<strong>Using thermal modelling to characterize the groundwater discharge towards a permanent pond (Do&ntilde;ana National Park, Spain)</strong>

Abstract

Abstract:We have modeled groundwater inputs to Santa Olalla pond, the only permanent pond of Doñana Biological Reserve (Andalusia, Southern Spain) by means of the application of a thermal modelling methodology. During the study period (February-May 2017) a chain of thermistors obtained hourly temperature data from the surface water and the groundwater in the sediment below. In addition, water level in the pond and in the aquifer near the shores was also monitored at similar time rates. Results showed that a net groundwater discharge occurs heterogeneously through the pond's bed. The comparison of these outcomes with previous studies made in the pond, such as hydrological water balances, is coherent and strengthens the existing hydrological knowledge of this water body. Finally, it has been detected that the pond is strongly influenced by the alterations of the sand aquifer, even if such alterations are produced away from the pond and at high depths. The effects of groundwater extractions for urban supply of a nearby coastal resort are immediately affecting the evolution of the water level, although this effect is not necessarily translated to water level depletion.