A Landform-Based Approach to the Estimation of Groundwater Recharge in Complex Glacial Topography

Abstract

The estimation of recharge in complex glacial topography is difficult to determine. This study utilizes an inverse numerical groundwater model and applies a landform-based approach to estimate this parameter in the stagnation complex of the Itasca moraine in north-western Minnesota. The landform assemblages were defined based on their glacio genie origin as well as topography, sedimentology, and stratigraphy. The Itasca moraine was chosen based on the numerous sedimentological and topographically distinct landform assemblages present. Eight separate landform assemblages were delineated and used as fundamental hydrostratigraphic units, each assigned specific parameters based their individual characteristics. The numerical flow simulation was set up in MODELCAD and run under steady state conditions with MODFLOW. The model was calibrated by varying the spatial distribution of recharge over each landform assemblage. A recharge value and range of recharge was determined for each landform assemblage.