In situ study of hydrochemical response of a fractured-layered carbonate regional aquifer: Comparative analyses of natural infiltration and artificial leakage of a large dam lake (Vouglans, Jura, France)

Abstract

Leakage detection and prediction of fractured rocks is an important question in hydropower engineering. Some of large water reservoirs are built in karstic carbonate areas. In order to understand underground circulations in the limestone/dolomite foundation of Vouglans dam (Jura, France), analysis of groundwater chemistry, according to geological conditions, is used. Statistical analyses (PCA and DFA) are used (i) to characterise more precisely the low contrast in chemical composition resulting from the interaction between surface water, groundwater and carbonate environment, and (ii) to reclassify individuals in homogeneous groups with respect to the variables studied. Three hydrodynamic behaviours were determined in the sector. The area of influence of the rapid transit of the lake water varies with the seasons, and particularly in response to changes of the water level of the lake. The hydrostatic pressure of the water column has an influence on the opening and closing of cracks at the bottom of the dam.