Erosividade das chuvas e perdas de solo na bacia Apodi-Mossoró no período de 1987-2018

Abstract

This study addresses the interaction between climatic variability, anthropogenic pressures, and their impacts on soil loss in the Apodi-Mossoró River basin, a typical scenario in the Brazilian semiarid region, during the period from 1987 to 2018. The synergy of these factors threatens ecosystems, reduces agricultural productivity, and underscores the need for sustainable management actions. Rainfall erosivity plays a crucial role in this context, as intense rains disaggregate the soil, carrying away particles and essential nutrients, thereby impairing fertility and productive capacity. The study employed the SWAT model to simulate soil and nutrient losses, which are essential for evaluating and proposing management and conservation strategies. The space-time analysis revealed critical areas, such as Upanema and Felipe Guerra, with high erosivity, indicating the need for prioritized soil conservation measures. The decrease in extreme rainfall, evidenced by negative trends in R95p values, requires a more in-depth assessment of the relationship between erosivity and sediment load. The calibration of flow in the SWAT model for the streamflow gauging stations Governador Dix-Sep Rosado and Mossoró adequately represented the overall behavior of the basin, despite discrepancies in some events. However, the discrepancy in the estimated flow, highlighted by a percentage error of 29.2%, emphasizes the need to review the model to improve the accuracy of hydrological simulations. The observed precipitation of 745 mm plays a central role in the basin's dynamics. The observed average soil loss of 3.64 tons per hectare per year indicates significant erosion, emphasizing the importance of soil management and conservation practices. However, the discrepancy in the estimated flow underscores the need for refinement in the SWAT model. It can be concluded that climatic variability and land use changes have sensitive impacts on soil and nutrient losses in the Apodi-Mossoró River basin during the analyzed period.