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Understanding Floodplain Connectivity in Indiana

Robert C. Barr
Research Scientist
Center for Earth and Environmental Science
Department of Earth Sciences
IUPUI - Indiana Fluvial Erosion Hazard Mitigation Program, Indiana FEH
Indianapolis, IN

Authors:  Robert Barr, Center for Earth and Environmental Science, Department of Earth Science, IU-Indianapolis
Ian Hahus, Christopher B. Burke Engineering, LLC
Cassie Hauswald, The Shine Foundation
Michael Dunn, The Nature Conservancy

The Indiana Fluvial Erosion Hazard Mitigation Program (Indiana FEH), in collaboration with The Nature Conservancy is using a novel GIS tool to do watershed-scale, reconnaissance-level mapping of floodplain connectivity. The tool uses the Indiana Regional Curves integrated into the State USGS StreamStats web application to deliver rapid delineation of floodplain connectivity. The tool has been used successfully in four river basins across the three broad physiographic regions of Indiana. Success has been determined by field observations and expert review by local floodplain and stormwater managers. The work is part of TNCs efforts to better educate Federal, State, and local agencies on the importance of natural infrastructure and to determine critical floodplain areas for preservation and reconnection. A secondary goal as the work continues is to be able to determine what percentage of the State’s rivers are functionally connected to their floodplains and at what river stages those connections become available. Additionally, the work shows promise for helping to identify other important geomorphological attributes of the stream, such as identifying stream reaches where stream power is increasing due to channel incision. Such locations can be self-reinforcing and lead to systemic bank failures and water quality degradation. The connectivity maps are also being tested for their ability to assist in high-level habitat evaluations for certain organisms, such as finding optimal locations for reintroduction of mussel species that have been locally extirpated. In this presentation we will review the tool, how it works, and show examples from ongoing work.