一种适用于寒区河流生态需水量计算方法

The Calculation Method for Ecological Water Requirement of River Course in Cold Area

河流生态需水量是维持河道内生态环境功能稳定必须保持的最小用水量,可为河流生态环境治理及合理开发利用水资源提供科学依据。我国北方寒冷地区河流,由于冬季连底冻、断流等现象,导致水资源开发利用和生态环境需水量之间矛盾加剧,如何确定寒区河流生态需水量十分重要。根据寒区河道径流变化特点,考虑冰冻期和非冰冻期,并选取95%保证率的月平均径流量和多年平均月径流量为指标,对河流生态需水的年内展布法进行了改进。以高纬度地区的呼玛河流域内5个主要水文控制断面为研究对象,选取1956-2016年总计61年的实测断面径流量资料,利用改进的年内展布法对呼玛河主要控制断面进行了基本生态需水量计算,并与Montanan(Tennant)等方法计算结果进行对比分析。结果表明:(1)呼玛河流域各主要水文站断面汛期(丰水期)生态需水量占多年年均同期径流量的25.8%~27.8%之间;非汛期(平水期)各主要水文站断面生态需水量占多年年均同期径流量的19.1%~24.0%之间,分析计算结果与Montana法(Tennant)的评价标准中所对应的河道状态与河道基本生态需水概念界定的生态功能目标相一致。(2)改进的年内展布方能够很好地体现北方寒区河流天然径流的年内汛期丰水、非汛期平水、冰冻期枯水甚至出现连底冻等真实的变化过程和规律,满足东北寒区河流生态功能保护目标对径流的实际需求,符合河流生态水文过程对径流的年内动态需求,可以推广应用于寒区河流基本生态需水量的计算。

River ecological water demand is the minimum water consumption that must be guaranteed to maintain the stability of ecological environment function in the river,which can provide a scientific and theoretical basis for river ecological environment governance and ratio⁃nal development and utilization of water resources.Due to the phenomena of continuous bottom freezing and cutoff in winter,the contradic⁃tion between the development and utilization of water resources and the ecological environmental water demand which intensifies the river of the cold regions in northern China.So an important problem is how to determine the ecological water demand of rivers in cold regions.According to the variation characteristics of river runoff in cold regions,considering the freezing period and non-freezing period,and selecting the monthly average runoff with ninety-five percent assurance rate and the multi-year average monthly runoff as indicators,this paper improves the annual distribution method of river ecological water demand.Taking five main hydrological control sections in the Huma River Basin in the high latitude region as the research object,the runoff data is taken in total of sixty-one years,measured sections from 1956 to 2016 are selected,and the basic ecological water demand of the main control sections of the Huma River is calculated by using the improved intra year distribution method,and the calculation results are compared with those of Montanan(Tennant)and those of other methods.The results show that:①the ecological water demand of the sections of the main hydrological stations in the Huma River Basin in the flood season(wet season)accounts for 25.8%~27.8%of the annual average runoff in the same period for many years.The cross-section ecological water de⁃mand of each main hydrological station in non flood season(normal season)accounts for 19.1%~24.0%of the annual average runoff in the same period over the years.The analysis and calculation results are consistent with the river state corresponding to the evaluation standard of Montana method(Tennant)and the ecological function goal defined by the concept of basic ecological water demand of the river.②The im⁃proved intra year distribution can well reflect the natural runoff of rivers in the northern cold region during the flood season,the non-flood season and the real change process and law of low water and even continuous bottom freezing in the freezing period,which can meet the ac tual needs of the river ecological function protection target for runoff in the northeast cold region,and meet the annual dynamic demands of the river ecological hydrological process for runoff.As a result,it can be popularized and applied to the calculation of the basic ecological water demand of rivers in the cold region.The actual demand of the river ecological function protection target for the runoff can be applied to the calculation of the basic ecological water demand of rivers in cold regions.