Simulation of ground water flow in the Glaciofluvial, Saginaw, Parma-Bayport, and Marshall Aquifers, Central Lower Peninsula of Michigan

Abstract

A steady-state finite difference model was developed to simulate ground-water flow in four regional aquifers in Michigan's Lower Peninsula. The Glaciofluvial, Saginaw, Parma-Bayport, and Marshall aquifers were simulated as layers 1 through 4, respectively, in the model. Separately calculated vertical conductances input to the model were used to simulate the intervening Till/"Red Beds", Saginaw, and Michigan confining units, respectively. The model domain was laterally bound by a continuous specifiedhead boundary, formed from Lakes Michigan, Huron, St. Clair, and Erie, together with the St. Clair and Detroit River connecting channels.The model was developed to quantify regional ground-water flow in the aquifer systems using independently determined recharge estimates. The flow model showed that groundwater heads and flows in the Glaciofluvial aquifer are controlled by local stream stages and discharges, resulting in localized flow cells accounting for 95-percent of the overall model water budget. Simulation of recharge to an unspecified water table also enabled the estimation of ground-water discharge to three Great Lakes.A computer diskette contains all MODFLOW and MODFLOWP input files, as well as digital model surfaces and several Fortran processing routines used to construct the surfaces. The diskette also provides the data used for calibration and sensitivity analysis.

Constraining groundwater flow in the glacial drift and saginaw aquifers in the Michigan Basin through helium concentrations and isotopic ratios

“…Glacial Drift aquifer recharge distances were estimated by considering the distance between the locations with highest hydraulic head values in southern Michigan as given by Hoaglund et al . () and the location of the respective samples.…”

“…() and Hoaglund et al . (); U, Th, and Li estimated from average lithological composition after Parker () and Tolstikhin et al . ().…”

“…This velocity range is consistent with results obtained through pumping tests (Mandle & Westjohn ) and groundwater flow modeling (Hoaglund et al . ). This reduction in the velocity field toward the discharge area is also in agreement with the observed decrease in hydraulic gradient (Fig.…”

“…); 5.37 m yr −1 for the Saginaw aquifer (Mandle ; Hoaglund et al . ; Castro et al . ), and 2.9 m yr −1 for the Marshall aquifer (Mandle ; Hoaglund et al .…”

“…However, Hoaglund et al . (, ) have argued that aquifers under the Lake Michigan lobe equilibrated back to steady state relatively quickly following the retreat of the LIS. In addition and more recently, groundwater flow simulations in both steady and transient states led to the establishment of similar groundwater flow patterns in the Michigan Basin (McIntosh et al .…”