Modelling of regional groundwater flow in Beijing Plain

A 3D transient groundwater flow model was established for Beijing Plain.The purposes of the model are to analyze current status and to predict future trends in groundwater resources.The model will be used also to simulate various groundwater resources development scenarios.A digital hydrogeological conceptual was constructed using all sorts of spatial and temporal data.A quasi steady state model was calibrated using the average values of water balance components in 1995 when groundwater levels show an equilibrium state.The steady state model created the initial conditions for a transient model.The transient model simulation time is from 1995 to 2005 with month as stress period.The transient model was calibrated against measured groundwater level series.The calibrated model was used to analyze groundwater flow systems and water balance.Compared to the 1960s,decline of groundwater levels occurred regionally,cone of depressions has been formed in aquifers of different depth.The consecutive drought years from 1999 to 2005 has caused dry rivers and reduced groundwater recharge.Operation of emergency well fields to meet demand of urban water supply has accelerated the decrease of groundwater levels.If current situation continues,groundwater in Beijing Plain will be depleted,a reduction in abstraction is urgent to achieve long-term groundwater sustainable development.