The Multi-dimensional thresholds of sediment yield in the area with abundant and coarse sediment on the Loess Plateau
黄土高原多沙粗沙区侵蚀产沙的多维临界

Sediment yield in the area with abundant and coarse sediment on the Loess Plateau is determined by natural processes and human action.This paper first distinguishes the natural and human factors influencing the sediment yield in the area,and then develops a single threshold response of each factor to the process of erosion and its intrinsic mechanism.On this basis,an integrated model of multi-dimensional thresholds taking into consideration the interactions between natural factors and human factors controlling sediment yield is developed to calculate the contribution of both natural factors and human factors to sediment yield.Also,the model quantifies the regulating objectives for soil and water conservation and the adjustment of the current measures taken to combat soil erosion are suggested.The results show that:(1)under the interaction between natural and human factors,the single threshold value of each factor tends to decline or be unchanged when a maximum value of the model is reached.(2)The intensity of erosion in the area is still increasing,almost 80% of which being caused by natural factors and 20% by human factors.Precipitation is the main factor that explains the intensity of soil erosion(about 61%).(3)Water and soil conservation techniques lag behind and can not prevent soil erosion and degradation.And(4)agricultural practice is the main human contributor to sediment yield,which implies that soil conservation methods should focus on the agricultural practices.