Temporal variations in water resources and water supply structure in Beijing

Men Baohui; Gao Hongbo; Bian Zongzhen; Zhou Xiaoxiao; Wang Hongrui

doi:10.13522/j.cnki.ggps.2025332

Abstract：[Objective]Beijing is a typical water-scarce megacity facing chronic water supply deficit.Alongside the optimization of regional water resource allocation,understanding temporal variations in water resources and water supply structure is crucial for improving water management and ensuring sustainable water utilization.This paper analyzes the dynamic changes in water resources and water supply structure in Beijing.[Method]Based on four decades of observational data,we constructed a framework by integrating the Copula function and convergent cross mapping(CCM)method to explore the nonlinear correlation between precipitation and total water resources and identify their causal relationships.Using this framework,we further analyzed temporal variations in Beijing's water resources.[Result]Overall,water resources in Beijing have exhibited a fluctuating upward trend over the past four decades;they show a strong correlation with precipitation.Significant upper-tail dependence exists between precipitation and water resources,with a correlation coefficient of 0.811,indicating high synchronicity during extreme wet hydrological events.A bidirectional mutual causal relationship was detected between precipitation variability and regional water resources.Thanks to the water supplies from the middle South-to-North Water Diversion canal and increased reuse of reclaimed water,the water supply structure in Beijing has undergone profound transformation over the past four decades.[Conclusion]The increased use of reclaimed water and water diverted from the Yangtze River Basin has reduced groundwater overexploitation.Interannual precipitation variations are key factor affecting regional water resources,underscoring the necessity of improving water resource management in the region.