Sam Buckland, Project Officer for the Sussex Flow Initiative describes how natural flood management is being used to tackle the climate emergency and biodiversity decline.
The Sussex Flow Initiative started in 2012 as a Natural Flood Management project supported by Sussex Wildlife Trust, the Woodland Trust, the Environment Agency and Lewes District Council. The project works across the ‘catchment scale’, in other words, over the area of land where water collects and feeds into ponds, lakes and rivers. The project involves communities and landowners in the Ouse catchment, an area of 672 km2 and over 122 km of watercourses. The scheme is creating and enhancing natural features that slow and store water within the landscape, which reduces flood risk to communities downstream. The impact of the project extends far beyond the catchment boundary and flood management. A healthy landscape and river network are vital for human health and wellbeing, providing a range of benefits such as clean water and air, and increased biodiversity.
In most cases, natural flood management focuses on reversing past activities (such as drainage) and restoring the ability of the land to slow and store water. As a result, water is once again allowed to seep into soils and drain slowly into surface waters. Water also moves deeper into the soil, helping to top up the store of groundwater and resulting in a steadier supply of water. Trees can also help to control floodwater because of their importance in the water cycle. They intercept rainfall, take up water from the soil, slow down surface run-off and floodwater and help water to move deeper into the soil and groundwater. These processes hold water on land and reduce the amount and speed of water flowing into streams and rivers. Tree planting has added benefits such as providing important habitat and food for a range of birds, bats and insects, as well as storing carbon. With the help of local volunteers, our project has planted over 60,100 trees. We have established more than 9 kilometres of new hedgerow and 8.5 hectares of woodland (equivalent to the area of 10 football pitches), including over 4 hectares of floodplain woodland and 450 rare black poplars.
Within the stream and river channels, we have been restoring meanders, bankside vegetation and in-channel wood. These are all lost natural features that slow water and make for a dynamic and healthy ecosystem. Our project has created nearly 5 million litres of new, seasonal water storage, including flood storage ponds, wader scrapes and meadow washlands. An incredibly important part of the project is to increase the skills, knowledge and understanding of natural flood management and empower people to take positive action.
One such way is through using large woody debris, creating ‘leaky’ wood dams that imitate those that built by an important animal that has been missing from our waterways for 400 years; the beaver. Leaky dams are a natural component of streams, forming clusters of dams, slowing the water’s speed, trapping sediment and pollutants, and creating a range of different stream habitats that are important for fish and invertebrates. The presence of woody debris can also help to make the landscape more resilient to drought by encouraging the formation of small pools and helping to restore the natural movement of water. Through contractor training days and volunteer tasks, our project has installed over 270 leaky dams across the Ouse catchment. Hopefully we will see the return of beavers to Sussex catchments in the future, and with it the biodiversity and the flood management that they deliver through coppicing and dam creation.
Our project is using natural features to slow and store water in the landscape. These measures are cheap, collaborative and easy to implement, as well as delivering many other multiple benefits to society. We know that multiple actions taken now can provide positive natural flood management and natural capital benefits long into the future.