Salinity and Temperature Variations near the Freshwater-Saltwater Interface in Coastal Aquifers Induced by Ocean Tides and Changes in Recharge
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Blanco Coronas, Ángela María; Calvache Quesada, María Luisa; López Chicano, Manuel; Martín Montañés, Crisanto; Jiménez Sánchez, Jorge; Duque Calvache, CarlosEditorial
MDPI
Materia
Geothermal gradient Saltwater intrusion Temperature fluctuations Tidal influence Groundwater recharge Climate change
Date
2022-09-09Referencia bibliográfica
Blanco-Coronas, A.M... [et al.]. Salinity and Temperature Variations near the Freshwater-Saltwater Interface in Coastal Aquifers Induced by Ocean Tides and Changes in Recharge. Water 2022, 14, 2807. [https://doi.org/10.3390/w14182807]
Sponsorship
Spanish Government CGL2016-77503-R IGME 10-1E-1284 IGME 15-CE3391; European Regional Development Fund (ERDF) of the European Union (EU); Next-Generation EU MZSA03; Junta de Andalucia RNM-369Abstract
The temperature distribution of shallow sectors of coastal aquifers are highly influenced
by the atmospheric temperature and recharge. However, geothermal heat or vertical fluxes due
to the presence of the saline wedge have more influence at deeper locations. In this study, using
numerical models that account for variable density, periodic oscillations of temperature have been
detected, and their origin has been attributed to the influence exerted by recharge and tides. The
combined analysis of field data and numerical models showed that the alternation of dry and wet
periods modifies heat distribution in deep zones (>100 m) of the aquifer. Oscillations with diurnal and
semidiurnal frequencies have been detected for groundwater temperature, but they show differences
in terms of amplitudes and delay with electrical conductivity (EC). The main driver of the temperature
oscillations is the forward and backward displacement of the freshwater–saltwater interface, and
the associated thermal plume generated by the upward flow from the aquifer basement. These
oscillations are amplified at the interfaces between layers with different hydraulic conductivity, where
thermal contours are affected by refraction.