ANALYSIS ON PECULIARITIES OF "92.8"FLOOD EVENT IN THE LOWER YELLOW RIVER

From 7~th through 13~th, August, 1992, a series of heavy rainstorms took place in Shaanxi province. The rainfall moved from the north to the south in sequence, resulting in flood events in tributaries of the Middle Yelow River, such as Huangfuchuan, Kuye, Wuding, Yanhe, Beiluo, Jinhe and Weihe rivers. These floods, converged from various tributaries, propagated downstream and formed four continuing flood crests at Huayuankou Hydrometric Station in the Lower Yellow River with a max. peak discharge of 6260m~3/s, which is referred as 92.8 flood. Although the peak discharge of 6260m~3/s is a frequent one for the Lower Yelow Rived, the water stage reached 94.33m, the second record of the station, even 0.34m higher than that in 1982 when the peak discharge was 15300 m~3/s. The 92.8 flood brought about a lot of damages, including inundation of 40000 ha of farmland on the floodplain of the Lower Yellow Rived The extremely high water stage, occurred in Huayuankou Hydrometric Station was caused directly by the previous deposition in main channel and unfavorable combination of incoming flow and sediment regime. But the primary cause is the change in incoming runoff and sediment load in the Lower Yellow River. Since the middle of 1980's remarkable reduction has taken place both in runoff and sediment load, and to some extent becomes definitely a tendency in furture. As some unforeseen troubles in flood control in Lower Yellow River might occur, more attention should be paid for it.