水文变异条件下的黄河干流生态径流特征及生态效应

黄河流域地表水文过程受气候变化与如水库拦蓄等人类活动的严重影响,发生显著变化,多次出现断流现象。深入理解水文变异条件下的径流特征及生态效应,对于黄河流域水资源管理及水资源可持续开发利用具有重要意义。基于此,论文利用多水文指标研究水文变异过程,结合基于流量历时曲线（FDC）的生态剩余和生态赤字等生态径流指标以及水文变异总体评价指标D_o和DHRAM（Dundee Hydrological Regime Alteration Method）来描述黄河干流大中型水利工程对下游河道水文情势的改变程度,并根据多样性指标SI和IHA（Indicators of Hydrologic Alteration）的拟合关系,进一步分析水文变异的生态效应。研究表明：1）水文情势变异后,FDC整体下移,低于25% FDC流量部分大幅增加,产生生态赤字;2）从上游到下游,降水对各站生态径流指标的影响逐步减小,水库对生态径流指标的影响愈益增大;3）各生态径流指标与大部分IHA指标具有较好的相关关系,能够体现IHA参数的主要信息,可作为衡量黄河流域年和季节径流变化的生态径流指标;4）综合D_o和DHRAM的评价结果,径流过程变异对各站生态风险的影响为：花园口、孙口和利津站为高风险,头道拐和兰州为中等风险,唐乃亥和龙门为低风险;各水文站SI值在20世纪80年代之后均出现下降趋势,其中花园口、孙口和利津3个站的下降幅度较大,生物多样性锐减。

Changes of Eco-flow due to Hydrological Alterations in theYellow River Basin

Streamflow changes of the Yellow River Basin are heavily influenced by climate changes and human activities such as construction of water reservoirs, hence significant hydrological alterations and even dry-up events happened. In this case, deep understanding of eco-flow changes as a result of hydrological alterations is of great scientific and practical merits in scientific water management and sustainable exploitation of water resources of the Yellow River Basin. Therefore, this study attempts to quantify eco-flow and ecohydrological processes, and describes changes of streamflow downstream to hydraulic facilities in the Yellow River Basin using integrated ecological evaluation index, D_o and DHRAM. Besides, SI and IHA 33 are used to analyze ecological effects of hydrological alterations. The results indicated that: 1) FDC is subject to general decrease due to hydrological alterations, and most streamflow components are lower than 25% FDC. Ecodeficit is evident in this case. 2) Impacts of precipitation on ecoflow indices are generally decreasing from upper to the lower Yellow River Basin while water reservoirs have enhancing influences on ecoflow indices. 3) ecohydrological indices are all in good relations with IHA, showing that ecohydrological variations are closely related to hydrological alterations in the Yellow River Basin. 4) Based on evaluation results with D_o and DHRAM, ecological environmental risks caused by hydrological alterations are higher at Huayuankou, Sunkou and Lijin stations, moderate at Toudaoguai and Lanzhou stations and lower at Tangnaihai and Longmen stations. Ecological diversity is in significant decrease from upper to the lower Yellow River Basin. The results of this study shed new light on sustainable exploitation of water resources and ecological health of the Yellow River Basin. Human activities should be adapted to eco-flow changes.