Operationalizing NOAA's Flood Inundation Mapping Services

NOAA’s Office of Water Prediction (OWP) develops and maintains flood inundation mapping software (https://github.com/NOAA-OWP/inundation-mapping) designed to produce synthetic rating curves and Height Above Nearest Drainage (HAND) grids for use in the production of flood inundation mapping (FIM) forecasts. HAND is an established technique that detrends digital elevation models (DEM) by normalizing elevations to the nearest relevant drainage line. Synthetic rating curves allow calculation of reach-averaged water surface elevations, based on National Water Model streamflow forecasts.

Recent developments aiming to operationalize HEC-RAS models have proven to be effective in producing reach-scale flood libraries. Since HEC-RAS is able to utilize hydraulic computations, these libraries can be rapidly deployed to supersede HAND FIM maps where HEC-RAS models are available. OWP is partnering with other flood management government agencies to collect as many other high-fidelity flood models as possible.

The goal of OWP’s flood inundation mapping project is to forecast flood inundation in near real time up to 10 days in advance across the United States, Puerto Rico, and the U.S. Virgin Islands, and to disseminate these forecasts to National Weather Service Weather Forecast Offices, River Forecasting Centers, core stakeholders, and the public. OWP targets 2026 for producing publicly accessible FIM to nearly 100% of the United States population.