Characterising rainfall regimes in relation to recharge of the Sierra de Gador-Campo de Dalias aquifer system (S-E Spain)

Elisabeth Frot,Albert Solé Benet,Bas Van Wesemael,Roland Souchez,Grégoire Vandenschrick

doi:10.4000/belgeo.16055

Abstract

This paper demonstrates the use of the deuterium excess parameter to distinguish between origin of precipitation in the Mediterranean basin. Isotope signatures in precipitation from the GNIP network around the Mediterranean basin and literature data are combined with isotopic data from aquifers in south east Spain to explain the typology of the precipitation events dominating recharge. Although precipitation from Atlantic origin (d-excess = 10‰) occurs more frequently in the western Mediterranean basin, the quantities in each event are generally moderate to low. Important rainfall events generally have Mediterranean origin (d-excess=15‰). The total precipitation in Gibraltar is a mixture between precipitation from both origins (d-excess in Gibraltar = 12.39‰). However, with increasing volume of the storms the Mediterranean character dominates. These heavier storms contribute mainly to recharge, as illustrated by the d-excess of 13.8‰ in deep groundwater of the Campo de Dalias (Almeria province). One of the challenges to meet ever-growing water demands is to increase recharge from events with a low return period yielding intermediate quantities per event, but forming the bulk of the annual precipitation.

Highlights

Electronic reference Elisabeth Frot, Bas van Wesemael, Grégoire Vandenschrick, Roland Souchez and Albert Solé Benet, « Characterising rainfall regimes in relation to recharge of the Sierra de Gador-Campo de Dalias aquifer system (S-E Spain) », Belgeo [Online], 2 | 2002, Online since 01 July 2002, connection on 19 April 2019
Deuterium excess as a parameter to reconstruct the origin of precipitation in the western Mediterranean
16 It was demonstrated that the deuterium excess of precipitation samples can be used as a parameter to distinguish between Atlantic and Mediterranean origin of individual events

Summary

Introduction

Electronic reference Elisabeth Frot, Bas van Wesemael, Grégoire Vandenschrick, Roland Souchez and Albert Solé Benet, « Characterising rainfall regimes in relation to recharge of the Sierra de Gador-Campo de Dalias aquifer system (S-E Spain) », Belgeo [Online], 2 | 2002, Online since 01 July 2002, connection on 19 April 2019. Underpinned by the existence of Atlantic and Mediterranean weather systems resulting in a clear distinction in isotopic signatures of the precipitation produced by these weather systems in the western part of the Mediterranean basin (Celle-Jeanton et al, 2001a; Lazaro et al, 2001). These isotopic studies directly link the isotopic signature of the precipitation to the prevailing weather conditions during the event. Most studies agree on the dominance of precipitation from Mediterranean origin This precipitation is often linked with large convective storms with a low return period locally referred to as «gotas frias» (AlonsoSarria et al, 2002). Many low intensity rainfall events have a Mediterranean origin (e.g. Cruz-San Julian et al, 1992) and, no information on the rainfall characteristics of individual events that favour recharge can be obtained

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