Out of sight, and to most people out of mind, a massive chalk sponge lies underground beneath the Downs as well as the city of Brighton & Hove itself – a giant natural reservoir that stores millions of litres of groundwater in the chalk block of our Biosphere between the River Adur in the west to the River Ouse in the east. This groundwater chalk ‘aquifer’ is much more than a natural phenomenon however, since it is a fundamental requirement of our daily survival here by providing all of our drinking water needs to Brighton & Hove and the surrounding area. Southern Water Services operate 14 groundwater abstraction sources from deep boreholes across the aquifer, which together can provide up to 189 million litres a day or 38,000 million litres of water a year – that’s the equivalent of around 15,200 Olympic size swimming pools full of water! It’s not just the huge amount of water stored in the groundwater aquifer that is important, but also the pure natural quality of the rain water that has filtered down through the soft permeable chalk rock over a period of many years. This natural cleansing action means that pure drinking water can be supplied to us with minimal treatment (and hence reduced cost), an ‘ecosystem service’ that nature provides us with for free and generally unappreciated. Our forebears understood the great importance of our natural water supply to the future success and growth of our settlements, hence the Brighton Corporation bought up much open downland in the early 20th Century to protect it from built development and ensure the sustained life of future generations.
The groundwater-fed scarp slope spring at FulkingThe water is not only important for people either, as the aquifer also sustains many rare and nationally important habitats, notably the rare chalk streams that issue from the steep scarp slope and feed large wetland areas such as the Lewes Brooks. However, our natural water resource of the aquifer is not without its pressures. A fine balance needs to be maintained between the needs of public water supply and the environment through careful management of the amount of water abstracted for us to use. Moreover, the quality of our groundwater is declining from pollution inadvertently arising from both rural and urban land uses. Apparent threats arise from the application and leaching of agricultural fertilisers and pesticides and other runoff, whilst in towns a diverse array of problems are manifest including leaky sewers and runoff from industrial sites and roads. This in turn relates to the threat of flooding to buildings from excess surface runoff. To help address these pressures, an exciting new catchment project is being developed to protect and improve the quality of groundwater in the Brighton Chalk and ensure it remains a sustainable resource, called the Brighton Chalk Management Partnership (CHAMP) project. The partnership involves the South Downs National Park Authority, Brighton & Lewes Downs Biosphere, Southern Water Services, Environment Agency, Brighton & Hove City Council, Natural England, RSPB and the University of Brighton. We hope to secure all of the required funding by this summer to be able to formally start work in the autumn – watch this space! P.S. For more information on the ‘hidden resource’ of groundwater, have a look at this short film for the global picture, plus the Biosphere videos for the local view. Christopher Manning Water Policy Officer South Downs National Park Authority