Discussion of ‘The use of electrical resistivity tomography in deriving local-scale models of recharge through superficial deposits’, by M.O. Cuthbert, R. MacKay, J.H. Tellam & R.D. Barker, Quarterly Journal for Engineering Geology and Hydrogeology , 42 , 199–209

Abstract

Cuthbert et al . (2009) present an interesting and detailed study of the effects that superficial glacial deposits have on recharge to a bedrock aquifer, in this case the Permo-Triassic Sandstone of the Tern catchment in the West Midlands of England. In their discussion they suggest that the current recharge model used by the Environment Agency may not be adequate for the purposes of groundwater abstraction management because it oversimplifies recharge processes through the superficial deposits. In the present discussion paper this point is further explored with reference to the original management objectives of the Environment Agency project that produced a regional groundwater model of the East Shropshire Permo-Triassic Sandstone of the Tern catchment, of which the recharge model was an integral part. The objectives of the East Shropshire groundwater model have been outlined by Streetly & Shepley (2005), in the final report of the Environment Agency project. This report provides an extensive description of the conceptual and numerical model; the main details of the latter have been summarized by Shepley & Streetly (2007). The other reports of the Environment Agency project (Bridge et al . 2002; Streetly et al . 2002; Streetly & Young 2004) quoted by Cuthbert et al . (2009), with the exception of Bridge et al . (2002) are intermediary reports, and not further referred to in this discussion paper. This discussion paper focuses on three aspects: (1) the philosophy behind using models for groundwater management decision making; (2) some background on the East Shropshire groundwater model; (3) an example of how the East Shropshire groundwater model has been used for groundwater management. This provides a basis for a more detailed appraisal of Cuthbert et al .'s work in the context of the management of the East Shropshire Permo-Triassic Sandstone aquifer. …