Spatial and Temporal Variability of Precipitation in the Tietê River Watershed: 1988 to 2017

Spatial and temporal variability of rainfall can lead to hydrological imbalances, causing social and economic impacts. Consequently, the study of precipitation variability is of utmost importance in various fields of knowledge, particularly in large hydrographic basins such as the Tietê River basin. One of the factors influencing spatial and temporal variability of precipitation is the occurrence of El Niño – Southern Oscillation (ENSO) events, which affect the temperature of the Pacific Ocean. This study aims to investigate the space-time variability of rainfall in the Tietê River basin between 1988 and 2017 and evaluate these variations in relation to ENSO events during this period. Utilizing public hydrological databases, 560 rainfall stations within the area of interest were analyzed through descriptive and geostatistical techniques. Subsequently, maps were generated using kriging. The results identified higher precipitation in the southeastern portion (near the coast) and lower precipitation to the west of the basin, highlighting that sub-basins do not necessarily exhibit analogous hydrological behavior. Temporal variability of rainfall across the basin was analyzed, revealing higher rainfall volumes in the years 1991, 1995, 2009, and 2015, and lower volumes in 1994, 2002, and 2014. Regarding the influence of ENSO events on basin rainfall, the data did not show a direct impact on the region as a whole or on individual sub-basins.