Groundwater Temperature as an Indicator of the Vulnerability of Karst Coastal Aquifers

Abstract

Coastal karst aquifers show a three-dimensional vulnerability, which consists of the whole of the “intrinsic vulnerability” and the “groundwater vulnerability to seawater intrusion”. The results of a study carried out in the Salento karst coastal aquifer (southern Italy) show that temperature, as well as being a reliable tracer of groundwater flow, is also an effective indicator of vulnerability in anisotropic media. The trend of isotherms related to a cross-section of the aquifer thermal field, combined with geological, geomorphological, and hydrogeological information, allows the role of faults and dolines in the mass transport from ground surface to be inferred. Isotherm trends may also give information on the permeability distribution along faults. A specific temperature value evidence the saltwater top, thus indicating the groundwater vulnerability to salinization.

A Modelling Approach for Assessing the Hydrogeological Equilibrium of the Karst, Coastal Aquifer of the Salento Peninsula (Southeastern Italy): Evaluating the Effects of a MAR Facility for Wastewater Reuse

“…Cotecchia et al [31] highlight three areas characterized by high head values along the NE-SW oriented line which roughly connects Otranto and a zone south of Gallipoli. A similar finding has been reported recently by Fidelibus and Pulido-Bosch [63]. This line corresponds to a major discontinuity feature, and the high head values detected would therefore have a structural cause and would generate drainage both towards the north and the south, determining a hydrogeological watershed.…”

A New Normalized Groundwater Age-Based Index for Quantitative Evaluation of the Vulnerability to Seawater Intrusion in Coastal Aquifers: Implications for Management and Risk Assessments

“…It is beyond the scope of this paper to review all these techniques. Others suggested temperature, a groundwater flow tracer, as a vulnerability indicator for salinization of coastal karst aquifers [39].…”

Drought Index as Indicator of Salinization of the Salento Aquifer (Southern Italy)

“…These elements constitute an interconnected discontinuity system, which determines a high anisotropy of the hydraulic conductivity, with a mean high permeability at regional scale. Freshwater, with a salt content varying between 0.2 and 0.5 g/L [16], floats on saltwater of marine origin as a lens because of different density; groundwater discharges through coastal springs (sub-aerial and submarine, concentrated and diffuse), with Total Dissolved Solids (TDS) varying between 3.5 and 20 g/L. Due to the presence of low permeability carbonate units and/or tectonics dislocation of the basement, saturated zone is often found under mean sea level.…”

“…Groundwater in the coastal aquifer of Salento (Puglia, Southern Italy) is highly vulnerable to salinization because of the structure of the aquifer, where discontinuities and karst forms are ways of fast and deep intrusion for seawater and saltwater [16]. In Salento, droughts may easily propagate their effects to the coastal aquifer, worsening qualitative and quantitative status of groundwater and causing cascade crisis [17].…”