Coastal Changes and Impacts

The next step in the data processing procedure was to threshold the difference grids to isolate areas of significant change. This procedure is commonly done in the image differencing method of change detection, and the threshold is often based on the standard deviation value of the differences. As implemented for this study, the thresholding approach incorporated the inherent absolute vertical...

The thresholding approach (described below) used to distinguish significant differences from the raw difference grids requires a measure of the absolute vertical accuracy of each input elevation dataset. The NED and SRTM data were compared to an independent reference geodetic control point dataset from NGS. These points have centimeter-level accuracy in their horizontal and vertical coordinates...

Located in the Pacific Ocean off the coast of California, the Channel Islands are a chain of eight islands where years of isolation has created unique fauna, flora, and archeological resources. Five of the islands are part of Channel Islands National Park (Anacapa, Santa Cruz, Santa Rosa, San Miguel, and Santa Barbara), and the waters surrounding these islands make up the Channel Islands National...

Accurate, high-resolution elevation information is vital to understanding the natural hazards that can impact the highly populated San Francisco Bay area, such as sea-level rise, winter storms, cliff erosion, and other coastal hazards. The San Francisco Bay estuary three-dimensional (3D) topobathymetric digital elevation model (TBDEM) was developed in collaboration between U.S. Geological Survey...

Pamlico Sound is ecologically important as it is the second largest estuary in the United States, and is the largest lagoon on the U.S. east coast. The sound is separated from the Atlantic Ocean by the Outer Banks, a series of low, sandy barrier islands that are vulnerable to hurricane storm surge and sea-level rise. The seamless high-resolution topobathymetric digital elevation model (TBDEM) for...

Accurate, high-resolution elevation information is vital to understanding the highly dynamic northern Gulf of Mexico coast, the location of North America’s largest delta system and the focus of one of the largest coastal restoration and flood risk reduction efforts in the United States. The northern Gulf of Mexico topobathymetric digital elevation model (TBDEM) was developed in collaboration...

With an estimated elevation of only 3-meters above sea level, the Majuro Atoll, capital of the Republic of the Marshall Islands (RMI), is extremely vulnerable to sea-level rise, tsunamis, storm surge, and coastal flooding that could impact the sustainability of the infrastructure, groundwater, and ecosystems. Located in the northern tropical Pacific Ocean, the waters surrounding the Majuro Atoll...

Mobile Bay is ecologically important as it is the fourth largest estuary in the United States. The Mobile Bay topobathymetric digital elevation model (TBDEM) was developed in collaboration between U.S. Geological Survey (USGS) Coastal and Marine Geology Program (CMGP) and USGS National Geospatial Program (NGP) using a combination of 71 disparate topographic and bathymetric datasets collected from...

Hurricane Sandy severely impacted the New Jersey/Delaware coast, altering the topography and ecosystems of this heavily populated region. In response to the storm, the U.S. Geological Survey (USGS) Coastal and Marine Geology Program in collaboration with USGS National Geospatial Program , and National Oceanic and Atmospheric Administration developed three-dimensional (3D) topobathymetric elevation...

Scientific research and applications assessing coastal landscape change and vulnerability are critical for applications such as shoreline mapping, hydrodynamic modeling, coastal vulnerability, and coastal geomorphology studies. However, very little ground truth data are available within the intertidal zone and adjacent beaches.

Defining near-shore water depth (bathymetry) is problematic because ships cannot operate close to the shore while collecting acoustic bathymetric soundings. Alternatively, optical green laser lidar sensors have been used to collect bathymetric points, however, these types of lidar acquisitions are costly for the footprint collected and are subject to bathymetric inaccuracies in turbid water...

This study explores the feasibility of using high-resolution digital elevation models (DEMs) constructed from airborne light detection and ranging (lidar) surveys to develop an automated procedure to extract levee longitudinal elevation profiles for both federal levees in Atchafalaya Basin and local levees in Lafourche Parish, south Louisiana. This approach can successfully accommodate abrupt...