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

S. CRESPO; MARÍA LAURA GOMEZ; JULIETA N. ARANIBAR; MARGIT SCHWIKOWSKI; RICARDO VILLALBA; SABINA BRUETSCH

Uspallata, Mendoza

Encuentro; Documenting, understanding, and proyecting changes in the hydrological cycle in the American Cordillera; 2013

IAI

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 andaltitude differences in recharge areas, provide chemical and isotope signatures to the water from different basin areas, allowing the identification of the geographic and geologic origin of riverwater. In these latitudes (~33oS), the Andes consist of two main mountain ranges with a North-South direction, the Cordillera Frontal and Cordillera Principal. These receive differing relative contributions of precipitation from Atlantic and Pacific moisture sources from east to west. This study will allow us to identify the differing contribution of 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, temperatures and moisture sources (Atlantic and/or Pacific oceans) for precipitation.