Geoprocessing and climate simulation applied to transposition between watershed in São Paulo state, Brazil

Abstract

The water crisis that hit the Southeast region of Brazil in the years 2014 and 2015 was generated by an atmospheric blocking associated with a high-pressure zone that persisted for more than 45 days, causing a drastic decrease in precipitation rates throughout the region. This fact had a major impact on the municipality of São Paulo, causing a crisis of lack of water availability. To face the problem of water shortages for the São Paulo Metropolitan Region, the water transposition from Paraíba do Sul River watershed to the Cantareira System was proposed to mitigate the referred crisis and other future ones. Therefore, to investigate the feasibility of the proposed solution becomes very important, given the changes in the rainfall profile generated by global climate changes that affect the climatic element precipitation. Geoprocessing techniques were associated with future rainfall data simulated by the HadCM3/Eta model using SRES (Special Report Scenarios Emission) A1B of IPCC (Intergovernmental Panel on Climate Change) to investigate the long-term feasibility of this proposal. The results point to the possibility of the project’s unsustainability until the year 2040, since only 35% of the year’s transposition may occur, reducing to 30% if only considering the 2030s.

Future scenarios (2021-2050) of extreme precipitation events that trigger landslides – a case study of the Paraitinga River watershed, SP, Brazil

“…In the summer period there was a decrease in rainfall averages during all months, with decreases of -6.25%, -12.6% and -13.6% in December, January, and February, respectively (Figure 4). When analyzing rainfall between the past and future periods ( Figure 5) there was no significant change in the irregular distribution of precipitation in the Paraitinga Watershed, with the values demonstrating a high correlation between the analyzed periods, a similar result to that obtained by Silva and Simões (2014) and Silva et al (2020). Examining the rainfall by the simulated grid in the past period during the rainy season, the time of the year most favorable for the occurrence of landslides (Table 4), the location with the highest precipitation was P9 (1452.0mm) located in the extreme northeast of the region, in the regions of the Serra da Bocaina mountains and Serra do Mar mountains, which has a strong influence on orographic precipitation.…”