Recharge estimation in aquifers of the Bogota Savannah

Recharge is a key factor for the sustainability of aquifers. In the Bogota Savannah there is an increasing interest in groundwater resources because of both the increase in water demand and climate change. Even though recharge studies in this region have traditionally focused on soil water balance approaches based on the use the FAO methodology for determining actual evapotranspiration levels, this work applies a frugal monthly water balance model and calibrates its lumped parameters through minimization of the error function between observed and simulated discharges in each hydrological basin. Model results indicate that recharge depends on the basin analyzed, and that the average model recharge in the Bogota Savannah is 112 mm yr-1, which is compared to the range of 8-81 mm yr-1 found in previous studies. This study suggests that caution should be used when decisions on the sustainability of groundwater resources in the Bogotá plain are based on a recharge estimate obtained from a single methodology, and that a multiple technique approach is recommended.