基于水热耦合平衡方程的六冲河上游流域径流变化归因分析

Attribution Analysis of Runoff Change in the Upper Reaches of the Liuchong River Basin Based on Coupled Water-energy Balance Equation

以贵州省六冲河上游流域为研究区域,首先通过Mann-Kendall检验和Pettitt法对六冲河七星关站年径流变化进行趋势和突变分析,找出突变点,再运用水热耦合平衡方程对突变点前后径流变化进行归因分析,通过对降水、潜在蒸散发以及下垫面的弹性系数进行敏感性分析,最后计算出降水、潜在蒸散发以及下垫面对径流变化的贡献率。结果表明:六冲河上游径流深在1971—2009年呈现显著下降趋势,在1986年发生显著突变,比较降水量、潜在蒸发量和下垫面指数对径流变化的敏感性,发现降水量弹性系数最大,其次是下垫面指数,最后是潜在蒸散发,表明径流对降水量的变化最为敏感,计算三者对径流显著减少的贡献程度,发现降水减少对径流减少的贡献率高达113.3%,其次是下垫面变化的影响,贡献率为14.4%,最后是潜在蒸散发增加带来的影响,贡献率为-27.7%。

Taking the upper reaches of the Liuchong River in Guizhou Province as the study area,this paper first analyzes the trend and abrupt change of the annual runoff at Qixingguan Station in the Liuchong River by the Mann-Kendall test and Pettitt test to find the abrupt change points,then,discusses the reasons of runoff change before and after the abrupt change points by the coupled water-energy balance equation,finally,calculates the contribution rates of precipitation,potential evapotranspiration and underlying surface to runoff change through the sensitivity analysis of their elastic coefficients.The results show that:The depth of runoff in the upper reaches of the Liuchong River shows a significant downward trend from 1971 to 2009,and a significant abrupt change occurred in 1986.By comparing the sensitivity of precipitation,potential evapotranspiration,and underlying surface to runoff change,it is found that the elastic coefficient of precipitation is the highest,followed by the underlying surface index,and finally the potential evapotranspiration,indicating that runoff is the most sensitive to the change of precipitation.In addition,based on the results of the contribution rate of the three factors to the reduction of runoff,it is found that the contribution rate of decreasing precipitation to runoff reduction is as high as 113.3%,followed by the change of underlying surface,with a contribution rate of 14.4%and finally the increasing potential evapotranspiration,with a contribution rate of-27.7%.