河流水文情势改变程度计算方法研究

Calculation method of river hydrological regime alteration degree

变异范围法是评估河流水文情势改变程度的重要方法。原有变异范围法只关注了河流水文指标值在目标区间内出现频率的变化,而忽略了指标值在目标区间内分布特征的变化,可能会低估河流水文情势的改变程度。为了更加全面地量化河流水文情势改变程度,引入均值及变异系数,反映水文指标值在目标区间内集中趋势及离散程度等分布特征的变化,并与原有变异范围法相结合,建立新的河流水文情势改变程度评估方法;以汉江为例,对改进的变异范围法进行了验证。研究结果表明:改进的变异范围法量化了原方法未考虑的水文情势改变特征:以皇庄站水文情势为例,相较于原有变异范围法得出的低程度改变度20.63%,改进的方法得出了50.71%的中度改变,能够更加全面和准确地量化河流水文情势改变程度,可为生态流量保障提供更合理的量化目标。

The Range of Variability Approach(RVA)is an important method for assessing the river hydrological regime alteration degree.The original RVA only focuses on the frequency changes of hydrological indicators within target intervals,but ignores their distribution characteristic changes,which may underestimate the alteration degree of hydrological regimes.In order to quantify the degree of change of river hydrological regime more comprehensively,the mean value and coefficient of variation were introduced to reflect the changes of distribution characteristics such as central tendency and dispersion degree of hydrological index values in the target interval,and a new evaluation method for the degree of change of river hydrological regime was established by combining the original variation range method.The Hanjiang River was adopted to test the effectiveness of the improved RVA.The results showed that the improved RVA can quantify the hydrological situation change characteristics which was not considered in the original method.Taking Huangzhuang hydrological situation as an example,the original variation range method obtained a low degree of change of 20.63%,the new method obtained a moderate degree of change of 50.71%.The improved RVA can assess the river hydrological regime alteration more comprehensively and accurately,and provide more reasonable quantitative targets for ecological flow assessment.