Coastal Change

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What is coastal change?

Sediments are the foundation of coastal systems, and the movement of these sediments can result in the evolution of entire ecosystems. USGS measures the amount of sediment present, and how it moves in various environments, such as wetlands, estuaries, beaches, and barrier islands. Processes such as erosion—sediments being taken away from one area of coastline—and deposition—when they are moved to another place—are driven by natural forces, including waves, wind, tides, and currents. These processes can shift shorelines in various directions and change the elevation of coastal environments, therefore influencing the areas that are habitable by people, plants, and animals. 

How does USGS study coastal change?  

Our scientists use many methods, both through direct measurements like coastal elevation profiles and indirectly using remote sensing, to characterize the shape of our coasts and how they are shifting over time. Some methods include light detection and ranging (LiDAR); amphibious tools and vehicles (technology suited for both land and water) for nearshore seafloor mapping; and satellite imagery, as well as elevation data collected on foot.  

USGS measures and monitors the position of shorelines along the entire U.S. coastline and how they have changed since the 1800s using a combination of historical and satellite imagery. These data are used to develop tools such as the Digital Shoreline Analysis System (DSAS) for users to both visualize and track these changes on their own. The Coastal National Elevation Database (CoNED) provides high-resolution digital coastal elevation data, and topobathymetric maps that are used to identify coastal features, hazard zones, changes in ecosystems and to form the foundation for developing models that simulate sediment transport and storm surge. These data help coastal managers, engineers, planners, and resource managers understand how coastal change and its associated hazards will influence our coastal habitats and communities. 

Changes to the coastline can affect where and how severely flooding may occur and how this could impact biodiversity persistence. USGS experts use a host of different high-tech devices to gather scientific data before, during, and after extreme storms. This information improves flood forecasting models, is used to update nationwide flood zone maps, helps emergency managers plan for future flooding events, and is critical for managing coastal species with specific habitat requirements.  

Visualizing Change

Modeling and Predicting Coastal Change 

Predictive modeling techniques are used to forecast how the coast will change in response to both natural processes and anthropogenic influences, as well as how these changes may affect the availability and distribution of habitat for coastal species of concern like piping plovers and sea turtles. This information is useful for informing conservation strategies for partners such as the National Park Service and the U.S. Fish and Wildlife Service.  

Some coastal change model forecasts are provided in real-time to show areas that are expected to erode, where sand washes away; overwash, where water overtops the dunes of a beach and pushes sand inland; or inundate, where the coast is completely and continuously submerged by high water levels like storm surge. These predictive models are tested and verified using remote sensing techniques including satellites, aerial imagery, and a collection of cameras that monitor coastal areas of interest.