Rill and sheet soil erosion estimation in an area undergoing desertification in the Brazilian semi-arid region

Abstract

Soil erosion is a serious world problem, especially in areas undergoing desertification. Rill and sheet erosions were estimated in one municipality of the largest desertification nucleus in the Brazilian semi-arid region. Measurements were made in plots located in combinations of the two main soil classes (Luvisol and Planosol, 58 and 40% of the municipal area) and the two predominant vegetation covers (sparse and open, 84 and 7% of the municipal area). The sparse vegetation has 320 plants ha−1 covering 25% of the soil surface and the open vegetation has 495 plants ha−1, covering 40% of the soil surface. Length, width, and depth of all rills were measured in the plots to calculate the soil losses. Sheet erosion was estimated assuming that the height of the soil close to the bases of trees and shrubs in relation to the soil surface away from these bases corresponded to the depth of the lost soil layer. Rill erosion was higher under the sparse vegetation than under the open vegetation: 400 versus 45 Mg ha−1. Sheet erosion did not differ among soils and covers (547–860 Mg ha−1). Soil loss in the municipality was 34 Tg and 24 Eg when extrapolating to the desertification nucleus. Erosion and low vegetation cover are cumulative reinforcing degradation drivers, leading to low crop and livestock productivity, poverty, and social vulnerability. Land use restriction is the main measure to reduce erosion, but it increases social problems.