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Ann E. Gibbs

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Historical shoreline positions along the mainland Beaufort Sea coast of Alaska were digitized and analyzed to determine the long-term rate of change. Average shoreline change rates and ranges from 1947 to the mid-2000s were determined every 50 meters between Barrow and Demarcation Point, at the U.S.-Canadian border. Results show that shoreline change rates are highly variable along the coast, with an average regional shoreline change rate of-2.0 m/yr and localized rates of up to -19 m/yr. The highest erosion rates were observed at headlands, points, and associated with breached thermokarst lakes. Areas of accretion were limited, and generally associated with spit extension and minor beach accretion. In general,...
Categories: Publication; Types: Citation
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The rugosity or complexity of the seafloor has been shown to be an important ecological parameter for fish, algae, and corals. Historically, rugosity has been measured either using simple and subjective manual methods such as ‘chain-and-tape’ or complicated and expensive geophysical methods. Here, we demonstrate the application of structure-from-motion (SfM) photogrammetry to generate high-resolution, three-dimensional bathymetric models of a fringing reef from existing underwater video collected to characterize the seafloor. SfM techniques are capable of achieving spatial resolution that can be orders of magnitude greater than large-scale lidar and sonar mapping of coral reef ecosystems. The resulting data provide...
Categories: Publication; Types: Citation; Tags: Coral Reefs
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Historical hydrographic data from the Washington/Oregon shelf are compared for the first time to identify bathymetric change on a regional scale. Offshore data sets exist for four time periods: 1800s, pre-1950s, post-1950s, and 1990s. Data from only two time periods, 1868-87 and 1926-27, cover the entire offshore region between Tillamook Head, Oregon and Grays Harbor, Washington. A confidence interval of + or -1.7 m is established for the bathymetric comparison between these two data sets. Wide trackline spacings within the 1868/87 surveys, sounding errors due to horizontal positioning inaccuracies and heavy seas and currents encountered during the surveys, questionable tidal correction methods, and vertical datum...
Categories: Publication; Types: Citation
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Underwater video footage was collected in nearshore waters (<60-meter depth) off the Hawaiian Islands from 2002 to 2011 as part of the U.S. Geological Survey (USGS) Coastal and Marine Geology Program's Pacific Coral Reef Project, to improve seafloor characterization and for the development and ground-truthing of benthic-habitat maps. This report includes nearly 53 hours of digital underwater video footage collected during four USGS cruises and more than 10,200 still images extracted from the videos, including still frames from every 10 seconds along transect lines, and still frames showing both an overview and a near-bottom view from fixed stations. Environmental Systems Research Institute (ESRI) shapefiles of individual...
Categories: Publication; Types: Citation; Tags: Data Series
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The Arctic Coastal Plain of northern Alaska, an area of strategic economic importance to the United States, is home to remote Native American communities and encompasses unique habitats of global significance. Coastal erosion along the Arctic coast is chronic and widespread; recent evidence suggests that erosion rates are among the highest in the world (up to ~16 m/yr) and may be accelerating. Coastal erosion adversely impacts energy-related infrastructure, natural shoreline habitats, and Native American communities. Climate change is thought to be a key component of recent environmental changes in the Arctic. Reduced sea-ice cover in the Arctic Ocean is one of the probable mechanisms responsible for increasing...
Categories: Publication; Types: Citation; Tags: Data Series
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