The United States has 95,000 miles of shoreline. These dynamic coastal regions
are vulnerable to flooding, property destruction, and beach erosion from
severe weather and sea level change.
Coastal areas rely on accurate elevation data to plan and recover when hazardous
situations arise.
These communities depend on up to date information for their management and
resiliency planning. As part of its mission,
NOAA's national geodetic survey (NGS) provides an accurate consistent and
current national shoreline.
NGS' mean high-water line is considered the nation's official shoreline.
It is used to create and maintain NOAA nautical charts.
These charts are used by commercial and recreational boaters to navigate safely
and avoid potential hazards.
NGS' shoreline is also a crucial source for defining our nation's boundaries and
territorial limits. Remotely-sensed data from aircraft is collected to map the
shoreline. The use of aircraft based sensors such as a digital camera and
topobathy lidar system allows large areas to be surveyed in a short amount of time.
Lidar which stands for light detection and ranging is a remote
sensing method that uses a laser to measure distances to a surface.
NGS uses a unique type of sensor called topobathy lidar
It collects wide swaths of elevation data on both land (or topography) and in
shallow water areas (or bathymetry). Bathymetric data has historically been
difficult to acquire in these highly dynamic coastal zones
since NOAA survey ships cannot travel safely close to the shoreline.
NGS' topobathy lidar system uses a green laser that operates in a circular
scan pattern to penetrate shallow water near the shore. The high density point data
is combined with GPS and other positional data to create precise 3d
topographic and bathymetric elevation models.
NGS uses coastal elevation data to map the mean high-water shoreline which is a
tidally-reference boundary. The shoreline is verified using aerial imagery that is
collected along with the lidar data. Topobathy lidar data collected by NGS is
freely available from NOAA's Digital Coast to use for applications and tools
to support decision-making in the coastal zone. Academic and research
organizations use coastal elevation lidar data to develop ocean and coastal
models. These 3d models help researchers understand ocean circulation. Elevation
data is an important part of the model because circulation is influenced by
friction—which is related to the height of the sea floor.
Coastal engineers and scientists use elevation data to understand sediment
movement, beach erosion, and sediment budgets.
This information is used to develop management plans to restore, monitor, and
maintain beaches in the coastal zone. Elevation data is also one of the most
important parameters for modeling inundation. Topobathy lidar data is
especially valuable due to its accuracy and it's seamless transition from land
to water.
Coastal managers and decision-makers use visualization tools that incorporate
these elevation models to understand vulnerability, increase resilience, and
develop hazard mitigation plans.
These are only a few of the many ways that elevation and shoreline data are
being used to help keep coastal communities safe and resilient.
NOAA topobathy lidar data is a critical component for meeting the challenges of
an uncertain future.