title: Simulation of future groundwater recharge using a climate model ensemble and SAR-image based soil parameter distributions - A case study in an intensively-used Mediterranean catchment.
abstract: We used observed climate data, an ensemble of four GCM-RCM combinations (global and regional climate models) and the water balance model mGROWA to estimate present and future groundwater recharge for the intensively-used Thau lagoon catchment in southern France. In addition to a highly resolved soil map, soil moisture distributions obtained from SAR-images (Synthetic Aperture Radar) were used to derive the spatial distribution of soil parameters covering the full simulation domain. Doing so helped us to assess the impact of different soil parameter sources on the modelled groundwater recharge levels. Groundwater recharge was simulated in monthly time steps using the ensemble approach and analysed in its spatial and temporal variability. The soil parameters originating from both sources led to very similar groundwater recharge rates, proving that soil parameters derived from SAR images may replace traditionally used soil maps in regions where soil maps are sparse or missing. Additionally, we showed that the variance in different GCM-RCMs influences the projected magnitude of future groundwater recharge change significantly more than the variance in the soil parameter distributions derived from the two different sources. For the period between 1950 and 2100, climate change impacts based on the climate model ensemble indicated that overall groundwater recharge will possibly show a low to moderate decrease in the Thau catchment. However, as no clear trend resulted from the ensemble simulations, reliable recommendations for adapting the regional groundwater management to changed available groundwater volumes could not be derived.
authors.affiliation: Forschungszentrum Jülich GmbH, Institut für Bio - und Geowissenschaften - Agrosphäre (IBG-3), 52425 Jülich, Germany. Electronic address: f.herrmann@fz-juelich.de.
authors.forename: Frank
authors.initials: F
authors.lastname: Herrmann
authors.affiliation: IRSTEA, UMR TETIS, Montpellier, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Baghdadi
authors.affiliation: Christian-Albrechts-Universität zu Kiel, Kiel, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Blaschek
authors.affiliation: Dipartimento di Ingegneria Civile, Ambientale e Architettura, Università di Cagliari, Cagliari, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Deidda
authors.affiliation: Christian-Albrechts-Universität zu Kiel, Kiel, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Duttmann
authors.affiliation: Université François Rabelais, UMR CNRS Citeres, Tours, France; Université d'Angers, UMR CNRS LETG, Angers, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: La Jeunesse
authors.affiliation: Université Catholique de Louvain, Louvain-la-Neuve, Belgium.
authors.forename: Haykel
authors.initials: H
authors.lastname: Sellami
authors.affiliation: Forschungszentrum Jülich GmbH, Institut für Bio - und Geowissenschaften - Agrosphäre (IBG-3), 52425 Jülich, Germany.
authors.forename: Harry
authors.initials: H
authors.lastname: Vereecken
authors.affiliation: Forschungszentrum Jülich GmbH, Institut für Bio - und Geowissenschaften - Agrosphäre (IBG-3), 52425 Jülich, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Wendland
keywords: Climate change; Groundwater recharge; Mediterranean; Synthetic Aperture Radar; mGROWA