汾河中下游河道生态需水量研究

汾河中下游流域地处我国黄土高原干旱、半干旱地区,水资源短缺与生态环境矛盾十分突出,从水资源开发利用中的生态环境问题出发,构建了适合汾河中下游生态需水量计算模型。河流生态需水量是一个随着时段、河段的不同而发生变化的动态值,把汾河中下游以水文站分成5段,分别计算了不同水文频率年各河段生态需水量,把河道生态需水量分为河道蒸发、渗漏、自净、输沙需水量和基础流量,并根据它们之间的相互关系,界定了总生态需水量。结果表明,汾河中下游20%,50%,70%和95%水文频率年河道生态需水量分别为6.17×108m3,3.78×108m3,2.37×108m3,1.59×108m3;占流域代表年径流量的百分比分别为55.43%,61.97%,61.27%,88.15%,且占多年平均流量的百分比分别为73.68%,45.10%,28.27%,18.92%。要实现汾河流域的可持续管理,必需采取切实有效的措施进行水资源开发调控,分时段分河段地进行水资源的合理利用。

Ecological Water Demands by Channels in Middle and Lower Reaches of Fenhe River

The middle and lower reaches of Fenhe River is in the arid and semi-arid area of the Loess Plateau of China and shortage of water resources and eco-environmental issues are very prominent.In views of the eco-environmental problems in development and utilization of water resources,this paper aims to construct a calculation model of ecological water demands in the middle and lower reaches of Fenhe River.Because the demands change with time and river sections,the middle and lower reaches of Fenhe River are divided into five sections according to hydrological stations for the calculation of ecological water demands with different hydrological frequencies.Ecological water demands are classified as river ecology surface evaporation,seepage demand,self-purification demand,sediment transport demand,and base flow demand.According to the relationship among them,total eco-environmental water demand is defined.Annual ecological water demands with the 4 hydrologic frequencies of 25%,50%,70%,and 95% are 617.43,377.94,236.93,and 158.56 million m³;the percentages over annual ecological water demand by channels are about 55.43%,61.97%,61.27%,and 88.15%;and the percentages over total flow averaged over years are 73.68%,45.10 %,28.27%,and 18.92%,respectively.It is necessary to take effective measures to control water resources for the sustainable management of Fenhe River basin and make use of water resources in different periods and reaches.