STRATIGRAPHIC FRAMEWORK MODELING FOR CONSTRAINING A HYDROLOGIC MODEL OF THE DENVER BASIN AQUIFER SYSTEM

A detailed stratigraphic framework is necessary to understand geologic controls on hydrologic responses in an aquifer system. A geologic framework for hydrologic models is commonly built from a variety of data and is often generalized during hydrologic model development. The purposes of this study are to use a Geographic Information System (GIS) to demonstrate how disparate data can be integrated in their true spatial context while maintaining a high level of consistency between the conceptual model of the system and the framework used in hydrologic modeling, and to test the effects of various stratigraphic interpretations on Denver Basin Aquifer System pumping scenarios. Geologic map data, stratigraphic picks from well logs, paleomagnetic data, pollen sample data, and digital elevation models within the Denver Basin Aquifer System were integrated using a GIS and three-dimensional geologic modeling software. As a result, the spatial distributions of the geologic units comprising the Denver Basin Aquifer System were redefined. A digital, three-dimensional stratigraphic framework model was developed for the entire Denver Basin Aquifer System. Properties critical to a hydrologic model were constrained within the stratigraphic framework and forced to follow patterns of geologic significance. This stratigraphic framework model is critical for visualizing three-dimensional geologic structures, permits transfer of detailed geologic information to a quantitative hydrologic model, and aids in the evaluation of ground-water resource depletion potential in the Denver Basin Aquifer System. Preliminary hydrologic modeling results indicate that minor variations in the stratigraphic framework produce significant differences in the predicted ground-water depletion.