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Natural flood management - planning and priorities for the Lake Superior’s south shore watersheds
Citation:
Hollenhorst, T., M. Wick, K. Magyera, AND F. Fitzpatrick. Natural flood management - planning and priorities for the Lake Superior’s south shore watersheds. Wisconsin Wetland Association Virtual Meeting, Duluth, MN, February 16 - 19, 2021.
Impact/Purpose:
Flood and coastal erosion risk can be reduced by implementing measures that help protect, restore and emulate natural functioning of catchments. These can include increased watershed storage, catchment and channel roughness and reconnection riparian areas. These techniques and analyses can then be helped to identify potential erosion hazards to protect vulnerable road-stream crossings. ********
Description:
Tributaries along the south shore of Lake Superior are known for severe flooding problems due to steep terrain, highly erodible soils and flashy hydrology. Reducing flood and coastal erosion risk involves implementing measures that help to protect, restore and emulate the natural functions of catchments, floodplains, rivers and the coast. We explored various natural flood management concepts for slowing the flow and mitigating flood effects in several watersheds along Lake Superior’s south shore. These included increasing storage, catchment and channel roughness, reconnecting riparian areas and other potential best management practices for natural flood management. To help prioritize areas where erosive flows might be mitigated, we assessed peak flow to drainage area ratios, potentially restorable wetlands and the proportion of open lands for catchments, watersheds and sub-watersheds throughout Lake Superior’s south shore. We also employed the Height Above Nearest Drainage (HAND) method of mapping riparian areas to help identify potential areas for reconnecting flood plains. These efforts will be used to help identify potential fluvial erosion hazards, such as the locations and extent of incised channels, gullies and eroding ravines and opportunities to repair degraded headwater streams, floodplains and wetlands to protect and improve vulnerable road-stream crossings.