What Do We Do?

A DEM is a high-resolution, digital spatial model depicting the bare surface of an area of Earth, comprised of cells representing a position and elevation relative to standardized datums. Our coastal DEMs integrate bathymetry (seafloor) and topography in coastal zones of United States properties, territories and select international properties.

Coastal zones support a vast array of dynamic natural processes and human activities that exert tremendous pressure on ecological and economic systems. Natural events, such as tsunamis, landslides and dune migration, as well as development activities, such as road construction and deforestation, can produce rapid and long-term change. Governments, research organizations, universities and conservation organizations rely on mapping of Earth's bare surface both above and below the ocean surface to make informed management and/or mitigation decisions about such interdependent processes and activities. A multitude of technologies, including airborne light detection and ranging (LiDAR) and ship-mounted multibeam swath sonar, provide dense data to enable the construction of coastal DEMs.

DEMs support a wide variety of uses, including modeling of surface processes, real-time tsunami and storm surge forecasting and warning, hazard mitigation and community preparedness, coastal change and terrain analysis, habitat mapping and conservation planning, ecosystem management, Earth visualization and exploration, and pollution monitoring and contaminant dispersal.

Examples of source data used in developing coastal DEMs:

  • airborne light detection and ranging (LiDAR)

  • multibeam swath sonar

  • single beam/trackline sonar

  • hydrographic surveys

  • satellite-derived topography

  • elevation contours

  • nautical charts

  • GPS surveys

  • total station surveys

  • photogrammetric mapping from aerial photography