Unstructured Modflow Model for Numerical Simulations of Groundwater Flow in Three-Dimensional Quaternary Aquifer of Beijing Plain, China

Numerical simulation models are very useful for assessing groundwater flow and levels in a given region. With the scarcity of available groundwater resources after the 2000s, the city of Beijing adopted policies for the rehabilitation of these resources. This study establishes a numerical simulation model that evaluates the influence of these projects on groundwater levels over a given period. To achieve this, an unstructured model was established for the Beijing Plain region and run using GMS 10.6 software with a finer mesh around reservoirs, water stations, major rivers and flow boundaries. The calibration and the identification results indicated a correlation R2 = 0.98 between calculated and observed heads. The model’s accuracy is good and the overall average relative error is less than 20%. The comparison of the calculated water balance with the results of numerous studies shows that the reliability of the equilibrium analysis result is relatively high. The groundwater numerical model is running to simulate the water level over a period of 15 years. Groundwater generally flows in a northwest/southeast direction. The simulation results also demonstrate the impact of some projects related to the South-to-North Water Transfer Project implemented for the restoration of overexploited groundwater resources. The model predicts a stabilized and significantly increasing groundwater level at the center of the Beijing area.