黄河唐乃亥—兰州段近期水沙变化特点分析

Analysis on the Varying Characteristics of Water and Sediment in Tangnaihai to Lanzhou Reach of the Yellow River

以黄河上游唐乃亥—兰州段1950年以来长系列实测资料为基础,分析研究了1997—2006年该河段干流水沙变化的特点。结果表明:来水量、来沙量减幅分别为18.5%～27.6%、23.1%～90.7%,沙量减幅大于水量的,而且水、沙量的减少主要发生在汛期;兰州站汛期水流过程主要集中在流量小于1 000 m3/s的小流量级,日均流量大于3 000 m3/s的情况没有出现;洪水出现场次减少,洪峰流量减小,洪水期水、沙量减小,洪水峰型变化不大。

This paper presented a study result on the varying characteristics of water and sediment in the reach from Tangnaihai to Lanzhou on the upper Yellow River from 1997 to 2006,with the observed data from 1950 to 2006.The results show that： the volume of runoff and amount of sediment of hydraulic stations reduce 18.5%-27.6%and 23.1%-90.7% respectively,the percentage of decreasing of the sediment is bigger than the water decreased and the water and sediment decreasing of flood season is much more than the other periods of the whole year.The most daily flow magnitude is less than 1 000 m3/s of flood season in Lanzhou,where more than 3 000 m3/s has not appeared.The frequency of flood has been decreased,runoff and sediment and the maximum flood peak discharge also have been also decreased in the flood seasons,but the type of flood peak type has changed little.