Investigando os impactos do clima futuro e do uso e cobertura da terra nos processos hidrossedimentológicos em uma bacia do bioma Caatinga

Abstract

Soil erosion by water is a natural process, but it can be intensified by human action such as when removing the vegetation cover, which causes a reduction in infiltration and an increase in surface runoff. Studies focused on this topic are of great relevance for the preservation of soils and water resources, especially in basins located in the Caatinga biome in Brazil, which are characterized by recurrent droughts and extreme events, which affect millions of people every year. Thus, investigating the impacts of future climate as well as the use and cover on hydro sedimentological processes in this biome are fundamental for managing the region's water resources. One of the ways to study future hydro sedimentological processes is through the coupling between simulated time series of precipitation and temperature data in a hydrological model. In the present study, the hydro sedimentological model Soil and Water Assessment Tools was used to assess the processes of surface runoff and sediment production in two different periods in the Sumé Representative Basin, which has a total area of 146.5 km² and is located in the semi-arid region of Paraíba. For the occurrence of modeling was necessary to use physical data of region, such as weather data, data about the use of land, soil type and digital elevation model; As a result, modeling was carried out for different realities (based on land use in the years 1984 and 2019) and different future land use scenarios (regular, optimistic and pessimistic) and future climate scenarios based on different levels of emissions of greenhouse gases (RCP 4.5 and RCP 8.5). To calibrate the model, SWAT-CUP software and a daily flow period, from March 27, 1977 to January 13, 1978 of the Gangorra sub-basin were used. A calibration result considered acceptable was obtained with the Nash-Sutcliffe’s coefficient of efficiency (COE) of 0.59 and the R² of 0.65. The results showed how much vegetation cover reduces surface runoff and sediment production in the different scenarios studied and how much these variables are influenced by land use, soil type and climate.