关键词: 黄河, “十大孔兑”, 侵蚀产沙, 风水两相耦合作用, 高含沙水流, 水土流失

Abstract: Sediment supply from the ten small tributaries causes strong sedimentation in the upper Yellow River. For the purpose of reducing sediment-related disasters through soil erosion control measures in the ten small tributaries, we studied the soil erosion regularity in the ten small tributaries based on data of sediment load, runoff and precipitation from 1960 to 2005. The total sediment supply in the 46 years was highly concentrated in a few years with large sediment load and runoff, and the sediment yield from the remaining years made little contribution. The cumulative maximum 1-year, 3-year, 5-year and 10-year sediment yield accounts for 21.26%, 37.18%, 47.92% and 69.29% of the 46-year's total, respectively. Comparison with during1960-1991, the annual sediment yield from the Xiliugou River during 1992-2005 decreased by 37%. This difference can be explained by two factors, the difference in rainstorms and the variation of vegetation. After 1990, although annual precipitation shows no significant change, the maximum 1-day rainfall has a decreasing trend (p<0.10). The NDVI shows an increasing trend (p<0.01), which is caused by the transfer of surplus rural labors out of the land. The specific sediment yield shows clear spatial difference. In the ten small tributaries, it increases from west to east, reaching the maximum in the Xiliugou River, and then decreases. In the same direction, annual precipitation increases, the frequency of sand-dust storms decreases, and the types of sand dunes gradually change from movable to semi-fixed ones. Thus, the wind-blown sand to the rivers decreases, while the erosion and sediment transport by water increases. The superposing of these two processes leads to the occurrence of a peak of specific sediment yield near the Xiliugou River.

Key words: Yellow River, ten small tributaries, erosion and sediment yield, wind-water two-phase coupling processes, hyperconcentrated flow, soil and water loss