Ion and Isotope Chemistry as indicators of different geographic regions contributions to flow in the Mendoza River Basin, Central Andes of Argentina

SEBASTIAN CRESPO; GOMEZ LAURA; ARANIBAR JULIETA; SCHWIKOWSKI MARGIT; VILLALBA RICARDO; BRUETSCH SABINA

Uspallata

Encuentro; IAI CRN2047B Documenting,understanding and projecting changes in the hydrological cycle in the american Cordillera; 2013

Inter American Institute, IANIGLA-Conicet

Water from the Mendoza river, in the North of Mendoza province (Argentina) provides water for domestic use, irrigation, industry and hydroelectric energy generation. This water supply is dependent on snow and ice melt. We propose that precipitation systems, and also geology and altitude differences in recharge areas, provide ionic and isotopic signatures to the water from different basin areas, allowing the identification of the geographic and geologic origin of river water. In these latitudes (~33°S), the Andes consist in two main mountain ranges with a North-South direction, the Cordillera Frontal and the Cordillera Principal. These receive differing relative contributions of precipitation from Atlantic and Pacific moisture sources from East to West. This study allow us to identify the differing precipitation from the Cordillera Principal and Cordillera Frontal to the streams of the Mendoza river basin. We expected to find a characteristic stable isotope composition of the water originating in these geographic regions; based on their differences in altitude, temperature and moisture sources (Atlantic and/or Pacific oceans) for precipitation.