生态补水是保持白洋淀水位，改善生态环境的重要保障。生态补水在流经高渗漏的自然河道时，水量损失过半；大流量、长时序的生态补水改变了河道水文条件，影响了周边厚包气带、大埋深的地下水，因此，从地表水与地下水相互作用的角度，研究生态补水对河岸带地下水的影响具有重要意义。本项目选取南水北调中线向白洋淀补水的典型河道，将河道－包气带土壤－地下含水层作为统一连续体，在定位观测、野外采样，室内测试的基础上，以氢氧稳定同位素示踪水分的运动、氮氧同位素识别氮污染的来源，综合运用多元环境同位素和水化学的方法，刻画地下水水位对补水“脉冲”响应的时空图谱，明确河道内生态补水对河岸带地下水的影响范围；阐明生态补水与地下水的定量相互作用关系；揭示生态补水影响下，河道-包气带-地下含水层中的水分运动和氮磷污染物迁移规律，解析生态补水过程对河岸带地下水的影响机理，为提高河道生态补水效果，改善白洋淀生态环境提供科学基础。

Ecological replenishment is an important guarantee for maintaining the water level of Baiyangdian Lake and improving the ecological environment. More than half of the replenishment water is loss, when the ecological hydration flows through the high-leakage natural river channel. The large-flow, long-time ecological hydration changes the hydrological conditions of the river, affecting the surrounding thick-vadose zone and the large-buried-depth groundwater. Therefore, it is important to study the impact of ecological hydration on groundwater in the riparian zone as the perspective of interaction between surface water and groundwater. The typical river channel of the Middle line of South-to-North Water Transfer Project is selected, taking the river channel -vadose zone- aquifer as a unified continuum. Based on the observation, sampling and analysis, the stable isotope of hydrogen and oxygen is used to trace water movement, nitrogen and oxygen isotope is used to identify the source of nitrogen pollutants. Multi-environmental isotope and water chemistry methods are used to describe the spatial and temporal map of groundwater level response to ecological replenishment "pulse", to clarify the ecological water supply in the river channel to the riparian groundwater, to clarify the quantitative interaction relationship between ecological replenishment and groundwater, to reveal the water movement and characteristic pollutant migration law in river channel - vadose zone- aquifer under the influence of river ecological water replenishment, and to analyze the ecological hydration process on riparian groundwater The impact mechanism provides a scientific basis for improving the ecological replenishment effect of the river and improving the ecological environment of Baiyangdian.