考虑不同水文年及IHA指标相关性的水文特征评估方法

变动范围法(RVA)是国内外评价河流水文特征变化的重要方法,但其存在忽略水文年变化特征及中低度改变指标的缺陷。针对此问题,采用CRITIC法结合欧氏距离对传统RVA进行改进,并将改进方法用于黄河源区(唐乃亥水文站),分析黄河源区径流量的水文指标变化趋势和整体水文变异程度。研究结果表明:唐乃亥水文站在1990年时水文情势发生突变,突变后流量呈减少趋势;受干扰后的唐乃亥水文站2/3月份平均流量、年最小7/30/90d流量、年最大90d流量、高流量平均延时、流量平均减少率/增加率共9个指标为中度改变,其余指标为低度改变;黄河源区水文特征年改变度为41.36%,水文指标整体改变度为27.33%,水文情势整体改变度为57.39%,属于中度改变。

A New Method to Assess Hydrological Regime Alterations Considering Hydrological Year Types and Correlation Among IHA

Range of Variability Approach (RVA) is an important method to evaluate the alteration of river streamflow. However, the traditional range of variability approach (RVA) has the drawback that variabilities of low and medium flow indicators are often ignored. To assess flow regime alterations more comprehensively, an improved RVA method was proposed based on the CRITIC method (Criteria Importance Through Intercriteria Correlation) combined with Euclidean distance. The observed streamflow data of the Tangnaihai station from 1960 to 2009 in the source region of the Yellow River were used to validate the rationality of the new method. Meanwhile, the change trend of hydrology index and the overall degree of hydrological variation in the region were analyzed. The results show that the annual streamflow indicate a decreasing trend after the mutation in 1990. After the disturbance, the overall changing degrees calculated by the improved method is 27.33%, belongs to medium change. Nine IHA indicators, including mean flow in February/March, annual minimum 7/30/90-day flow, annual maximum 90-day flow, mean duration of high flow, decreasing rate and increasing rate of flow, belong to moderate change, while the rest of the indicators belong to low change. Compared with the traditional RVA, the improved RVA method can effectively consider the impact of low and medium indices and make the evaluation results more objective.