Karst springs along the Murge Adriatic coastline (Apulia, southern Italy)

Apulia is an almost entirely karst region in southern Italy, being characterized by several thousand-meter-thick Mesozoic carbonate succession, diffusely outcropping in the Gargano (north), Murge (center) and Salento (south) areas. It is surrounded by Adriatic and Ionian seas for most of its extent, with over 850 km of coasts and a significant, but not yet quantified, amount of freshwater gushing out along coastline or offshore. Mainly the coastal sectors of Apulian aquifers are then strongly exposed to seawater intrusion phenomena for both natural causes, due to the presence of fractures and karst forms, or human induced causes, such as sea level rise and over-exploitation. Focusing on Murge area, the groundwater discharge to the sea typically occurs in a diffuse way, through groundwater fractures; locally it is concentrated where karst conduits reach the sea or coastal zones, that is where the hydraulic function of karst conduits for freshwater transfer prevails. Many thermal anomalies have been detected in the past thanks to multi-spectral aerial surveys (visible, infrared and thermal infrared), due to differences in temperatures between spring water and seawater. In this work, we describe the Adriatic coast between the city of Monopoli and the Torre Canne place: in this area, the main known springs show average discharges ranging from 300-400 to 600 l/s, with maximum peaks slightly lower than 1.200 l/s. This is the coastal stretch where most of the thermal anomalies have been recognized as submarine springs. In addition, at several other locations, in the immediate proximity and along the coasts, there are proofs of water emergencies. To provide a contribution aimed at improving the knowledge about hydrogeology of this sector of Murge, we present new data on the karst coastal springs and a first attempt to link them with those coming out from the main inland recharge area.