Stable isotopes applications for the assessment of the hydrological cycle process: precipitation and small catchments in São Paulo State, BR

Abstract

Stable isotopes (´2H e ´18O) constitute an excellent tracer for water movement through the water cycle, and has been employed as auxiliary tolls to interpreting about climatic controls over precipitation, as well as to determine the origin of water in catchments. In tropical zones, the climatic key drivers over isotopic composition of the precipitation remains a controversial subject in the scientific community. Some researchers have proposed the influence of local process over precipitations while other researchers have proposed the importance of process in regional scale, as Rayleigh distillation. Stable isotopes also have been employed as complementary tolls to understand hydrological process in small catchments, improving the understanding of these mechanisms and processes, to estimate the Mean Transit Time (MTT), to identify the involved in the origin of water in streams, as well as to calibrate and/or validate hydrological models through the estimation of specific hydrological parameters. Based on the water isotopic transformations through hydrological cycle, this project has two main purpose: evaluate the isotopic variations in the precipitation in selected points along the São Paulo state, in order to understand the climatic controlling factors over the precipitation isotopic composition, contributing to improve the knowledge about the precipitation in tropical regions. The second objective is to determine the MTT in small catchments located at Rio Jacaré Pepira watershed, based on the isotopic variations groundwater and superficial water, contributing to quantify the water balance. (AU)