干旱区生态环境知识资源中心

The management of sedimentation problems in rivers and reservoirs depend greatly on the sediment yield from the basin land surface. In order to evaluate the effects of land use, slope and vegetal cover on the sediment production rates, several experimental erosion plots of loom 2 and four micro-basins of about one half of a hectare were installed in an experimental basin located in the typically semiarid region of the State of Paraiba in the northeast of Brazil. The experimental basin known as the experimental Basin of Sume, is situated within the Representative Basin of Sume. The erosion plots and micro-basins were adequately equipped to determine the total runoff volume as well as the sediment yield. In all the cases,the sediment yield was calculated from the mean concentration of sediments in the runoff obtained from various samples. Measurements of runoff and erosion under diverse conditions of management of the erosion plots and the micro-basins have been carried out since 1982. The paper presents an analysis of the relative influence of the various factors on surface runoff and land erosion. The most significant result seems to be the enormous degree of protection offered by the fragile native vegetation against surface erosion. This ability seems possible of restoration by letting the vegetation grow back even after complete clearance.