基于时变Budyko公式的年径流变化机理分析——以贵州省六硐河为例

Analysis of Annual Runoff Change Mechanism Based on Time-Varying Budyko Formula——A Case Study of Liudong River in Guizhou Province

气候变化与人类活动是流域径流变化的重要原因。随着人类活动逐渐频繁,不同地区的水文情势不同程度地发生着变化,因此对径流变化机理的分析一直是水文学界的重要议题之一。Budyko水热耦合平衡公式是常用的径流变化机理分析工具,因其一方面考虑了一定的物理成因,另一方面公式参数较为简单,由此在径流变化归因较长时间尺度分析上得到了广泛应用,但当前对时变形式的Budyko公式研究及应用仍有待加强。以贵州省六硐河流域为例,通过Mann-Kendall检验和突变检验方法对研究区年径流进行趋势和突变分析,基于水热耦合平衡原理构造了包括线性、二次多项式以及具有物理机制等形式的Budyko参数时变辨识公式,以Nash效率系数为评价指标,验证最适应研究区的水热耦合公式,最后计算降水量、潜在蒸散发量和人类活动等因素对径流变化的贡献率,进行六硐河流域径流变化归因分析。研究结果表明,近年来随着气候变化影响加剧,六硐河流域径流呈明显的下降趋势,在1997年发生显著性突变。比较降水量、潜在蒸散发量和人类活动因素对径流的敏感性,发现降水减少是流域径流减少的主导因素,其贡献率为49%。同时,随着人类经济社会的发展,大型水利设施的兴建,人类活动对流域径流变化的影响在逐步显现,其贡献率约为26%。

Climate change and human activities are important causes of runoff changes in watersheds.The Budyko hydrothermal coupled equilibrium equation is a common tool for runoff change analysis,because it takes into account certain physical causes on the one hand,and the parameters of the equation are simple on the other hand,so it has been widely used in runoff change attribution for a long time.However,the current research and application of Budyko’s formula for time-varying forms still need to be strengthened.Therefore,this paper first analyzes the trend and abrupt change of annual runoff in the study area by Mann-Kendall test and abrupt change test,and then constructs the timevarying Budyko formula based on the principle of hydrothermal coupling equilibrium,including linear,quadratic polynomial and physical mechanism,and uses Nash efficiency coefficient as the evaluation index to verify the most suitable.Finally,the contribution of precipitation,potential evapotranspiration and human activities to the runoff change is calculated,and the attribution analysis of the runoff change in the Liudong River basin is carried out.The results of this study show that the runoff of the river basin has been decreasing in recent years with the impact of climate change,with a significant change in 1997.A comparison of the sensitivity of precipitation,potential evapotranspiration and human activities to runoff show that the decrease in precipitation is the dominant factor in the decrease in runoff,with a contribution of 49%.Meanwhile,with the development of human economy and society and the construction of large water conservancy facilities,the influence of human activities on runoff changes in the basin is gradually emerging,with a contribution rate of about 26%.