Improved estimate of groundwater recharge in the central part of Valle Argentino, province of La Pampa, Argentina

Abstract

The processes that control the recharge have difficulties for their quantification due to hydroclimatic variability and different particularities of the aquifer system. Sometimes, the different methods for recharge assessment provide results with a high degree of uncertainty. The purpose of this paper is to estimate groundwater recharge in the central part of Valle Argentino, whose hydrogeological potential comes from a sand dune system that plays an important role as recharge area. It was considered interesting to update the previous estimates with new data from the General Acha and Padre Buodo sites. The recharge was obtained from a daily water balance (Visual Balan code) and the water-table fluctuation (WTF) method. The mean yearly values of recharge obtained range from 35 to 53 mm, with maximums between 76 and 112 mm and minimums between 0 and 21 mm. The greater values caused water table rises from 0.60 to just over 1 m, while a low or null recharge is linked to a drop in water levels of between 0.4 and 0.8 m, caused by the predominance of the groundwater outflow. This fluctuation of water table has a severe impact in the water storage in the aquifer, which represents the main source of groundwater for human and livestock consumption in this area. The integration of results in a conceptual model that explain the hydrodynamic behaviour of the system constitutes a relevant contribution to groundwater resource management.