Hydrostratigraphic Framework and Physicochemical Status of Groundwater in the Gioia Tauro Coastal Plain (Calabria—Southern Italy)

Abstract

In this study, we analysed the Gioia Tauro Plain (Tyrrhenian coast, southern Italy) in terms of hydrostratigraphy and the physicochemical status of groundwater. We investigated the hydrostratigraphic framework of the area identifying a deep aquifer (made by late Miocene succession), an aquitard (consisting of Pliocene clayey and silty deposits) and a shallow aquifer (including Late Pleistocene and Holocene marine and alluvial sediments) using subsoil data (boreholes and geophysics). Our reconstruction showed that the structural geology controls the spatial pattern of the aquitard top and the shallow aquifer thickness. Furthermore, we evaluated the hydraulic conductivity for the shallow aquifer using an empirical method, calibrated by slug tests, obtaining values ranging from 10−4 to 10−5 m/s with a maximum of 10−3 m/s located close to inland dune fields. The piezometric level of the shallow aquifer recorded a significant drop between the 1970s and 2021 (−35 m as the worst value). It is the effect of climate and soil use changes, the latter being the increased water demand for kiwi cultivation. Despite the overexploitation of the shallow aquifer, shallow groundwater is fresh (736 µS/cm as mean electrical conductivity) except for a narrow coastal area where the electrical conductivity is more than 1500 µS/cm, which can be due to the seawater intrusion. What was more complex was the physicochemical status of the deep aquifer characterised by high temperature (up to 25.8 °C) and electrical conductivity up to 10,520 µS/cm along the northern and southern plain boundaries marked by tectonic structures. This issue suggested the dominant role of the local fault system that is likely affecting the deep groundwater flow and its chemical evolution.

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)

“…The seasonal trend of ground displacements (shown by the time series) that are related to piezometric level fluctuations is in agreement with observations made by other authors for test sites located, for example, in the United States [80,81], Mexico [82], and Italy [70]. Furthermore, considering that the shallow aquifer mainly includes coarsegrained sediments with high permeability [41], the seasonal trend of ground deformations reflects the compaction and dilation of the aquifer system in response to the seasonal fluctuations of the groundwater level linked to natural recharge and exploitation.…”

“…We analysed the spatial pattern of the vertical velocity depending on the shallow aquifer thickness. The plain is characterised by a shallow and unconfined aquifer consisting of Late Pleistocene and Holocene marine and alluvial sediments, an aquitard made up of Pliocene clayey and silty rhythmites, and a deep aquifer made up of late Miocene deposits [41].…”

“…The Gioia Tauro groundwater system consists of three main hydrogeological units. From top to bottom, these include (i) the shallow and unconfined aquifer that includes all the Quaternary sediments; (ii) the aquitard, made up of the Pliocene clayey and silty deposits of the Trubi Formation; (iii) the deep aquifer, consisting of Late Miocene clastic deposits and limestone [41]. The plain is characterised by a mean precipitation rate of about 1000 mm [42].…”

Groundwater Resources Management: Reconciling Demand, High Quality Resources and Sustainability

“…The complexity of the hydrostratigraphic framework could be a key feature to be clarified for groundwater management purposes, especially in the case of a coastal plane, as shown by Cianflone et al [12]. They define the hydrostratigraphic framework and physicochemical status of the Gioia Tauro Plain, Tyrrhenian coast, southern Italy.…”

“…The first theme concerns modelling efforts supporting the sustainable management of aquifer systems [8,9]. The second theme is focused on groundwater vulnerability assessments against external pollution, focusing on groundwater quality management [10][11][12][13]. The third theme explores the potentiality of geophysics tools supporting groundwater management in the case of coastal aquifers [14][15][16].…”