基于水循环分析的水资源乘数效应评价:以黄河上游北川河流域为例

Evaluation of water resource multiple effect based on the analysis of water circulation:An example of the Beichuan River Basin upstream of the Yellow River

针对半干旱地区大规模植被恢复对流域水资源的影响,引入经济学的乘数效应理论,探索创建了基于流域水循环演变的水资源效应评价模型,从广义水资源的角度出发,评价了植被恢复引起水循环演变条件下水资源效应的变化趋势。结果表明:大规模植被恢复引起北川河流域水循环条件发生明显变化,在降水条件基本稳定的情况下,植被恢复前后地表产流系数从0.254降为0.207,基流系数从0.156降为0.134;陆地水循环过程中,土壤-植被系统的有效用水占比增加,土壤水-地下水系统有效用水占比减小;单位降水量(100 mm)的狭义水资源效应降低了7.2 mm,涵盖生态效应的广义水资源效应增加了5.2 mm,水循环变化引起流域水资源效应提高。植被恢复引起降水在不同水循环环节上分配的变化趋势符合国家以生态为核心的布局,对提高半干旱地区流域水资源综合效应发挥着重要作用。

To evaluate the effect of large-scale vegetation restoration on water resources in semi-arid areas,an evaluation model was created based on analysis of water circulation in watersheds in referencing to the Keynesian multiplier theory.Further,the variation trend of such effect with changing water circulation caused by vegetation restoration was evaluated from the perspective of generalized water resources.The water circulation conditions in the Beichuan River Basin have significantly changed owing to large-scale vegetation recovery.The surface flow coefficient before and after the vegetation recovery reduced from 0.254 to 0.207,and the base current coefficient reduced from 0.156 to 0.134 under nearly stable precipitation.The proportion of the effective water volume increased in the soil-vegetation system and decreased in the soil-groundwater system under terrestrial water circulation.The localized water resources response to 100 mm precipitation reduced by 6.55 mm;however,the generalized water responses response,with ecological response included,increased by 45.37 mm,or a 25.78%increase.Thus the change in water circulation significant increased water resources response to rainfall in the Beichuan River Basin.This changing trend of precipitation distribution in different water circulation sections as a result of vegetation recovery aligns well with the country’s core strategy for ecosystem conservation,and plays an important role in improving the overall water resources response to rainfall the semi-arid area.