Temperature distribution in coastal aquifers: Insights from groundwater modeling and field data

This study was supported by grant CGL2016-77503-R from the Ministry of Economy and Competitiveness (MINECO), cofounded by the European Regional Development Fund (ERDF) of the European Union (EU), and the RNM-369 research group of the regional government of Andalusia. The authors also thank the State Harbors (Ministry of Public Services, Government of Spain) for providing the sea temperature dataset. One of the authors conducted this work as part of the activities of the Aarhus University Centre for Water Technology, WATEC. Funding for open access charge: Universidad de Granada/CBUA.The temperature distribution in coastal aquifers is determined by the effect of different heat sources: surface water recharge, sea infiltration, and geothermal heat. In previous studies, the signal generated in groundwater by each source was individually studied, and in the case of geothermal heat, it was often not considered. This research is the first in considering all possible sources of heat in a coastal aquifer simultaneously by using a combination of field data and numerical modeling to present a reference model based on the characteristics of a real aquifer. The position of the freshwater-saltwater interface (FSI) and its effect on temperature distribution have been modeled considering variable-density flow, coupled heat and solute transport. This study broadens the theoretical knowledge of temperature distribution in coastal aquifers based on a sensitivity analysis of hydraulic and thermic parameters. Furthermore, a case study (the Motril-Salobreña aquifer) was modeled with field data calibration to test the applicability to real aquifers. The new insights gained through this study provide integrated knowledge of the temperature distribution in coastal areas and establish the basis for future research using heat as a tracer in seaside aquifers.Ministry of Economy and Competitiveness (MINECO) CGL2016-77503-RJunta de Andalucia RNM-369Universidad de Granada/CBU