Impact of hillslope vegetation restoration on gully erosion induced sediment yield

Facing the eco-environmental construction on the Loess Plateau, especially the vegetation restoration in the semiarid areas, as well as the dam system engineering construction that is about to start, how can the vegetation restoration gain the optimum ecological benefits following the improvement of the preservation rates of trees and grass on the basis of guaranteeing water storage and silt trapping effects? What techniques should be taken to restore vegetation? These questions critical to environmental management on the Loess Plateau have to be settled urgently. According to the different macroscopic spatial distribution patterns of forest and grass on the Loess Plateau, this paper analyzes the macroscopic hillslope and gully management relationship in the middle Yellow River and weight of natural and human factors in erosion-induced sediment yield in the context of environmental background of the major silt producing areas. In light of the current status of the integrated management of small watersheds and soil and water conservation measure arrangement schemes of hillslopes and gullies on the Loess Plateau, this paper discusses the impact of vegetation restoration on gully erosion induced sediment yield and the effect of vegetation caused sediment reduction. Studies indicate that there exists an erosional environmental background related to the natural and human activities in the sediment yield peak values of the sandy and coarse sandy areas in the middle Yellow River, sediment yield modulus is closely related to the synthetic effect of environmental elements, and the rainstorms, reclamation rate and forest coverage are the main factors affecting sediment yield modulus in the sandy and coarse sandy areas. The key to control soil erosion in the sandy and coarse sandy areas is the conversion of farmland into forestland and grassland, the reduction of reclamation rate and the increase of tree and grass vegetation. Small catchment management should adhere to the principle of simultaneous control of hillslope and gully erosion and combination of biological measures with engineering measures. Engineering measures play an important role in the hillslope vegetation restoration in the initial period. Vegetation restoration can result in a reduction of erosion induced sediment yield in gullies of Yangjiagou by over 75%. © Science in China Press 2006