Enhanced Geology of the Chalk Aquifer (Northern France) From Ert Imaging for Hydrogeological Purposes

Abstract

Summary This study is part of a large multidisciplinary project aiming at characterize the geometry of the Chalk aquifer and its structures (faults, fracturing…), in two well fields in the South of Lille metropolis (Northern France), for hydrogeology purposes, especially drinking water production. We focus on two main results obtained through Electrical Resistivity Tomography (ERT) imaging. First, we define a petrophysical-linked electrical signature of the Chalk that allows us to image the hydrogeological stratification of the aquifer. Then, we refine the geological settings of the largest and the most exploited (in terms of water resource) well field which is also the most affected by water quality problems. We identify a fracturing corridor inside the unaltered Chalk and we precise the geometry of the overlying Tertiary formations (Louvil Clays). The refinement of the geological structures enhances our understanding of the Chalk hydrosystem functioning that represents a key issue to guarantee the sustainable management of a water resource.