Any day now a 1,000 tonne, 150 metre long machine will break through a temporary plug of concrete to complete boring tunnels for Crossrail in London. This is currently the largest civil engineering project in Europe, creating a new railway crossing London from East to West. 42 kilometres of new tunnels have been bored and new underground stations dug out. This summer will also see the breaching of a sea wall to flood low lying farmland to help create a new area of salt marsh wetlands for birds and other flora and fauna. So what's the connection?
The mis-named Wallasea Island is an area of land to the east of London, separated from the North Sea by Foulness Island. Wallasea is almost completely surrounded by rivers but there is land access. It is surrounded by a sea wall which has become increasingly ineffective as sea levels rise and the SE of Britain tilts, the effect of the loss of the ice sheet that covered Scotland and the north of England in the last ice age. There is about a one in four chance of it being flooded in a year.
The North Sea itself presents a flood danger at particular times of the year and in certain weather conditions. Strong winds from the west in the winter can push water up the English Channel and over the north of the British Isles to raise the level of the North Sea. High spring tides and a low pressure area sitting over the sea can be deadly - in 1953 such a combination of conditions caused over 2,500 deaths in the UK, Belgium and the Netherlands and at sea.
Most of Wallasea Island was used for farming. Raising the surrounding sea wall would not have been cost-effective and, more importantly, only directs flood waters further inland. One answer might have been to simply abandon the land but it is now considerably below sea level. Flooding would have meant the currents would have washed away surrounding mud flats, further increasing the threat of floods further inland. Instead the Royal Society for the Protection of Birds (RSPB) and Crossrail came up with a scheme to use most of the spoil from the tunnel boring to build up the land and re-create a salt marsh habitat. This will have lagoons and raised islands to provide a refuge for wildlife.
In April, the last of 3 million tonnes of Crossrail spoil was delivered by boat to a specially built jetty on Wallasea. The work of establishing the salt marshes is well advanced although the scheme is not due to be completed for another 10 years.
The aim of this project is to combat the threats from climate change and coastal flooding by recreating the ancient wetland landscape of mudflats and saltmarsh, lagoons and pasture. It will also help to compensate for the loss of such tidal habitats elsewhere in England.
Once completed, this will provide a haven for a wonderful array of nationally and internationally important wildlife and an amazing place for the local community, and those from further afield, to come and enjoy.
Although the reserve is planned to be in development until around 2025, you're welcome to come along and view the progress as each phase comes to life and the marshland naturally regenerates. The current sea wall access along the Allfleets Marsh Trail sea wall is a wonderful place to come to relax and enjoy, whether for walking, cycling, birdwatching, painting, photography or simply taking in the sea air.
As well as providing a habitat for resident birds, the east of England is also an important "staging post" for migrating birds so the projects is a win win win. It has provided a way for Crossrail to dispose of millions of tonnes of "waste", it has provided the RSPB with materials to build up and remodel the land and it will provide a haven for wildlife and for people visiting.
