GIS-BASED THREE-DIMENSIONAL GEOLOGIC AND HYDROGEOLOGIC MODELING OF THE MILAN, OHIO 1:24,000 QUADRANGLE
We used the detailed three-dimensional geologic model and merged it with an equally detailed groundwater-flow model to produce a more realistic understanding of the controls that glacial geology and geomorphology exert on shallow ground-water flow systems. The top of the geologic model was the surface topography (digital elevation model), which was also used to derive the drainage network that is an important boundary condition in the ground-water flow model. The bottom of the geologic model was the top surface of the Devonian Ohio Shale. Flow in the shallow saturated zone reflected strong control by surface topography and assumed hydraulic properties of the mapped sedimentary units. In contrast, the flow at depth was not strongly influenced by the topography of the Ohio Shale but did show some tendency for regional flow toward Lake Erie.
The resultant three-dimensional geologic model and companion ground-water modeling results can be used to produce a range of derivative products such as maps of recharge and discharge areas. Such products can be used to address the wide variety of water management, land use, environmental, and resource issues that are crucial to local, state, and federal agencies, private industry, and the general public.