新疆主要河流水文极值变化趋势

水文极值是工程水文计算的基础资料,实测样本资料的变化直接影响水文设计值。基于1956-2006年的实测洪峰、洪量、年最小流量、最枯月径流量等资料,分析了各水文要素的变化及其趋势。结果表明:20世纪80年代中期以来超标准洪峰、洪量的频次增加,大多数河流洪水峰、量都呈增大变化趋势,说明新疆洪水又进入活跃期,在工程水文设计洪水计算中要应尽可能搜集和利用近期暴雨和洪水资料,在洪水系列中增加更多大洪水信息,提高设计洪水计算成果的稳定性。年最小流量和最枯月径流量是维持河流生命和河道两岸自然生态的基础流量,基流量增大有利于对生态补给、水利发电,水库蓄水,径流年内分配趋于均匀有利于水量年内调节。但在枯水径流分析计算中应充分重视不同年份最枯水量出现时间有明显推迟的迹象。

Variable tendency of hydrological extreme of the main rivers in Xinjiang

The hydrological extreme is the basic data for the engineering hydrology calculation, the variation of the observed data of hydrological extreme will effect directly on hydrological design. Based on the observed extreme da-ta which including flood crest, flood peak discharge, annual maximum flow and minimum monthly runoff, the varia-tion and tendency of each hydrological element were analyzed from 1956 to 2006 in this paper. The results show that the superflow and flood-peak frequency have increased since the middle of 1980s, and the flood crest and flood peak discharge are also present in increased tendency for the most rivers in Xinjiang. It indicates clearly that the flood in Xinjiang has entered into an active stage owing to the climate change. It is of great importance to calculate the flood in the engineering hydrology design, to collect and use more rainstorm and flood datum in near future, to increase more cataclysm information in flood series, and to improve the stability of flood design. According to the analyzed results, it is proved that the annual minimum flow and the minimum monthly runoff are the basic runoff to maintain the natural ecosystem safety both side of river bank. With the increase of the basic river runoff, it will be propitious to the ecological water requirement, hydropower and reservoir storage. Meantime, with the annual distri-bution of runoff tends to uniform, it also will be propitious to the annual water resources allocation. During the anal-ysis and calculation of low runoff, more attention should be paid to that the appearance time of minimum monthly runoff appears a clear delayed variation in different years.