Managing Soil Erosion on the Loess Plateau of China to Control Sediment Transport in the Yellow River-A Geomorphic Perspective

A key part of the strategy to manage the problems of flooding and sedimentation of the lower Yellow River in China is the control of soil erosion on the loess plateau. Land use practices are assumed to be the root cause of the high sediment yield and therefore able to be controlled. An analysis of the geomorphology of the loess plateau region shows that there are natural causes of high sediment yield. Loess is a highly erodible material, and the zonal distribution in China of the climatic factors which maximise erosion shows that the loess plateau is located where the potential for erosion, particularly of coarse sediment, is at a maximum. This area would be a zone of high soil erosion even if there were no loess present. Convex slope profiles are the predominant slope form in this landscape such that farming practices are confined to the plateau surface and the gentler upper slopes of the convex profiles. The lower ends of the convex slopes are too steep for farming and are often near vertical. These are therefore the locations of highest sediment production and are little affected by land use activities. Changes to the social and economic basis of agriculture in China over the past 20 years have caused an increase in pressure on land resources and it is unlikely that farmers will manage their land to control sediment yield unless this also increases productivity. The extent to which it will be possible to mobilise the rural population to participate in land management activities for soil erosion control and environmental benefits is also a key issue in this debate. The paper concludes that the reduction in sediment yield from the Loess Plateau by soil erosion control and revegetation is unlikely to be of sufficient magnitude to have a significant impact on the management of the lower Yellow River.