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This research underlines the need to improve water management policies for areas linked to confined karstic aquifers subjected to intensive exploitation, and to develop additional efforts towards monitoring their subsidence evolution. We analyze subsidence related to intensive use of groundwater in a confined karstic aquifer, through the use of the InSAR technique, by the southern coast of Spain (Costa del Sol). Carbonates are overlain by an unconfined detritic aquifer with interlayered high transmissivity rocks, in connection with the Mediterranean Sea, where the water level is rather stable. Despite this, an accumulated deformation in the line-of-sight (LOS) direction greater than −100 mm was observed by means of the ERS-1/2 (1992–2000) and Envisat (2003–2009) satellite SAR sensors. During this period, the Costa del Sol experienced a major population increase due to the expansion of the tourism industry, with the consequent increase in groundwater exploitation. The maximum LOS displacement rates recorded during both time spans are respectively −6 mm/yr and −11 mm/yr, respectively. During the entire period, there was an accumulated descent of the confined water level of 140 m, and several fluctuations of more than 80 m correlating with the subsidence trend observed for the whole area. Main sedimentary depocenters (up to 800 m), revealed by gravity prospecting, partly coincide with areas of subsidence maxima; yet ground deformation is also influenced by other factors, the main ones being the fine-grained facies distribution and rapid urbanization due to high touristic pressure. © 2018 Elsevier B.V.

Knowledge of aquifer geometry is essential for efficient and sustainable groundwater management, particularly in carbonate aquifers due to uncertainties inherent to karstic systems. The geological structure and hydrogeological continuity of Los Chotos-Sazadilla-Los Nacimientos and La Serreta-Gante-Cabeza Montosa carbonate aquifers (Jaén; SE Spain) have been established through structural measurements, geophysical prospecting –magnetic, gravity and time-domain electromagnetics (TDEM)– and the study of piezometric levels. Yet the scarce hydrogeological data, the complexity of the tectonic structure and the presence of Plio-Quaternary rocks covering the highly permeable carbonate rocks make it difficult to establish a robust conceptual hydrogeological model of the aquifer. This study focuses on an area where hydrogeological disconnection between the two aquifers was traditionally assumed, given the diapiric emplacement of low permeable rocks between them. The new geophysical data demonstrate connection between aquifers that implies greater groundwater reserves than previously supposed. This field example supports the suitability of the combined use of electromagnetic methods with gravity and magnetic research that have been poorly combined up to recent times for hydrogeological studies., This work was financed by the Diputación Provincial de Jaén and through the project CGL-2010-21048, and the Junta de Andalucía group RNM148 and P09-RNM-5388.