Due to the large number of previous studies realized in the coastal aquifer Motril-Salobreña (Granada, Spain) exhaustive chemical control reveals the existence of a maximun relative of salinity in the groundwater in the central sector, specifically in one well located more than 1500 meters far the coastline. Water is eventually pumped from this well for supplying Motril town needs.
First reports and publications point to the existence of a possible mixture of a freshwater and seawater, so a deeper study have been carried out into this issue. A three boreholes monitoring station was stablished along a perpendicular profile regarding the coastline, but also following groundwater flow lines. A monthly physicochemical control was done in each one of these point in different deeps during the 2014/2015 hydrological year. Mayor, minor and trace ions were determined in all samples, but in some of them the isotopes ratios δ 15Nnitrate, δ 18Onitrate, δ 11B, δ 34Ssulfate, δ 18Osulfate y 87Sr/ 86Sr were analyzed.
The results confirm that the anomaly is limited to the north of profile marked by the wells in this study, but they are not conclusive regarding the origin of this relatively high mineralization of water. However, results allow to discard present and old water mixture (connate or trapped water), as well as gypsum dissolution (due to the possible presence of this rock in the bottom of the aquifer), as sources of salinity.