黄土区潜水补给的方式、速率与控制因素

黄土区深厚不饱和区形成的“地下水库”主导流域水文过程，但地下水枯竭问题日益凸显，亟需调控地下水管理措施。然而，黄土区地下水的补给机制备受争议，且控制因子不明确，需要系统的研究来解析这些问题。针对潜水的上方来水(降水)和下方来水(承压水)补给的两类不同观点，考虑空间变异性选择地下水循环系统相对独立的多个黄土塬，考虑时间变异性动态采集降水、土壤水、潜水和承压水，考虑方法不确定性测定水样的水化学、稳定和放射性同位素等多种示踪剂含量。建立多种示踪剂联用的方法，判别活塞流、优先流和承压水补给潜水的主导性；基于示踪剂的质量平衡法，量化主导补给方式下的补给速率；分析补给的季节性和对暴雨的响应来探讨时间变异性，识别气候、土壤、植被和水文地质等对补给空间变异的主导性。考虑多种不确定性系统揭示黄土塬的地下水补给机制，获得的结果可外推到其他黄土区，推进对黄土区水文过程的理解，促进水资源的可持续利用。

The large groundwater reservior stored in the thick loess deposits dominates the watershed-scale hydrological processes; however, the groundwater is being depleted, and it is urgent to adjust the management of groudwater resources. However, the groundwater recharge mechanism in controversial, and the controlling factors of groundwater recharge remain unclear. It is thus urgent to clarify the groundwater recharge mechanism for sustainable management of groundwater resources. Multiple loess tablelands will be chosen as study areas to consider the spatial variability, while samples of precipitation, soil water, unconfined and confined groundwater will be collected dynamically to consider temporal variability, and multiple tracers including hydrochemistry, stable and radioative isotopes in water will be determined to consider the uncertainties in research methods. After developing the framework for combined application of multiple tracers, the domiance of piston flow, preferential flow or confined water to recahrge unconfined water will be evaluated. Using mass balance method of tracers, the recharge rates will be quantified. The seasonality and response to rainstorms of recharge will be investigated to discuss the temporal variability in recharge. The multicollinearity will be analyzed to investigate the dominance of climate, soil and vegetation on the spatially varied groundwater recharge. Taking into account the uncertainties from methods and spatiotemporal variability, the groundwater recharge mechanism in the loess tablelands will be discussed to the greatest extent. The results can be extrapolated to the whole Loess Plateau to improve the understanding of hydrological processes and sustainable utilization of water resources.