The coarse sediment yields in different earth layers of 6 tributaries in the reach of Hekouzhen to hongmen are studied and analysed in the paper through grain size analysis according to field samples.

At the heavy and coarse sediment region in the middle reaches of the Yellow river basin,because of the high population density,insufficient cereals supplement,deficient fuel ,fertilizer and forage resource,and serious soil erosion, the contradiction between population and environment becomes the principle factor which restricts the economic development of this region.

The formation of the area with abundant and coarse sediment in the Loess Plateau is affected not only by the factors with natural belt traits and non-belt traits but also historical human activities and socio-economic development.

The high intensive sediment yield in the area with abundant and coarse sediment of the Loess Plateau results from the joint action of natural and human factors,and there are multi-dimensional threshold in the process of sediment yield.

Composing analysis of coarse sediment particle diameter in the key branches of rich and coarse sediment areas in the middle stream of Yellow River;

Analyses on the variation of vegetation coverage and water/sediment reduction in the rich and coarse sediment area of the Yellow River basin;