Impacts of changes in land cover and land use on the hydrological cycle of the Tapuio River sub-basin/AL

Abstract

The climate forecasts in the IPCC latest assessment report (AR6) point to rising global temperatures. The northeastern semi-arid region is characterized by extreme droughts and intense rainfall, indicating a scenario of climatic extremes. Climate change directly affects the hydrological cycle because it modifies the entire dynamics of the system, causing major environmental impacts in river basins. These impacts are intensified by changes in land cover, favoring modifications to landscapes through alternative land uses. In this sense, the study arises from the need to analyze how changes in land use and cover can affect the dynamics of the hydrological cycle in the Tapuio river sub-basin from a space-time perspective. The region was chosen based on the observation of data collected during the IV scientific expedition to the Lower São Francisco. For the study, a simulation was carried out using the SWAT tool with land use and land cover data (2000 and 2020), soil type, slope and climate data (precipitation and temperature). The simulation generated the delimitation of 24 microbasins and 553 HRUs for the year 2000 and 662 for the year 2020, as well as visualizing the main parameters of the hydrological cycle. It was found that there was a significant increase in surface runoff of 4%, sediment production of 9% and a reduction in potential evapotranspiration of 0.42%. The conclusive analyses indicate that the conversion of the savannah formation use classes for pasture and temporary crops would have been the main cause of the changes in the hydrological cycle in the Tapuio river sub-basin.