梯级水库建设运行对河流径流影响定量化分析

Quantitative analysis on influence of cascade reservoir on downstream runoff during construction and operation period

掌握河流径流特性是梯级水库自规划到建设、再到投运期间贯穿始终的重要研究工作。以金沙江中游梯级水库为研究对象,分析该河段梯级水库自2010年相继蓄水发电以来对干流径流特性的影响。以流域出口控制站攀枝花站为研究对象,石鼓站为参照站,选择不均匀系数(变差系数)为指标,采用双样本F检验、Mann-Kendall突变检验和流量历时曲线等方法,从年际、年内、月内等多个时间尺度视角出发,对其径流变化及其分配特性进行定量化分析。分析结果表明:(1)金沙江中游梯级对径流的年际变化规律影响有限;(2)金沙江中游梯级对径流的年内逐月分配有一定影响,但影响程度有限;(3)金沙江中游梯级对径流的月内分配尤为显著,在梯级水库建设运行期高流量分布存在着枯季偏大、汛期偏小的普遍规律,而低流量分布无论枯季、汛期均呈现偏小的态势,而且量化影响更为明显。分析成果可为实际应用提供一定的参考。

The river runoff characteristics plays an important research role in the entire life cycle of cascade reservoirs from planning, construction to operation.The cascade reservoirs at the middle reaches of Jinsha River are used to study the impact of impoundment and power generationon on the downstream runoff characteristics since 2010.The Panzhihua station at the outlet of watershed is treated as the research object, while the Shigu station is seen as the reference object.The nonuniform coefficient, i.e variation coefficient, is selected as an index.The two sample F-test, Mann-Kendall test and flow duration curve are used to quantitatively analyze the multi-scale(inter-annual, intra-annual, intra-month)change of runoff variation and distribution.The results show that:(1) the impact of cascade reservoirs on the interannual runoff change is limited;(2) there are certain impacts on monthly distribution of annual runoff;(3) there are particularly significant impacts on runoff distribution in a month at the construction and operation periods, namely the high flow at dry season is large but small at flood season, while the low flow is always small no matter in flood season or dry season.The results can provide reference for practical application.