The Washington DC Flood Inundation Mapping Project: Development and Use of Mapping in a High-Profile, Multiple-Threat Area

The District of Columbia is unique not only because of its high-profile assets near waterways, including national memorials and major roadways; but also because the District can experience flooding both of a freshwater nature and a tidal nature.

In 2012, the National Weather Service (NWS) began utilizing a coupled unsteady HEC-RAS model to forecast the combined effects of tides and freshwater at two gauged locations in Washington, D.C.  Coordination efforts amongst local, regional, and federal agencies increased following Superstorm Sandy, and in 2014, the District of Columbia Silver Jackets team was formed, co-led by the U.S. Army Corps of Engineers, National Park Service, and DC Department of Energy & Environment. One of the earliest decisions of the team was to pursue development of flood inundation mapping for the District.

In 2014, the D.C. Silver Jackets team obtained funding for a non-structural project to improve the modeling, and develop inundation mapping to be displayed on National Weather Service and United States Geological Survey websites. These displays allow the real-time NWS point forecasts at three forecast locations to be linked to associated mapping, providing critical information to officials and the general public so that they take actions to reduce flood risk.

This presentation will describe the project as a whole, demonstrate the mapping tool, and describe the unique challenges encountered in attempting to paint a picture of the flood risk in the Washington, D.C. region.