Significance of Preferential Infiltration Areas for Groundwater Recharge Rate Estimated with APLIS in the Mountain Karst Aquifer System of Sierra de las Nieves (Southern Spain)

Researchers have been troubled with finding a reliable technique for estimating groundwater recharge in carbonate aquifers. Many studies have recognized the importance of preferential flow in karst systems. Despite this evidence, preferential infiltration has no effect on estimating recharge with a classical soil water budget. The present research aims to determine the significance of the correct location of preferential infiltration areas in estimating recharge with the APLIS method. The study was carried out in Sierra de las Nieves aquifer (Southern Spain). The effect of correctly estimating the preferential infiltration areas is studied through different levels of complexity in the geomorphological information: (i) a classical geomorphologic map with pothole databases available, (ii) a reviewed geomorphologic map, and (iii) fracture density and epikarst cartography obtained with field work and remote sensing interpretation. The obtained results provided a mean difference of more than 10 % of recharge in the whole aquifer, and up to 20 % when the pixel scale is considered at.