Understanding the patterns and variabilities in nearshore and deep ocean currents is an important component in developing predictive models. Such models allow us to determine the likely transport patterns for sediments and pollutants, allowing planners to make informed decisions based on the forces at work in a given area.
Open-File Report 2010-1037: Turbidity on the Shallow Reef off Kaulana and Hakioawa Watersheds, North Coast of Kaho‘olawe, Hawai‘i Measurements of Turbidity and Ancillary Data on Winds, Waves, Precipitation, and Stream flow Discharge, November 2005 to June 2008 The island of Kaho‘olawe has particular cultural and religious significance for native Hawaiians. Once known as Kanaloa, the island was a center for native Hawaiian navigation. In the mid-20th century, the island was used as a bombing range by the U.S. Navy, and that practice, along with the foraging by feral goats, led to a near-complete decimation of vegetation. The loss of ground cover led to greatly increased erosion and run-off of sediment-laden water onto the island’s adjacent coral reefs. Litigation in 1990 ended the U.S. Navy’s use of the island as a bombing range, and in 1994 the island was transferred to the Kaho‘olawe Island Reserve Commission (KIRC), http://kahoolawe.hawaii.gov/. As a result of the litigation, the U.S. Navy began a 10-year clean-up effort that was the foundation for the present restoration effort by KIRC (Slay, 2009). The restoration effort is centered on revegetating the island, reducing erosion, and limiting run-off onto adjacent reefs. Restoration efforts to mitigate sediment runoff to streams and gulches by restoring native vegetation and minimizing erosion have focused on two watersheds, Kaulana and Hakioawa, on the northeast and northwest sides of the island, respectively. Stream flow and sediment gages were installed by the U.S. Geological Survey Pacific Islands Water Science Center in each of the watersheds, and a weather station was established upland of the watersheds. For this study, turbidity monitors were installed on the insular shelf off the two watersheds to monitor the overall quality of reef waters and their changes in response to rain and stream flow discharge events. Posted: 2010-03-19
California Seafloor Mapping Program The California Seafloor Mapping Program (CSMP) is a cooperative program to create a comprehensive coastal/marine geologic and habitat base map series for all of California’s State waters. The Ocean Protection Council authorized funds to establish the CSMP in 2007 (OPC, 2007) and assembled a team of experts from state and federal agencies, academia, and private industry to develop the best approach to mapping and classifying estuarine and marine geologic habitats, while at the same time updating all nautical charts. Initiated in 2008, the CSMP is collecting bathymetry (underwater topography) and backscatter data (providing insight into the geologic makeup of the seafloor) that will be turned into habitat and geologic base maps for all of California’s state waters (mean high water line out to three nautical miles). Although the CSMP was originally developed to support the design and monitoring of marine reserves through the Marine Life Protection Act (CDFG, 2007), accurate statewide mapping of the seafloor will: - improve climate change and ocean circulation models; - help evaluate the potential for ocean energy; - improve our understanding of ecosystem dynamics; - identify submerged faults and improve our understanding of tsunami potential - enable more effective regulation of offshore development; - improve maritime safety; and - improve our understanding of sediment transport and sand delivery. Posted: 2010-02-23
Santa Barbara-Ventura Coastal Processes Study - USGS WCMG Santa Barbara/Ventura Coastal Processes Study of the USGS Western Coastal and Marine Geology Team. Whereas coastal urban development and infrastructure are largely fixed with respect to location, shoreline and bluff positions can change substantially over time in response to natural processes. These natural coastal changes can damage or undermine urban structures, resulting in substantial property loss for federal, state, local and individual land owners. Urban development can also indirectly influence coastal change by interrupting natural supplies or transport of sediment in littoral cells. Thus, it is important to evaluate the rates, patterns and causes of coastal change to better manage sediment resources and predict change hazards in coastal urban settings. The Santa Barbara and Ventura County coast represents a littoral cell along the California coast extending from (at least) Point Conception to the Mugu submarine canyon. The beaches along this littoral cell are an important economic resource to the region, and there is evidence that shoreline and bluff erosion are impacting these beaches. Coastal change in the Santa Barbara/Ventura region is complicated, however, by the irregular coastline (there are numerous rocky headlands, river deltas and offshore reefs), variability in wave forcing, structures such as harbors, groins, piers, dams and landscape urbanization, variability in tectonic uplift, and limited information on littoral sediment sources. In response to the potential for coastal change, BEACON (Beach Erosion Authority for Clean Oceans and Nourishment) and the City of Carpinteria have provided a combined $700K in funding for USGS WCMG to evaluate the coastal change patterns and processes along the Santa Barbara/Ventura County coast until the end of 2008. Posted: 2009-11-24
USGS Scientists in Samoa and American Samoa Studying Impacts of Recent Tsunami, October-November 2009 On September 29, 2009, a magnitude-8.0 submarine earthquake occurred at 6:48a.m. Samoa Standard Time approximately 190 km (120 mi) south of Samoa and triggered a tsunami that caused more than 100 deaths and widespread damage in Samoa, American Samoa, and Tonga. Observers reported four tsunami waves that ranged from approximately 1.5 to 6 m high and reached as far as 1.5 km inland. A rapid-response team of USGS scientists is traveling to American Samoa to collect data that will be quickly degraded or destroyed by recovery activity and natural processes. USGS Western Coastal and Marine Geology (WCMG) oceanographer Bruce Jaffe arrived in Pago Pago, on the island of Tutuila, American Samoa, on October 4 and was joined later in the week by fellow WCMG scientists Bruce Richmond, Mark Buckley, Guy Gelfenbaum, Steve Watt, and Alex Apotsos. Oceanographer Walter Dudley of the University of Hawai‘i, Hilo, will work with the USGS team. The team will collect time-sensitive data to help them determine the height of tsunami waves at various sites and the distances the waves traveled inland. They will study the transport of sediment and other debris, look for and measure evidence of subsidence and uplift caused by the earthquake, document erosion caused by the tsunami waves, and make other observations critical to the better understanding of tsunami impacts and processes. Posted: 2009-11-24
Open-File Report 2009-1195: Coastal Circulation and Sediment Dynamics in War-in-the-Pacific National Historical Park, Guam Flow in and around coral reefs affects a number of physical, chemical and biologic processes that influence the health and sustainability of coral reef ecosystems. These range from the residence time of sediment and contaminants to nutrient uptake and larval retention and dispersal. As currents approach a coast they diverge to flow around reef structures, causing high horizontal and vertical shear. This can result in either the rapid advection of material in localized jets, or the retention of material in eddies that form in the lee of bathymetric features. The high complexity and diversity both within and between reefs, in conjunction with past technical restrictions, has limited our understanding of the nature of flow and the resulting flux of physical, chemical, and biologic material in these fragile ecosystems. Posted: 2009-10-13
USGS Northern Gulf of Mexico (NGOM) The goal of the USGS Northern Gulf of Mexico project is to understand the evolution of coastal ecosystems on the Northern Gulf Coast, the impact of human activities on these ecosystems, and the vulnerability of ecosystems and human communities to more frequent and more intense hurricanes in the future. Posted: 2009-05-28
Scientific Investigations Report 2008-5094: Connections Among the Spatial and Temporal Structures in Tidal Currents, Internal Bores, and Surficial Sediment Distributions Over the Shelf off Palos Verdes, California 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. Posted: 2009-05-28
Open-File Report 2009-1073: The Framework of a Coastal Hazards Model—A Tool for Predicting the Impact of Severe Storms The U.S. Geological Survey (USGS) Multi-Hazards Demonstration Project in Southern California (Jones and others, 2007) is a five-year project (FY2007-FY2011) integrating multiple USGS research activities with the needs of external partners, such as emergency managers and land-use planners, to produce products and information that can be used to create more disaster-resilient communities. The hazards being evaluated include earthquakes, landslides, floods, tsunamis, wildfires, and coastal hazards. For the Coastal Hazards Task of the Multi-Hazards Demonstration Project in Southern California, the USGS is leading the development of a modeling system for forecasting the impact of winter storms threatening the entire Southern California shoreline from Pt. Conception to the Mexican border. The modeling system, run in real-time or with prescribed scenarios, will incorporate atmospheric information (that is, wind and pressure fields) with a suite of state-of-the-art physical process models (that is, tide, surge, and wave) to enable detailed prediction of currents, wave height, wave runup, and total water levels. Additional research-grade predictions of coastal flooding, inundation, erosion, and cliff failure will also be performed. Initial model testing, performance evaluation, and product development will be focused on a severe winter-storm scenario developed in collaboration with the Winter Storm Working Group of the USGS Multi-Hazards Demonstration Project in Southern California. Additional offline model runs and products will include coastal-hazard hindcasts of selected historical winter storms, as well as additional severe winter-storm simulations based on statistical analyses of historical wave and water-level data. The coastal-hazards model design will also be appropriate for simulating the impact of storms under various sea level rise and climate-change scenarios. The operational capabilities of this modeling system are designed to provide emergency planners with the critical information they need to respond quickly and efficiently and to increase public safety and mitigate damage associated with powerful coastal storms. For instance, high resolution local models will predict detailed wave heights, breaking patterns, and current strengths for use in warning systems for harbor-mouth navigation and densely populated coastal regions where beach safety is threatened. The offline applications are intended to equip coastal managers with the information needed to manage and allocate their resources effectively to protect sections of coast that may be most vulnerable to future severe storms. Posted: 2009-05-26
Open-File Report 2009-1029: Coastal processes study of Santa Barbara and Ventura Counties, California By Patrick L. Barnard, David L. Revell, Dan Hoover, Jon Warrick, John Brocatus, Amy E. Draut, Pete Dartnell, Edwin Elias, Neomi Mustain, Pat E. Hart, and Holly F. Ryan. The Santa Barbara littoral cell (SBLC) is a complex coastal system with significant management challenges. The coastline ranges broadly in exposure to wave energy, fluvial inputs, hard structures, and urbanization. Geologic influence (structural control) on coastline orientation exerts an important control on local beach behavior, with anthropogenic alterations and the episodic nature of sediment supply and transport also playing important roles. Posted: 2009-03-27
Scientific Investigations Report 2007-5101: The Coral Reef of South Moloka‘i, Hawai‘i—Portrait of a Sediment-Threatened Fringing Reef In this landmark volume, U.S. Geological Survey researchers and their colleagues have developed and applied a remarkably integrated approach to the reefs of Moloka‘i, combining geology, oceanography, and biology to provide an in-depth understanding of the processes that have made these reefs grow and that now limit them. They have joined old fashioned natural history of marine animals and plants with study of the geological evolution of the island, hydrology, meteorology, and land-use history, to an arsenal of new methods of remote sensing, including aerial photography, laser ranging, infrared thermal mapping, seismic reflection, in-situ instrumentation to measure chemical parameters of water quality, and direct measurements of the physical driving forces affecting them—such as wave energy, currents, sedimentation, and sediment transport. They provide a level of documentation and insight that has never been available for any reef before. Posted: 2008-11-19
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 This U.S. Geological Survey Data Series report presents time-series photographs of the sea floor obtained from an instrumented tripod deployed in western Massachusetts Bay (site LT-A, 42? 22.6' N., 70? 47.0' W., 32 m water depth) from December 1989 to October 1996. The photographs provide time-series observations of changes of the sea floor, near-bottom water turbidity, and life on the sea floor. The photographs, obtained every 4 or every 6 hours, are presented as individual photographs (in .png format) and as a movie (in .avi format). Posted: 2008-11-17
USGS Data Series 266, Time-series photographs of the sea floor in western Massachusetts Bay, 1996 - 2005 Title Page This U.S. Geological Survey Data Series report presents time-series photographs of the sea floor obtained from an instrumented tripod deployed in western Massachusetts Bay (site LT-A, 42? 22.6' N., 70? 47.0' W., 32 m water depth) from December 1989 to October 1996. The photographs provide time-series observations of changes of the sea floor, near-bottom water turbidity, and life on the sea floor. The photographs, obtained every 4 or every 6 hours, are presented as individual photographs (in .png format) and as a movie (in .avi format). Posted: 2008-11-17
Documentation of the U.S. Geological Survey Oceanographic Time-Series Measurement Database, USGS Open-File Report 2007-1194, Title Page Observations of ocean current and hydrographic measurements primarily from the coastal United States are provided in this database. Data is available in the raw sample interval logged by the instrument, and optionally as hourly averaged, and low-pass filtered files. Data served may include measurements of currents, light transmission (beam attenuation), temperature, conductivity, density, oxygen, salinity, and other parameters. Time range: 1975 - present" Posted: 2008-11-17
Open-File Report 2008-1295: Coastal Circulation and Sediment Dynamics in Hanalei Bay, Kaua'i, Part IV, Measurements of Waves, Currents, Temperature, Salinity, and Turbidity, June-September 2006 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. Posted: 2008-10-08
WCMG Coastal Processes Studies California's beaches and nearshore regions are valuable economic and recreational resources but also provide habitats for numerous sensitive species. During winter storms, the coast represents a potentially dangerous interface between ocean and land, nature and humans. Storms produce high waves, strong currents, and elevated sea level that can rapidly erode beaches and inundate low-lying coastal regions, damaging and/or destroying public and private infrastructure as well as stressing coastal ecosystems. Over longer-time scales (e.g. decadal), persistent erosion exacerbated by the pressures of coastal development, reduction in sediment availability and climate change, can result in severely depleted beaches. The USGS performs research along the California coast to understand the physical processes that control coastal change on time scales from individual storms to decades to support the efforts of local, state and government agencies to make informed coastal management decisions to most effectively preserve and protect this valuable resource. Posted: 2008-09-23
Open-File Report 2008-1215: Winds, Waves, Tides, and the Resulting Flow Patterns and Fluxes of Water, Sediment, and Coral Larvae off West Maui, Hawaii A series of recent studies has focused on the flow patterns and particle fluxes along the coast of West Maui, Hawaii, USA, from Honolua south to Puumana. From those studies a relatively good understanding has emerged of the physical processes that influence the relative amount of suspended sediment in nearshore waters and the circulation patterns that transport sediment and coral larvae along the coast and between islands. This report is a synthesis of our existing knowledge on the nature of flow and transport off West Maui. Posted: 2008-07-02
Scientific Investigations Report 2008-5042: Update on Regulation of Sand Transport in the Colorado River by Changes in the Surface Grain Size of Eddy Sandbars over Multiyear Timescales In settings where the transport of sand is partially or fully supply limited, changes in the upstream supply of sand are coupled to changes in the grain size of sand on the bed. In this manner, the transport of sand under the supply-limited case is “grain-size regulated.” Since the closure of Glen Canyon Dam in 1963, the downstream reach of the Colorado River in Marble and Grand Canyons has exhibited evidence of sand-supply limitation. Sand transport in the river is now about equally regulated by changes in the discharge of water and changes in the grain sizes of sand on the channel bed and eddy sandbars. Previous work has shown that changes in the grain size of sand on the channel bed (driven by changes in the upstream supply of sand owing to both tributary floods and high dam releases) are important in regulating sand transport over timescales of days to months. In this study, suspended-sand data are analyzed in conjunction with bed grain-size data to determine whether changes in the sand grain size on the channel bed, or changes in the sand grain size on the surface of eddy sandbars, have been more important in regulating sand transport in the postdam Colorado River over longer, multiyear timescales. The results of this study show that this combined theory- and field-based approach can be used to deduce which environments in a complicated setting are most important for regulating sediment transport. In the case of the regulated Colorado River in Marble and upper Grand Canyons, suspended-sand transport has been regulated mostly by changes in the surface grain size of eddy sandbars. Posted: 2008-04-29
USGS Open-File Report 2007-1310: Submarine Ground Water Discharge and Fate Along the Coast of Kaloko-Honokohau National Historical Park, Hawai'i; Part I; Time-Series Measurements of Currents, Waves, Salinity and Temperature: November, 2005-July, 2007 The impending development for the west Hawai‘i coastline adjacent to Kaloko-Honokōhau National Historical Park (KAHO) may potentially alter coastal hydrology and water quality in the marine waters of the park. Water resources are perhaps the most significant natural and cultural resource component in the park, and are critical to the health and well being of six federally listed species. KAHO contains ecosystems of brackish anchialine pools, two 11-acre fishponds, and 596 acres of coral reef habitats, all fed by groundwater originating upslope. The steep gradients on high islands, combined with typically porous substrates and high rainfall levels at upper elevations, make these settings especially vulnerable to shifts in submarine groundwater discharge (SGD) and its entrained nutrients and pollutants. Little is known about the magnitude, rate, frequency, and variability of SGD and its influence on contaminant loading to Hawaiian coastal environments. Recent studies show that groundwater flux through the park is vital to many ecosystem components including anchialine ponds and wetland biota. The function of these ecosystems may be vulnerable to changes in groundwater flow stemming from natural changes (climate and sea level) and land use (groundwater pumping and contamination). Oki and others (1999) showed that increased groundwater withdrawals for urban development since 1978 likely decreased groundwater flux to the coast by 50%. During this same time, the quality of groundwater has been vulnerable to increases in contaminant and nutrient/fertilizer additions associated with industrial, commercial and residential use upslope from KAHO (Oki and others, 1999). High-resolution measurements of waves, currents, water levels, temperature and salinity were collected in the marine portion of the park from November, 2005, through July, 2006, to establish baseline information on the magnitude, rate, frequency, and variability of SGD. These data are intended to help researchers and resource managers better understand the hydrodynamics of the oceanographic environment in the park’s coastal waters as it pertains to the pathway of SGD and associated nutrient and contaminant input to the park’s coral reef ecosystem. Measurements were made of the oceanographic environment (waves, tides, currents, salinity and temperature) using hydrodynamic techniques to characterize and quantify the distribution, input and throughput of freshwater and associated nutrient/contaminant within the near shore environment of KAHO through the emplacement of a series of bottom-mounted instruments deployed in water depths less than 15 m. This study was conducted in support of the National Park Service (NPS) by the U.S. Geological Survey (USGS) Coastal and Marine Geology Program’s Coral Reef Project. These measurements support the ongoing studies of the Coral Reef Project to better understand the transport mechanisms of sediment, larvae, nutrients, pollutants and other particles on Pacific coral reefs. Subsequent reports will address the spatial and temporal variability in groundwater input and the associated nutrient flux in the park’s waters Posted: 2008-03-11
Open-File Report 2007-1412: Carpinteria Coastal Processes Study, 2005-2007; Final Report The United States Geological Survey (USGS), in collaboration with the University of California, Santa Cruz (UCSC), conducted a two-year study of the beach and nearshore coastal processes for the City of Carpinteria and adjacent beaches. The work was performed in response to and worked directly with the United States Army Corps of Engineers (USACE) Project Management Plan (PMP) for the City of Carpinteria: Carpinteria Shoreline, Santa Barbara County, California PMP (June 2003). Posted: 2008-02-04
The Massachusetts Bay Internal Wave Experiment, August 1998: Data Report, USGS DS 85, Version 2.0, Start Page This data report presents a description of the Massachusetts Bay Internal Wave Experiment (MBIWE) field program carried out in August 1998, an overview of the data through summary plots and statistics, and the time-series data in NetCDF format. The objective of this report is to make the data available in digital form and to provide summary plots and statistics to facilitate browsing of the data set. Posted: 2008-02-01
USGS Monterey Bay Science USGS Monterey Bay Science - USGS research in the Monterey Bay National Marine Sanctuary and coastal watersheds of central California Posted: 2008-01-01
USGS Coastal Change Hazards USGS Coastal Change Hazards - Focuses on hurricanes, tsunamis, sea-level rise, shoreline erosion, wetland destruction, and other issues relevant to coastal zone management and disaster preparedness. Posted: 2008-01-01
Coastal and Marine Knowledge Bank An initiative to develop and present a national-scale, interdisciplinary scientific framework for marine environments, the coastal zone, and coastal watersheds Posted: 2007-11-28
Open-File Report 2007-1305: Bathymetry, Substrate and Circulation in Westcott Bay, San Juan Islands, Washington Nearshore bathymetry, substrate type, and circulation patterns in Westcott Bay, San Juan Islands, Washington, were mapped using two acoustic sonar systems, video and direct sampling of seafloor sediments. The goal of the project was to characterize nearshore habitat and conditions influencing eelgrass (Z. marina) where extensive loss has occurred since 1995. A principal hypothesis for the loss of eelgrass is a recent decrease in light availability for eelgrass growth due to increase in turbidity associated with either an increase in fine sedimentation or biological productivity within the bay. To explore sources for this fine sediment and turbidity, a dual-frequency Biosonics sonar operating at 200 and 430 kHz was used to map seafloor depth, morphology and vegetation along 69 linear kilometers of the bay. The higher frequency 430 kHz system also provided information on particulate concentrations in the water column. A boat-mounted 600 kHz RDI Acoustic Doppler Current Profiler (ADCP) was used to map current velocity and direction and water column backscatter intensity along another 29 km, with select measurements made to characterize variations in circulation with tides. An underwater video camera was deployed to ground-truth acoustic data. Seventy one sediment samples were collected to quantify sediment grain size distributions across Westcott Bay. Sediment samples were analyzed for grain size at the Western Coastal and Marine Geology Team sediment laboratory in Menlo Park, Calif. These data reveal that the seafloor near the entrance to Westcott Bay is rocky with a complex morphology and covered with dense and diverse benthic vegetation. Current velocities were also measured to be highest at the entrance and along a deep channel extending 1 km into the bay. The substrate is increasingly comprised of finer sediments with distance into Westcott Bay where current velocities are lower. This report describes the data collected and preliminary findings of USGS Cruise B-6-07-PS conducted between May 31, 2007 and June 5, 2007. Posted: 2007-10-18
USGS Data Series 265, Time-Series Photographs of the Sea Floor in Western Massachusetts Bay, Version 1, 1989-1993, USGS Data Series 265, Title Page This U.S. Geological Survey (USGS) Data Series report presents time-series photographs of the sea floor obtained from an instrumented tripod deployed in western Massachusetts Bay (42° 22.6' N., 70° 47.0' W., 30 m water depth) from December 1989 to March 1990; July 1990 to October 1990; and October 1990 to February 1991. The objective of this report is to enable easy and rapid viewing of the photographs and to provide a medium-resolution digital archive. The images, obtained every 6 hours, are presented as a movie (in .avi format that may be viewed using an image viewer such as QuickTime or Windows Media Player) and as individual images (.jpg format.)" /> Coastal and Marine Geology Program
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