19/09/23 - Andy Farrant (BGS) - Applied Geological Mapping in Southeast England

The Chalk of southern England is the UK’s premier aquifer and is host to many major engineering schemes such as the Lower Thames Crossing and HS2. The pressure on the Chalk aquifer, both in terms of groundwater quality and availability is increasing. Water quality is impacted by point source and diffuse contamination including nitrates and pesticides. Groundwater resources are impacted by the demands of an increasing population; regulation and the impacts of climate change. These all necessitate improved aquifer management and better groundwater models. Similarly engineering schemes increasingly need more detailed geological data prior to excavation. This requires a better understanding of the host rock, particularly its spatial and stratigraphical variability. Recent work has demonstrated the importance of lithological variations, stratigraphical discontinuities and tectonic structures on both the hydrogeological and engineering properties of the Chalk. The introduction of a high-resolution stratigraphy for mapping which highlights these variations in engineering and hydrogeological properties has revolutionized our understanding of this rather unusual rock unit. Working in collaboration with the Environment Agency and the water industry, BGS is creating a new suite of detailed geological maps and 3D models across much of the Chalk outcrop in southern England. This talk will outline the recent geological mapping work by the British Geological Survey, focussing on the Chilterns, and the impact this has for both groundwater management and engineering schemes.

Andy Farrant is a Regional Geologist, Southeast England. He joined BGS in 1996 after doing a PhD at Bristol University on landscape evolution. He has spent most of his career at BGS working on the Chalk of southern England, updating the geological maps across much of Hampshire, the South Downs, parts of the North Downs and up into the Chilterns, plus some work in the Yorkshire Wolds, working in collaboration with the Environment Agency and water companies. He also has a background in karst geomorphology and hydrogeology, which has proved useful working on Chalk terrains!