Geoenvironment and environmental fragility of the São Silvestre stream watershed, Minas Gerais

Abstract

Geoenvironments are geographic compartments whose territorial extent presents homogeneity regarding certain environmental factors of interest and, associated with the use of indicators, can assist in the effective management of a watershed. Thus, the objective of the work was to characterize and map the geoenvironmental units of the São Silvestre/MG stream watershed and evaluate its potential environmental fragility. Geology, pedology and geomorphology maps, whose intersection allowed the compartmentalization of homogeneous geoenvironmental units, were elaborated for the identification of the geoenvironments. In order to define the degree of potential fragility, the pedological, slope, and rainfall erosivity conditions in the watershed area were evaluated, which allowed the assessment of its natural fragility to soil loss by erosion. The compartmentalization into geoenvironments allowed the identification of five geoenvironmental units, which present similar geological and pedo-geomorphological characteristics. The degree of potential fragility was considered low and medium in the watershed, with a predominance of the medium category (more than 70% of the geoenvironments). It is noteworthy that the low to medium potential fragility indicator represents lower chances of soil loss by natural erosion, which reduces the risks of sediment carriage and deposition and the respective alterations in the quality and quantity of water in the watershed. To maintain the low fragility and improve the medium fragility, adequate soil management, the use of soil and water conservation practices, and environmentally sustainable soil use and occupation are recommended.