Characterisation of Ionian-Lucanian coastal plain aquifer (Italy)

The considered study area is, subjected to a semiarid climate, lying in Southern Italy. Data coming from 1130 boreholes have been considered to define the geological and hydrogeological set-up of the study area and for estimating the groundwater use and the salt-related groundwater quality degradation. The aquifers are constituted by marine terraces deposits, river valley alluvial deposits and alluvial and coastal deposits. Groundwater flow is mainly unconfined in the marine terraces and in the river valleys while it becomes mostly confined in the coastal plain aquifer. Being the direct natural recharge extremely low, the recharge of this coastal aquifer is mainly guaranteed by the discharge from upward aquifers and from the river leakage. Two dominant types of groundwater have been distinguished: the HCO3-Ca type (in the marine terraces and in the alluvial deposits) and SO4-Cl-Na type (in the coastal plain deposits). The variability of major ions contents is related to many factors such as the different lithologies of the aquifers, the seawater intrusion, the mixing with river water and the impact of intensive farming. As regards the presence of the seawater intrusion in the study area, the analysis of the concentration maps of TDS, groundwater electrical conductivity and of the ions present in seawater, generally indicate that seawater contamination is relevant along a strip of land stretching for 2.5-3 km from the coastline inwards. The new acquired knowledge permits to delineate scenarios useful for an optimization of the groundwater resources tapping and for pursuing the safeguard of them.