Berkshire Downs Chalk Operational Catchment

About

The Berkshire Downs Chalk Groundwater Body (GWB) describes part of the Chalk Group and Upper Greensand geological strata that lie beneath the Berkshire Downs. The Berkshire Downs Chalk GWB is located on the western part of the London Basin syncline. The Berkshire Downs Chalk GWB coincides with the entire River Kennet Catchment and part of the Pang Catchment. The River Kennet is located in the western part of the London basin; hence tributaries of the River Kennet flow from springs that emanate from the northern and southern dip slopes of the London Basin. A similar scenario applies to the River Pang. The Chalk and Upper Greensand Aquifers are water-bearing permeable strata that provide a high level of storage. Since they support regionally important groundwater supplies these aquifers are classified as Principal Aquifers. The Chalk is exposed at the surface for a large part of the Berkshire Downs Chalk GWB and in these areas the Chalk is susceptible to vertical migration of chemicals, including fertilisers. In the south eastern areas of the GWB the Chalk it is confined and protected by the London Clay, Lambeth Group, the Bracklesham Group or in places by clay-with-flints drift geology, which directly overlies the Chalk. Where the Chalk is confined it is generally protected from vertical migration of chemicals used at the surface.