Abstract Recharge through the glacial drift, which covers significant areas of the United Kingdom’s aquifers, is a potentially important component of the groundwater inflows to the underlying aquifers. However, its estimation has largely been based on rather crude assumptions based on the available drift maps, which present few data on the thickness or variability of these materials. Invasive and non-invasive field investigations in Shropshire UK, have shown the significance of the lateral and vertical variability of the glacial drift in the vicinity of the Potford Brook and Platt Brook catchments. The gathered data have been used to develop conceptual models of the heterogeneity of the drift materials and these have formed the basis for numerical models to assess the impact of the heterogeneity of the drift formations on the recharge to the underlying Triassic Sandstone. Interference between the vegetated soil layer and the underlying clay materials leads to marked differences in the recharge estimates for the alternative conceptual models. Recharge rates are found to vary between 0.9 and 200 mm year^-1 for the materials mapped as the same type in the current drift mapping. The numerical results are providing valuable information on the required form of an upscaled recharge model.

Keywords electrical resistance tomography; glacial drift; numerical modelling; recharge; Triassic Sandstone; UK; upscaling