Development on or near bluffs and steep slopes often results in erosion, slope failure, landslides, and visual impacts to these sensitive natural features. Geological factors include bedrock type and location, soil type, slope angle. Hydrological factors include the quality of vegetation cover, intensity and duration of precipitation, and the presence of springs. The interaction of these factors affects bluff and slope stability. Land development and land alteration change the way water moves across and through the land and along with increased frequency and intensity of rainfall can increase risks.
Professional inventories and studies can help communities better assess failure risk, so they can put appropriate measures in place to ensure future development is safe and does not increase risk. To learn what other communities are doing and available resources, see:
Strategies for reducing the risk of slope failure will vary depending on local risk factors. General approaches include:
The following materials provide basic information on the risks and mitigation approaches for local governments and property owners:
It can be difficult to determine whether a slope meets the bluff definition without field verification. The DNR bluff mapping tool, combined with LiDAR-based elevation data, can analyze slope features to identify where bluffs may exist.
The Minnesota DNR Bluff Mapping Tool is a GIS-based add-on available on the Minnesota Geospatial Commons. This tool is only for planning purposes. A field survey would be necessary to locate more definitive bluff boundaries for building purposes.