Toward Near-Real-Time Forecast Flood Inundation Map Services

Realtime and Forecast Flood Inundation Maps are a critical need before, during and after flood events. When intersected with geospatial datasets including infrastructure and demographic information, they not only alert stakeholders of at risk areas but also help position response resources effectively before and during events. The NOAA National Weather Service has a mission to issue forecasts for the protection of lives and property and the enhancement of the national economy. This includes forecasts for floods and the resulting inundation. Though floods are local, this mission spans the entire country. Although continental scale hydrologic modeling capabilities have improved significantly over the last decade, the computational cost of running hyper-resolution (sub-kilometer scale) hydrodynamic models remains high. As such, approximate flood inundation mapping techniques are needed to support national scale applications and compliment engineering scale mapping capabilities. In support of the 2018 and 2019 Department of Commerce /National Oceanic and Atmospheric Administration Agency Priority Goal to mitigate flood impacts, the National Weather Service’s Office of Water Prediction has demonstrated a novel approach to real-time flood inundation mapping capability, implemented as a service, over the state of Texas. This capability uses the Height Above Nearest Drainage (HAND) method to infer forecast stage given forecast streamflow and forecast inundation extent given forecast stage. As part of the demonstration, a system was setup to use both official forecasts from the West Gulf River Forecast Center and National Water Model. This talk will describe the development, evaluation and implementation of the demonstrated flood inundation mapping capability and the prospects for scaling to the nation.