植被重建影响下的降雨-产流阈值及水循环再分配

Global vegetation increases a lot in recent 30 years, influencing the mass-energy condition, which leads to changes in soil water, evapotranspiration and runoff. The streamflow thus shows a complex behavior characterized by nonlinearity and geographic separation. Under the influence of large scale revegetation, the runoff generation process of the middle river basin of yellow river is not clarified owing to the great variability of rainfall threshold for runoff generation. At the same time, soil water and evapotranspiration change a lot. The water cycle redistribution under the influence of revegetation is not revealed till now. Therefore, the Jinghe river basin in middle yellow river is selected as study region to study the rainfall threshold for runoff generation and water cycle redistribution under the influence of revegetation. The contents include: (1) to identify the relation between impact factors and rainfall threshold for runoff generation, thereby clarify the drivers of threshold, (2) to improve the parameter of runoff model and the control factor of threshold, and describe the runoff process under the influence of water cycle redistribution based on the revised model, (3) to build a series of different scenarios of revegetation, and simulate the soil water, evapotranspiration and runoff process, therefore reveal the corresponding water cycle redistribution under different revegetation scenarios. The results will innovate the theory of rainfall threshold for runoff generation and facilitate the understanding on water cycle redistribution, which can be a great support for the formulation of ecological restoration plan and water resources management strategies.

近30年来，全球植被显著增加，影响流域水热条件，土壤水、蒸散发和产流过程发生改变，径流呈现非线性与分异性并存的复杂特征。我国黄河中游流域在植被大规模重建影响下，降雨-产流阈值发生变异，产流过程不明，土壤水和蒸散发亦发生变化，植被重建影响下的水循环要素再分配不清楚。为此，本项目以黄河中游泾河流域为研究区，开展植被重建影响下降雨-产流阈值及水循环再分配研究，研究内容包括：（1）分析降雨-产流阈值的影响因素与阈值的关系，揭示阈值变化的驱动机制；（2）改善模型产流参数方案和阈值表征因子，开展流域水文模拟，阐明水循环要素再分配下的径流过程；（3）建立植被重建不同情景，基于分布式水热耦合模型，模拟流域土壤水、蒸散发及径流过程，阐明植被重建不同情景下水循环要素再分配。研究成果将在植被重建影响下的降雨-产流阈值理论和水循环再分配方面形成创新，为制定流域生态恢复方案和水资源管理措施提供决策依据。

近30年来，全球植被显著增加，影响流域水热条件，土壤水、蒸散发和产流过程发生改变，径流呈现非线性与分异性并存的复杂特征。我国黄河中游流域在植被大规模重建影响下，降雨-产流阈值发生变异，产流过程不明，土壤水和蒸散发亦发生变化，植被重建影响下的水循环要素再分配不清楚。针对上述问题，以黄河中游泾河流域等半干旱流域为研究区，开展了降雨-产流阈值与水文过程变化研究，（1）分析了关键影响因素与降雨-产流阈值的关系，阐述了阈值变化的驱动机制，（2）提出了相对蓄水容量概念，推导出相对蓄水容量垂向和空间分布曲线及其数学表达式，用以表征流域动态产流阈值，改善了水文模型的产流计算方案，解析了水循环要素再分配下的阈值变化及径流过程，（3）建立了基于动态时间扭曲的水文情势变化评估新方法，分析了植被重建影响下流域水文情势变化情况。研究成果在植被重建影响下的降雨-产流阈值理论和水循环再分配方面形成创新，为制定流域生态恢复方案和水资源管理措施提供了决策依据。