Top chalk structure and Palaeogene stratigraphy in the Ravensbourne Catchment, South London

The Chalk aquifer in the Central London Basin is mainly well confined, with the Chalk cropping out in the Chilterns and the North Downs. Within this simplified hydrogeological framework, the Ravensbourne catchment in South East London is complicated by having; • Unconfined Chalk; • Significant areas where the London Clay is absent, and • Significant areas where the Harwich Formation crops out. The result is a hydrogeologically complex groundwater catchment within which there are many groundwater abstractions for public and private use. Understanding how these abstractions affect the groundwater system and water balance is important for future water resource planning and management (particularly for Thames Water the water undertaker). This report provides the results of a 10-day study whose aim was to improve our understanding of the geological structure and stratigraphy of the Ravensbourne area. The report focuses on two main aspects: • Top Chalk structure • Palaeogene stratigraphy and its possible influence on aquifer properties