USGS Flood Information

Floods can occur any time of year, and high-quality flood information is essential for flood forecasting and planning, emergency response, and recovery efforts. The USGS mission to protect life and property is a critical aspect of its role in the nation. By providing reliable scientific information about natural disasters, including flooding, the USGS can help minimize the risk, loss of life, and loss of property from floods. Key activities to this mission are to anticipate, monitor, and respond to hydrologic hazards by providing reliable water data and technical expertise to partner agencies and communities across the Nation. Our flood information provides real-time situational awareness, informs flood predictions, facilitates flood impact response and assessments, supports floodplain and flood inundation mapping, guides infrastructure design and operation, helps map contaminant transport, and more.

The USGS supports these activities through data collection, publication of flood-related publications, analysis of flood exceedance probabilities and magnitudes, and development of methods to estimate floods at unmonitored locations throughout the nation. The USGS develops and deploys observational systems for identifying and tracking flood hazards, providing operational support during extreme hydrologic events, providing data for recovery, and informing community planning and hazard mitigation strategies. These efforts include:

• Operating hydrologic networks , including providing real-time water levels and stream discharge, making field measurements to ensure the accuracy and completeness of our streamflow records, collecting annual peak discharge data, and installing rapid-deployment gages to temporarily expand our observational network during large flood events.
• Supporting flood forecasting by providing the National Weather Service with real-time water conditions, which they combine with their meteorological data to forecast flood magnitude and timing.
• Collecting ephemeral flood data, including deploying temporary water and meteorological data sensors ahead of large storms, computing peak flows, and collecting and surveying high-water marks to determine peak water levels after floodwaters recede. These types of field data are vital to emergency response and recovery, but most must be collected in person during or immediately after a storm when conditions may be dangerous. Our field personnel are dedicated to collecting and relaying flood data whenever safe conditions allow.
• Documenting and analyzing flood extents and impacts, including surveying of flooded areas, creating hydraulic models, and developing flood inundation maps
• Distributing timely and reliable flood-related information through online data portals and tools, programmatic web services, direct communication, internal and interagency flood operational calls, and support from USGS hydrologic science experts.

During a flood, the USGS works directly with flood response agencies like the National Weather Service (NWS), Federal Emergency Management Agency (FEMA), U.S. Army Corps of Engineers (USACE), and state and local emergency management agencies to help them access and understand USGS flood data so they can make informed decisions and protect lives and property. USGS maintains two national response coordination teams -- the inland Flood Team and the Coastal Storm Team -- that liaise with our external partners and ensure a unified and effective response to major flood events. The response coordination teams supplement USGS operations and networks to acquire additional priority flood data to meet partner needs.

Learn more about how we study floods, how we measure and map flooding, and how we support flood event response by exploring the links listed on the Science tab.

Featured Flood Products

The USGS offers multiple products to help visualize current flood conditions, estimate flood quantiles, evaluate how large floods measure up historically, and access USGS flood response activities and data, including:

• Water Data for the Nation delivery tools
  • National Water Dashboard: Access current flood and high-flow conditions, along with other streamflow information.
  • WaterAlert: The WaterAlert service provides notifications to your email or phone for changes in water conditions based on thresholds you choose at USGS streamgages of interest to you.
  • State Pages: Access current water conditions from all monitoring locations in a state that collect continuous data records
  • Explore Water Data: A dynamic tool to filter and locate monitoring locations and water data that meet customizable use cases, such as flooding comparisons.
• Hydrologic Imagery Visualization and Information System (HIVIS): View still-frame images and timelapse videos from over 1,000 active webcams.
• Real-Time Flood Impact API: Displays locations where surveyed critical safety or infrastructure features near a USGS streamgage may be currently flooded.
• Flood Event Viewer: Explore streamflow, storm tide, wave height, high-water marks, and deployed sensor data for current and historical storm events.
• Flood Inundation Mapper: Explore sets of local inundation maps that show where flooding would occur – and how deep it might be - given a selected stream condition
• StreamStats web application and web page: Explore flood statistics at USGS streamgages, plot current conditions with respect to flood statistics, and provide estimates of flood quantiles at ungaged locations.