USGS - science for a changing world

Coastal Changes and Impacts

Climate change is a significant factor that affects both the natural and human components of the coastal landscape. Therefore, assessments and monitoring of vulnerable coastal lands are needed in locations where an ever-increasing population lives in communities at risk from sea-level rise, inundation, and storm surge.

The objective of the U.S. Geological Survey Coastal Changes and Impacts focus area at the Earth Resources Observation and Science Center is to conduct research and applications to assess the interactions between human inhabitants, natural features, and environmental conditions in coastal landscapes. This work focuses on the geographic nature of coastal changes through use of high- resolution, high-accuracy imagery and elevation data that are critical for mapping sea-level rise, flood hazard and inundation, and for characterizing storm surge dynamics.

New York


During the coming decades, coastlines will respond to widely predicted sea-level rise, storm surge, and coastal inundation flooding from disastrous events, such as hurricanes or nor'easters. Physical processes in the coastal environments are controlled by the geomorphology of both "over-the-land" topography and "underwater" bathymetry; therefore, many applications of geospatial data in coastal environments require detailed knowledge of near-shore topography and bathymetry (topobathymetry). High-resolution coastal elevation data is critical to depict regions prone to these climate change impacts, and are essential to planners and managers responsible for mitigating the associated risks and costs to both human communities and ecosystems.

By progressively constructing enhanced integrated topobathymetric elevation models for an evolving set of U.S. coastal regions and ecosystems, the U.S. Geological Survey (USGS) Coastal National Elevation Database Applications (CoNED) Project provides important information for a range of applications needed for climate change analysis in sensitive coastal regions, including:

Elevation Derivatives for National Applications (EDNA)

EDNA is a multi-layered database derived from a version of the NED, which has been hydrologically conditioned for improved hydrologic flow representation. The seamless EDNA database provides 30-meter resolution raster and vector data layers. Hydrologically conditioned elevation data, systematically and consistently processed to create hydrologic derivatives, can be useful in many topologically based visualization and investigative applications. Drainage areas upstream or downstream from any location can be accurately traced facilitating flood analysis investigations, pollution studies, and hydroelectric power generation projects.

Center for LIDAR Information Coordination and Knowledge

There has been increasing demand for research utilizing all information generated from light detection and ranging (lidar) remote sensing data and not just bare earth DEMs. While this technology has been a proven mapping tool, effective for generating bare earth DEMs, research on using the entire point cloud of this remote sensing data for scientific applications have been slowed by the high cost of collecting lidar, a steep learning curve on research and understanding involving utilizing the entire point cloud. The goal of CLICK is to facilitate data access, user coordination and education of lidar remote sensing for scientific needs.

Topographic Change

The USGS has developed a national inventory of significant topographic changes based on seamless multi-temporal elevation data and land cover data. The NED and the Shuttle Radar Topography Mission (SRTM) data form a unique pair of seamless elevation datasets that can be used to detect and analyze 20th century topographic surface changes in the United States. The need for more comprehensive information on the nature and extent of recent human geomorphic activity led to a spatial emphasis for the first ever accounting of topographic change across the United States. The primary types of topographic changes resulting from human geomorphic activity include surface mining, road construction, urban development, dam construction, and landfills.

CoNED Project Viewer

The U.S. Geological Survey (USGS) Coastal National Elevation Database Applications (CoNED) Project Viewer contains integrated topobathymetric data (topobathy) of merged renderings of both topography (land elevation) and bathymetry (water depth). These data provide important information for a range of applications needed for climate change analysis in sensitive coastal regions, including:


The USGS and the National Geospatial-Intelligence Agency (NGA) have collaborated on the development of a notably enhanced global elevation model called the Global Multi-resolution Terrain Elevation Data (GMTED2010), which has replaced GTOPO30 as the elevation dataset of choice for global and continental scale applications. The new model has been generated at three separate resolutions of 30 arc-seconds, 15 arc-seconds, and 7.5 arc-seconds. An additional advantage of this new multi-resolution global model is that seven new raster elevation products are available at each resolution. The new elevation products have been produced using the following aggregation methods: minimum elevation, maximum elevation, mean elevation, median elevation, standard deviation of elevation, systematic subsample, and breakline emphasis. The primary source dataset for the new global model is the 1 arc-second void-filled SRTM data.


GTOPO30 is a global DEM with a horizontal grid spacing of 30 arc seconds (approximately 1 kilometer). GTOPO30 was derived from several raster and vector sources of topographic information. For easier distribution, GTOPO30 has been divided into tiles. Detailed information on the characteristics of GTOPO30 including the data distribution format, the data sources, production methods, accuracy, and hints for users, is found in the GTOPO30 README file.

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Page Last Modified: November 15, 2016