黄河上中游近期水沙变化分析

根据黄河上、中游干流及重点支流水文泥沙定位观测资料统计,对1997—2006年水沙变化特点进行了分析.结果表明,与1970—1996年相比,黄河流域上、中游各区间降水量普遍减少,减幅在3%~11%;上游降水径流关系没有明显变化,而中游地区降水径流关系变化明显;干支流实测水沙量减少,减幅由上游至下游逐渐增大,径流量减少幅度从上游的20%至下游达到40%左右;对于输沙量,除河源区变化不明显外,干流各站沙量减幅在27%以上,头道拐至潼关各站减幅为57%~87%;干支流洪水发生场次普遍减少,且洪量减幅小于同期沙量减幅,前者为8%~46%,后者则为57%~64%;随输沙量减少,泥沙组成也发生变化,不同区域存在着泥沙中值粒径增大、变细和变化不大3种类型.

Analysis on Short-term Variation of Runoff and Sediment Load in the Upper and Middle Reaches of Yellow River

According to the statistic to long-term observation data of the main stream and main branch in the upper and middle reaches of Yellow River,the variation characteristic of runoff and sediment load from 1997 to 2006 was analyzed.The results show that,comparing with the data from 1970 to 1996,the pecipitation in the upper and middle reaches of Yellow River decreases universally,the value is from 3% to 11%,the relation between precipitation and runoff has not obvious change in the upper reaches,the relation between precipitation and runoff has obvious change in the middle reaches,the quantity of runoff and sediment in the main stream and branch decrease,the decrease value becomes big little by little,the value of runoff decreases from 20% in the upstream to 40% in the downstream,the decrease value of sediment is above 27% for sediment transport at every station in the main stream except source area with no obvious change in Yellow River,and the decrease vlaue is from 57% to 87% from Toudaoguai to Tongguan,the number of flood is universally decreasing in the main strean and branch,and the decrease value of flood quantity is from 8% to 46%,and the decrease value of sediment quantity is 57% to 64%,the composition of sediment changes with the quantity of sediment transport decreasing,the mediangrain size of sediment exists three states at every area,such as becoming big,becoming thin,or becoming little.