Simulation of Underground Freshwater Exploitation and Analysis of Environmental Impact in Hangzhou Bay New Area, China

The Hangzhou Bay New Area is located in a coastal plain area where the groundwater storage environment is relatively fragile and lacks water resources. Recognizing the regularity of groundwater circulation in this area and conducting an analysis of the evolution of groundwater quality can provide support for its potential as an emergency groundwater source. In order to assess the impact of emergency groundwater extraction on the surrounding environment, a 3-D groundwater flow and a solute displacement model were developed to quantify changes in water level, groundwater recovery capacity, salinity, and landing funnel. The numerical model was calibrated by values recorded with the actual observation well and solved by MODFLOW and MT3DMS modules in GMS (groundwater modeling system). The simulation results indicated that under the conditions of emergency grades I, II, and III, the maximum depths of the water level in the half year of mining were 38.5 m, 24 m, and 18.5 m, respectively, the areas of dropping funnel were 53.75 km2, 33.026 km2, and 25.273 km2, respectively, and the widths of saltwater intrusion were 931 m, 585 m, and 413 m, respectively. The numerical simulation provides a reference for the rational allocation, development, and utilization of groundwater resources in the emergency water source area of the Hangzhou Bay New Area.