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近年来,长江上游已建成一批大型水库,其运行调度必然会对下游的径流产生影响。水文变化指标法(IHA)和水文变化幅度法(RVA)是以水流的量、时间、频率、延时和变化率5种基本特征为基础,对建坝前后的河道水文情势变化进行定量分析的方法。根据长江流域大型水库群建设的实际情况,利用Mann-Kendall秩次相关检验法划分了宜昌站建库前后的流量序列,用来评估长江上游大型水库群对宜昌站水文情势的改变情况。M-K相关检验发现,宜昌站的年最小流量已经在2000年发生了显著性地变化;IHA和RVA分析成果表明,宜昌站的水文情势已经发生了中等程度的改变,主要是与小流量相关的一些因子,如1~3月平均流量、最小流量六个因子、低脉冲发生次数及持续时间等;随着以三峡水库为核心的上游大型水库群建成并投入运行,未来长江下游河道径流还将发生进一步的改变。
In recent years, a number of large reservoirs have been built in the upper reaches of the Yangtze River, and their operation dispatching will inevitably affect downstream runoff. Hydrological change indicator method (IHA) and hydrological change margin method (RVA) are based on five basic characteristics of water flow volume, time, frequency, delay and rate of change, and quantitative analysis of hydrological changes before and after river dam construction method. According to the actual situation of large reservoirs in the Yangtze River Basin, the flow series before and after the construction of Yichang Station are divided by Mann-Kendall rank correlation test to evaluate the change of hydrological conditions of Yichang Station by the large reservoirs in the upper reaches of the Yangtze River. The MK correlation test found that the annual minimum flow rate of Yichang Station has changed significantly in 2000. The results of IHA and RVA analyzes show that the hydrological regime of Yichang Station has changed moderately, mainly due to the low flow rate Factors such as the average flow from January to March, the minimum flow rate of six factors, the number of low-pulse occurrence and duration, etc .; with the Three Gorges Reservoir as the core of the upstream large reservoirs completed and put into operation, the future runoff in the lower reaches of the Yangtze River will also occur Further changes.