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Coastal Inundation Dashboard

What is Inundation?

Inundation is the amount of water that occurs above normally dry ground as a result of flooding. Along the coast, there are a few common sources of inundation including abnormally high tides, storm surge, persistent onshore winds and waves. In rivers and tidal estuaries, runoff from excessive rainfall can provide another source of inundation. The combination of all of these potential factors makes up the total water level.

Inundation is most commonly referenced to the average daily highest tide, or Mean Higher High Water (MHHW) tidal datum. Inundation typically begins when water levels reach above this level. In most locations across the U.S., a relationship exists between tidal datums and the land elevation.

Overview of the tool

Coastal Inundation Dashboard provides real-time water levels, 48-hour forecasts of water levels and historic flooding information at a majority of coastal water level stations operated by the National Ocean Service (NOS) Center for Operational Oceanographic Products & Services (CO-OPS). The product features both a map based view where users can see which stations across the U.S. may be flooding, and a more detailed station view where real-time water levels and historical data for a specific location are highlighted. Emergency managers and other coastal decision makers can use this information to understand and prepare for the impacts of coastal flooding. The coastal planning community can use this information to gain a better understanding of past peak water level events and the increased frequency of days when flooding is possible as sea levels change.

Most stations in Alaska and all Great Lakes stations are not yet available in this product, however CO-OPS is working with partner agencies on establishing relationships between measured water levels and flooding in order to provide the same level of information for all locations in the near future. By default, water levels are displayed relative to Mean Higher High Water (MHHW), the average highest tide in a day, but can be adjusted to other Tidal Datums as needed.

Monitoring water levels during Hurricanes and Tropical Storms

When the National Weather Service issues a tropical storm or hurricane watch or warning for the U.S. or its territories, CO-OPS will begin to monitor water levels in the path of the storm. This will be available as a customized view on the Coastal Inundation Dashboard map that will show the latest tropical cyclone forecast track and intensity information, active storm surge watches or warnings, and coastal flood watches, warnings or advisories issued by NWS. A summary of coastal water level conditions will be updated three times a day. Tropical cyclones and other strong coastal storms, such as nor’easters, can elevate water levels by several feet or more above normal tide levels, which can cause flooding along the coast.

In most cases, the threshold at which these impacts may occur is defined by local National Weather Service (NWS) forecast offices. In some instances, this threshold is derived from an empirical relationship between known flood elevations and tidal range outlined in NOAA Technical Report NOS CO-OPS 086 - Patterns and Projections of High Tide Flooding.

  • Storm QuickLook - Web product focused on disseminating real-time storm surge observations due to tropical storms or hurricanes.
  • NOAA High Tide Bulletin - An interactive map to show each region of the U.S. when and why their region may experience higher than normal high tides.
  • Sea Level Trends Online - A map of sea level rise and fall, trends, and anomalies.
  • Inundation Analysis Information - Analytic tool that shows how often and for how long certain areas of the coast experience high or low water. This information can be used for coastal restoration, coastal engineering and mapping projects.
  • NWS Watches, Warnings & Advisories - Nationwide map of all active watches, warnings and advisories issued by the National Weather Service.
  • NWS Advanced Hydrologic Prediction Service (AHPS) - Interactive map displaying river and coastal water level and flood information for NOAA and non-NOAA stations.

Screenshot of the Coastal Inundation Dashboard
Coastal Inundation Dashboard

The Inundation Dashboard application is at

Revised: 08/08/2018
NOAA / National Ocean Service
Web site owner: Center for Operational Oceanographic Products and Services