Drought index as indicator of salinization of the Salento Aquifer (Southern Italy)

Salento peninsula (Southern Italy) hosts a coastal carbonate and karst aquifer. The semi-arid climate is favourable to human settlement and the development of tourism and agricultural activities, which involve high water demand and groundwater exploitation rates, in turn causing groundwater depletion and salinization. In the last decades these issues worsened because of the increased frequency of droughts, which emerges from the analysis of Standardized Precipitation Index (SPI), calculated during 1949-2011 on the base of monthly precipitation. Groundwater level series and chloride concentrations, collected over the extreme drought period 1989-1990, allow a qualitative assessment of groundwater behaviour, highlighting the concurrent groundwater drought and salinization.