Shoreline Mapping

The United States has approximately 95,000 miles of coastline. It is NOAA's mission to survey these coastal regions and navigable shoreline water areas and provide an official and accurate delineation of the National Shoreline. These surveys provide shoreline data for nautical chart production and accurate geographical references needed for managing coastal resources.

Accurate nautical charts are directly dependent upon well established, accurate, consistent, current shoreline delineation. In tidal areas, these shorelines' mean high water (MHW) and mean lower low water (MLLW) are used to depict the coastline on NOAA nautical charts (both paper and electronic). MHW defines the boundary between private and state or Federal ownership. MLLW sets the boundary between state and Federal authority. NOAA's coastal mapping provides the critical baseline data for defining America's marine territorial limits, including its Extended Economic Zone. These shoreline data are considered the legal authority when determining the official shoreline for the United States.

There are at present several different shoreline definitions in use by various Federal, state, and local authorities. Often, these authorities use or produce maps depicting mean sea level as the shoreline. Obvious confusion can result from this profusion of shoreline definitions. This confusion can contribute to ill-informed decision making that may in turn have critical or even catastrophic consequences.

There also exists a serious deficiency in providing the National Shoreline. Approximately one-third of the U.S. shoreline has never been mapped by NOAA. Much of what has been done was performed prior to 1970. The accuracy, consistency, and currency of these areas of the coastline cannot be assured. The coastline is subject to ceaseless natural and man-made processes which continually alter the shape and character of the shoreline.

America needs an official, consistent, accurate, up-to-date National Shoreline. It is NOAA's goal to accelerate the modernization of the nation's definition and depiction of the shoreline through development and application of state-of-the-art mapping techniques.

As part of its goal, NOAA intends to resurvey and map those portions of the coastline deemed critical on a 5-year average cycle and other areas on a 10-year average cycle. This can be accomplished by working closely with partners in both the public and private sectors. (An area is determined to be critical based on the level of economic activity, the potential for alteration, and its environmental sensitivity.)

Accurate surveys of the Nation's coastal regions and navigable shoreline water areas are the primary responsibility of the Remote Sensing Division of the National Geodetic Survey's (NGS). The method used today by NGS to delineate the shoreline is analytical stereo photogrammetry using tide-coordinated aerial photography controlled by kinematic Global Positioning System (GPS) techniques. This process produces an accurate, digital product.

The National Shoreline products will be: a seamless, digital database of the U.S. Shoreline, an aerial photograph database, and a remote sensing digital database.

The National Shoreline is key to the economic sustainability and growth of the Nation's shipping, manufacturing, export, coastal development, insurance industries.

A fully up-to-date, consistent, accurate National Shoreline can:

• Provide an official U.S. shoreline for a multitude of users.
• Improve electronic charts for navigation including real-time tides measured by GPS at the actual location of the ship.
• Provide large-scale shoreline delineation in harbors for the production of docking charts, allowing vessels to dock safely in low visibility conditions using large-scale electronic charts.
• Increase the rate and accuracy of chart revision surveys to complement an accelerated chart publication cycle.
• Provide a smooth transition between the ocean and land interface for more accurate modeling of storm surge, coastal flooding, and pollution trajectory modeling.
• Increase the efficiency and volume of coastal surveys (hydrographic and photogrammetric) to provide accurate digital data for managing America's coastal resources.
• Increase accuracy of land and marine Geographic Information Systems (GIS), resulting in improved management decision making.
• Provide for more accurate environmental analysis and monitoring.

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