GEOLOGIC FRAMEWORK MODELS FOR SOCIETAL DECISION MAKING IN THE METRO-CHICAGO URBAN FRINGE

Subsurface geologic framework models (GFM) comprehensively describing rock and sediment body geometries and properties in 3D are required for robust and reliable process modeling used to guide societal decisions on the management of natural resources. GFMs require comprehensive and best-available geologic data, both descriptive and quantitative. Data are managed in a dynamic system with ongoing entry of new information and output for 2-D and 3-D digital modeling of lithology, lithostratigraphy, and structure.

Urban areas and urban-fringe communities have significant need for such information to use as guidance on pressing questions of resource character and occurrence, impacts of development actions/inaction, hazard avoidance, and sustainable management. Accordingly, the Illinois State Geological Survey has undertaken development and implementation of an integrated digital approach to creating subsurface GFMs as the platform for local/regional decision support. This program is aimed mainly at shallow groundwater resource issues and outcomes for the metropolitan Chicago region, which, with 7.5 million people in a 4-county area, is in great need of comprehensive geologic input to decisions.

The ISGS approach to creating GFMs of meto-Chicago has been to acquire and develop software tools, build and outfit facilities, and test and refine approaches via projects in cooperation with county and municipal governments. Projects have been funded using a combination of federal assistance via the National Cooperative Geologic Mapping Program, appropriated state funds, local funds and in-kind support. These programs are closing in on realization and demonstration of an integrated 3-D geological modeling approach, supported by digital data management, targeted drilling and seismic data collection for data infill and hypothesis testing, 3-D visualization, and immersive analysis/interpretation. They are emphasizing application of geologic knowledge to guide development and use of groundwater flow models, selection and refinement of interactive delivery tools for distribution of 3-D models, and development of custom 2-D derivative maps as decision support for stakeholders, mainly local and regional decision makers, government regulators and environmental and engineering consultants.