Common land, water supply and flood management
Common land plays a crucial role in the supply of Britain’s drinking water and flood management.
Many upland commons of England and Wales fall within catchments close to major centres of population, and contribute to regulated supply. Their strategic importance for water management will increase as climate change affects the frequency and intensity of precipitation.
Common land or grazings constitute 19%, 15%, and 12% of the English, Welsh, and Scottish uplands respectively. The chemical water quality of most upland commons is stable or improving, although dissolved organic matter becomes an issue especially after rewetting of dried peat. In compliance with European legislation, water companies increasingly work to reduce sedimentation and water discolouration at source rather than focusing on downstream purification, within a strategy of whole-catchment intervention. Such approaches require close collaboration with commoners on issues of stocking, vegetation, and drainage management.
The speed of water run-off in upland areas impacts on river capacity downstream. Increased vegetation, together with improved soil structure and permeability in upland catchments, slows surface run-off and reduces spate flows and flooding. This can be achieved by minimizing soil compaction through ensuring appropriate grazing levels and stocking with smaller hill breeds.
430,000ha of the English and Welsh commons are in the uplands where they contribute to major catchments.
Over 10% of all Britain’s water derives from common land.
Of particular importance are commons in the Welsh Borders, the Lake District, and Dartmoor.
Commons of the Nant Crew catchment flow into Cantref Reservoir in the Brecon Beacons, which supplies water to Swansea and Port Talbot.
Nearly all drinking water in Devon and Cornwall comes from the south-west uplands, where 26% is common land.
There are 19 abstraction points and four reservoirs on Dartmoor, 40% of which is common land.
United Utilities owns 15,500ha of land in the Thirlmere and Haweswater catchments to protect the quality of water entering reservoirs. Some 57% of this land is registered common. The catchments supply 650 megalitres of water per day to Manchester and the North West of England.
Commoners are increasingly involved in catchment management aimed at ensuring quality control at source, and reduced flooding. Examples include the Nant Crew catchment scheme, the Slowing the Flow project based in the North York Moors, the Upstream Thinking Project run by South West Water, and the Sustainable Catchment Management Programme run by United Utilities. The initiatives involve peat bog restoration, blocking grips and gullies, stabilising tributaries, and managing stocking levels and winter grazing. Such schemes can generate benefits to wildlife, including internationally important wetlands, whilst making such areas more resilient to long-term climate change.