Two Dimensional Capability Expands Flood Modeling Applications (Source: Worldwater: Stormwater Management)

Feb 8, 2017

By Luis Alday

The National Flood Insurance Program’s (NFIP) goal is to diminish the impact of flooding on private and public structures. It does so by providing affordable insurance to property owners and by encouraging communities to adopt and enforce floodplain management regulations. Hydraulic models have played a critical role in helping agencies and engineers determine floodplain limits.

The Federal Emergency Management Agency (FEMA) presents a listing of nationally and locally accepted hydraulic models that meet NFIP’s requirements for flood hazard mapping activities. The list comprises models that professional engineers can utilize to perform engineering analysis and mapping for flood insurance studies. The approved hydraulic models can be divided into:

• One-Dimensional Steady Flow Models
• One-Dimensional Unsteady Flow Models
• Two-Dimensional Steady/Unsteady Flow Models\

The U.S. Army Corps of Engineers (USACE) Hydrologic Engineering Center’s River Analysis System (HEC-RAS) computer program is generally used in the preparation of studies and re-studies for the NFIP. In February 2016, HEC-RAS released Version 5.0 of the program with the added ability to perform two-dimensional (2D) hydrodynamic flow routing within the unsteady flow analysis portion of HEC-RAS.