三峡水库对坝下河流水文情势影响研究

Impact of Three Gorges Reservoir on the Downstream Hydrology of Yangtze River

选取三峡水库下游宜昌水文站1950-2016年近70年的流量资料,采用Mann-Kendall法,分析宜昌水文站流量变化趋势。基于水文改变指标法（IHA）和变化范围法（RVA）评价三峡工程蓄水前后宜昌水文站32个IHA指标的水文改变程度,分析高度改变的水文指标,并基于32个IHA指标计算的水文改变度（D0）和DHRAM,分析三峡水库蓄水前后宜昌水文站整体水文情势变化,对宜昌站的水文改变程度进行定量评价。结果表明,在研究期间内,宜昌站年均流量呈减少趋势,在Mann-Kendall趋势检验中通过了95%的显著性检验,表明年均流量减少趋势显著;非汛期流量增加,汛期流量减少;年均最小流量和年均最大流量分别表现为增大和减少的趋势,年最小流量出现时间提前;低脉冲发生频率消失,高脉冲发生次数和历时略有下降;上升率和下降率均有减少趋势,逆转次数的水文改变度达到100%。通过DHRAM和D0计算后,水文情势整体为中度改变。

The Yichang gauging station of the Yangtze River is 44 km downstream of Three Georges Reservoir.In this study,changes in the hydrologic regime resulting from impoundment of Three Georges Reservoir was analyzed based on flow data from the gauging station from 1950 to 2016.Flow trends and hydrologic alteration were analyzed using the Mann-Kendall method with the Range of Variability Approach（RVA）and Indictors of Hydrologic Alteration（IHA）.Changes in 32 IHA,D_0（degree of hydrologic alteration）and the Dundee Hydrological Regime Assessment Method（DHRAM）were employed to assess changes in river hydrology at the Yichang station.Results show that mean annual discharge decreased during the study period at a Mann-Kendall confidence level of 95%.Annual minimum flow increased,annual maximum flow decreased and the minimum flow occurred earlier in the year.The low pulse count was eliminated and the high pulse count and duration decreased slightly.Both rise and fall rates decreased and the number of flow reversals nearly doubled.Impoundment of Three Gorges Reservoir affected the hydrological regime at the Yichang station and,based on values of D_0 and DHRAM,the alteration was moderate.