Hydrogeological and Hydrogeochemical Characterization and Implications for Consumptive Groundwater Use of a Large Glacial-Drift Aquifer System in Southwest Michigan. Part 2.

摘要

A steady state simulation of the regional groundwater flow system was developed in order to (1) better understand the data needs for an improved model and (2) provide an estimate of the impacts that groundwater withdrawals have on groundwater discharge to streams, wetlands and lakes in the Schoolcraft aquifer. A 2-D finite element model was utilized to simulate groundwater flow. Evapotranspiration from the wetlands was modeled as a linear function of water table elevation. The model was used to obtain a steady state solution prior to groundwater pumping. The modeling provided an excellent means for identifying additional data needs, which include data on the geology that influences flow at the boundaries of the modeled region and in the vicinity of wetlands. The model was run to obtain the impacts of groundwater withdrawals in order to provide a complete picture of the method of analysis and an estimate of the impacts that pumping has on streams and wetlands. Eighty nine pumping wells were incorporated into the model. Analysis of the simulation results showed that six wetlands in the study area were effected significantly by pumping. The simulation results also indicated that the reduction in groundwater flux to streams and lakes was higher than the reduction in groundwater flux to wetlands because of the distributions of the pumping wells. As more data become available on the geology and hydrology it will make sense to improve the description of model features and obtain an improved assessment.