Methodology to Incorporate Historic/Prehistoric Surface Hydrology layer in Mn/Model Using Existing GIS Data

Project summary:

The goal of this research was to develop methods for identifying indicators of historic and prehistoric surface hydrologic features in available Geographic Information System (GIS) data to create a GIS layer representing relict hydrography for inclusion in Mn/Model, the Minnesota Department of Transportation's statewide archaeological predictive model. The research addressed the limitations imposed on the current predictive model by the absence of historic and prehistoric surface water features, such as drained lakes and wetlands. Because several important variables are derived from surface hydrography in Mn/Model, the use of historic/prehistoric hydrologic features, instead of strictly modern features, will greatly improve its predictive accuracy. Historic and prehistoric hydrologic features were primarily recognized by the presence of hydric soil map units in the Soil Survey Geographic data (SSURGO) data using taxonomic great groups, hydric rating, and drainage classes. Drained wetlands (where available), geomorphology, landform sediment assemblages, National Wetland Inventory (NWI), and other GIS datasets were used to clarify the extent and shape of historic water features based on the previously identified soil types. The National Wetlands Inventory (NWI) and Minnesota Department of Natural Resources surface hydrology data defined modern hydrography for this study. Georeferenced US General Land Office Survey (GLO) plat maps defined historic hydrography. Prehistoric hydrography was defined as any feature not present in modern data or in the GLO record. This research resulted in an automated tool, developed using ArcGIS ModelBuilder and based on ESRI ArcGIS ArcInfo 9.2, which can be used on any county in the state where the input data are available. Four tools were created in an ArcGIS Toolbox named "MnModel Historic Features Tools." Together, the tools produce a reasonable vector representation of historic/prehistoric lake, wetland, and riverine features from existing GIS data at a 1:24,000 scale. Each tool produces a shapefile that can be used separately or with the output from the other tools. Additionally, it is possible to combine the outputs from the four tools and Landform Sediment Assemblages (where available) into a shapefile containing key fields that distinguish the polygons by the source of the record, how it was derived (e.g., soils, topography), and the feature type (lake, wetland, river).