Graphical representation of flood inundation for NWS flood categories are based on steady state hydraulic modeling of water surface elevations for incremented discharges. Map shows approximate inundation areas for given water surface elevations and should not be used for navigation or permitting or other legal purposes, but strictly as a planning reference tool.
Site-specific information:
The purpose of a flood forecast inundation map is to communicate flood risk based on best available information at the time of map development. This flood forecast inundation map has been compiled using the best information available and is believed to be accurate; however, its preparation required many assumptions. Actual conditions during a flood event, such as natural phenomena e.g. sedimentation, erosion, debris build-up, cascading escalating risks or man-made interactions, e.g. flood protection measurements from sandbagging to exercising varying flood operation schema may vary from those modeled in the map. The limits of flooding shown should only be used as a guideline for emergency planning and response actions. Actual areas inundated will depend on specific flooding conditions and may differ from the areas shown on the map.
The risk of flooding behind levees depends on many factors that cannot be entirely predicted in advance. These factors include whether the levee overtops, length of time the levee overtops, whether the overtopping leads to breach formation, and whether weakness in the levee or foundation leads to levee breach formation prior to overtopping.
For documented levee systems, sufficient information was available to model a levee overtopping scenario, flooding behind the levees is shown only after river elevations reach the top of levee. No specific level of protection is implied for any levee depicted on these maps.
