Environmental isotope concepts of precipitation and surface water and groundwater in the Central Andes: A review

Abstract

A preliminary review of existing information on the isotopic composition of oxygen (δ18O) and hydrogen (δ2H) of the water molecule in the northern sector of the Chilean Andes, between 17°30´ S and 25°30´ S, is presented. During the austral summer, the winds from the east favour the arrival of Atlantic humidity, dominantly through the Amazonas Basin, which produces more than the 80% of the annual precipitation. The Central Andes cordillera acts as a barrier to the wet air from the south-eastern Atlantic and in the Chilean northern coast produces the driest climatic area of the Earth. What is known about isotopic hydrology is briefly reviewed. This knowledge has allowed answers to questions such as the origin of precipitation, the possible links between basins, and the detection of processes that modify water isotopy, such as evaporation and geothermal effects. It has been observed in the surface water, groundwater and rainfall of northern Chile, that there is an enrichment in heavy isotopes in the north-south direction, from the region of Arica and Parinacota to the Antofagasta region. Continuing the research on precipitation and surface and groundwater isotopy is essential to achieve sustainable management of water resources and to understand current climate conditions and the past and future variations.