Preliminary Evaluation of the Ground-Water-Flow System in the Twin Cities Metropolitan Area, Minnesota

摘要

A preliminary quasi-three-dimensional finite-difference ground-water-flow model of the seven-county Twin Cities Metropolitan area was constructed and used to evaluate parameter sensitivity and adequacy of available data. Fourteen geologic units that underlie the study area were grouped into nine hydrogeologic units and were incorporated into a five-layer model. Analyses of available data and results of steady-state simulations indicate that critical data needs for improving the simulation model include spatial and temporal variations in ground-water withdrawals and potentiometric levels, and hydraulic properties of the drift filling or partly filling bedrock valleys. Areal distribution of calcium, sodium, sulfate, and chloride concentrations were analyzed to provide information on the hydrologic and geochemical relationships between aquifers.