Following the extreme flooding that occurred in March and August of 2016, St. Tammany Parish identified the need for better flood risk products to support planning of regional drainage improvement projects and to improve emergency response during extreme weather events. Since January of 2017, Duplantis Design Group with support from CE Hydro, has provided planning and modeling services to St. Tammany Parish to improve flood risk awareness and reduce flood risk in the Tchefuncte River Basin. Through a comprehensive inventory of existing H&H models in St. Tammany Parish, DDG identified an existing regional 2D HEC-RAS 5 model originally developed by USACE to evaluate impacts following the 2016 storms. The model was significantly improved by integrating channel geometry from previous basin-wide studies including the most recent models completed in support of FEMA’s Flood Insurance Study for St. Tammany Parish. The model was calibrated for multiple events.
The new 2D model was used as the basis of a Dynamic Flood Inundation Mapping (DFIM) tool developed by CE Hydro. The DFIM tool, prepared specifically for St. Tammany Parish, produces forecasted inundation extents in real time based on observed and forecasted precipitation and tidal boundary conditions. The main component of the tool is a Python program, a widely used general programming language. In the future, St. Tammany Parish emergency managers will be able to use this application to increase response times, identify evacuation routes, inform road closures, and many other benefits.
In addition to the DFIM tool, DDG and CE Hydro are using the 2D model to identify and evaluate locations for regional detention to reduce the risk of flooding in the Tchefuncte River Basin. The results of the modeling analysis will be used in the future to support a FEMA grant application and serve as the basis of project design.