Spatiotemporal analysis of the influence of relief on rainfall trends in the central region of the State of São Paulo

Understanding the temporal and spatial behavior of precipitation in tropical areas is of extreme relevance, considering its impact on urban and rural dynamics, and, consequently, on strategic planning. With this in mind, the study aimed to analyze the trends of daily rainfall through rainfall indices for the central region of the State of São Paulo, in order to understand its spatial distribution, as well as to evaluate possible trends for this location, which is part of the well-known tropical dynamics (seasonally rainy/dry). Forty years of daily rainfall data were analyzed at 31 rain gauge stations, using rainfall indices from the Rclimdex and the detection of outliers for extreme rainfall events (46mm), and the Laplace test for trends. The results indicate a reduction in annual rainfall accumulations and an increase in episodes of extreme rainfall. Thus, annual rainfall tends to concentrate, as annual volumes are decreasing while daily accumulations are increasing. It was also noted that in episodes of extreme rainfall, there is a marked presence of the orographic effect, which influences rainfall values, resulting in a distinct pluviometric behavior for mountainous areas, compared to other areas where the relief is flatter.