Recharge sources and hydrogeological effects of irrigation and an influent river identified by stable isotopes in the Motril-Salobreña aquifer (Southern Spain) (pages 2261–2274)

摘要

Measurement of the stable isotopes oxygen-18 and deuterium in water is an important tool to characterize aquifer rechargensources. In the driest areas of the Mediterranean, this application is of special interest due to the scarcity of water andnthe resulting common incidence of human influence on natural hydrological systems. The Motril-Salobre˜na detrital aquifern(southern Spain) is a clear example of such an impact as inhabitants have designed irrigation systems and a dam was recentlynbuilt across the course of the Guadalfeo River, which feeds the aquifer. The sampling of (river or ground) water has allowed thendetermination of stable isotope contents (oxygen-18 and deuterium), both temporally and spatially, and the relative importancenof the main recharge sources in certain sectors. In addition, we were able to infer seasonal trends and to improve existingnknowledge of the main flow paths and the position of a seasonal groundwater divide. Data analysis shows evaporation playsna minor role (despite the high temperatures in the zone), scarce rainwater influence, and the overwhelming contribution ofnrecharge from the Guadalfeo River and from the carbonate aquifer (Escalate aquifer) in contact with the Motril-Salobre˜nanaquifer. Irrigation return flow during the summer months comprises the main recharge due to the significant volumes ofnwater that infiltrate. The construction of the dam will almost certainly entail great changes in the current dynamics of thenhydrogeology of the Motril-Salobre˜na aquifer; therefore, knowledge of its behaviour is crucial in order to carry out sustainablenuse of its groundwater resources. Copyright  2011 John Wiley & Sons, Ltd.