Estimation of sediment production and soil loss in a water supply basin for the metropolitan region of São Paulo - Brazil

Abstract

The Jaguarí river basin has outstanding importance in the national scenario for being located between the largest industrial and population centers in the country and for the process that involves the management of its water resources. The main purpose of the basin's reservoirs is to supply water to the population of the metropolitan region of São Paulo, and before that, there are pressures and conflicts between the different actors interested in water resources, as well as creating protection policies, establishing the need for sustainable use conservation units, support environmental protection policies, resulting in proposals for nature conservation measures and promotion of the population's quality of life. Hydrological models represent an alternative to verify the impacts resulting from anthropic actions in water availability and production of sediments in large hydrographic basins. The models can simulate/indicate how changes in the environment are reflected in the hydro sedimentological balance of a basin. This study aims to assess soil loss in the Jaguari River basin using the Soil and Water Assessment Tool (SWAT) to determine quantity and quality of the sediment production, the loss of soil, and resulting impacts to the Jaguarí River basin. Calibration and validation were performed to verify the suitability of the model and the spatialization of the factors that make up the Modified Universal Soil Loss Equation (MUSLE). The SWAT model proved to be suitable for the simulation of sediments; although the basin does not present a large area with potential for erosion risk, conservation measures can be taken to effectively control soil loss in susceptible areas. The average soil loss in the basin was 1.71 Mg ha−1 year−1 and the simulated and observed Sediment Delivery Rate (SDR) was 5.5% and 4.7%, respectively.