Why does southern Wealden and Eastbourne flood?

Geology and landscape

The land in Eastbourne and southern Wealden is challenging. 

To the west of Eastbourne, the South Downs discharge water into chalk streams that flow down towards the town. 

Much of the area is reclaimed marshland, such as the Eastbourne Levels. Traditionally, the land was used for grazing. Water was managed with systems of channels and ditches, with an occasional drenching from the sea. But now there are houses, roads, and other infrastructure that need protection from freshwater and the sea.

There are areas of impermeable geology which don’t let water seep through. This makes it hard to control the direction and speed of water flowing through the area. Some flood prevention methods, such as sustainable drainage systems (SuDS) and soakaways, don’t work in these areas.

Urbanisation

Towns have hard surfaces such as concrete and tarmac which don’t allow rainwater to seep away safely. They create surface water which then ‘runs off’, potentially causing flooding in nearby areas and potentially overwhelming drains.

Giving the water more chances to drain away safely, through lawns and flower beds for example, and collecting rainwater using water butts and other sustainable drainage systems (SuDS) can to help.

Old sewer system

Our drainage relies on Victorian sewers, which are not designed for the current population levels or changes in climate. Some are now under buildings, making repairs difficult and replacements expensive. 

We have ‘combined’ sewers, where water from bathrooms, roofs, factories and farms all goes through the same pipes. The water mixes together and is contaminated, making the impact of flooding much worse.

Climate change

Intense, sudden rainfall is more frequent. These heavy downpours overwhelm sewers.

We are also at risk of ‘tidal lock’. This is when there is a high tide at the same time as rainfall, which prevents the drains from discharging and leads to water backing up inland. Climate change is causing sea levels to rise, so this will become a more frequent problem.