Characterization of aquifer heterogeneity and tracer test simulations by incorporating geologic information in the form of outcrop analog and well core at a distal and medial outwash aquifer in Schoolcraft, Michigan

The integration of geostatistics and geologic data in the form of outcrop analogs and well core produced detailed models of aquifer heterogeneity using two methods, zonal kriging and transition probability geostatistics (Carle and Fogg, 1996). This study was conducted at the Schoolcraft Plume A site, located in Kalamazoo County, Michigan. Sediments at this site were deposited as outwash medial and distal to the Kalamazoo Moraine. Using core data from the site and outcrop analog data from nearby sand and gravel pits, the aquifer was separated into major sedimentologic units to preserve abrupt changes in hydraulic conductivity and to better honor the assumption of stationarity. For the first geostatistical method, zonal kriging was used to estimate hydraulic conductivity distribution. After geostatistic estimation all the zones were combined to produce a complete aquifer realization. A non-zonal krige was also generated using the same conditioning data but without the geologically based zones. Both the zonal krige and the non-zonal krige hydraulic conductivity values were used as inputs for three dimensional ground water flow models and transport simulations. The zonal krige more accurately simulates the migration of an injected tracer pulse.