基于多种水文学方法的汉江子午河生态流量研究

Study on the Ecological Flux of the Ziwu River in Hanjiang River Based on Several Hydrological Methods

汉江支流的子午河是陕西省"引汉济渭"工程的两大水源之一,为了维持下游河道的生态环境健康,子午河上的三河口水库下泄流量必须满足生态环境用水和生态流量过程的要求。采用两河口水文站的流量观测资料,运用变化范围法(RVA)、Q90法、多年日流量资料排频法,分析计算子午河年内生态流量过程,研究该河道维持多种生态环境目标所需要的生态需水量。研究结果表明:RVA法和Q90法计算得到的年生态需水量分别为46 344.3、11 574.0万m^3;多年日流量资料排频法获得的保证率(60%、70%、80%、90%)对应的年生态需水量分别为47 262.6、38 170.5、30 316.0、22 799.5万m^3。多年日流量资料排频法中,60%保证率对应的年生态需水量最大,可以达到较高的生态环境保护目标;Q90法获得的年生态需水量最小,对应最低的生态环境保护目标。计算得到的生态流量过程线可为水库调度和生态环境保护提供科学指导。

Ziwu River, one of the two huge water resources for Hanjiang-to-Weihe Diversion Project, is located in the tributary of the Hanjiang River. In order to maintain the ecological health of the downstream, the discharge of Sanhekou Reservoir must meet the re- quirements of the ecological environment and ecological water flow. Therefore, for the two hydrological stations of Sanhekou Reservoir, the method of Range of Variability Approach （RVA） ,Q90 method and daily mean method of flow discharge were used for research on required ecological flow of maintaining a variety of eco-environmental objectives. The annual ecological water requirement calculated by RVA method and Q90 method were respectively 463.44 ×106 m3 and 115.74 × 106 m3. Annual daily flow discharge frequency method obtained the annual ecological water demand of 472.62 × 106 m3 ,381.71 × 106 m3 ,303.16 × 106 m3 ,228.00 × 109 m3 with the respec- tive guarantee of 60% , 70% , 80% and 90%. Comparing ecological water demands calculated by the three methods, the annual eco- logical water demand corresponded to 60% guarantee rate is the largest, and can achieve high ecological and environmental protection goals, while Q90 law requires a minimum amount of water, and corresponds to the lowest ecological environmental protection target. The calculated ecological flow process line can provide guidance for reservoir operation and ecological environment protection.