Uso de técnicas geofísicas para caracterizar la extrusión de agua salina en un acuífero costero mediterráneo bicapa (Río Vélez, provincia de Málaga)

Abstract

The river Vélez delta (Malaga province) is a two-layer aquifer. The groundwater overexploitation during the 1993-1995 drought period led to a quite general seawater intrusion in both layers, particularly severe in the deepest one (confined). The important aquifer recharge associated to the 1996-1997 abnormally rainy period has induced the flushing of most of the brackish and saline water. This study shows the status of the aquifer in September 2003 by means of geophysical techniques (FDEM soundings and Electrical Resistivity Imaging) and logs of electrical conductivity of the water in boreholes. The confined aquifer seems completely recovered, as flushing by freshwater continues. The phreatic aquifer had a rapid recovery after the recharge event, although during this study the presence of brackish waters –similar to those which existed before the recharge- has been identified. The geophysical methods have identified the vertical and lateral distribution of these waters, which now show different patterns with respect to the situation immediately after the drought