Wallasea Island Case Study: What were the Wallasea Island management options?

At Wallasea the old sea walls on the north shore were in a very poor condition. Without intervention, there was a high risk that the walls would fail in future, leading to flooding of the farmland.

The Department for Environment, Food and Rural Affairs and the Environment Agency manage the risk of flooding in the UK. They try to reduce the probability or chance of flooding, through land management and building flood defences, and reducing the impact of flooding, for example through controlling development. They manage the Wallasea Island Project, where the aim is to provide environmentally and economically sustainable flood defence measures and to improve biodiversity.

At Wallasea there were three main options:

Option 1: Do nothing

In some coastal areas councils cannot afford to protect the coast. This option would leave the sea defences to crumble, and the land to be flooded, leading to loss of farmland.

Option 2: Rebuild the existing sea wall

Sea walls are strong but are costly to construct (£6000 per metre) and require maintenance. Sea walls can reflect waves and funnel high tides, moving the flood hazard elsewhere.

Option 3: Managed realignment

In the past, high flood tides and surges were absorbed by salt marshes along the coast. These areas were reclaimed for farmland, such as the wheat fields on Wallasea Island. Since the Second World War there has been a food surplus in the UK, which means this farmland is no longer so important. The managed realignment project on Wallasea Island would give more space for water by working with natural processes: the new wetland would increase storm protection as storm waves would lose their energy as they flowed over the site.

Option 3 was chosen at Wallasea for the following main reasons:

  • A sufficiently large site to attract vast numbers of birds, including those that had used other wetland sites
  • Little chance of the surrounding estuary being damaged
  • No adverse effect on those using the area
  • Remote estuary location
  • The site was not protected for its conservation interest and there was limited public interest in the area
  • No opposition as Wallasea Farms, the existing landowner, was concerned about the poor state of the old sea defences and offered full support for the project

The Environment Agency investigated the tidal and environmental impact of managed re-alignment. The main area of concern was to make sure that there was no negative impact on the River Crouch and the people, businesses, fisheries and boats that use it. The EA took measurements to work out how the tides in the Crouch and Roach estuaries behave, then compared these with models of what would happen after the wetland was created. Surveys were undertaken of existing wildlife on the site to ensure maximum protection was possible for creatures such as reptiles, water voles, insects and ground nesting birds.

How did the Wallasea Island Project Develop? >>>

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Fiona Eastham Guest

Thanks.... as a Geography Teacher I found this really useful!

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Ellie Coleman Guest

Thanks.... as a Geography Teacher I found this really useful!

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