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Rainfall is the major contribution for groundwater recharge in arid and semiarid climates, therefore a key factor in water resources estimation. This work presents the results of an in-depth study in Doñana National Park (DNP) concerning groundwater recharge behavior over a long period (1975-2016). The spatio-temporal kriging algorithm was used as a supportive tool to improve the reconstruction of the spatio-temporal rainfall variability. One of the main findings was that monthly recharge estimations range between 21% and 91% of the maximum rainfall, being overestimated in areas that also demonstrate spatial heterogeneity in rainfall distribution. In the light of these results, for water management purposes in the Mediterranean area, rainfall spatio-temporal scale is a critical aspect and it must be taken into account in groundwater reservoir allocation. Moreover, it is highlighted that local studies of rainfall and recharge, in an area of high ecological fragility, are essential to developing management strategies that prevent climate change effects and guarantee optimal conditions for groundwater resources in the future., Área de Geología Ambiental y Geomatemáticas, Instituto Geológico y Minero de España, España, Facultad de Ciencias Geológicas, Universidad Complutense de Madrid, España, Departamento de Sistemas Físicos, Químicos y Naturales, Universidad Pablo de Olavide, España

[EN] Groundwater is one of the most important hydric resources of the Spain territory. Nevertheless, heavy groundwater withdrawal generates severe consequences, being land subsidence one of them. The Interferometric Synthetic Aperture Radar (InSAR) technique have been recently exploited to detect and monitor aquifer related deformations. In the present work, relationship between piezometric levels drawdowns and land subsidence has been studied for the higher withdrawals areas within Almonte-Marismas aquifer system (which holds the Doñana Natural Space). Four datasets of radar satellite images, obtained from Sentine-1 satellite, have been processed using the InSAR technique in the period 2014 - 2020. Results show that in some of these areas, like those surrounding El Rocío and Matalascañas villages, the correlation between these two variables is high., [ES] El agua subterránea es uno de los recursos hídricos más importantes en el territorio español. La gran cantidad de agua que se retira de ellos puede tener graves consecuencias, entre las que destaca, en algunos acuíferos, la subsidencia del terreno. La técnica de interferometría radar (InSAR), ha sido desarrollada en las últimas décadas para detectar y monitorear las deformaciones relacionadas con los acuíferos. En este trabajo se estudia la posible relación existente entre la variación de los niveles piezométricos y el movimiento del terreno en zonas con grandes extracciones del acuífero Almonte-Marismas (sobre el que se ubica el Espacio Natural de Doñana). Para ello, se han analizado los datos de deformación del terreno obtenidos del satélite Sentinel-1 en el periodo 2014-2020 Los resultados muestran que, en alguna de estas zonas, como las cercanas a las poblaciones de El Rocío y Matalascañas, la correlación entre ambas variables es alta., Este trabajo es parte de las actividades subvencionadas dentro del Sistema Nacional de Garantía Juvenil (PEJ2018-002477), financiado por la Fundación Tripartita para la Formación en el Empleo, la iniciativa YEI (Youth Employment Initiative) y el Fondo Social Europeo (FSE). Los datos Copernicus Sentinel-1 se obtuvieron y procesaron en la plataforma GEP de la ESA en el marco del GEP Early Adopters Programme. Agradecemos al IGME y a la CHG por proporcionar los datos de piezometría, así como a la Junta de Andalucía por suministrar los datos meteorológicos.

The study presents daily values of inward and outward vapor flux crossing the soil-atmosphere boundary in dependence on meteorological parameters and soil moisture. Measurements of vapor flux, soil moisture and meteorological parameters were evaluated during days without rainfall between 2015 and 2019. Vapor flux data were obtained at 1 min intervals by a precision lysimeter installed in the Doñana National Park, southwest Spain. Meteorological data were measured on-site at 10-min intervals, including temperature, relative humidity, wind velocity and net radiation. After manual and automatic noise elimination of the lysimeter data, time series of a summer and winter period were generated for selected relevant parameters. Furthermore, daily cumulative data of inward and outward vapor flux were calculated for the entire period and analyzed for their control by meteorological parameters and soil moisture. Results show moderate correlations of daily outward vapor flux on the diurnal amplitudes of temperature and humidity whereas daily inward vapor indicates moderate correlations with temperature and soil moisture. A correction coefficient for potential evaporation to estimate actual evaporation was determined based on soil moisture and air temperature., Unidad de Sevilla, Instituto Geológico y Minero de España, España, Departament d'Enginyeria Civil i Ambiental, Universitat Politècnica de Catalunya, España, Grupo de Hidrogeología, Universitat Politècnica de Catalunya, España, Grupo de Hidrogeología, Consejo Superior de Investigaciones Científicas, España

Oxygen measurements of soil air were carried out to determine daily variations and seasonality of oxygen in soil air and their dependence on ambient parameters such as groundwater chemistry, hydrodynamics and physico-chemical sediment characteristics. Two field sites in the Donana National Park were equipped with fibre-optic oxygen- and temperature sensors down to 6 m below the groundsurface, and oxygen was sampled from November 2010 until July 2012. One of the sites lies in the saltmarshes and the other in the dune belt, so providing coverage of contrasting hydrogeochemical conditions. Sediments from both locations were analyzed for physico-chemical parameters. Furthermore, groundwater levels were measured and samples taken for hydrochemical analysis. Soil gas in the salt marsh ranged from anaerobic conditions during the wet season to aerobic conditions in the dry period, which is related to the anaerobic groundwater and the high amount of electron donors in the sediment. The location in the dune belt yielded aerobic conditions throughout the year due to the minor amount of organic carbon in the sediments and the high oxygen content of the groundwater. The oxygen time series exhibits daily oscillations related to microbiological activity in the root zone of the Juniperus Sabina tree.