从黄河下游"92.8"洪水看游荡性河段高含沙水流的河床演变特性

黄河下游花园口92.8洪水属于含沙量中等偏高的高含沙水流，洪峰也只是常遇流量级(6260m

Fluvial Processes at Flow with Hyperconcentration of Sediment in Wandering Reach of the Lower Yellow River

From 7 through 13, August 1992, a series of heavy rainstorms took place in Shaanxi Province. The rainfall moved from north to south in sequence, resulted in flood events in the tributaries of the Middle Yellow River, such as Huangfuchuan, Kuye, Wuding, Yanhe, Beiluo, Jinhe and Weihe rivers. These floods concentrated from various tributaries, propagated downstream and formed four continuous peak flows at Huayuankou Hydrometric Station in the Lower Yellow River with a max. peak discharge of 6260m3/s. The flood process is referred to as \!92.8" flood. Although the peak discharge of 6260m3/s is a medium-scale one to the Lower Yellow River, however, the water stage reached 94.33m, and it is the second highest water stage at the station which is even 0.34m higher than that in 1982 when the peak discharge was 15300m3/s.The \!92.8" flood brought about a lot of damages, including inundatin of 40000 ha of farmland on the floodplain of the Lower Yellow River. Based on field investigation, analysis on specific features of the flood is presented in this paper.The extremely high water stage, occurred in Huayuankou Hydrometric Station was caused directly by the previous deposition in the main channel and unfavorable combination of incoming flow and sediment regime. But the primary cause is the change in runoff and sediment load from the Upper and Middle Yellow River. Since the middle of 1980's remarkable reduction has taken place in the Lower Yellow River both in runoff and sediment load. Further reduction of them in the future seems to be a definite tendency. As some unforeseen troubles in flood control in Lower Yellow River might occur, more attention should be paid for it.