改进的年内展布法在河流生态需水计算中的应用

Application of Improved Dynamic Calculation Method to Ecological Water Demands

为更合理地适应我国季节性河流的径流分布特征,对原有的年内展布法进行改进。在计算河流的生态需水量之前,先对天然径流资料进行三性审查,并依据丰平枯的划分标准划分计算时段,以各时段90%保证率下的多年平均月径流量与该时段多年平均月径流量的比值计算各时段同期均值比,最后结合各月多年平均流量计算生态需水量。以松花江干流上游段的下岱吉断面为例,运用改进后的年内展布法计算该断面的生态需水量,将其计算结果与原年内展布法、最小月平均流量法、流量历时曲线法以及90%保证率法作对比,并用Tennant评价标准评价其计算结果。对比分析后发现,改进的年内展布法计算得出的生态需水量较好地反映了河流径流年内分布特征,符合河流丰平枯的变化规律,且在枯水期能更好满足河道内水生生物的生存需求,整体上更利于河流的生境。

In order to adapt to the runoff distribution characteristics of seasonal rivers in China more reasonably,the original dynamic calcula⁃tion method is improved.Before calculating the ecological water demand of the river,the reliability,representativity and consistency analysis of the natural runoff data is done,and the calculation period is divided according to the division standard of wet,normal and dry period.Meanwhile,based on the ratio of annual average monthly runoff with 90%guarantee rate and annual average monthly runoff,the ratios of the same periods are calculated,and the ecological water demand can be determined combined with the monthly average runoff.Taking Xiadaiji station in the Songhua River basin as an example,the ecological water demand of the station is calculated by using the improved annual dy⁃namic calculation method.The calculation results are compared with those of the original annual dynamic calculation method,the monthly minimum value method,the flow duration curve method and the 90%guarantee rate method.The Tennant evaluation standard is used to eval⁃uate the calculation results.After comparative analysis,it is found that the ecological water demand calculated by the improved annual distri⁃bution method better reflects the annual distribution characteristics of river runoff,which conforms to the changeable rule of river flood.It can also better meet the survival needs of aquatic organisms in the river in the dry period,which is more conducive to the river habitat as a whole.