Orange County Branch Newsletter
Natural Valley Procedure for Hydraulic Analysis and Floodplain Mapping of Non-Accredited Levee Systems Using HEC-RAS 2-D
In the August luncheon, Dr. Dragi Stefanovic of Tetra Tech, Inc., presented a new procedure for hydraulic analysis and floodplain mapping of “Without Levee” (Natural Valley) conditions in accordance with latest FEMA guidelines for Analysis and Mapping of Non-Accredited Levee Systems. An unsteady hydraulic model (HEC-RAS) is developed to analyze flows in the main river, while two-dimensional flood routing (HEC-RAS 2-D) is utilized for the floodplain mapping on the landward side of a levee. The advantages and challenges of the new approach are discussed with special emphasis on the long awaited HEC-RAS Version 5.0 featuring a two-dimensional modeling component.