黄土高原多沙粗沙区侵蚀模型探讨

国内外曾研究出不同类型的坡面侵蚀计算模型，但还没有一个成熟的流域侵蚀计算模型，至今流域侵蚀量仍以输沙量替代。本文充分利用黄河中游不同区域具有大量淤地坝的条件，再通过侵蚀影响因素机理的分析、在侵蚀形态类型区的划分等基础上探讨侵蚀变权模型的建设。首先选择了155个“闷葫芦”淤地坝，采集每个坝的年均淤积量，以及相应流域的侵蚀影响因素：植被盖度、降雨量、沟谷密度、切割深度、地表组成物质、>15°的坡耕地面积比等资料，采用变权形式，建立侵蚀强度宏观估算模型。最后用年降水量与年输沙量的关系对模型进行改进。

A STUDY ON THE EROSION MODEL IN AREASWITH HIGH AND COARSE SEDIMENT YIELD

Many kinds of models of slope erosion have been developed in home and abroad, but there is not a mature model reckoning the erosion on the basin scales. Thus, sediment discharges measured at the outlets of the basins are usually used as the volumes of sediment erosion in the basins. Taking the advantage of availability of lots of sediment barriers scattered in the middle Yellow River, an erosion model with a varying weight of factors was constructed in the paper through analyzing the mechanisms of influences of factors on erosion and by dividing the areas with different erosive landforms. The data of 155 barriers with 100% sediment detention efficiency were used in developing the model. These data include the annual volumes of sediment accumulation in each of the sediment barriers and the values of factors influencing erosion in the basins, upstream to these barriers. The factors are vegetation coverage, precipitation, density of gullies, depth of dissection, properties of surface material, and percentage of cultivated lands in the slopes with a gradient larger than 150. The model was developed using the method of varying weights and has been checked up and improved by the relation between annual precipitation and sediment discharge. It can be used to estimate the erosion intensity on the basin scales in the areas with high and coarse sediment yield. The model is: Log (T m)=21.3/(3/G m+55/Q sd +9/Z x+10/W x)+ (0.92-1.69/(3/G m+70/Q sd +8/Z x+9/W x)) * ln (P s*P d)+0.67*R d-6.85