Estimation of Erosion Rate in a Hydrographic Basin in a Deforestation Area in the Brazilian Amazon, Eastern Mato Grosso

Abstract

The central region of Brazil, particularly the state of Mato Grosso, has experienced substantial land-cover changes resulting from the conversion of forest areas to soybean and cotton cultivation. This expansion of agricultural land has intensified soil erosion and increased the potential for sediment loss within tropical river basins. This study aims to estimate soil loss in the Curisevo River Basin using the Universal Soil Loss Equation (USLE). The methodology involved developing a spatial database in the QGIS Geographic Information System (GIS), incorporating information on slope, soil characteristics, and land cover within the Curisevo River Basin. Rainfall erosivity was estimated using precipitation data obtained from the National Institute of Meteorology, while soil erodibility was estimated based on soil characteristics and guidelines for the state of Mato Grosso. Land-cover characteristics were derived from remote-sensing imagery, with agricultural land, pasture, and forest areas identified and mapped through spatial analysis. Slope data were obtained from the Shuttle Radar Topography Mission (SRTM) dataset and processed using QGIS to generate the required spatial variables for the USLE model. The Curisevo River Basin covers approximately 1.18 million hectares, and the analysis estimated an annual soil erosion rate of approximately 134,526 t ha⁻¹ year⁻¹, equivalent to approximately 16 million tonnes of sediment annually. These findings demonstrate the considerable magnitude of soil loss associated with land-cover change and agricultural expansion within the basin. The study also highlights the applicability of GIS-based USLE modelling for quantifying spatial patterns of soil erosion and assessing the effects of climatic, pedological, geomorphological, and land-cover characteristics on erosion processes. The findings are particularly relevant to environmental management in the context of continued deforestation and agricultural expansion in the Amazon region. Excessive soil loss can reduce the availability and productivity of arable land, contribute to agricultural and food-security challenges, and deteriorate water quality through increased sediment delivery to rivers and other aquatic systems. Consequently, spatial assessment of soil erosion can provide valuable evidence for developing appropriate land-management and soil-conservation strategies aimed at reducing erosion, protecting water resources, and promoting sustainable watershed management.