Understanding Coastal Change

Understanding changes to our coastlines over both short and long periods of time is essential for coastal community resilience and planning. By comparing pre- and post-storm conditions, scientists can look at how storm events impact coastal beaches, barrier islands and associated estuaries in the greater context of understanding how our coastal areas are evolving over the long-term. Through quantitative analysis and mapping, scientists model and forecast impacts in specific coastal areas and can assess vulnerability to future storms. These capabilities allow scientists to develop greater understanding of how estuaries and the greater barrier island landscape evolves in response to storm events. USGS scientists develop and refine coastal-impact forecasting models as tools for communities and resource planners to use in developing long-term coastal planning scenarios and protect, restore and manage, resilient coastal communities and healthy wetlands and estuaries. View Fact Sheet

Science

A number of ocean front homes were destroyed or severely damaged during Hurricane Sandy on Fire Island, NY. The photo shows what remains of houses in the community of Davis Park

Rapid, Quantitative Evaluation of Coastal and Offshore Landform Change

As Hurricane Sandy moved northward along the U.S. Atlantic coast in October 2012, U.S. Geological Survey scientists worked to determine where and how the storm’s waves and surge might dramatically reshape the beaches and dunes that stand between the storm and coastal developments. Through a complex modeling process that uses coastal elevations, wave forecasts, and potential storm surge, they predicted coastal change hazards, such as shoreline and dune erosion, that might be expected during a Sandy landfall.

Screenshot of the interactive map showing Hurricane-Induced Coastal Erosion Hazards. Visualization of coastal change probabilities based on analysis of dune elevations and water levels.

Updates to Coastal Vulnerability Forecasting Models

Post-Sandy lidar elevation data are being used to update assessments of storm-induced coastal erosion hazards for Northeast beaches and revise forecasts of coastal change that identify areas vulnerable to future extreme, and potentially catastrophic, erosion. Extensive data sets on beach morphology and storm hydrodynamics are being used to identify the type of coastal change that occurred and to verify the accuracy of the pre-landfall coastal change predictions. Social, economic, and infrastructure/critical facility elements will be added to these assessments to facilitate dialogue on societal vulnerability and decision-making in order to reduce risk.

Map of the northern east coast showing the probabilities of collision, overwash, and inundation for the sandy beaches from the mouth of the Chesapeake Bay to Long Island, NY.

Linking Coastal Processes and Vulnerability

Understanding what makes coastal areas more or less vulnerable to major storms is foundational information for coastal zone managers. Research at Fire Island and the Delmarva peninsula is continuing to refine our ability to identify which areas are most vulnerable and why.

Before and after photo pairs show examples of coastal change resulting from Hurricane Isaac.

Historical Storms

One of the goals of the USGS Coastal and Marine Geology Program (USGS-CMG) is a nationally consistent assessment of coastal change hazards. Tropical and extra-tropical storms provide a powerful force that generates dangerous waves and currents capable of moving large amounts of sand, destroying buildings and infrastructure, and reshaping our nation’s coastline.

Image of the Fire Island coastal landscape including the sandy beach and the Fire Island lighthouse in the distance.

Fire Island

USGS scientists are integrating analyses of short- and long-term coastal change to better understand what factors affect coastal shorelines and how geologic controls, sea-level rise and human activities contribute to their vulnerability. Results of the research at Fire Island are applicable to other barrier systems.

Barrier islands are dynamic systems that also provide protection from future storms to the built environment. A thorough understanding of the long-term and short-term evolution of barrier islands can lead to the development of models that better predict future changes to coastal environments. Decades of USGS coastal research at Fire Island, combined with observations from the Hurricane Sandy event, help build this scientific understanding

Map of wetlands

Wetlands and Estuaries

Estuaries play a critical part in barrier island evolution as well as changes to tidal circulation and water quality. The USGS will assess the estuarine and adjacent wetland sediment responses of multiple Atlantic lagoonal estuaries to major storm events such as Hurricane Sandy. Evaluations of sediment transport, geomorphic change, circulation, wetland stability, and stratigraphic history will support development of models of storm impacts on estuarine health, vulnerability of adjacent communities, and the resilience of restored and natural wetlands.

Map of wetlands

Sea Level Rise

Estuaries play a critical part in barrier island evolution as well as changes to tidal circulation and water quality. The USGS will assess the estuarine and adjacent wetland sediment responses of multiple Atlantic lagoonal estuaries to major storm events such as Hurricane Sandy. Evaluations of sediment transport, geomorphic change, circulation, wetland stability, and stratigraphic history will support development of models of storm impacts on estuarine health, vulnerability of adjacent communities, and the resilience of restored and natural wetlands.

Data and Tools

Coastal Topography–Northeast Atlantic Coast, Post-Hurricane Sandy, 2012

Coastal Topography–Northeast Atlantic Coast, Post-Hurricane Sandy, 2012

This Data Series contains lidar-derived bare-earth (BE) topography, dune elevations, and mean-high-water shoreline position datasets for most sandy beaches for Fire Island, New York, and from Cape Henlopen, Delaware to Cape Lookout, North Carolina. The data were acquired post-Hurricane Sandy, which made landfall as an extratropical cyclone on October 29, 2012.

 ADCP data from Mashapaquit Creek, West Falmouth Harbor, Massachusetts

Modeling Fluxes Between Watersheds, Wetlands, Estuaries and Coasts

This website describes several interdisciplinary projects that aim to quantify and understand flux mechanisms through observations and numerical modeling. Both the spatial and temporal timescales of these mechanisms are important, and therefore require modern instrumentation and state-of-the-art hydrodynamic models.

Pre-Storm and Post-Storm 3D Lidar Topography: Fire Island, NY

Aerial Photography

Coastal imagery of pre- and post storm conditions from Hurricane Sandy.

Oblique aerial photographs of Pelican Island and Fire Island, New York showing the landscape in Map 21, 2009 and November 5, 2012. The view is looking northwest across Fire Island towards Great South Bay. This location is within Fire Island National Seashore near Old Inlet—a very narrow portion of the island that has experienced breaching in previous large storms. The island breached during Sandy, creating a new inlet. Despite the breach, the fishing shack (yellow arrow) remained standing.

Before/After Photo Pairs

Photos pairs are used to compare the pre-storm and post-storm conditions at locations representing a broad range of coastal configurations and their response to the storm. Prestorm photos were acquired during a baseline survey May 21, 2009 and post-storm photos were acquired November 4-6, 2012.

LIDAR Topography of the elevation difference between Pelican Island and Fire Island, New York.

Before/After LIDAR Topography

The USGS acquired an airborne LIDAR survey of post-storm topography of Fire Island on November 5, 2012, to measure coastal change resulting from Hurricane Sandy. Comparisons of the post-storm elevation data to LIDAR data collected prior to Sandy’s landfall are used to characterize the nature, magnitude, and spatial variability of hurricane-induced coastal changes, such as beach erosion, overwash deposition, and island breaching. These measurements complement field-based observations of coastal change that were collected immediately prior to and three days after landfall.

Illustrated graphic of three mobile phones in a bucket to represent the icon for Coastal Change Hazards Portal

Coastal Change Hazards Portal

The USGS has developed a Coastal Change Hazards portal that provides users with direct access to basic and applied research, scientific information, and data on coastal hazards to see, explore, download, and share. Watch the Tutorial Video to get started.

Contacts

Understanding Coastal Change Team Lead

John Haines

jhaines@usgs.gov

Partners

Federal Emergency Management Agency (FEMA)

National Oceanic & Atmospheric Administration (NOAA)

National Park Service

State of New Jersey

State of New York

U.S. Army Corps of Engineers

U.S. Fish and Wildlife Service