Determination of groundwater recharge rates in the North China Plain using

半干旱的华北平原（NCP）人口稠密，水资源短缺，这一点从河流干涸和地下水位迅速下降中可见一斑。特别是地下水，是一种质量好、数量有限、更新有限的重要水资源。本项目旨在通过地球化学和地球物理数据与地下水动力学综合模型的整合，为该地区宝贵的地下水资源的可持续管理提供关键信息。对环境示踪剂（稳定同位素、14C、氚、惰性气体等）的分析可以确定地下水的停留时间和补给速率。数值地下水流动和输送模型能够将水力和示踪数据集成到具有预测能力的系统的机械视图中。该项目建立在主要研究人员之前的工作基础上，他们已经建立了一个地下水模型和石家庄地区的示踪数据集，石家庄地区是一个主要的补给区，也是长江流域过度开采最严重的地区之一。该项目将结合这两种方法，并将其扩展到整个NCP的规模，以便更好地了解补给速率和机制。德国合作伙伴收集的示踪剂数据将提供不可或缺的地下水补给和年龄数据，大大减少中国合作伙伴正在开发的模型的不确定性。相反，该模型提供了整合和解释德国合作伙伴收集的数据集的基本工具。这种联合方法还将为与参与中德水资源联合倡议的其他研究小组建立联系提供许多机会，从与地下水示踪剂解释相关的地块尺度上的不饱和带研究，到与流域尺度上的地下水模型相关的气候和遥感数据。

The semi-arid North China Plain (NCP) is heavily populated and suffers from water scarcity, made evident by the drying-up of rivers and by rapidly falling groundwater levels. Especially the groundwater represents a vital water resource of high quality but finite quantity and limited renewal. This project aims to provide key information for the sustainable management of the precious groundwater resources in this area by integration of geochemical and geophysical data with a comprehensive model of the subsurface water dynamics. The analysis of environmental tracers (stable isotopes, 14C, tritium, noble gases, etc.) enables determination of groundwater residence times and recharge rates. Numerical groundwater flow and transport models enable the integration of hydraulic and tracer data into a mechanistic view of the system with predictive capabilities.The project builds on previous work of the principal investigators, who have established both a groundwater model and a tracer data set from the Shijiazhuang area, a major recharge area but also one of the most heavily overexploited parts of the NCP. This project will combine the two approaches and expand them to the scale of the entire NCP in order to arrive at a much better constrained and detailed understanding of the recharge rates and mechanisms. The tracer data gathered by the German partner will provide indispensible groundwater recharge and age data to significantly reduce the uncertainty in the model being developed by the Chinese partner. Conversely, the model provides an essential vehicle to integrate and interpret the data sets collected by the German partner. The combined approach will also offer many opportunities for links with other research groups taking part in the Sino-German joint initiative on water resources, ranging from studies of the unsaturated zone at the plot scale that are relevant for the interpretation of the groundwater tracers to climatological and remote sensing data that can be linked to the groundwater model on the basin scale.