Different Ground Subsidence Contributions Revealed by Integrated Discussion of Sentinel-1 Datasets, Well Discharge, Stratigraphical and Geomorphological Data: The Case of the Gioia Tauro Coastal Plain (Southern Italy)

Groundwater is the main water supply for agricultural and industrial needs in many coastal plains worldwide. Groundwater depletion often triggers land subsidence, which threatens manmade infrastructure and activities and aggravates other geohazards. We applied a multi-temporal interferometric synthetic aperture radar technique to Sentinel-1 datasets to detect ground motion in the Gioia Tauro plain (Calabria, Southern Italy) from 2018 to 2021. The InSAR data were analysed through the integrated use of groundwater head, stratigraphical and geomorphological data, and land use information to distinguish the potential subsidence divers. The results show that subsiding areas, with a mean rate of about 10 mm/yr, are in the middle of the plain, and their location is influenced by the spatial distribution of compressible sediments included in the shallow aquifer. Furthermore, the subsidence arrangement is spatially accordant with the main groundwater depression area, which can be ascribed to the ongoing and increasing water pumping for predominantly agricultural usage. We also observed that subsidence (up to 10 mm/yr) affects the western dock of the Gioia Tauro harbour, in front of which, in very shallow water, are two submarine canyon heads already affected by slides in the past.