The Salento Peninsula with a surface area of 3400 km2, is a coastal karstic aquifer with a regional flow system. The coastal karst aquifer of Salento belongs to the Apulia carbonate platform (a succession of Jurassic–Cretaceous carbonate rocks from about 3 to 5 km thick), the upper part of the Apulia foreland emerged at the end of Cretaceous. Cretaceous limestone and dolomitic limestone form the geological basement, which outcrops in large areas with patchy covers of clay, sand, and calcarenite of Miocene to Pleistocene.
The karst surface shows karst plains, fracture zones, dolines, sinkholes and hundreds of endorheic basins. The whole of subsurface features causes high anisotropy of the hydraulic conductivity, which is high at the regional scale (hydraulic gradient about 0.02 ‰).
Freshwater floats on saltwater as a lens and discharges to the sea through brackish coastal and submarine springs. The scale of the flow system is regional and the piezometric surface reaches max values of 4 m amsl in the NW and SE sectors of the Peninsula. Precipitation is 638 mm/year, while the yearly average (over 50 years) of effective infiltration is 132 mm/year. Freshwater salt content varies between 0.2 and 0.5 g/L.
|Aquifer extension||3807 km²|
|Mean Annual Recharge||739 million m³/y|
|Total exploitation||445 million m³/y (average 1985-2000)|
|Land use (referred to part of the aquifer, the Lecce Province, that extends for 2799 km²)||
The groundwater salinization emerged in Salento, and with more evidence in the Lecce province, in the 1960s, when the exploitation of groundwater for agricultural purposes started to grow. Thereafter the salinization has relentlessly advanced because of the continuous increase of groundwater exploitation for agriculture, but also for urban growth and tourism. The agriculture and tourism have a high impact also on the fragmentation and the health of the 44 protected areas (35 sites of community interest, 2 special protected areas, 5 regional natural parks, 1 marine protected area, 1 regional reserve), many of which are groundwater-dependent ecosystems.