The Indiana Silver Jackets Hazard Mitigation Task Force has initiated a multi-agency program to identify, study and provide mitigation planning resources for communities who would like to adopt Fluvial Erosion Hazard (FEH) avoidance strategies. The resources provided by this project enable individuals and communities to better recognize areas prone to natural stream-erosion processes and adopt strategies to avoid FEH-related risks. The FEH features define approximate setbacks for communities to better manage river corridors. The setbacks vary based on the stream’s recent migration history (actively migrating or relatively stationary).
For actively migrating and relatively stationary streams, a GIS analysis algorithm generated bankfull width values for each stream segment using regional curves that are based on drainage area within each physiographic region in Indiana. For relatively stationary streams, the analysis used these values to create buffer zones of at least one bankfull width on each side (a total corridor width of 3 times bankfull width) or 100 feet on each side of the bank, whichever is greater. For actively migrating streams, GIS generated a total corridor width of 8 times bankfull width, which was manually edited and refined to reflect the digital elevation model and stream meander evidence.
It should be noted that the refined corridors were created at a map scale of approximately 1:10,000 to 1:15,000. The depicted areas are not meant to be accurate beyond providing an approximate boundary of potential stream migration. This data is provided for informational purposes only, and is not intended for use in project design or parcel level site analysis. A more detailed analysis of the localized geology and fluvial mechanics is necessary for the proper evaluation of the fluvial erosion hazard.
Local counties and communities wishing to adopt these maps as the basis of their erosion hazard mitigation programs would need to establish guidelines and protocols to allow the acceptance of more detailed procedure and data than that used as part of the Indiana Silver Jackets erosion hazard mapping program.
Indiana Fluvial Erosion Hazard mitigation maps and data are hosted by the Indiana Department of Natural Resources and are available at:https://indnr.maps.arcgis.com/apps/webappviewer/index.html?id=43e7b307a0184c7c851b5068941e2e23