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    • Extreme Water Levels from CO-OPS

    Metadata Updated: March 13, 2024

    Extremely high or low water levels at coastal locations are an important public concern and a factor in coastal hazard assessment, navigational safety, and ecosystem management. The probability that water levels will exceed a given elevation is based on a statistical analysis of historical extremely high and low water levels. This product provides annual exceedance probability levels for select Center for Operational Oceanographic Products and Services (CO-OPS) water level stations with at least 30 years of data. When used in conjunction with real-time station data, exceedance probability levels can be used to evaluate current conditions and determine whether a rare event is occurring. This information may also be instrumental in planning for the possibility of dangerously high or low water events at a local level.

    The extreme levels measured by the CO-OPS tide gauges during storms are called storm tides, which are the total observed seawater level during a storm, resulting from the combination of storm surge and the astronomical tide. They do not include wave runup, the movement of water up a slope. Therefore, the 1% annual exceedance probability levels do not necessarily correspond to the Base Flood Elevations (BFE) defined by the Federal Emergency Management Administration (FEMA), which are the basis for the National Flood Insurance Program. The 1% annual exceedance probability levels more closely correspond to FEMA's Still Water Flood Elevations (SWEL). The peak levels from tsunamis, which can cause high-frequency fluctuations at some locations, have not been included in this statistical analysis due to their infrequency during the periods of historic record.

    Access & Use Information

    License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

    Downloads & Resources

    Dates

    Metadata Date February 29, 2024
    Metadata Created Date June 30, 2023
    Metadata Updated Date March 13, 2024
    Reference Date(s) 2013 (creation), 2013 (publication)
    Frequency Of Update annually

    Metadata Source

    Harvested from NOS CO-OPS

    Other Data Resources

    Additional Metadata

    Resource Type Dataset
    Metadata Date February 29, 2024
    Metadata Created Date June 30, 2023
    Metadata Updated Date March 13, 2024
    Reference Date(s) 2013 (creation), 2013 (publication)
    Responsible Party (Point of Contact, Custodian)
    Contact Email
    Guid gov.noaa.nmfs.inport:69876
    Access Constraints Cite As: Center for Operational Oceanographic Products and Services, [Date of Access]: Extreme Water Levels from CO-OPS [Data Date Range], https://www.fisheries.noaa.gov/inport/item/69876., Access Constraints: None., Use Constraints: While most of the results are based on verified data, there are situations where a station malfunctions during a storm, but post-storm visits allow to discern how high the water reached from a mud/debris line on site or at nearby buildings. If the debris lines are leveled to the station bench marks or to a known datum such as NAVD88, that was added to the instrument-observed levels as the maximum for that month. None of that information is captured in any of our other published products. An accurate exceedance probability analysis strongly depends on not missing the most extreme levels during the period of observations., Distribution Liability: While most of the results are based on verified data, there are situations where a station malfunctions during a storm, but post-storm visits allow to discern how high the water reached from a mud/debris line on site or at nearby buildings. If the debris lines are leveled to the station bench marks or to a known datum such as NAVD88, that was added to the instrument-observed levels as the maximum for that month. None of that information is captured in any of our other published products. An accurate exceedance probability analysis strongly depends on not missing the most extreme levels during the period of observations.
    Bbox East Long 180
    Bbox North Lat 61.3
    Bbox South Lat -14.3
    Bbox West Long -180
    Coupled Resource
    Frequency Of Update annually
    Harvest Object Id 6c659288-e601-46ee-9a3f-3e89abc71ee2
    Harvest Source Id 217272a2-c20f-4b9e-a0e1-e42a6d539971
    Harvest Source Title NOS CO-OPS
    Licence NOAA provides no warranty, nor accepts any liability occurring from any incomplete, incorrect, or misleading data, or from any incorrect, incomplete, or misleading use of the data. It is the responsibility of the user to determine whether or not the data is suitable for the intended purpose.
    Lineage Observed data are recorded and transmitted, then go through a quality control procedure and are loaded into a database. For Extreme Water Levels, typically the verified monthly and annual maxima/minima are used. Prior to the extreme analysis being completed, the long term sea level trend is removed so that maximum or minimum levels reached by an event in the past can be compared to an equivalent event today.
    Metadata Language eng
    Metadata Type geospatial
    Old Spatial {"type": "Polygon", "coordinates": [[[-180.0, -14.3], [180.0, -14.3], [180.0, 61.3], [-180.0, 61.3], [-180.0, -14.3]]]}
    Progress onGoing
    Spatial Data Service Type
    Spatial Reference System
    Spatial Harvester True
    Temporal Extent Begin 2013

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