Perda de solo por erosão hídrica e a influência da apropriação e ocupação do relevo na bacia hidrográfica do Ribeirão São Lourenço, município de Ituiutaba-MG

Abstract

Soil erosion is a natural process of landscape shaping that occurs continuously on the Earth's surface. However, anthropogenic activities tend to intensify this process, increasing soil loss and associated environmental impacts. Land appropriation and occupation contribute to the destabilization of natural processes by disrupting the dynamic equilibrium and altering hydrological processes, especially water infiltration into the soil. In this context, the watershed has been widely adopted as a unit of analysis, as it enables the integration of physical and socioeconomic aspects. The main objective of this research is to understand soil loss resulting from water erosion, as well as to analyze land appropriation and occupation patterns within the Ribeirão São Lourenço watershed, located in the municipality of Ituiutaba, Minas Gerais, Brazil, and the environmental responses to these interventions. To achieve this objective, the following methodological procedures were adopted: (a) literature review of key concepts; (b) collection of data and cartographic bases; (c) extraction of morphometric parameters; (d) fieldwork for sample collection and photographic records; (e) morphological and granulometric soil analysis; (f) preparation of thematic maps, including location, fluvial hierarchy, hypsometry, slope, geology, geomorphology, soils, land use and land cover, and erosive features; and (g) determination and spatialization of the factors of the Universal Soil Loss Equation (USLE), namely: R factor (rainfall erosivity), K factor (soil erodibility), LS factor (topographic factor), and CP factor (cover, management, and conservation practices). The results indicate that the Ribeirão São Lourenço watershed has a drainage area of 294.11 km² and a perimeter of 119.02 km. The study area shows a low propensity for major flooding due to its elongated shape. In addition, the gently undulating relief, with low altimetric amplitude, combined with low hydrographic and drainage densities, indicates lower susceptibility to intense erosive processes. Regarding the USLE factors, the R factor presents an average value of 7720.49 MJ·mm·ha⁻¹·h⁻¹·year⁻¹, with an average annual precipitation of 1363.6 mm. The K factor ranges from 0.0479 to 0.0792 t·ha·h·ha⁻¹·MJ⁻¹·mm⁻¹, associated with Oxisols, Gleysols, Entisols, and Inceptisols developed over the Marília, Vale do Rio do Peixe, and Serra Geral formations. The predominant LS factor ranges from 0 to 2, covering approximately 82.3% of the area, reflecting low slopes. The CP factor ranges from 0, in areas with adequate soil cover and management, to 1, in areas of exposed soil. Regarding annual soil loss, 72.9% of the watershed presents losses of up to 10 t·ha⁻¹·year⁻¹, indicating a predominance of low-intensity sheet erosion. However, 268 occurrences of linear erosive features were identified, mainly concentrated in the upper and lower courses of the watershed, as well as in headwater areas. The integrated analysis of the sampling points showed that land appropriation and occupation have intensified erosive dynamics and, consequently, soil loss, reflecting the current morphodynamics of the watershed. In this context, the research contributes not only to the advancement of academic knowledge but also provides relevant support for territorial management and urban and environmental planning, aiming at soil and water conservation through an integrated socio-environmental approach.