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Items below are listed from most recently updated to least recently updated.
These are results 1 through 25 of 257 matches.
| Publication Open-File Report 2010-1037: Turbidity on the Shallow Reef off Kaulana and Hakioawa Watersheds, North Coast of Kaho‘olawe, Hawai‘i |
| Research Project USGS Scientists in Samoa and American Samoa Studying Impacts of Recent Tsunami, October-November 2009 |
| Research Project Southern California Coastal Hazards - USGS WCMG |
| Research Project Santa Barbara-Ventura Coastal Processes Study - USGS WCMG |
| Publication Open-FIle Report 2009-1190: 2008 Weather and Aeolian Sand-Transport Data from the Colorado River Corridor, Grand Canyon, Arizona |
| Publication Open-File Report 2009-1195: Coastal Circulation and Sediment Dynamics in War-in-the-Pacific National Historical Park, Guam |
| Publication Scientific Investigations Report 2009-5116: Topographic Change Detection at Select Archeological Sites in Grand Canyon National Park, Arizona, 2006–2007 |
| Research Project USGS Northern Gulf of Mexico (NGOM) |
Description: The topography of the Continental Shelf in the central portion of the Southern California Bight has rapid variations over relatively small spatial scales. The width of the shelf off the Palos Verdes peninsula, just northwest of Los Angeles, California, is only 1 to 3 km. About 7 km southeast of the peninsula, the shelf within San Pedro Bay widens to about 20 km. In 2000, the Los Angeles County Sanitation District began deploying a dense array of moorings in this complex region of the central Southern California Bight to monitor local circulation patterns. Moorings were deployed at 13 sites on the Palos Verdes shelf and within the northwestern portion of San Pedro Bay. At each site, a mooring supported a string of thermistors and an adjacent bottom platform housed an Acoustic Doppler Current Profiler. These instruments collected vertical profiles of current and temperature data continuously for one to two years. The variable bathymetry in the region causes rapid changes in the amplitudes and spatial structures of barotropic tidal currents, internal tidal currents, and in the associated nonlinear baroclinic currents that occur at approximate tidal frequencies. The largest barotropic tidal constituent is M2, the principal semidiurnal tide. The amplitude of this tidal current changes over fairly short along-shelf length scales. Tidal-current amplitudes are largest in the transition region between the two shelves; they increase from about 5 cm/s over the northern San Pedro shelf to nearly 10 cm/s on the southern portion of the Palos Verdes Shelf. Tidal-current amplitudes are then reduced to less than 2 cm/s over the very narrow section of the northern Palos Verdes shelf that lies just 6 km upcoast of the southern sites. Models suggest that the amplitude of the barotropic M2 tidal currents, which propagate toward the northwest primarily as a Kelvin wave, is adjusting to the short topographic length scales in the region. Semidiurnal sea-level oscillations are, as expected, independent of these topographic variations; they have a uniform amplitude and phase structure over the entire region. Because the cross-shelf angle of the seabed over most of the Palos Verdes shelf is 1 to 3 degrees, which is critical for the local generation and/or enhancement of nonlinear characteristics in semidiurnal internal tides, some internal tidal-current events have strong asymmetric current oscillations that are enhanced near the seabed. Near-bottom currents in these events are directed primarily offshore with amplitudes that exceed 30 cm/s. The spatial patterns in these energetic near-bottom currents have fairly short-length scales. They are largest over the inner shelf and in the transition region between the Palos Verdes and San Pedro shelves. This spatial pattern is similar to that found in the barotropic tidal currents. Because these baroclinic currents have an approximate tidal frequency, an asymmetric vertical structure, and a somewhat stable phase, they can produce a non-zero depth-mean flow for periods of a few months. These baroclinic currents can interact with the barotropic tidal current and cause an apparent increase (or decrease) in the estimated barotropic tidal-current amplitude. The apparent amplitude of the barotropic tidal current may change by 30 to 80 percent or more in a current record that is less than three months long. The currents and surficial sediments in this region are in dynamic equilibrium in that the spatial patterns in bottom stresses generated by near-bed currents from surface tides, internal tides, and internal bores partly control the spatial patterns in the local sediments. Coarser sediments are found in the regions with enhanced bottom stresses (that is, over the inner shelf and in the region between the Palos Verdes and San Pedro shelves). Finer sediments are found over the northwestern portion of the Palos Verdes shelf, where near-bottom currents are relatively weak. The nonlinear asymmetries in the internal tidal-period current oscillations cause a net transport of suspended material along and off the shelf, reinforcing the mean flow patterns that also carry sediment either into Santa Monica Bay or offshore and onto the adjacent slope.
| Publication Open-File Report 2009-1029: Coastal processes study of Santa Barbara and Ventura Counties, California |
| Publication Open-File Report 2008-1191: Geologic Resource Evaluation of Kaloko-Honokōhau National Historical Park, Hawai‘i; Geology and Coastal Landforms |
| Publication Open-File Report 2008-1192: Geologic Resource Evaluation of Pu‘uhonua O Hōnaunau National Historical Park, Hawai‘i; Part I, Geology and Coastal Landforms |
| Publication USGS Gulf Coast Science Conference and Florida Integrated Science Center Meeting: Proceedings with Abstracts, October 20-23, 2008, Orlando, Florida |
Description: n October of 2001 and August of 2002, the U.S. Geological Survey conducted geophysical surveys of the Lower Atchafalaya River, the Mississippi River Delta, Barataria Bay, and the Gulf of Mexico south of East Timbalier Island, Louisiana. This report serves as an archive of unprocessed digital marine seismic reflection data, trackline maps, navigation files, observers' logbooks, GIS information, and formal FGDC metadata. In addition, a filtered and gained GIF image of each seismic profile is provided. Refer to the Acronyms page for expansion of acronyms and abbreviations used in this report.
| Publication Scientific Investigations Report 2007-5101: The Coral Reef of South Moloka‘i, Hawai‘i—Portrait of a Sediment-Threatened Fringing Reef |
| Publication USGS Data Series 265, Time-Series Photographs of the Sea Floor in Western Massachusetts Bay, Version 2, 1989 - 1996, USGS Data Series 265, Title Page |
| Publication USGS Data Series 266, Time-series photographs of the sea floor in western Massachusetts Bay, 1996 - 2005 Title Page |
| Publication USGS Open-File Report 2004-1358 |
| Publication USGS OFR 2007-1366: Sidescan-Sonar Imagery and Surficial Geologic Interpretations of the Sea Floor in Central Rhode Island Sound, Title Page |
| Publication USGS OFR 2008-1004: Sea-Floor Character and Sedimentary Processes in the Vicinity of Woods Hole, Massachusetts, Title Page |
| Publication Bathymetric Survey of the Nearshore from Belle Pass to Caminada Pass, Louisiana: Methods and Data Report |
| Publication Open-File Report 98-139: Multibeam Data and Socio-Economic Issues in West-Central San Francisco Bay |
Description: High-resolution measurements of waves, currents, water levels, temperature, salinity and turbidity were made in Hanalei Bay, northern Kaua‘i, Hawai‘i, during the summer of 2006 to better understand coastal circulation, sediment dynamics, and the potential impact of a river flood in a coral reef-lined embayment during quiescent summer conditions. A series of bottommounted instrument packages were deployed in water depths of 10 m or less to collect long-term, high-resolution measurements of waves, currents, water levels, temperature, salinity, and turbidity. These data were supplemented with a series of profiles through the water column to characterize the vertical and spatial variability in water column properties within the bay. These measurements support the ongoing process studies being conducted as part of the U.S. Geological Survey (USGS) Coastal and Marine Geology Program’s Pacific Coral Reef Project; the ultimate goal is to better understand the transport mechanisms of sediment, larvae, pollutants, and other particles in coral reef settings. Information regarding the USGS study conducted in Hanalei Bay during the 2005 summer is available in Storlazzi and others (2006), Draut and others (2006) and Carr and others (2006). This report, the last part in a series, describes data acquisition, processing, and analysis for the 2006 summer data set.
| Publication Professional Paper 1756: The Role of Eolian Sediment in the Preservation of Archeologic Sites Along the Colorado River Corridor in Grand Canyon National Park, Arizona |
| Research Project Research Projects - USGS WCMG, Applied Sediment Transport |
| These are results 1 through 25 of 257 matches. |