were good places to get rid of rubbish. Once washed away, one did not have to think about it again. Unfortunately, this is still the attitude by some as sewer pipes are sometimes ‘misconnected’ into the river rather than into the sewage system, towards treatment plants.
The natural source of the Beverley Brook is the Surrey Hills above Epsom, however, the aquifer supplying the water has been completely abstracted (drained), meaning that it runs dry. Today, the Beverley Brook’s water comes from treated water from the Hogsmill Sewage Treatment Works.
Why does this matter?
Barnes and the surrounding areas are very low lying – the highest point in Barnes is only 8m above sea level. Naturally and before creation of the flood wall, the inside meander of the Thames that Barnes sits on would be flooded regularly. However, due to hard engineering this process is no longer allowed to occur. As such, the tide and high river levels will try to find ways behind the flood wall wherever possible. This pressure, combined with the pluvial and fluvial flood risks, tide lock, modification of the natural channel and pressures from urbanisation, encroachment and development on the floodplain mean that Barnes is very prone to flooding. Additionally, Barnes sits in Flood Zones 2 and 3 and is shown as being at risk if the Thames Barrier fails.
We cannot tear Barnes down and start again elsewhere. Nor can we change the natural processes that are currently occurring due to our previous activities by enhancing those activities. Instead, we must work with nature to make sure that we, our properties and possessions, as well as the land around us, can cope with these flooding events in the future. We must enhance our flood resilience by ensuring capacity and attenuation of water entering the appropriate drainage channels and remember that what is happening is inevitably because of human activity.
Barnes Common
Vine Road Pavilion
Vine Road
Barnes SW13 0NE