Abstract

Mississippi River Floodplain Delineation for FEMA Flood Insurance Rate Maps
Track: Water Resources
Author(s): Michael Mechenich

The Federal Emergency Management Agency is in the process of updating its Flood Insurance Rate Maps. The work often involves transferring existing floodplain boundaries, based on existing studies, from paper to digital form. When a new study has been conducted, and revised flood elevations obtained, new floodplain boundaries may be delineated. The process involves the creation of a land surface DEM and a flood surface DEM, and the intersection of the two to obtain an area of flooding. For the Mississippi River, land surface data comes largely in the form of LIDAR acquired by the U.S. Army Corps of Engineers, flood surface data from cross sections used in the 2004 USACE Flow Frequency Study. The delineation is done using simple Python scripts and tools available in the 3D Analyst extension. After careful cleanup and incorporation into the new maps, the floodplain becomes the basis for management and regulation.

Michael Mechenich
Illinois State Water Survey
2204 Griffith Drive
Champaign , Illinois 61820
United States
Phone: 217-244-2774
E-mail: mmecheni@uiuc.edu