Caracterização climática da bacia hidrográfica do Rio Cuiabá e simulações de cenários futuros

Abstract

It is expected that climate change will alter the future climate, causing significant changes in the hydrological cycle, influencing the intensity and frequency with which extreme events will occur and thus affecting human natural systems, especially food production and water supply. In the present study, the objective is to identify the current climate of the Upper and Middle Cuiabá River Basin through the space-time variation of climate variables as well as future climate changes in the BHC. Historical and future rainfall data from the CMIP6 CNRM-ESM2-1 model were analyzed for the periods 2021-2040, 2041-2060, 2061-2080 and 2081-2100, in the SSP126 scenario, spatial resolution of ~1km. Historical data on average, maximum and minimum air temperature, precipitation, water vapor pressure, global solar radiation and wind speed for the period 1970-2000 at the same spatial resolution. The space-time variation of current and future climate variables were characterized by mapping and statistical analyses, considering monthly variation, dry and rainy seasons as well as annual totals. Data from MapBiomas referring to land use and occupation were analyzed and revealed that between 1985 and 2021 the main changes that occurred in the BHC were the replacement of natural areas by anthropized areas, especially for pasture and agriculture. The climatic variables showed characteristic seasonality and variation within the geographical region of the BHC, with the highest values in the rainy season and the lowest in the dry season. According to the climate classification of Thornthwaite and Mather (1955), the climate varies from: a small area in the extreme northeast of the basin Humid B3, Humid B2, Humid B1, Sub-humid C2 and a small area in the northwest region classified as Sub-humid section C1. Future projections indicate that there may be an increase in air temperatures by at least 2°C by the end of the 21st century. Changes between the duration of the dry and rainy periods were identified in all projections, as well as a future process of reduction in accumulated annual precipitation, with the northwest/southeast region being the most vulnerable, implying the disappearance of the most humid climate classes and the increase in extension of the drier classes.