Updating the Minnesota Wetlands Inventory: Phase 2

PROJECT OVERVIEW
The National Wetland Inventory, a program initiated in the 1970s, is an important tool used at all levels of government and by private industry and non-profit organizations for wetland regulation and management, land use and conservation planning, environmental impact assessment, and natural resource inventories. The data behind the National Wetlands Inventory for Minnesota is now considerably out-of-date and a multi-phase, multi-agency collaborative effort coordinated by the Minnesota Department of Natural Resources is underway to update the data for the whole state. This appropriation is being used to conduct the second phase of this effort, which involves updating wetland maps for 13 counties in east-central Minnesota surrounding the greater Twin Cities metropolitan area, evaluating imagery sources and mapping technologies for use in future mapping of agricultural regions of the state, and acquiring additional data needed to update wetland maps for southern Minnesota.

OVERALL PROJECT OUTCOME AND RESULTS
Updated wetland maps were created for 13 counties in east-central Minnesota (7,150 square miles), encompassing the Twin Cities metropolitan area. Wetlands in Minnesota were originally mapped by the U.S. Fish and Wildlife Service in the early 1980's as part of the National Wetlands Inventory (NWI). Although still widely used for land use planning, wetland permit screening and natural resource management, the original maps have grown increasingly out-of-date due to landscape alterations over the years. The data created for this project marks the first significant update to the NWI in Minnesota.

The new maps are much more accurate, capture more detail, and provide more information than the original maps. Besides showing the location, size, and type of each wetland, the updated map data includes information on the wetland's landscape position and hydrologic characteristics, which can be useful in assessing the benefits provided, such as water quality improvement, flood storage, and fish and wildlife habitat. Updating the NWI is a key component of the State's strategy to monitor and assess wetlands in support of efforts to assure healthy wetlands and clean water for Minnesota. The DNR is planning to complete the NWI update for the entire state by 2020.

Accomplishments for this project phase also include acquiring high-resolution, spring leaf-off digital aerial imagery for 23,900 square miles of southern Minnesota, acquiring field validation data for southern Minnesota, and developing wetland mapping procedures for the agricultural region of Minnesota.

PROJECT RESULTS USE AND DISSEMINATION
Imagery acquired for this project is available to the public through the Minnesota Geospatial Information Office (MnGeo): http://www.mngeo.state.mn.us/chouse/wms/geo_image_server.html. The MnGeo imagery service receives about one million page requests per month for the southern Minnesota imagery. This is the first publicly available leaf-off imagery data for southern Minnesota since 1991.

The updated wetland map data are available through an interactive mapping application on the DNR's website at: http://www.dnr.state.mn.us/eco/wetlands/map.html. The data can also be downloaded, free of charge, for use in geographic information system applications through the DNR's data deli at: http://deli.dnr.state.mn.us/. The data will eventually be incorporated into the national "Wetland Mapper" application maintained by the U.S. Fish and Wildlife Service.

The wetland mapping procedures and accuracy results for the 13-county updated NWI data are presented and discussed in a manuscript that has been submitted to the journal Wetlands, a publication of the Society of Wetland Scientists (SWS). Information from this project was also presented at the SWS annual conference in Duluth, MN in 2013. In addition, a press release was distributed regarding the updated NWI data and the story was published on several online news websites.

Researchers at the University of Minnesota Remote Sensing and Geospatial Analysis Laboratory conducted an extensive study of the effects of digital elevation model (DEM) preprocessing and mapping methods on the accuracy of wetlands maps in three different physiographic regions of Minnesota. This research covered two study sites in agricultural areas including the Minnesota River Headwaters (Big Stone County) and Swan Lake (Nicollet County) as well as a comparison site from northern Minnesota (St. Louis and Carlton Counties). The results of this effort were compiled and submitted for publication in several peer-reviewed scientific journals along with results from the earlier phase of the NWI update project. Three hard copies and one electronic copy of these publications have been submitted with the final report to LCCMR. There have also been numerous presentations at professional conferences.

Project Publications:

• Influence of Multi-Source and Multi-Temporal Remotely Sensed and Ancillary Data on the Accuracy of Random Forest Classification of Wetlands in Northern Minnesota (PDF - 2.7 MB)
• Comparison of Flow Direction Algorithms in the Application of the CTI for Mapping Wetlands in Minnesota (PDF - 15.3 MB)
• The Effects of Data Selection and Thematic Detail on the Accuracy of High Spatial Resolution Wetland Classifications (PDF - 0.2 MB)
• A semi-automated, multi-source data fusion update of a wetland inventory for east-central Minnesota, USA (PDF - 1.4 MB)
• Wetland Mapping in the Upper Midwest United States: An Object-Based Approach Integrating Lidar and Imagery Data (PDF - 1 MB)