考虑植被对降雨变化响应的流域水量平衡
Water balance in a watershed considering the response of vegetation cover to rainfall changes

为研究降雨变化对流域水量平衡的直接及间接影响，该文基于Eagleson的生态水文最优性理论，建立了植被盖度降雨响应模型，用归因分析法区分了由降雨变化直接引起的水量平衡变化以及植被响应降雨变化对水量平衡产生的间接影响，并在科尔沁地区西拉木伦-老哈河流域对该方法进行了应用。研究结果表明：植被盖度和降雨量之间存在正相关关系，这一关系受到降雨强度和降雨频率的影响。降雨量增加主要增加了蒸散发和非生长季土壤水分蓄变量的占比。降雨量增加对水量平衡各项变化的直接贡献都是正向的，而植被响应降雨后对水量平衡变化产生的间接贡献对除了蒸散发以外的各项均为负向的。蒸发系数和降雨之间的关系受到植被对降雨变化响应的影响。
Abstract：This study distinguishes the direct and indirect effects of rainfall changes on the water balance in a watershed. The water balance is used to build a model based on Eagleson's ecohydrological optimality theory to describe the vegetation cover response to rainfall changes. An attribution analysis distinguishes the direct effect of rainfall on the water balance shifts and the indirect effect of vegetation cover which is influenced by the rainfall. This method is applied to the Xilamulun-Laoha River basin in the Horqin Sands area. The results show a positive correlation between the vegetation cover and the rainfall with the relationship affected by the rainfall intensity and frequency. Increased rainfall mainly increases the evapotranspiration and soil water storage during the non-growing season. Increased rainfall has a positive effect on every water balance term. However, the indirect effects of the vegetation cover result in negative changes to all the water balance terms, except for the evapotranspiration. The relationship between the evapotranspiration efficiency and the rainfall is affected by the response of the vegetation cover to rainfall changes.