The Development of a Karst Feature Database for Southeastern Minnesota

Southeastern Minnesota is part of the Upper Mississippi Valley Karst (Hedges & Alexander 1985) that includes southwestern Wisconsin and northeastern Iowa. Karst lands in Minnesota developed in Paleozoic carbonate and sandstone bedrock. A significant sandstone karst has developed in Pine County (Shade et al. 2000). Most surficial karst features, such as sinkholes, are only in those areas with less than 50 ft (~15 m) of sedimentary cover over bedrock surface (Fig. 1). Few scientific descriptions of the Upper Mississippi Valley Karst exist. Nevertheless, the karst lands of southeastern Minnesota present an ongoing challenge to environmental planners and researchers and have been the focus of a series of research projects and studies for over 30 years. Since the early 1980s, the Minnesota Geological Survey and Department of Geology and Geophysics at the University of Minnesota have been mapping karst features and publishing various versions of their results in the form of 1:100,000 scale County Geologic Atlases. In the mid-1990s, the Minnesota Department of Natural Resources was assigned responsibility for the hydrogeology portions of the County Atlases and is now responsible for the karst mapping. Dalgleish and Alexander (1984a), Alexander and Maki (1988), Witthuhn and Alexander (1995), Green et al. (1997), Shade et al. (2001), and Tipping et al. (2001) published sinkhole distribution maps for Winona, Olmsted, Fillmore Counties, Leroy Township, Pine and Wabasha Counties respectively. Published atlases of Washington, Dakota, and the counties of the Twin Cites Metro area contain limited information on sinkhole occurrences. As geographic information systems, (GIS), global positioning systems, and web tools became more accessible to resource managers in the 1990s, the need for a state-wide, Web-accessible, and GIS-compatible karst feature base has become increasingly evident. Several factors hindered the development of this database. Karst features have not been inventoried in significant areas. Where data exist, they are often decades old and exist as difficult to obtain paper copies in researchers’ files. Several generations of students and workers have gathered the data, and the format, quality, and completeness vary greatly. The data were organized into county databases and incompatibilities between adjacent counties were introduced. All of these challenges only serve to emphasize the need for state-wide data sets and, indeed, for interstate compilations. A successful model for such a database already exists in Minnesota. The Geological Survey’s County Water-Well Index (CWI) successfully supplies current users with readily accessible information about Minnesota’s millions of water wells while continually updating and improving the database and delivery system. The Database Management System (DBMS) we are building builds on the lessons that have been learned from the CWI project. Experts in GIS, computer science and geology have constructed a karst feature GIS database that displays and allows analysis of sinkhole and other karst feature distributions across existing county boundaries. The ongoing research focused on the management of the GIS-based Karst Feature Database of Southeastern Minnesota, statistical analysis of karst feature distribution and sinkhole formation, and 2D and 3D visualization of karst feature distribution in southeastern Minnesota. THE DEVELOPMENT OF A KARST FEATURE DATABASE FOR SOUTHEASTERN MINNESOTA