Another key to restoring natural dynamism in the landscape is to allow water to express itself.
At the heart of Knepp is the River Adur restoration project. Carried out by the Environment Agency in 2011, and funded by Natural England and the Knepp Estate, this has involved removing four weirs and filling in a 1.5 mile drainage canal. The canal was constructed in the 19th century to make the floodplain suitable for agricultural use but the narrow, flood-prone water-meadows – or ‘laggs’, as they are known locally – had only ever provided poor quality grazing.
Returning this stretch of the Adur to its original meanders, and reconnecting it with 3.5 miles of restored floodplains upstream, has revitalised the water system. Woody debris has been introduced into the restored meanders to imitate and accelerate the natural processes of the river. The restored wetlands of the floodplain are now ideal habitat for wading birds, amphibians, water insects, important marsh plants and riverine trees like the nationally scarce black poplar.
Following the removal of the weirs, sea trout are now migrating up the river in numbers. Meanwhile, the natural activity of the floodplain helps filter and improve the quality of the water passing through it. It also slows down floodwater, protecting areas downstream from flood damage.
But it is not just the river that is important. Our focus is on restoring the full range of hydrological processes, from the moment raindrops fall on the land, filtering through vegetation and the soil, to their passage into watercourses towards the sea.
Other work, such as reconnecting waterways between Knepp Lake and the river, has been carried out to ease the passage of eels as they travel to and from their breeding grounds in the Sargasso Sea. We have also excavated shallow ‘scrapes’ in areas across the floodplain to attract wildlife. Some of these will dry out completely in the summer, while others remain wet all year round – a combination that supports a variety of invertebrates, such as beetles, bugs and molluscs, a number of which are rare and of importance to conservation.
In 2015, the River Adur restoration project at Knepp won the Innovative & Novel Project category in the UK River Prize.