USING 3D MODELS TO BETTER UNDERSTAND THE EFFECTS OF SUPERFICIAL DEPOSITS ON AQUIFER RECHARGE (Invited Presentation)

The regulatory Environment Agency of England and Wales (EA) commissioned a regional 3D geological model of the Holderness area in Yorkshire, UK, in order for them to better understand the influence of superficial deposits on recharge of the underlying regionally important Chalk aquifer. This was to enable the EA to make better informed decisions when setting abstraction levels in public supply and commercial boreholes. Each geological unit in the 3D model was attributed with permeability information to enable the EA to pinpoint areas where permeable superficial units directly overlie the Chalk, and identify potential pollution pathways into the Chalk aquifer.

Existing published research on the area from boreholes and temporary coastal exposures indicates a complex sequence of glacial deposits from several ice advances and phases of decay and an earlier wave cut platform scoured into the Chalk bedrock. The 3D model, constructed using the GSI3D software and workflow, reveals this complexity and enables the user to peel away each layer to reveal the distribution of concealed units. As well as visualising the superficial geology of the region in three dimensions for the first time, the 3D model revealed a previously unknown sand and gravel-filled channel at the coast beneath Hornsea Mere, where the EA had recorded unusually high water levels in a monitoring borehole.