WASHINGTON — NOAA’s flood inundation mapping tool reached near-total coverage of the continental United States, giving emergency managers and communities in virtually every flood-prone area access to real-time flood data, on Sept. 24.
The milestone means that Americans across the country can now access detailed projections of flood extent and depth during events — information that was previously unavailable in many at-risk communities.
The tool is used by FEMA, state emergency management agencies and local governments to make life-safety decisions before and during flood events. Real-time flood mapping allows officials to identify which roads, buildings and neighborhoods are at risk of inundation, guiding evacuation orders and resource deployment.
Flooding is the most common and one of the deadliest natural disasters in the United States, causing billions of dollars in damage and dozens of deaths annually. The frequency and severity of flood events have increased in recent decades, driven by a combination of development patterns and more extreme precipitation events.
NOAA’s National Water Center operates the mapping tool, which integrates data from stream gauges, weather radar, satellite observations and hydrologic models to produce real-time flood projections.
Prior to the tool’s expansion, many communities — particularly in rural areas and smaller watersheds — lacked access to granular flood mapping data, forcing emergency decisions to be made with limited information.
The achievement has implications for the National Flood Insurance Program, which provides coverage to more than 5 million policyholders. More accurate flood mapping data could improve risk assessment and pricing for flood insurance, an issue of direct concern to homeowners in flood-prone areas.
The Association of State Floodplain Managers has described national flood mapping coverage as one of the most important tools for reducing flood-related deaths and property losses in the United States.