A new conceptual groundwater-flow system for the central South Downs aquifer

The central part of the South Downs Chalk aquifer is intensely used for public water supply. Although the aquifer has a long history of careful development and management, the outline conceptual groundwater-flow vision has not been formally investigated for many years. A major programme of work has now been completed which (a) provides a new insight into the hydraulic workings of the aquifer, and (b) highlights a number of hitherto poorly understood concepts controlling groundwater movement in the Chalk. These include the key role of geological structure and the occurrence of hard bands and karst-type groundwater flow as major controls over preferred flow-paths. The new conceptualisation concludes that the main discharge area for the aquifer is laterally to the north-south rivers and not directly southwards to the sea.