Susceptibilidade natural à erosão nas áreas de pastagem da sub-bacia hidrográfica do ribeirão Santa Cruz, no município de Muniz Freire (ES)

Abstract

Livestock, although it has significant economic relevance, is the cause of several problems related to erosion. This fact becomes even more worrying in the context of a hydrographic basin. Thus, the objective of this work was to assess the natural vulnerability to erosion in the pasture areas of the hydrographic sub-basin of the Santa Cruz stream (HBSCS), in order to support improvements related to soil conservation associated with local economic productivity. The procedures took place with the aid of the ArcGIS® geographic information system. The cartographic databases were the websites of GEOBASES, the National Water Agency and the Jones dos Santos Neves Institute. Initially, HBSCS was delimited to later acquire features (vector files) related to the location of pastures covered by HBSCS. The Universal Soil Loss Equation was used to estimate potential erosion. For this, the following data were obtained: erosivity, erodibility, ramp length and slope. Erosion was mapped, quantified and classified. The natural intensity of erosion ranges from 0 ton/ha.year to 6814 ton/ha.year, with an arithmetic mean of 569.740 ton/ha.year and standard deviation equal to 345.013 ton/ha.year. The class with the highest intensity is “moderate to strong”. However, when combined, the “moderate to strong” and “strong” classes comprise 65.666%. The lower intensity classes, “weak” and “moderate”, together, represent only 33.652%. The values can be attributed, mainly, to the ignorance on the part of the rural producers about the most favorable places for the installation of pastures. Therefore, it is extremely necessary to adopt measures favorable to soil conservation, such as the correct management of livestock, especially in areas with a greater erosive tendency. It is expected that studies with a similar theme will continue, considering, for example, the influence of management on HBSCS erosion.