Alaska Tidal Datum Portal
The Alaska Division of Geological & Geophysical Surveys (DGGS) has a coastal community geohazards evaluation and geologic mapping program that is funded through the federal Coastal Impact Assistance Program (CIAP). Since this program was launched in 2010, fieldwork has been conducted in seven coastal communities and includes field efforts to rapidly document the impacts of severe storms on Alaska’s coastline. Accurate vertical datums in the coastal environment are critical to the evaluation of natural hazard vulnerability in support of local and regional planning. Appropriate tidal data must be considered in the siting, design, construction, and operations of development projects to ensure protection of human life, property, and the coastal environment.
The NOAA Center for Operational Oceanographic Products and Services (CO-OPS) provides infrastructure and expertise for all verified tidal measurements and is the ultimate authority on tidal datums in the United States. NOAA’s National Geodetic Survey maintains the National Spatial Reference System (NSRS) that is used to relate tidal datums to geodetic datums. NOAA is currently in the process of improving tidal measurements in Alaska and will eventually extend a program called VDatum to our state. As of 2013, the minimal record of tide measurements and limited number of recent tide gauge installations mean it may still be several years before this tool is available for Alaska’s coast. DGGS has identified a critical need to improve awareness and facilitate access to tidal datum information in Alaska during this interim period.
The calculator function and information presented on this site are provided as a convenience until VDatum becomes available for Alaska. Values obtained on this site should not be used for rigorous emergency, planning or construction purposes. Because the relationships between local tidal and geodetic elevations can change with time, the most up-to-date measurement sources must be consulted, independent of this site, to ensure accurate transformations for these high-stakes applications.
The development of this site was partially funded with qualified outer continental shelf oil and gas revenues by the Coastal Impact Assistance Program, Fish & Wildlife Service, and U.S. Department of the Interior. The views and conclusions contained herein are those of the authors and should not be interpreted as representing the opinions or policies of the U.S. government. Mention of trade names or commercial products does not constitute their endorsement by the U.S. government.