2017 Excellence in GIS Award Winner – Education and Nonprofit

Excellence in GIS – Education and Nonprofit – Environment, Health & Safety

Soil Based Flood Inundation Maps for Indiana

Considering the increasing threat of floods and the associated damages, there is a need to have flood risk information for all streams in Indiana. Most flood insurance rate maps from Indiana cover major rivers in urban areas, but many lower order streams in rural areas do not have any information on floodplains. Considering the cost associated with preparing such maps through engineering studies, it is not feasible to conduct engineering studies for all streams in Indiana. The challenge is to come up with an alternative and more economical way to get floodplain maps for all streams in Indiana

Dr. Venkatesh Merwade, in collaboration with Indiana Silver Jackets, and funding from the Indiana Office of Community and Rural Affairs (OCRA) developed a soil-based approach for mapping the floodplains in Indiana. This proposed approach is based on the public domain SSURGO soil database that is available from the Natural Resources Conservation Services (NRCS) for the entire United States. This simple approach uses key attributes from the SSURGO database along with some historical information on floods collected during the soil survey to map the floodplains. Using this approach, one can create a floodplain map for any county in Indiana or any other state in just few hours. In this project. Dr. Merwade’s group created the maps for all counties in Indiana and compared these maps to available FEMA maps for validation. Overall, the soil-based floodplain maps overlap close to 80 percent, which is very good considering that FEMA maps too are not accurate and have uncertainty associated with them.

The soil based floodplain maps for all counties in Indiana are now available through Purdue University Libraries web site.  These maps provide a useful resource for all communities and flood management officials where no other information on flood risk exists.  Considering the success of this project for Indiana, soil based floodplain maps were created for the entire contiguous U.S.

Dr. Venkatesh Merwade, Lyles School of Civil Engineering, Purdue University

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