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The wetlands that Crossrail built

An unlikely nature reserve on the Essex coast

Simon Barnes | July 23rd 2015

Londoners have been grumbling about the hold-ups and diversions caused by the Crossrail project since 2009, and will continue to do so until late 2018. When the new railway line is at last completed it will run over 100km between Reading and Heathrow in the west and Shenfield and Abbey Wood in the northeast. Currently employing 10,000 people, Crossrail will increase London’s rail capacity by 10%. There will be ten new stations and 42km of freshly dug tunnels. But one question remains: what the hell are they doing with all that dirt?

The somewhat unexpected answer is that they’re building a nature reserve in the Thames estuary. It’s on Wallasea Island (above), which lies 8km north of Southend-on-Sea, the same sinister landscape in which the escaped convict, Magwitch, demanded that Pip fetch him food and a file to cut his fetters in “Great Expectations”.

When the tide is right you can drive onto the island along a causeway. If you like mud and sky it’s a great place, because there are extraordinary quantities of both. That also makes it heaven for many species of wading bird. The mud of estuaries is spectacularly rich in nutrients, and therefore in the invertebrates that live in the mud and attract the wading birds that patrol the water’s edge. Different species with different kinds of bill pursue different invertebrates at different depths in the mud.

The construction of the nature reserve is a joint project with the RSPB, and the aim is to recreate a wild habitat. The first objective was to raise up the island by an average of 1.5 metres. If this wasn’t done the entire place would eventually be lost to rising sea levels. The resulting land has been sculpted into seawalls and lagoons. A decisive moment has just been reached: the new seawall has been deliberately breached in one area, called “Cell 1”, literally opening the floodgates and turning this new land into wetland.

The process began in 2006, and it is estimated that by 2025 the island will hold 148 hectares of mudflat, 192 of saltmarsh and 76 of shallow saline lagoons. Within three years 90% of the anticipated saltmarsh plants will have established themselves. The ground lackey moth is expected to breed here. Hefty numbers of avocets, redshanks and lapwings will come, all birds that have for centuries been associated with this landscape, albeit in much smaller quantities. And intriguingly, the island is also likely to bring in species that have only recently become British breeding birds, moving their range further north in response to climate change. Black-winged stilt and spoonbill were once regarded as exoticisms: it’s likely that Wallasea will be exactly what they are looking for.

Essex coastal marsh is among the richest and most important landscapes in the country. It was once much more extensive: 400 years ago there were 30,000 hectares of intertidal saltmarsh in the county; now there are 2,500. The rewilding of the Essex coast will be a radical change of direction.

Crossrail is reckoned to be Europe’s largest construction project. To use it for the benefit of wildlife represents another drastic change of direction. As Martin Harper, the RSPB’s conservation director, says, “We need to exploit this inventiveness to unlock other projects on a similar scale for the benefit of wildlife, people and the economy.”

The work continues: by the time Crossrail is finished, 2,400 shiploads of dirt will have been taken from London to Wallasea. But that’s still not enough. The island will then need an additional 10m tonnes of dirt; the RSPB is still looking for partners for the last 7m.

But stand there today with your back to the massive vehicles that are transforming the place, and you can see mud and sky and the hectic brown waters of the Thames estuary, and you can hear the sharp triple-note of the redshanks and forget for a moment that humanity exists. That’s the most remarkable thing of all in this remarkable partnership.

 

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