Variaciones de salinidad en Las Albuferas de Adra (Almería)

Abstract

Water level and water salinity (expressed as electrical conductivity, EC) of the two Adra lagoons -"Honda" and "Nueva"- have been periodically recorded during the years 7999 and 2000. EC was also measured in a number of open wells and shallow piezometers around the lagoons. Data obtained have been compared with previous EC measures, dating back to 1 984. Salinity evolution in the lagoons is mainly conditioned by evaporation and rain-induced dillution effects. Evaporative concentration is comparatively less intense in the Nueva lagoon, due to its higher water storage. Dillution is more effective in the Honda lagoon because of the Incidence of esporadic runoff which doesn't affect to the Nueva. Then, the range in EC variations is higher in the Honda than in the Nueva, and the seasonal evolution can show different trends during the normal hydroperiod. As an average, the salinity in both lagoons is fairly similar to that of the shallow groundwater in the sector of the aquifer where the lakes are located (mean values of 3-7 mS/cm of EC). A trend has been Identified of increasing salinity with the vicinity of the sea shore. This is in agreement with geophysical data which suggest the existence of brackish connate waters in recent littoral sediments below the lagoons