Internal tides affect benthic community structure in an energetic submarine canyon off SW Taiwan

Science.gov (United States)

Liao, Jian-Xiang; Chen, Guan-Ming; Chiou, Ming-Da; Jan, Sen; Wei, Chih-Lin

2017-07-01

Submarine canyons are major conduits of terrestrial and shelf organic matter, potentially benefiting the seafloor communities in the food-deprived deep sea; however, strong bottom currents driven by internal tides and the potentially frequent turbidity currents triggered by storm surges, river flooding, and earthquakes may negatively impact the benthos. In this study, we investigated the upper Gaoping Submarine Canyon (GPSC), a high-sediment-yield canyon connected to a small mountain river (SMR) off southwest (SW) Taiwan. By contrasting the benthic meiofaunal and macrofaunal communities within and outside the GPSC, we examined how food supplies and disturbance influenced the benthic community assemblages. The benthic communities in the upper GPSC were mainly a nested subset of the adjacent slope assemblages. Several meiofaunal (e.g. ostracods) and macrofaunal taxa (e.g. peracarid crustaceans and mollusks) that typically occurred on the slope were lost from the canyon. The polychaete families switched from diverse feeding guilds on the slope to motile subsurface deposit feeders dominant in the canyon. The diminishing of epibenthic peracarids and proliferation of deep burrowing polychaetes in the GPSC resulted in macrofauna occurring largely within deeper sediment horizons in the canyon than on the slope. The densities and numbers of taxa were depressed with distinct and more variable composition in the canyon than on the adjacent slope. Both the densities and numbers of taxa were negatively influenced by internal tide flushing and positively influenced by food availability; however, the internal tides also negatively influenced the food supplies. While the meiofauna and macrofauna densities were both depressed by the extreme physical conditions in the GPSC, only the macrofaunal densities increased with depth in the canyon, presumably related to increased frequency and intensity of disturbance toward the canyon head. The population densities of meiofauna, on the

Partly standing internal tides in a dendritic submarine canyon observed by an ocean glider

Science.gov (United States)

Hall, Rob A.; Aslam, Tahmeena; Huvenne, Veerle A. I.

2017-08-01

An autonomous ocean glider is used to make the first direct measurements of internal tides within Whittard Canyon, a large, dendritic submarine canyon system that incises the Celtic Sea continental slope and a site of high benthic biodiversity. This is the first time a glider has been used for targeted observations of internal tides in a submarine canyon. Vertical isopycnal displacement observations at different stations fit a one-dimensional model of partly standing semidiurnal internal tides - comprised of a major, incident wave propagating up the canyon limbs and a minor wave reflected back down-canyon by steep, supercritical bathymetry near the canyon heads. The up-canyon internal tide energy flux in the primary study limb decreases from 9.2 to 2.0 kW m-1 over 28 km (a dissipation rate of 1 - 2.5 ×10-7 Wkg-1), comparable to elevated energy fluxes and internal tide driven mixing measured in other canyon systems. Within Whittard Canyon, enhanced mixing is inferred from collapsed temperature-salinity curves and weakened dissolved oxygen concentration gradients near the canyon heads. It has previously been hypothesised that internal tides impact benthic fauna through elevated near-bottom current velocities and particle resuspension. In support of this, we infer order 20 cm s-1 near-bottom current velocities in the canyon and observe high concentrations of suspended particulate matter. The glider observations are also used to estimate a 1 °C temperature range and 12 μmol kg-1 dissolved oxygen concentration range, experienced twice a day by organisms on the canyon walls, due to the presence of internal tides. This study highlights how a well-designed glider mission, incorporating a series of tide-resolving stations at key locations, can be used to understand internal tide dynamics in a region of complex topography, a sampling strategy that is applicable to continental shelves and slopes worldwide.

Submarine tectonic relief off Enshunada. Enshunadaoki no hendo chikei

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Iwabuchi, Y; Sasahara, N; Hamamoto, F [Maritime Safety Agency, Tokyo (Japan); Yoshioka, S [10th Resional Maritime Safety Headquarters, Kagoshima (Japan); Kondo, T [Maritime Safety School, Kyoto (Japan)

1991-08-15

This paper reports on the results of investigations on the submarine relief structure off the Enshunada (a sea area which is on the south of the Tenryu River mouth and has about 50km east and west and about 100km north and south) using a bathymetric surveying ship equipped with a narrow multibeam echo sounder. The submarine relief structure of this sea area is clarified into the following topographical districts arranged north to south (each extends roughly in the northeast-southwest direction): the Enshu trough and Tenryu submarine canyon upper valley located in the center thereof, ridges represented by No.l and No.2 Tenryu knolls, the ridge and trough zone where minor ridges and troughes appear complicatedly and repeatedly, and the Nankai trough. The paper contains causes of formation of the Tenryu submarine canyon, the Ryuyo submarine canyon which is located in the northwestern slope of No.2 Tenryu knoll and has a distinct shape, oval-shaped domes scattered in the bottom of Nankai trough, etc. and also opinions on landslide topography seen in the ridge and trough zone. 13 refs., 5 figs., 1 tab.

Anatomy of La Jolla submarine canyon system; offshore southern California

Science.gov (United States)

Paull, C.K.; Caress, D.W.; Lundsten, E.; Gwiazda, R.; Anderson, K.; McGann, M.; Conrad, J.; Edwards, B.; Sumner, E.J.

2013-01-01

An autonomous underwater vehicle (AUV) carrying a multibeam sonar and a chirp profiler was used to map sections of the seafloor within the La Jolla Canyon, offshore southern California, at sub-meter scales. Close-up observations and sampling were conducted during remotely operated vehicle (ROV) dives. Minisparker seismic-reflection profiles from a surface ship help to define the overall geometry of the La Jolla Canyon especially with respect to the pre-canyon host sediments. The floor of the axial channel is covered with unconsolidated sand similar to the sand on the shelf near the canyon head, lacks outcrops of the pre-canyon host strata, has an almost constant slope of 1.0° and is covered with trains of crescent shaped bedforms. The presence of modern plant material entombed within these sands confirms that the axial channel is presently active. The sand on the canyon floor liquefied during vibracore collection and flowed downslope, illustrating that the sediment filling the channel can easily fail even on this gentle slope. Data from the canyon walls help constrain the age of the canyon and extent of incision. Horizontal beds of moderately cohesive fine-grained sediments exposed on the steep canyon walls are consistently less than 1.232 million years old. The lateral continuity of seismic reflectors in minisparker profiles indicate that pre-canyon host strata extend uninterrupted from outside the canyon underneath some terraces within the canyon. Evidence of abandoned channels and point bar-like deposits are noticeably absent on the inside bend of channel meanders and in the subsurface of the terraces. While vibracores from the surface of terraces contain thin (art seafloor mapping and exploration tools provides a uniquely detailed view of the morphology within an active submarine canyon.

Anatomy of La Jolla submarine canyon system; offshore southern California

Science.gov (United States)

Paull, C.K.; Caress, D.W.; Lundsten, E.; Gwiazda, R.; Anderson, K.; McGann, M.; Conrad, J.; Edwards, B.; Sumner, E.J.

2013-01-01

An autonomous underwater vehicle (AUV) carrying a multibeam sonar and a chirp profiler was used to map sections of the seafloor within the La Jolla Canyon, offshore southern California, at sub-meter scales. Close-up observations and sampling were conducted during remotely operated vehicle (ROV) dives. Minisparker seismic-reflection profiles from a surface ship help to define the overall geometry of the La Jolla Canyon especially with respect to the pre-canyon host sediments. The floor of the axial channel is covered with unconsolidated sand similar to the sand on the shelf near the canyon head, lacks outcrops of the pre-canyon host strata, has an almost constant slope of 1.0° and is covered with trains of crescent shaped bedforms. The presence of modern plant material entombed within these sands confirms that the axial channel is presently active. The sand on the canyon floor liquefied during vibracore collection and flowed downslope, illustrating that the sediment filling the channel can easily fail even on this gentle slope. Data from the canyon walls help constrain the age of the canyon and extent of incision. Horizontal beds of moderately cohesive fine-grained sediments exposed on the steep canyon walls are consistently less than 1.232 million years old. The lateral continuity of seismic reflectors in minisparker profiles indicate that pre-canyon host strata extend uninterrupted from outside the canyon underneath some terraces within the canyon. Evidence of abandoned channels and point bar-like deposits are noticeably absent on the inside bend of channel meanders and in the subsurface of the terraces. While vibracores from the surface of terraces contain thin (< 10 cm) turbidites, they are inferred to be part of a veneer of recent sediment covering pre-canyon host sediments that underpin the terraces. The combined use of state of the art seafloor mapping and exploration tools provides a uniquely detailed view of the morphology within an active submarine canyon.

Isotopic evidence for the influence of typhoons and submarine canyons on the sourcing and transport behavior of biospheric organic carbon to the deep sea

Science.gov (United States)

Zheng, Li-Wei; Ding, Xiaodong; Liu, James T.; Li, Dawei; Lee, Tsung-Yu; Zheng, Xufeng; Zheng, Zhenzhen; Xu, Min Nina; Dai, Minhan; Kao, Shuh-Ji

2017-05-01

Export of biospheric organic carbon from land masses to the ocean plays an important role in regulating the global carbon cycle. High-relief islands in the western Pacific are hotspots for such land-to-ocean carbon transport due to frequent floods and active tectonics. Submarine canyon systems serve as a major conduit to convey terrestrial organics into the deep sea, particularly during episodic floods, though the nature of ephemeral sediment transportation through such canyons remains unclear. In this study, we deployed a sediment trap in southwestern Taiwan's Gaoping submarine canyon during summer 2008, during which Typhoon Kalmaegi impacted the study area. We investigated sources of particulate organic carbon and quantified the content of fossil organic carbon (OCf) and biospheric non-fossil carbon (OCnf) during typhoon and non-typhoon periods, based on relations between total organic carbon (TOC), isotopic composition (δ13 C, 14C), and nitrogen to carbon ratios (N/C) of newly and previously reported source materials. During typhoons, flooding connected terrestrial rivers to the submarine canyon. Fresh plant debris was not found in the trap except in the hyperpycnal layer, suggesting that only hyperpycnal flow is capable of entraining plant debris, while segregation had occurred during non-hyperpycnal periods. The OCnf components in typhoon flood and trapped samples were likely sourced from aged organics buried in ancient landslides. During non-typhoon periods, the canyon is more connected to the shelf, where waves and tides cause reworking, thus allowing abiotic and biotic processes to generate isotopically uniform and similarly aged OCnf for transport into the canyon. Therefore, extreme events coupled with the submarine canyon system created an efficient method for deep-sea burial of freshly produced organic-rich material. Our results shed light on the ephemeral transport of organics within a submarine canyon system on an active tectonic margin.

Geo-hazard by sediment mass movements in submarine canyons

Science.gov (United States)

Ghaith, Afif; Fakhri, Milad; Ivaldi, Roberta; Ciavola, Paolo

2017-04-01

Submarine mass movements and their consequences are of major concern for coastal communities and infrastructures but also for the exploitation and the development of seafloor resources. Elevated awareness of the need for better understanding of the underwater mass movement is coupled with great advances in underwater mapping technologies over the past two decades. The seafloor in the Nahr Ibrahim and Saida regions (Lebanon) is characterized by deep canyons, reaching one thousand meters depths in proximity of the coast. Signs of submarine mass movement instability related to these canyons create a connection between shallow and deep water. The presence of these canyons in a tectonically active area generates a particular drained mechanism to the sediment in form of mass movement and slumping. Identification of potential areas where slope movements could be triggered requires data with high spatial resolution. Since this area is poorly explored, in the framework of an international project between Lebanese Navy, Lebanese National Center for Marine Sciences, University of Ferrara and Italian Hydrographic Institute, we analyse the morpho-bathymetric and sedimentological characters of the coastal and shelf sectors. Multibeam echosounder and sub-bottom profiler acoustic systems calibrated with ground truths (sediment grab and core samples) allow us to characterize the nature of seafloor and sub-seafloor with particular detail to the geotechnical properties of sediments and high resolution seismic stratigraphy of the shallow layers. The detection of particular undersea features provides detail maps which are in support to littoral morpho-dynamics, coastal transport and sediment budget. Multilayer hydro-oceanographic map, referring to the seafloor dynamics in connection with deep water environment and drainage system, in accordance to the International Hydrographic Standards and nautical supports, are produced. This high resolution multibeam bathymetry dataset, integrated

Seasonal pathways of organic matter within the Avilés submarine canyon: Foodweb implications

NARCIS (Netherlands)

Romero-Romero, S.; Molina-Ramírez, A.; Höfer, J.; Duineveld, G.C.A.; Rumín-Caparrós, A.; Sanchez-Vidal, A.; Canals, M.; Acuña, J.L.

2016-01-01

The transport and fate of organic matter (OM) sources within the Avilés submarine canyon (Cantabrian Sea, Southern Bay of Biscay) were studied using carbon and nitrogen stable isotope ratios. The isotopic composition of settling particles and deep bottom sediments closely resembled that of surface

Food-web dynamics and isotopic niches in deep-sea communities residing in a submarine canyon and on the adjacent open slopes

NARCIS (Netherlands)

Demopoulos, A.W.J.; McClain-Counts, J.; Ross, S.W.; Brooke, S.; Mienis, F.

2017-01-01

Examination of food webs and trophic niches provide insights into organisms’ functionalecology, yet few studies have examined trophodynamics within submarine canyons, wherethe interaction of canyon morphology and oceanography influences habitat provision and fooddeposition. Using stable isotope

Microbial Communities in Sunken Wood Are Structured by Wood-Boring Bivalves and Location in a Submarine Canyon

Science.gov (United States)

Fagervold, Sonja K.; Romano, Chiara; Kalenitchenko, Dimitri; Borowski, Christian; Nunes-Jorge, Amandine; Martin, Daniel; Galand, Pierre E.

2014-01-01

The cornerstones of sunken wood ecosystems are microorganisms involved in cellulose degradation. These can either be free-living microorganisms in the wood matrix or symbiotic bacteria associated with wood-boring bivalves such as emblematic species of Xylophaga, the most common deep-sea woodborer. Here we use experimentally submerged pine wood, placed in and outside the Mediterranean submarine Blanes Canyon, to compare the microbial communities on the wood, in fecal pellets of Xylophaga spp. and associated with the gills of these animals. Analyses based on tag pyrosequencing of the 16S rRNA bacterial gene showed that sunken wood contained three distinct microbial communities. Wood and pellet communities were different from each other suggesting that Xylophaga spp. create new microbial niches by excreting fecal pellets into their burrows. In turn, gills of Xylophaga spp. contain potential bacterial symbionts, as illustrated by the presence of sequences closely related to symbiotic bacteria found in other wood eating marine invertebrates. Finally, we found that sunken wood communities inside the canyon were different and more diverse than the ones outside the canyon. This finding extends to the microbial world the view that submarine canyons are sites of diverse marine life. PMID:24805961

Submarine canyons as coral and sponge habitat on the eastern Bering Sea slope

Directory of Open Access Journals (Sweden)

Robert J. Miller

2015-07-01

Full Text Available Submarine canyons have been shown to positively influence pelagic and benthic biodiversity and ecosystem function. In the eastern Bering Sea, several immense canyons lie under the highly productive “green belt” along the continental slope. Two of these, Pribilof and Zhemchug canyons, are the focus of current conservation interest. We used a maximum entropy modeling approach to evaluate the importance of these two canyons, as well as canyons in general, as habitat for gorgonian (alcyonacean corals, pennatulacean corals, and sponges, in an area comprising most of the eastern Bering Sea slope and outer shelf. These invertebrates create physical structure that is a preferred habitat for many mobile species, including commercially important fish and invertebrates. We show that Pribilof canyon is a hotspot of structure-forming invertebrate habitat, containing over 50% of estimated high-quality gorgonian habitat and 45% of sponge habitat, despite making up only 1.7% of the total study area. The amount of quality habitat for gorgonians and sponges varied in other canyons, but canyons overall contained more high-quality habitat for structure-forming invertebrates compared to other slope areas. Bottom trawling effort was not well correlated with habitat quality for structure-forming invertebrates, and bottom-contact fishing effort in general, including longlining and trawling, was not particularly concentrated in the canyons examined. These results suggest that if conserving gorgonian coral habitat is a management goal, canyons, particularly Pribilof Canyon, may be a prime location to do this without excessive impact on fisheries.

AUV Mapping and ROV Exploration of Los Frailes Submarine Canyon, Cabo Pulmo National Marine Park, Baja California Sur, Mexico

Science.gov (United States)

Troni, G.; Caress, D. W.; Graves, D.; Thomas, H. J.; Thompson, D.; Barry, J. P.; Aburto-Oropeza, O.; Johnson, A. F.; Lundsten, L.

2015-12-01

Los Frailes submarine canyon is located at the south boundary of the Cabo Pulmo National Marine Park on the southeast tip of the Baja California Peninsula. During the Monterey Bay Aquarium Research Institute (MBARI) 2015 Gulf of California expedition we used an autonomous underwater vehicle (AUV) to map this canyon from 50 m to 450 m depths, and then explored the canyon with a small remotely operated vehicle (ROV). This three day R/V Rachel Carson cruise was a collaboration with the Center for Marine Biodiversity and Conservation at Scripps Institution of Oceanography and the Centro para la Biodiversidad Marina y la Conservación in La Paz. The MBARI AUV D. Allan B. collected high resolution bathymetry, sidescan, and subbottom profiles of Los Frailes submarine canyon and part of the north Cabo Pulmo deep reef. In order to safely generate a 1-m lateral resolution multibeam bathymetry map in the nearshore high relief terrain, the mapping operations consisted of an initial short survey following the 100-m isobath followed by a series of short, incremental AUV missions located on the deep edge of the new AUV bathymetry. The MBARI Mini-ROV was used to explore the submarine canyon within the detailed map created by the MBARI AUV. The Mini-ROV is a 1.2-m-long, 350 kg, 1,500-m-depth-rated ROV designed and constructed by MBARI. It is controlled by six 600-watt thrusters and is equipped with a high-definition video camera and navigation sensors. This small ROV carries less accurate, lower cost navigation sensors than larger vehicles. We implemented new algorithms to localize combining Doppler velocity log sensor data and low-cost MEMS-based inertial sensor data with sporadic ultra-short baseline position measurements to provide a high accuracy position estimation. The navigation performance allowed us to colocate the ROV video imagery with the 1-m resolution bathymetric map of the submarine canyon. Upper Los Frailes Canyon is rugged and, aside from small sand pockets along

Tidal and flood signatures of settling particles in the Gaoping submarine canyon (SW Taiwan) revealed from radionuclide and flow measurements

Science.gov (United States)

Huh, C.-A.; Liu, J.T.; Lin, H.-L.; Xu, J. P.

2009-01-01

Sediment transport and sedimentation processes in the Gaoping submarine canyon were studied using sediment trap and current meter moorings deployed at a location during the winter (January-March) and the summer (July-September) months in 2008. At the end of each deployment, sediment cores were also collected from the canyon floor at the mooring site. Samples from sediment traps and sediment cores were analyzed for 210Pb and 234Th by gamma spectrometry. In conjunction with particle size and flow measurements, the datasets suggest that sediment transport in the canyon is tidally-modulated in the drier winter season and flood (river)-dominated in the wetter summer season. From the magnitude and temporal variation of sediment flux in the canyon with respect to the burial flux and sediment budget on the open shelf and slope region, we reaffirm that, on annual or longer timescales, the Gaoping submarine canyon is an effective conduit transporting sediments from the Gaoping River's drainage basin (the source) to the deep South China Sea (the ultimate sink). ?? 2009 Elsevier B.V.

Food-web dynamics and isotopic niches in deep-sea communities residing in a submarine canyon and on the adjacent open slopes

Science.gov (United States)

Demopoulos, Amanda W.J.; McClain-Counts, Jennifer; Ross, Steve W.; Brooke, Sandra; Mienis, Furu

2017-01-01

Examination of food webs and trophic niches provide insights into organisms' functional ecology, yet few studies have examined trophodynamics within submarine canyons, where the interaction of canyon morphology and oceanography influences habitat provision and food deposition. Using stable isotope analysis and Bayesian ellipses, we documented deep-sea food-web structure and trophic niches in Baltimore Canyon and the adjacent open slopes in the US Mid-Atlantic Region. Results revealed isotopically diverse feeding groups, comprising approximately 5 trophic levels. Regression analysis indicated that consumer isotope data are structured by habitat (canyon vs. slope), feeding group, and depth. Benthic feeders were enriched in 13C and 15N relative to suspension feeders, consistent with consuming older, more refractory organic matter. In contrast, canyon suspension feeders had the largest and more distinct isotopic niche, indicating they consume an isotopically discrete food source, possibly fresher organic material. The wider isotopic niche observed for canyon consumers indicated the presence of feeding specialists and generalists. High dispersion in δ13C values for canyon consumers suggests that the isotopic composition of particulate organic matter changes, which is linked to depositional dynamics, resulting in discrete zones of organic matter accumulation or resuspension. Heterogeneity in habitat and food availability likely enhances trophic diversity in canyons. Given their abundance in the world's oceans, our results from Baltimore Canyon suggest that submarine canyons may represent important havens for trophic diversity.

Near-bottom particulate matter dynamics in the Nazare submarine canyon under calm and stormy conditions

NARCIS (Netherlands)

Martín, J.; Palanques, A.; Vitorino, J.; Oliveira, A.; de Stigter, H.C.

2011-01-01

Two mooring lines equipped with near-bottom sediment traps were deployed in the axis of the Nazare submarine canyon at similar to 1600 and similar to 3300 m depth, respectively. We studied time-series of particle flux, composition (biogenic silica, carbonates, organic matter and lithogenic

Submarine canyons represent an essential habitat network for krill hotspots in a Large Marine Ecosystem.

Science.gov (United States)

Santora, Jarrod A; Zeno, Ramona; Dorman, Jeffrey G; Sydeman, William J

2018-05-15

Submarine canyon systems are ubiquitous features of marine ecosystems, known to support high levels of biodiversity. Canyons may be important to benthic-pelagic ecosystem coupling, but their role in concentrating plankton and structuring pelagic communities is not well known. We hypothesize that at the scale of a large marine ecosystem, canyons provide a critical habitat network, which maintain energy flow and trophic interactions. We evaluate canyon characteristics relative to the distribution and abundance of krill, critically important prey in the California Current Ecosystem. Using a geological database, we conducted a census of canyon locations, evaluated their dimensions, and quantified functional relationships with krill hotspots (i.e., sites of persistently elevated abundance) derived from hydro-acoustic surveys. We found that 76% of krill hotspots occurred within and adjacent to canyons. Most krill hotspots were associated with large shelf-incising canyons. Krill hotspots and canyon dimensions displayed similar coherence as a function of latitude and indicate a potential regional habitat network. The latitudinal migration of many fish, seabirds and mammals may be enhanced by using this canyon-krill network to maintain foraging opportunities. Biogeographic assessments and predictions of krill and krill-predator distributions under climate change may be improved by accounting for canyons in habitat models.

Multibeam bathymetric survey of the Ipala Submarine Canyon, Jalisco, Mexico (20°N): The southern boundary of the Banderas Forearc Block?

Science.gov (United States)

Urías Espinosa, J.; Bandy, W. L.; Mortera Gutiérrez, C. A.; Núñez Cornú, Fco. J.; Mitchell, N. C.

2016-03-01

The Middle America Trench bends sharply northward at 20°N. This, along with the close proximity of the Rivera-North America Euler pole to the northern end of this trench, sharply increases the obliquity of subduction at 20°N. By analogy with other subduction zones with similar sharply changing obliquity, significant trench parallel extension is expected to exist in the forearc region near the bend. To evaluate this possibility, multibeam bathymetric, seafloor backscatter and sub-bottom seismic reflection data were collected in this area during the MORTIC08 campaign of the B.O. El Puma. These data image in detail a large submarine canyon (the Ipala Canyon) extending from the coast at 20°05‧N to the Middle America Trench at 19°50‧N. This canyon is 114 km long and is fed by sediments originating from two, possibly three, small rivers: the Ipala, Tecolotlán and Maria Garza. This canyon deeply incises (up to 600 m) the entire continental slope and at least the outer part of the shelf. Within the canyon, we observe meanders and narrow channels produced by turbidity flows indicating that the canyon is active. In the marginal areas of the canyon slumps, rills, and uplifts suggest that mass movements and fluid flow have had a major impact on the seafloor morphology. The seafloor bathymetry, backscatter images and sub-bottom reflection profiles evidence the tectonic processes occurring in this area. Of particular interest, the canyon is deflected by almost 90° at three locations, the deflections all having a similar azimuth of between 125° and 130°. Given the prominence and geometry of this canyon, along with its tectonic setting, we propose that the presence of the canyon is related to extension produced by the sharp change in the plate convergence. If so, the canyon may lie along the southeast boundary of a major forearc block (the Banderas Forearc Block).

A new model for turbidity current behavior based on integration of flow monitoring and precision coring in a submarine canyon

Science.gov (United States)

Symons, William O.; Sumner, Esther J.; Paull, Charles K.; Cartigny, Matthieu J.B.; Xu, Jingping; Maier, Katherine L.; Lorenson, Thomas; Talling, Peter J.

2017-01-01

Submarine turbidity currents create some of the largest sediment accumulations on Earth, yet there are few direct measurements of these flows. Instead, most of our understanding of turbidity currents results from analyzing their deposits in the sedimentary record. However, the lack of direct flow measurements means that there is considerable debate regarding how to interpret flow properties from ancient deposits. This novel study combines detailed flow monitoring with unusually precisely located cores at different heights, and multiple locations, within the Monterey submarine canyon, offshore California, USA. Dating demonstrates that the cores include the time interval that flows were monitored in the canyon, albeit individual layers cannot be tied to specific flows. There is good correlation between grain sizes collected by traps within the flow and grain sizes measured in cores from similar heights on the canyon walls. Synthesis of flow and deposit data suggests that turbidity currents sourced from the upper reaches of Monterey Canyon comprise three flow phases. Initially, a thin (38–50 m) powerful flow in the upper canyon can transport, tilt, and break the most proximal moorings and deposit chaotic sands and gravel on the canyon floor. The initially thin flow front then thickens and deposits interbedded sands and silty muds on the canyon walls as much as 62 m above the canyon floor. Finally, the flow thickens along its length, thus lofting silty mud and depositing it at greater altitudes than the previous deposits and in excess of 70 m altitude.

Geomorphic characterization of four shelf-sourced submarine canyons along the U.S. Mid-Atlantic continental margin

Science.gov (United States)

Obelcz, Jeffrey; Brothers, Daniel S.; Chaytor, Jason D.; ten Brink, Uri S.; Ross, Steve W.; Brooke, Sandra

2013-01-01

Shelf-sourced submarine canyons are common features of continental margins and are fundamental to deep-sea sedimentary systems. Despite their geomorphic and geologic significance, relatively few passive margin shelf-breaching canyons worldwide have been mapped using modern geophysical methods. Between 2007 and 2012 a series of geophysical surveys was conducted across four major canyons of the US Mid-Atlantic margin: Wilmington, Baltimore, Washington, and Norfolk canyons. More than 5700 km2 of high-resolution multibeam bathymetry and 890 line-km of sub-bottom CHIRP profiles were collected along the outer shelf and uppermost slope (depths of 80-1200 m). The data allowed us to compare and contrast the fine-scale morphology of each canyon system. The canyons have marked differences in the morphology and orientation of canyon heads, steepness and density of sidewall gullies, and the character of the continental shelf surrounding canyon rims. Down-canyon axial profiles for Washington, Baltimore and Wilmington canyons have linear shapes, and each canyon thalweg exhibits morphological evidence for recent, relatively small-scale sediment transport. For example, Washington Canyon displays extremely steep wall gradients and contains ~100 m wide, 5–10 m deep, v-shaped incisions down the canyon axis, suggesting modern or recent sediment transport. In contrast, the convex axial thalweg profile, the absence of thalweg incision, and evidence for sediment infilling at the canyon head, suggest that depositional processes strongly influence Norfolk Canyon during the current sea-level high-stand. The north walls of Wilmington, Washington and Norfolk canyons are steeper than the south walls due to differential erosion, though the underlying cause for this asymmetry is not clear. Furthermore, we speculate that most of the geomorphic features observed within the canyons (e.g., terraces, tributary canyons, gullies, and hanging valleys) were formed during the Pleistocene, and show only

Canyons off northwest Puerto Rico

International Nuclear Information System (INIS)

Gardner, W.D.; Glover, L.K.; Hollister, C.D.

1980-01-01

The Nuclear-Research Submarine NR-1 was used to study morphoplogy, sediment, and sediment-water interactions off the northwest coast of Puerto Rico. New detailed bathymetry from the surface-support ship, USS Portland, shows several submarine canyons in the area, some of them unreported previously. The north coast canyons, Arecibo, Tiberones and Quebradillas, are primarily erosional features although no recent turbidity-current evidence is seen. The canyons are presently filling with river-transported sediments. (orig./ME)

Climate and sea level controlled sedimentation processes in two submarine canyons off NW-Africa

OpenAIRE

Pierau, Roberto

2008-01-01

This study focuses on the trigger mechanisms of gravity-driven sediment transport in two submarine canyons at the passive continental margin off NW-Africa during the past 240 kyr. The sedimentary records allow to determine the turbidite emplacement times based on high resolution age models. The sediment textures of the turbidites were studied by using X-ray radiographies. The sedimentary properties like the terrigenous silt size distribution and XRF-core scanning element data allow to identif...

Seasonal pathways of organic matter within the Avilés submarine canyon: Food web implications

Science.gov (United States)

Romero-Romero, Sonia; Molina-Ramírez, Axayacatl; Höfer, Juan; Duineveld, Gerard; Rumín-Caparrós, Aitor; Sanchez-Vidal, Anna; Canals, Miquel; Acuña, José Luis

2016-11-01

The transport and fate of organic matter (OM) sources within the Avilés submarine canyon (Cantabrian Sea, Southern Bay of Biscay) were studied using carbon and nitrogen stable isotope ratios. The isotopic composition of settling particles and deep bottom sediments closely resembled that of surface particulate OM, and there were no marked differences in the isotopic composition of settling particles inside and outside of the AC. This indicates that the Avilés Canyon (AC) receives inputs of sinking OM mostly from the upper water column and less through advective near-bottom down-canyon transport. Sinking OM fluxes are of marine and terrestrial origin in proportions which vary seasonally. Analysis of δ13C in the canyon fauna indicates a dependence on OM mainly produced by marine phytoplankton. A tight coupling of isotopic signatures between pelagic organisms and benthic suspension feeders reflects an active biological vertical transport of OM from the surface to the deep-sea. The food web presented seasonal variations in the trophic niche width and the amplitude of the primary carbon sources, reflecting seasonality in the availability of fresh particulate OM. Those seasonal changes are larger for benthic organisms of lower trophic levels.

Newly recognized turbidity current structure can explain prolonged flushing of submarine canyons.

Science.gov (United States)

Azpiroz-Zabala, Maria; Cartigny, Matthieu J B; Talling, Peter J; Parsons, Daniel R; Sumner, Esther J; Clare, Michael A; Simmons, Stephen M; Cooper, Cortis; Pope, Ed L

2017-10-01

Seabed-hugging flows called turbidity currents are the volumetrically most important process transporting sediment across our planet and form its largest sediment accumulations. We seek to understand the internal structure and behavior of turbidity currents by reanalyzing the most detailed direct measurements yet of velocities and densities within oceanic turbidity currents, obtained from weeklong flows in the Congo Canyon. We provide a new model for turbidity current structure that can explain why these are far more prolonged than all previously monitored oceanic turbidity currents, which lasted for only hours or minutes at other locations. The observed Congo Canyon flows consist of a short-lived zone of fast and dense fluid at their front, which outruns the slower moving body of the flow. We propose that the sustained duration of these turbidity currents results from flow stretching and that this stretching is characteristic of mud-rich turbidity current systems. The lack of stretching in previously monitored flows is attributed to coarser sediment that settles out from the body more rapidly. These prolonged seafloor flows rival the discharge of the Congo River and carry ~2% of the terrestrial organic carbon buried globally in the oceans each year through a single submarine canyon. Thus, this new structure explains sustained flushing of globally important amounts of sediment, organic carbon, nutrients, and fresh water into the deep ocean.

Transport and fluxes of terrestrial polycyclic aromatic hydrocarbons in a small mountain river and submarine canyon system.

Science.gov (United States)

Lin, Bing-Sian; Lee, Chon-Lin; Brimblecombe, Peter; Liu, James T

2016-08-01

Polycyclic aromatic hydrocarbon (PAH) concentrations in the Gaoping River were investigated in the wet and dry seasons. PAH characteristics allowed us to trace the particulate matter transported in a river-sea system containing a small mountain river, continental shelf, and submarine canyon. PAH signatures of the Gaoping River showed that particles were rapidly transported from the high mountain to the Gaoping coastal areas in the wet season, even arriving at the deep ocean via the Gaoping Submarine Canyon. By contrast, in the dry season, the particles were delivered quite slowly and included mostly pyrogenic contaminants. The annual riverine flux estimates for PAHs were 2241 kg in the Gaoping river-sea system. Only 18.0 kg were associated with the dissolved phase; the rest was bound onto particles. The fluxes caused by typhoons and their effects accounted for 20.2% of the dissolved and 68.4% of the particulate PAH fluxes from the river. Normalized partition coefficients for organic carbon suggested that PAHs were rigid on the particles. Distinct source characteristics were evident for PAHs on riverine suspended particles and coastal surface sediments: the particles in the wet season (as background signals) were similar to petrogenic sources, whereas the particles in the dry season had characteristics of coal burning and vehicular emissions. The sediments in the northwestern shelf were similar to pyrogenic sources (including vehicular emissions and coal and biomass burning), whereas the sediments in the canyon and southeastern shelf arose from mixed sources, although some diesel signature was also evident. Copyright © 2016 Elsevier Ltd. All rights reserved.

Modeled alongshore circulation and morphologic evolution onshore of a large submarine canyon

Science.gov (United States)

Hansen, J. E.; Raubenheimer, B.; List, J. H.; Elgar, S.; Guza, R. T.; Lippmann, T. C.

2012-12-01

Alongshore circulation and morphologic evolution observed at an ocean beach during the Nearshore Canyon Experiment, onshore of a large submarine canyon in San Diego, CA (USA), are investigated using a two-dimensional depth-averaged numerical model (Delft3D). The model is forced with waves observed in ~500 m water depth and tidal constituents derived from satellite altimetry. Consistent with field observations, the model indicates that refraction of waves over the canyon results in wave focusing ~500 m upcoast of the canyon and shadowing onshore of the canyon. The spatial variability in the modeled wave field results in a corresponding non-uniform alongshore circulation field. In particular, when waves approach from the northwest the alongshore flow converges near the wave focal zone, while waves that approach from the southwest result in alongshore flow that diverges away from the wave focal zone. The direction and magnitude of alongshore flows are determined by a balance between the (often opposing) radiation stress and alongshore pressure gradients, consistent with observations and previous results. The largest observed morphologic evolution, vertical accretion of about 1.5 m in about 3 m water depth near the wave focal zone, occurred over a one-week period when waves from the northwest reached heights of 1.8 m. The model, with limited tuning, replicates the magnitude and spatial extent of the observed accretion and indicates that net accretion of the cross-shore profile was owing to alongshore transport from converging alongshore flows. The good agreement between the observed and modeled morphology change allows for an in-depth examination of the alongshore force balance that resulted in the sediment convergence. These results indicate that, at least in this case, a depth-averaged hydrodynamic model can replicate observed surfzone morphologic change resulting from forcing that is strongly non-uniform in the alongshore. Funding was provided by the Office of Naval

Let's Bet on Sediments! Hudson Canyon Cruise--Grades 9-12. Focus: Sediments of Hudson Canyon.

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National Oceanic and Atmospheric Administration (DOC), Rockville, MD.

These activities are designed to teach about the sediments of Hudson Canyon. Students investigate and analyze the patterns of sedimentation in the Hudson Canyon, observe how heavier particles sink faster than finer particles, and learn that submarine landslides are avalanches of sediment in deep ocean canyons. The activity provides learning…

Shelf erosion and submarine river canyons: implications for deep-sea oxygenation and ocean productivity during glaciation

Directory of Open Access Journals (Sweden)

I. Tsandev

2010-06-01

Full Text Available The areal exposure of continental shelves during glacial sea level lowering enhanced the transfer of erodible reactive organic matter to the open ocean. Sea level fall also activated submarine canyons thereby allowing large rivers to deposit their particulate load, via gravity flows, directly in the deep-sea. Here, we analyze the effects of shelf erosion and particulate matter re-routing to the open ocean during interglacial to glacial transitions, using a coupled model of the marine phosphorus, organic carbon and oxygen cycles. The results indicate that shelf erosion and submarine canyon formation may significantly lower deep-sea oxygen levels, by up to 25%, during sea level low stands, mainly due to the supply of new material from the shelves, and to a lesser extent due to particulate organic matter bypassing the coastal zone. Our simulations imply that deep-sea oxygen levels can drop significantly if eroded shelf material is deposited to the seafloor. Thus the glacial ocean's oxygen content could have been significantly lower than during interglacial stages. Primary production, organic carbon burial and dissolved phosphorus inventories are all affected by the erosion and rerouting mechanisms. However, re-routing of the continental and eroded shelf material to the deep-sea has the effect of decoupling deep-sea oxygen demand from primary productivity in the open ocean. P burial is also not affected showing a disconnection between the biogeochemical cycles in the water column and the P burial record.

The End of Monterey Submarine Canyon Incision and Potential River Source Areas-Os, Nd, and Pb Isotope Constraints from Hydrogenetic Fe-Mn Crusts

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Conrad, T. A.; Nielsen, S.; Ehrenbrink, B. P. E.; Blusztajn, J.; Hein, J. R.; Paytan, A.

2015-12-01

The Monterey Canyon off central California is the largest submarine canyon off North America and is comparable in scale to the Grand Canyon. The age and history of the Monterey Canyon are poorly constrained due to thick sediment cover and sediment disruption from turbidity currents. To address this deficit we analyzed isotopic proxies (Os, Pb, Nd) from hydrogenetic ferromanganese (Fe-Mn) crusts, which grow over millions of years on elevated rock surfaces by precipitation of metals from seawater. Fe-Mn crusts were studied from Davidson Seamount near the base of the Monterey submarine fan, the Taney Seamount Chain, and from Hoss Seamount, which serves as a regional control (Fig.). Fe-Mn crusts were dated using Os isotope ratios compared to those that define the Cenozoic Os isotope seawater curve. Four Fe-Mn crust samples from Davidson and Taney Seamounts deviate from the Os isotopic seawater curve towards radiogenic values after 4.5±1 Ma. Osmium is well mixed in the global ocean and is not subject to significant diffusive reequilibration in Fe-Mn crusts. We therefore attribute deviations from the Os isotope seawater curve to large-scale terrestrial input that ended about 4.5±1 Ma. The two Davidson samples also show more radiogenic Nd isotope values from about 4.5±1 Ma. Lead isotopes in one Davidson Seamount crust, measured by LA-ICPMS, deviate from regional values after 4.5±1 Ma for about 500 ka towards terrestrial sources. The Taney Seamount Fe-Mn crust does not deviate from regional Nd nor Pb isotope values due to its greater distance from Monterey Canyon and the shorter marine residence times of Nd and Pb. Isotope plots of our crust data and compiled data for potential source rocks indicate that the river that carved Monterey Canyon carried sediment with values closer to the Sierra Nevada than to a Colorado Plateau source, with cessation of major riverine input occurring approximately 4.5±1 Ma, an age that we interpret as the end of the Monterey Canyon

Late Quaternary evolution of the San Antonio Submarine Canyon in the central Chile forearc (∼33°S)

Science.gov (United States)

Laursen, Jane; Normark, William R.

2002-01-01

Hydrosweep swath-bathymetry and seismic-reflection data reveal the morphology, sedimentary processes, and structural controls on the submarine San Antonio Canyon. The canyon crosses the forearc slope of the central Chile margin for more than 150 km before it empties into the Chile Trench near 33°S latitude. In its upper reaches, the nearly orthogonal segments of the San Antonio Canyon incise ∼1 km into thick sediment following underlying margin-perpendicular basement faults and along the landward side of a prominent margin-parallel thrust ridge on the outer mid-slope. At a breach in the outer ridge, the canyon makes a sharp turn into the San Antonio Reentrant. Resistance to erosion of outcropping basement at the head of the reentrant has prevented the development of a uniformly sloping thalweg, leaving gentle gradients (6°) across the lower slope. Emergence of an obstruction across the head of the San Antonio Reentrant has trapped sediment in the mid-slope segments of the canyon. Presently, little sediment appears to reach the Chile Trench through the San Antonio Canyon. The development of the San Antonio Canyon was controlled by the impact of a subducted seamount, which formed the San Antonio Reentrant and warped the middle slope along its landward advancing path. Incision of the canyon landward of the outer mid-slope ridge may be ascribed to a combination of headward erosion and entrenchment by captured unconfined turbidity currents. Flushing of the canyon was likely enhanced during the lowered sea level of the last glaciation. Where the canyon occupies the triangular embayment of the reentrant at the base of the slope, sediment has ponded behind a small accretionary ridge. On the trench floor opposite the San Antonio Canyon mouth, a 200-m-thick levee–overbank complex formed on the left side of a distributary channel emanating from a breach in the accretionary ridge. Axial transfer of sediment was inhibited to the north of the San Antonio Canyon mouth

Direct sampling during multiple sediment density flows reveals dynamic sediment transport and depositional environment in Monterey submarine canyon

Science.gov (United States)

Maier, K. L.; Gales, J. A.; Paull, C. K.; Gwiazda, R.; Rosenberger, K. J.; McGann, M.; Lundsten, E. M.; Anderson, K.; Talling, P.; Xu, J.; Parsons, D. R.; Barry, J.; Simmons, S.; Clare, M. A.; Carvajal, C.; Wolfson-Schwehr, M.; Sumner, E.; Cartigny, M.

2017-12-01

in the experiment. The comprehensive scale of the Monterey Coordinated Canyon Experiment allows us to integrate sediment traps with ADCP instrument data and seafloor core samples, which provides important new data to constrain how, when, and what sediment is transported through submarine canyons and how this is archived in seafloor deposits.

Demography and movement patterns of leopard sharks (Triakis semifasciata) aggregating near the head of a submarine canyon along the open coast of southern California, USA

Science.gov (United States)

Nosal, D.C.; Cartamil, D.C.; Long, J.W.; Luhrmann, M.; Wegner, N.C.; Graham, J.B.

2013-01-01

The demography, spatial distribution, and movement patterns of leopard sharks (Triakis semifasciata) aggregating near the head of a submarine canyon in La Jolla, California, USA, were investigated to resolve the causal explanations for this and similar shark aggregations. All sharks sampled from the aggregation site (n=140) were sexually mature and 97.1 % were female. Aerial photographs taken during tethered balloon surveys revealed high densities of milling sharks of up to 5470 sharks ha-1. Eight sharks were each tagged with a continuous acoustic transmitter and manually tracked without interruption for up to 48 h. Sharks exhibited strong site-fidelity and were generally confined to a divergence (shadow) zone of low wave energy, which results from wave refraction over the steep bathymetric contours of the submarine canyon. Within this divergence zone, the movements of sharks were strongly localized over the seismically active Rose Canyon Fault. Tracked sharks spent most of their time in shallow water (≤2 m for 71.0 % and ≤10 m for 95.9 % of time), with some dispersing to deeper (max: 53.9 m) and cooler (min: 12.7 °C) water after sunset, subsequently returning by sunrise. These findings suggest multiple functions of this aggregation and that the mechanism controlling its formation, maintenance, and dissolution is complex and rooted in the sharks' variable response to numerous confounding environmental factors.

Direct Measurements of the Evolution and Impact of Sediment Density Flows as they Pass Through Monterey Submarine Canyon, Offshore California

Science.gov (United States)

Paull, C. K.; Talling, P.; Maier, K. L.; Parsons, D. R.; Xu, J.; Caress, D. W.; Gwiazda, R.; Lundsten, E. M.; Anderson, K.; Barry, J.; Chaffey, M. R.; O'Reilly, T. C.; Rosenberger, K. J.; Gales, J. A.; McGann, M.; McCann, M. P.; Simmons, S.; Sumner, E.

2017-12-01

Sediment density flows flushing through submarine canyons carry globally significant amounts of material into the deep sea to form many of the largest sediment accumulations on Earth. Despite their global significance, these flows remain poorly understood because they have rarely been directly measured. Here we provide an initial overview of the recently completed Coordinated Canyon Experiment (CCE), which was undertaken specifically to provide detailed measurements of sediment density flows and their impact on seafloor morphology and sedimentology. No previous study has deployed as extensive an array of monitoring sensors along a turbidity current pathway. During the 18 months of the CCE, at least 15 sediment density flows were recorded within the axis of Monterey Canyon. Because no external triggers (i.e., earthquakes or floods) correlate with these flows, they must have originated as failures in the canyon floor or canyon flanks. Three flows ignited and ran out for > 50 km from water depths of 1,860 m, reaching velocities up to 8.1 m/s. The rest of the flows died out within the array. During these events, large objects on or in the canyon floor were displaced substantial distances downslope, including a 7.1 km downslope movement of an entire mooring; a 4.6 km displacement of an 860 kg instrument frame followed by repeated down canyon displacements of this same frame after it was entombed in sediment; and multiple depth changes of man-made boulders containing acceleration and pressure sensors. During this same time interval the canyon floor was mapped six times with autonomous underwater vehicles covering the canyon thalweg at the upper and lower end of the instrument array (200-540 and 1350-1880 m water depths). The repeated mapping surveys reveal that flows caused +3 to -3 m bathymetric changes within a continuous clearly defined 200 m wide swath running along the canyon axis in 540 m water depth. This study shows that sediment density flows caused massive

Application of a new genetic classification and semi-automated geomorphic mapping approach in the Perth submarine canyon, Australia

Science.gov (United States)

Picard, K.; Nanson, R.; Huang, Z.; Nichol, S.; McCulloch, M.

2017-12-01

The acquisition of high resolution marine geophysical data has intensified in recent years (e.g. multibeam echo-sounding, sub-bottom profiling). This progress provides the opportunity to classify and map the seafloor in greater detail, using new methods that preserve the links between processes and morphology. Geoscience Australia has developed a new genetic classification approach, nested within the Harris et al (2014) global seafloor mapping framework. The approach divides parent units into sub-features based on established classification schemes and feature descriptors defined by Bradwell et al. (2016: http://nora.nerc.ac.uk/), the International Hydrographic Organization (https://www.iho.int) and the Coastal Marine and Ecological Classification Standard (https://www.cmecscatalog.org). Owing to the ecological significance of submarine canyon systems in particular, much recent attention has focused on defining their variation in form and process, whereby they can be classified using a range of topographic metrics, fluvial dis/connection and shelf-incising status. The Perth Canyon is incised into the continental slope and shelf of southwest Australia, covering an area of >1500 km2 and extending from 4700 m water depth to the shelf break in 170 m. The canyon sits within a Marine Protected Area, incorporating a Marine National Park and Habitat Protection Zone in recognition of its benthic and pelagic biodiversity values. However, detailed information of the spatial patterns of the seabed habitats that influence this biodiversity is lacking. Here we use 20 m resolution bathymetry and acoustic backscatter data acquired in 2015 by the Schmidt Ocean Institute plus sub-bottom datasets and sediment samples collected Geoscience Australia in 2005 to apply the new geomorphic classification system to the Perth Canyon. This presentation will show the results of the geomorphic feature mapping of the canyon and its application to better defining potential benthic habitats.

Sorting of Terrestrial and Marine Organic Matter along a Marginal Submarine Canyon: Radiocarbon and Biomarker Signatures of Surface Sediments

Science.gov (United States)

Close, H. G.; Doherty, S.; Campbell, P.; McCarthy, M. D.; Prouty, N.

2016-02-01

Submarine canyons are incised features of many continental margins that can have significant influence on the hydrodynamic distribution of sediments and organic matter (OM) eroded and deposited from the continents. Baltimore Canyon, on the U.S. mid-Atlantic margin, contains a complex set of sedimentary processes that simultaneously create unique benthic habitats and control the deposition of OM. Along the canyon axis, loci of net erosion, net deposition, and intense winnowing each host diverse faunal assemblages and varying mixtures of sedimentary OM derived both from production in the overlying water column and from mobilized sediments. Bioavailable components of this deposited OM sustain benthic communities, while recalcitrant components can contribute to long-term carbon burial in the deep sea. Here we probe in detail the terrestrial versus marine origins of OM along a transect of Baltimore Canyon, as well as its bioavailability for benthic fauna, in order to explore how canyon-specific sediment dynamics might emplace a functional sorting of OM from shelf to open ocean. Determining the provenance of sedimentary OM is a continual challenge: commonly-measured bulk geochemical properties often provide insufficient information to distinguish end-member sources. We present a novel approach to separate functional classes of OM and investigate sources and degradative pathways of OM in Baltimore Canyon. In combination with bulk geochemical characteristics, surface sediments from water depths of 200-1200 meters were sequentially extracted (solvent-extracted, acid-hydrolyzed, and demineralized) to separate pools containing different prevalence of terrigenous, marine, and recalcitrant OM. Each class was analyzed for biomarker distributions; amino acid content, 13C signatures, and degradation indicators; bulk carbon and nitrogen isotopes; and radiocarbon content in order to characterize potential end-member sources within the mixture, as well as their age profiles. These

Defining biological assemblages (biotopes) of conservation interest in the submarine canyons of the South West Approaches (offshore United Kingdom) for use in marine habitat mapping

Science.gov (United States)

Davies, Jaime S.; Howell, Kerry L.; Stewart, Heather A.; Guinan, Janine; Golding, Neil

2014-06-01

In 2007, the upper part of a submarine canyon system located in water depths between 138 and 1165 m in the South West (SW) Approaches (North East Atlantic Ocean) was surveyed over a 2 week period. High-resolution multibeam echosounder data covering 1106 km2, and 44 ground-truthing video and image transects were acquired to characterise the biological assemblages of the canyons. The SW Approaches is an area of complex terrain, and intensive ground-truthing revealed the canyons to be dominated by soft sediment assemblages. A combination of multivariate analysis of seabed photographs (184-1059 m) and visual assessment of video ground-truthing identified 12 megabenthic assemblages (biotopes) at an appropriate scale to act as mapping units. Of these biotopes, 5 adhered to current definitions of habitats of conservation concern, 4 of which were classed as Vulnerable Marine Ecosystems. Some of the biotopes correspond to descriptions of communities from other megahabitat features (for example the continental shelf and seamounts), although it appears that the canyons host modified versions, possibly due to the inferred high rates of sedimentation in the canyons. Other biotopes described appear to be unique to canyon features, particularly the sea pen biotope consisting of Kophobelemnon stelliferum and cerianthids.

Macro- and megafauna recorded in the submarine Bari Canyon (southern Adriatic, Mediterranean Sea using different tools

Directory of Open Access Journals (Sweden)

G. D'ONGHIA

2015-01-01

Full Text Available Macro- and megafauna were recorded in the submarine Bari Canyon (southern Adriatic Sea, Mediterranean Sea during an oceanographic cruise carried out in May-June 2012 and an experimental fishing survey conducted in November 2013. During the former, a total of 20 benthic samples were taken using a Van Veen grab at depths between 268 and 770 m and 4 deployments of a baited lander, for about 43 hours of video records, were carried out at depths between 443 and 788 m. During the latter, 8 longline fishing operations were conducted from 338 down to 612 m. Eighty-five living benthic and benthopelagic species were recorded: 29 Porifera, 1 Cnidaria, 2 Mollusca, 11 Annelida, 1 Arthropoda, 19 Bryozoa, 3 Echinodermata and 19 Chordata. A total of 51 species are new records for the Bari Canyon, 29 new records for the Adriatic Sea. Among the Porifera Cerbaris curvispiculifer is a new addition for the Italian Sponge Fauna. The first certain record of living specimens for the bryozoan Crisia tenella longinodata is reported. A total of 6 Mediterranean endemic species have been identified: 4 Porifera and 2 Annelida. The bathymetric range of some species has been extended. New information acquired for deep sea species confirms their importance in the structure of cold-water coral communities. This study has updated the knowledge on the biodiversity of the Adriatic Sea, as well as of the Bari Canyon in particular, one of the sites designated as “jewels of the Mediterranean” for which urgent conservation measures are needed.

Submarine canyons off the Coromandel coast

Digital Repository Service at National Institute of Oceanography (India)

Varadachari, V.V.R.; Nair, R.R.; Murty, P.S.N.

During the 26th Cruise of I.N.S. `KISTNA', a bathymetric survey was carried out in some detail off the Pondicherry coast. This survey has revealed the existence of three sets of distinctly separate canyons between Cuddalore and Palar River...

Distributions and habitat associations of deep-water corals in Norfolk and Baltimore Canyons, Mid-Atlantic Bight, USA

NARCIS (Netherlands)

Brooke, S.D.; Watts, M.W.; Heil, A.D.; Rhode, M.; Mienis, F.; Duineveld, G.C.A.; Davies, A.J.; Ross, S.W.

2017-01-01

A multi-disciplinary study of two major submarine canyons, Baltimore Canyon and Norfolk Canyon, off the US mid-Atlantic coast focused on the ecology and biology of canyon habitats, particularly those supporting deep-sea corals. Historical data on deep-sea corals from these canyons were sparse with

Bioavailability of sinking organic matter in the Blanes canyon and the adjacent open slope (NW Mediterranean Sea)

Science.gov (United States)

Lopez-Fernandez, P.; Bianchelli, S.; Pusceddu, A.; Calafat, A.; Sanchez-Vidal, A.; Danovaro, R.

2013-05-01

Submarine canyons are sites of intense energy and material exchange between the shelf and the deep adjacent basins. To test the hypothesis that active submarine canyons represent preferential conduits of available food for the deep-sea benthos, two mooring lines were deployed at 1200 m depth from November 2008 to November 2009 inside the Blanes canyon and on the adjacent open slope (Catalan Margin, NW Mediterranean Sea). We investigated the fluxes, biochemical composition and food quality of sinking organic carbon (OC). OC fluxes in the canyon and the open slope varied among sampling periods, though not consistently in the two sites. In particular, while in the open slope the highest OC fluxes were observed in August 2009, in the canyon the highest OC fluxes occurred in April-May 2009. For almost the entire study period, the OC fluxes in the canyon were significantly higher than those in the open slope, whereas OC contents of sinking particles collected in the open slope were consistently higher than those in the canyon. This result confirms that submarine canyons are effective conveyors of OC to the deep sea. Particles transferred to the deep sea floor through the canyons are predominantly of inorganic origin, significantly higher than that reaching the open slope at a similar water depth. Using multivariate statistical tests, two major clusters of sampling periods were identified: one in the canyon that grouped trap samples collected in December 2008, concurrently with the occurrence of a major storm at the sea surface, and associated with increased fluxes of nutritionally available particles from the upper shelf. Another cluster grouped samples from both the canyon and the open slope collected in March 2009, concurrently with the occurrence of the seasonal phytoplankton bloom at the sea surface, and associated with increased fluxes of total phytopigments. Our results confirm the key ecological role of submarine canyons for the functioning of deep-sea ecosystems

Influence of the Nazaré Canyon, central Portuguese margin, on late winter coccolithophore assemblages

NARCIS (Netherlands)

Guerreiro, C.; Sá, C.; de Stigter, H.; Oliveira, A.; Cachão, M.; Cros, L.; Borges, C.; Quaresma, L.; Santos, A.I.; Fortuño, J.-M.; Rodrigez, A.

2014-01-01

This paper presents a first attempt to characterize coccolithophore assemblages occurring in the context of an active submarine canyon. Coccolithophores from the upper-middle sections of the Nazaré Canyon (central Portuguese margin) – one of the largest canyons of the European continental margin –

Deciphering the Temporal and Spatial Complexity in Submarine Canyons in Antarctica: the Role of Mixed Layer Depth in Regulating Primary Production

Science.gov (United States)

Carvalho, F.; Kohut, J. T.; Schofield, O.; Oliver, M. J.; Gorbunov, M. Y.

2016-02-01

There is a high spatial and temporal variability in the biophysical processes regulating primary productivity in submarine canyons in the West Antarctic Peninsula (WAP). WAP canyon heads are considered biological "hotspots" by providing predictable food resource and driving penguin foraging locations. Because the physiology and composition of the phytoplankton blooms and the physical mechanisms driving them aren't well understood, we aim to characterize the dynamics of the spring phytoplankton bloom at the head of a canyon in the WAP. A 6-year record of Slocum glider deployments is analyzed, corresponding to over 16,000 water column profiles. The mixed layer depth (MLD), determined by the maximum of the buoyancy frequency criteria, was found to be the MLD definition with the highest ecological relevance. The same holds true for other regions in Antarctica such as the Ross and Amundsen Seas. A FIRe sensor on a glider was used to evaluate physiological responses of phytoplankton to canyon dynamics using fluorescence kinetics. Initial results show a spatial influence, with increased photosynthetic efficiencies found at the canyon head. The strongest signal was the seasonal cycle. The shoaling of the MLD in early January results in increased chlorophyll a concentrations and as MLD deepens in mid season due to wind forcing, phytoplankton concentrations decrease, likely due to decreased light availability. A consistent secondary peak in chlorophyll matches a shoaling in MLD later in the growth season. A steady warming and increase in salinity of the MLD is seen throughout the season. Spatial differences were recorded at the head of the canyon and result from the local circulation. Shallower MLD found on the northern region are consistent with a fresher surface ocean (coastal influence) and increased chlorophyll concentrations. The southern region is thought to be more oceanic influenced as intrusions of warm deep water (mUCDW) to the upper water column were recorded

Origin and transport of trace metals deposited in the canyons off Lisboa and adjacent slopes (Portuguese Margin) in the last century

NARCIS (Netherlands)

Costa, A.M.; Mil-Homens, M.; Lebreiro, S.M.; Richter, T.O.; de Stigter, H.; Boer, W.; Trancoso, M.A.; Melo, Z.; Mouro, F.; Mateus, M.; Canário, J.; Branco, V.; Caetano, M.

2011-01-01

Submarine canyons play an important role in the transfer of contaminated sediments from shelf areas to the deeper ocean. To evaluate the importance of submarine canyons adjacent to the Tagus and Sado estuaries (Portuguese Margin) as sediment pathway major and trace elements, (210)Pb radionuclides,

Morphology, processes and geohazards of giant landslides in and around Agadir Canyon, northwest Africa - Cruise MSM32 - September 25 - October 30, 2013 - Bremen (Germany) - Cádiz (Spain)

OpenAIRE

Krastel, Sebastian; Böttner, Christof; Cartigny, Matthieu; Feldens, Peter; Fu, Lili; Glogowski, Silke; Guggolz, Theresa; Hellmann, Sebastian; Hühnerbach, Veit; Jähmlich, Heiko; Kraus, Katrin; Kretschmer, Jacob; Matthew, Duncan; Meier, Daniela; Mücke, Isabell

2014-01-01

Agadir Canyon is one of the largest submarine canyons in the World, supplying giant submarine sediment gravity flows to the Agadir Basin and the wider Moroccan Turbidite System. While the Moroccan Turbidite System is extremely well investigated, almost no data from the source region, i.e. the Agadir Canyon, are available. Understanding why some submarine landslides remain as coherent blocks of sediment throughout their passage downslope, while others mix and disintegrate almost immediately af...

Spatial and temporal infaunal dynamics of the Blanes submarine canyon-slope system (NW Mediterranean); changes in nematode standing stocks, feeding types and gender-life stage ratios

Science.gov (United States)

Ingels, Jeroen; Vanreusel, Ann; Romano, Chiara; Coenjaerts, Johan; Mar Flexas, M.; Zúñiga, Diana; Martin, Daniel

2013-11-01

Despite recent advances in the knowledge of submarine canyons ecosystems, our understanding of the faunal patterns and processes in these environments is still marginal. In this study, meiobenthic nematode communities (from 300 m to 1600 m depth) obtained in November 2003 and May 2004 at eight stations inside and outside Blanes submarine canyon were analysed for nematode standing stocks (SSs), feeding types and gender-life stage distributions. Environmental data were obtained by sediment traps and current meters, attached to moorings (April 2003-May 2004), and sediments samples analysed for biogeochemistry and grain size (May 2004). In November 2003, nematode SSs decreased with increasing depth (367.2 individuals and 7.31 μg C per 10 cm2 at 388 m water depth to 7.7 individuals and 0.18 μg C per 10 cm2 at 1677 m water depth), showing a significant negative relation (abundance: R2 = 0.620, p = 0.020; biomass: R2 = 0.512, p = 0.046). This was not the case in May 2004 (283.5 individuals and 3.53 μg C per 10 cm2 at 388 m water depth to 490.8 individuals and 4.93 μg C per 10 cm2 at 1677 m water depth; abundance: R2 = 0.003, p = 0.902; biomass: R2 = 0.052, p = 0.587), suggesting a temporal effect that overrides the traditional decrease of SSs with increasing water depth. Both water depth and sampling time played a significant role in explaining nematode SSs, but with differences between stations. No overall differences were observed between canyon and open slope stations. Nematode standing stock (SS) patterns can be explained by taking into account the interplay of phytodetrital input and disturbance events, with station differences such as topography playing an important role. Individual nematode size decreased from November 2003 to May 2004 and was explained by a food-induced genera shift and/or a food-induced transition from a ‘latent’ to a ‘reproductive’ nematode community. Our results suggest that size patterns in nematode communities are not solely

Architecture and development of a multi-stage Baiyun submarine slide complex in the Pearl River Canyon, northern South China Sea

Science.gov (United States)

Wang, Lei; Wu, Shi-Guo; Li, Qing-Ping; Wang, Da-Wei; Fu, Shao-Ying

2014-08-01

The Baiyun submarine slide complex (BSSC) along the Pearl River Canyon of the northern South China Sea has been imaged by multibeam bathymetry and 2D/3D seismic data. By means of maximum likelihood classification with slope aspect and gradient as inputs, the BSSC is subdivided into four domains, denoted as slide area I, II, III and IV. Slide area I is surrounded by cliffs on three sides and has been intensely reshaped by turbidity currents generated by other kinds of mass movement outside the area; slide area II incorporates a shield volcano with a diameter of approximately 10 km and unconfined slides possibly resulting from the toe collapse of inter-canyon ridges; slide area III is dominated by repeated slides that mainly originated from cliffs constituting the eastern boundary of the BSSC; slide area IV is distinguished by a conical seamount with a diameter of 6.5 km and a height of 375 m, and two slides probably having a common source that are separated from each other by a suite of residual strata. The BSSC is interpreted to be composed of numerous slide events, which occurred in the period from 10.5 to 5.5 Ma BP. Six specific factors may have contributed to the development of the BSSC, i.e., gas hydrate dissociation, gas-bearing sediments, submarine volcanic activity, seismicity, sedimentation rate and seafloor geomorphology. A 2D conceptual geological model combining these factors is proposed as a plausible mechanism explaining the formation of the BSSC. However, the BSSC may also have been affected by the Dongsha event (10 Ma BP) as an overriding factor.

The Black Canyon of the Gunnison: Today and Yesterday

Science.gov (United States)

Hansen, Wallace R.

1965-01-01

Since the early visit of Captain John William Gunnison in the middle of the last century, the Black Canyon of the Gunnison has stirred mixed apprehension and wonder in the hearts of its viewers. It ranks high among the more awesome gorges of North America. Many great western canyons are as well remembered for their brightly colored walls as for their airy depths. Not so the Black Canyon. Though it is assuredly not black, the dark-gray tones of its walls and the hazy shadows of its gloomy depths join together to make its name well deserved. Its name conveys an impression, not a picture. After the first emotional impact of the canyon, the same questions come to the minds of most reflective viewers and in about the following order: How deep is the Black Canyon, how wide, how does it compare with other canyons, what are the rocks, how did it form, and how long did it take? Several western canyons exceed the Black Canyon in overall size. Some are longer; some are deeper; some are narrower; and a few have walls as steep. But no other canyon in North American combines the depth, narrowness, sheerness, and somber countenance of the Black Canyon. In many places the Black Canyon is as deep as it is wide. Between The Narrows and Chasm View in the Black Canyon of the Gunnison National Monument (fig. 15) it is much deeper than wide. Average depth in the monument is about 2,000 feet, ranging from a maximum of about 2,700 feet, north of Warner Point (which also is the greatest depth anywhere in the canyon), to a minimum of about 1,750 feet at The Narrows. The stretch of canyon between Pulpit Rock and Chasm View, including The Narrows, though the shallowest in the monument, is also the narrowest, has some of the steepest walls, and is, therefore, among the most impressive segments of the canyon (fig. 3). Profiles of several well-known western canyons are shown in figure 1. Deepest of these by far is Hells Canyon of the Snake, on the Idaho-Oregon border. Clearly, it dwarfs the

Marine litter on the floor of deep submarine canyons of the Northwestern Mediterranean Sea: The role of hydrodynamic processes

Science.gov (United States)

Tubau, Xavier; Canals, Miquel; Lastras, Galderic; Rayo, Xavier; Rivera, Jesus; Amblas, David

2015-05-01

Marine litter represents a widespread type of pollution in the World's Oceans. This study is based on direct observation of the seafloor by means of Remotely Operated Vehicle (ROV) dives and reports litter abundance, type and distribution in three large submarine canyons of the NW Mediterranean Sea, namely Cap de Creus, La Fonera and Blanes canyons. Our ultimate objective is establishing the links between active hydrodynamic processes and litter distribution, thus going beyond previous, essentially descriptive studies. Litter was monitored using the Liropus 2000 ROV. Litter items were identified in 24 of the 26 dives carried out in the study area, at depths ranging from 140 to 1731 m. Relative abundance of litter objects by type, size and apparent weight, and distribution of litter in relation to depth and canyon environments (i.e. floor and flanks) were analysed. Plastics are the dominant litter component (72%), followed by lost fishing gear, disregarding their composition (17%), and metal objects (8%). Most of the observed litter seems to be land-sourced. It reaches the ocean through wind transport, river discharge and after direct dumping along the coastline. While coastal towns and industrial areas represent a permanent source of litter, tourism and associated activities relevantly increase litter production during summer months ready to be transported to the deep sea by extreme events. After being lost, fishing gear such as nets and long-lines has the potential of being harmful for marine life (e.g. by ghost fishing), at least for some time, but also provides shelter and a substrate on which some species like cold-water corals are capable to settle and grow. La Fonera and Cap de Creus canyons show the highest mean concentrations of litter ever seen on the deep-sea floor, with 15,057 and 8090 items km-2, respectively, and for a single dive litter observed reached 167,540 items km-2. While most of the largest concentrations were found on the canyon floors at

Facies and depositional model of Almada Canyon, Almada Basin, Bahia, Brazil; Facies e modelo deposicional do Canyon de Almada, Bacia de Almada, Bahia

Energy Technology Data Exchange (ETDEWEB)

D' Avila, Roberto Salvador Francisco; Souza Cruz, Carlos Emanoel de; Oliveira Filho, Jose Souto; Jesus, Candida Menezes de; Cesero, Pedro de; Dias Filho, Dorval Carvalho; Lima, Claudio Coelho de; Queiroz, Claudia Lima de; Santos, Saulo Ferreira; Ferreira, Eduardo Araripe [PETROBRAS, Santos, SP (Brazil). Unidade de Negocio de Exploracao]. E-mail: rdavila@petrobras.com.br

2004-11-01

In the continental portion of the Almada Basin outcrops of canyon filling deposits are represented by turbidite channels and associated facies from Urucutuca Formation. The canyon - semi-exhumated - eroded basement and pre-Cenomanian sedimentary rocks. The field study of the outcrops and cores obtained in adjacent perforations lead to the understanding of the facies and processes that controlled the deposition of these channeled turbidite that can be compared to the reservoirs of many oil fields in Brazil. The Almada canyon is a submarine conduct of tectonic origin that was enlarged by the repeated passing of turbidity currents. During the rift phase and the Albian period, compressive events reactivated old N E and N W faults in the basement as trans current fault systems. The continuation of these stresses, from the Cenomanian to the Maastrichtian, developed normal faults that controlled a submarine canyon that connected the continent, where an estuary was formed between the mountains, to the deep marine region of the basin. The canyon has received sediments brought by catastrophic fluvial floods coming from the surrounding mountains, which formed hyperpicnal flows that have evolved as turbidity currents, thus causing erosion of the substrate and carrying a huge volume of sediments to the basin. A part of that load was deposited in the canyon and formed turbidite channels filled by conglomerates, sandstones and shales. These moderately to highly efficient turbidite are intercalated to pro delta pelites and low density turbid plumes deposits, which have mostly been re mobilized as slump and debris flows (chaotic deposits). Pelites were accumulated mainly in the normal fluvial sedimentation phases, when the sandy sediment was retained next to the canyon head and were reworked by the tides on the upper part of the estuary. (author)

Are deep-sea organisms dwelling within a submarine canyon more at risk from anthropogenic contamination than those from the adjacent open slope? A case study of Blanes canyon (NW Mediterranean)

Science.gov (United States)

Koenig, Samuel; Fernández, Pilar; Company, Joan B.; Huertas, David; Solé, Montserrat

2013-11-01

Due to their geomorphological structure and proximity to the coastline, submarine canyons may act as natural conduit routes for anthropogenic contaminants that are transported from surface waters to the deep-sea. Organisms dwelling in these canyon environments might thus be at risk of experiencing adverse health effects due to higher pollution exposure. To address this question, chemical and biochemical analyses were conducted on two of the most abundant deep-sea fish species in the study area, namely Alepocephalus rostratus and Lepidion lepidion, and the most abundant deep-sea commercial decapod crustacean Aristeus antennatus sampled inside Blanes canyon (BC) and on the adjacent open slope (OS). Persistent organic pollutants (POPs) levels, including polychlorinated biphenyl (PCB), dichlorodiphenyltrichloroethane (DDT) and derivatives, hexachlorocyclohexanes (HCHs) and hexachlorobenzene (HCB) were determined in muscle tissue of selected samples from 900 m and 1500 m depth. Potential effects resulting from contaminant exposure were determined using hepatic biomarkers such as ethoxyresorufin-O-deethylase (EROD), pentoxyresorufin-O-deethylase (PROD), catalase (CAT), carboxylesterase (CbE), glutathione-S-transferase (GST), total glutathione peroxidase (GPX), glutathione reductase (GR) and superoxide-dismutase (SOD) enzyme activities and lipid peroxidation levels (LP). L. lepidion and A. antennatus tissues exhibited higher POP levels inside BC compared to the OS at 900 m depth. These findings were consistent with biomarker data (i.e. enzymatic response to presence of contaminant agents). Elevated xenobiotic-metabolizing (EROD and PROD) and antioxidant enzymes (CAT and GPX) indicated higher contaminant exposure in both species caught within BC. No difference in POP accumulation between sites was observed in L. lepidion at 1500 m depth, nor in biomarker data, suggesting that the pollution gradient was less pronounced at greater depths. This trend was further corroborated

Macrofaunal Patterns in and around du Couedic and Bonney Submarine Canyons, South Australia.

Directory of Open Access Journals (Sweden)

Kathleen E Conlan

Full Text Available Two South Australian canyons, one shelf-incising (du Couedic and one slope-limited (Bonney were compared for macrofaunal patterns on the shelf and slope that spanned three water masses. It was hypothesized that community structure would (H1 significantly differ by water mass, (H2 show significant regional differences and (H3 differ significantly between interior and exterior of each canyon. Five hundred and thirty-one species of macrofauna ≥ 1 mm were captured at 27 stations situated in depth stratified transects inside and outside the canyons from 100 to 1500 m depth. The macrofauna showed a positive relationship to depth in abundance, biomass, species richness and community composition while taxonomic distinctness and evenness remained high at all depths. Biotic variation on the shelf was best defined by variation in bottom water primary production while sediment characteristics and bottom water oxygen, temperature and nutrients defined biotic variation at greater depth. Community structure differed significantly (p<0.01 among the three water masses (shelf-flowing South Australian current, upper slope Flinders current and lower slope Antarctic Intermediate Water (H1. Although community differences between the du Couedic and Bonney regions were marginally above significance at p = 0.05 (H2, over half of the species captured were unique to each region. This supports the evidence from fish and megafaunal distributions that the du Couedic and Bonney areas are in different bioregions. Overall, the canyon interiors were not significantly different in community composition from the exterior (H3. However, both canyons had higher abundance and/or biomass, increased species dominance, different species composition and coarser sediments near the canyon heads compared to outside the canyons at the same depth (500 m, suggestive of heightened currents within the canyons that influence community composition there. At 1000-1500 m, the canyon interiors were

The propagation of sound in narrow street canyons

Science.gov (United States)

Iu, K. K.; Li, K. M.

2002-08-01

This paper addresses an important problem of predicting sound propagation in narrow street canyons with width less than 10 m, which are commonly found in a built-up urban district. Major noise sources are, for example, air conditioners installed on building facades and powered mechanical equipment for repair and construction work. Interference effects due to multiple reflections from building facades and ground surfaces are important contributions in these complex environments. Although the studies of sound transmission in urban areas can be traced back to as early as the 1960s, the resulting mathematical and numerical models are still unable to predict sound fields accurately in city streets. This is understandable because sound propagation in city streets involves many intriguing phenomena such as reflections and scattering at the building facades, diffusion effects due to recessions and protrusions of building surfaces, geometric spreading, and atmospheric absorption. This paper describes the development of a numerical model for the prediction of sound fields in city streets. To simplify the problem, a typical city street is represented by two parallel reflecting walls and a flat impedance ground. The numerical model is based on a simple ray theory that takes account of multiple reflections from the building facades. The sound fields due to the point source and its images are summed coherently such that mutual interference effects between contributing rays can be included in the analysis. Indoor experiments are conducted in an anechoic chamber. Experimental data are compared with theoretical predictions to establish the validity and usefulness of this simple model. Outdoor experimental measurements have also been conducted to further validate the model. copyright 2002 Acoustical Society of America.

Distribution of cold-water corals in the Whittard Canyon, NE Atlantic Ocean

OpenAIRE

Morris, Kirsty J.; Tyler, Paul A.; Masson, Doug G.; Huvenne, Veerle A.I.; Rogers, Alex D.

2013-01-01

The deep-sea floor occupies about 60% of the surface of the planet and is covered mainly by fine sediments. Most studies of deep-sea benthic fauna therefore have concentrated on soft sediments with little sampling of hard substrata, such as rocky outcrops in submarine canyons. Here we assess the distribution and abundance of cold-water corals within the Whittard Canyon (NE Atlantic) using video footage from the ROV Isis. Abundances per 100 m of video transect were calculated and mapped using ...

Megafauna of vulnerable marine ecosystems in French mediterranean submarine canyons: Spatial distribution and anthropogenic impacts

Science.gov (United States)

Fabri, M.-C.; Pedel, L.; Beuck, L.; Galgani, F.; Hebbeln, D.; Freiwald, A.

2014-06-01

Vulnerable Marine Ecosystems (VME) in the deep Mediterranean Sea have been identified by the General Fisheries Commission for the Mediterranean as consisting of communities of Scleractinia (Lophelia pertusa and Madrepora oculata), Pennatulacea (Funiculina quadrangularis) and Alcyonacea (Isidella elongata). This paper deals with video data recorded in the heads of French Mediterranean canyons. Quantitative observations were extracted from 101 video films recorded during the MEDSEACAN cruise in 2009 (Aamp/Comex). Qualitative information was extracted from four other cruises (two Marum/Comex cruises in 2009 and 2011 and two Ifremer cruises in 1995 and 2010) to support the previous observations in the Cassidaigne and Lacaze-Duthiers canyons. All the species, fishing impacts and litter recognized in the video films recorded from 180 to 700 m depth were mapped using GIS. The abundances and distributions of benthic fishing resources (marketable fishes, Aristeidae, Octopodidae), Vulnerable Marine Species, trawling scars and litter of 17 canyons were calculated and compared, as was the open slope between the Stoechades and Toulon canyons. Funiculina quadrangularis was rarely observed, being confined for the most part to the Marti canyon and, I. elongata was abundant in three canyons (Bourcart, Marti, Petit-Rhône). These two cnidarians were encountered in relatively low abundances, and it may be that they have been swept away by repeated trawling. The Lacaze-Duthiers and Cassidaigne canyons comprised the highest densities and largest colony sizes of scleractinian cold-water corals, whose distribution was mapped in detail. These colonies were often seen to be entangled in fishing lines. The alcyonacean Callogorgia verticillata was observed to be highly abundant in the Bourcart canyon and less abundant in several other canyons. This alcyonacean was also severely affected by bottom fishing gears and is proposed as a Vulnerable Marine Species. Our studies on anthropogenic

Recent sediment transport and deposition in the Nazaré Canyon, Portuguese continental margin.

NARCIS (Netherlands)

de Stigter, H.C.; Boer, W.; de Jesus Mendes, P.A.; Jesus, C.C.; Thomsen, L.; van den Bergh, G.D.; van Weering, T.C.E.

2007-01-01

Processes, pathways and fluxes of sediment transport and deposition in the Nazaré submarine canyon, Portuguese continental margin, were investigated by water column profiling of suspended particulate matter, recording of near-bottom currents and suspended particulate matter fluxes with benthic

Influence of submarine morphology on bottom water flow across the western Ross Sea continental margin

Science.gov (United States)

Davey, F.J.; Jacobs, S.S.

2007-01-01

Multibeam sonar bathymetry documents a lack of significant channels crossing outer continental shelf and slope of the western Ross Sea. This indicates that movement of bottom water across the shelf break into the deep ocean in this area is mainly by laminar or sheet flow. Subtle, ~20 m deep and up to 1000 m wide channels extend down the continental slope, into tributary drainage patterns on the upper rise, and then major erosional submarine canyons. These down-slope channels may have been formed by episodic pulses of rapid down slope water flow, some recorded on bottom current meters, or by sub-ice melt water erosion from an icesheet grounded at the margin. Narrow, mostly linear furrows on the continental shelf thought to be caused by iceberg scouring are randomly oriented, have widths generally less than 400 m and depths less than 30m, and extend to water depths in excess of 600 m.

Stresses in a submarine topography under ocean waves

Energy Technology Data Exchange (ETDEWEB)

Mei, C.C.; McTigue, D.F.

1984-09-01

The problem of submarine slope stability is of interest to both offshore engineering and geology. In an uneven topography, the weight above a horizontal plane induces two-dimensional variation in the static stress field. The action of wave pressure, which changes with depth, further introduces excess pore pressure and dynamic stresses in the sea bottom. In the present paper, we combine a simple analytical theory for the static stress by the present authors, and the recent solution by Mei and Foda for wave-induced stresses in a plane poro-elastic sea bed to account for mild bottom slope and wave shoaling, and obtain the effective stress field in a submarine topography under sea waves. Sample results are given for a ridge and a canyon. In particular, the dynamic pore pressure and the combined static and dynamic effective stresses are presented.

Structure-forming corals and sponges and their use as fish habitat in Bering Sea submarine canyons.

Science.gov (United States)

Miller, Robert J; Hocevar, John; Stone, Robert P; Fedorov, Dmitry V

2012-01-01

Continental margins are dynamic, heterogeneous settings that can include canyons, seamounts, and banks. Two of the largest canyons in the world, Zhemchug and Pribilof, cut into the edge of the continental shelf in the southeastern Bering Sea. Here currents and upwelling interact to produce a highly productive area, termed the Green Belt, that supports an abundance of fishes and squids as well as birds and marine mammals. We show that in some areas the floor of these canyons harbors high densities of gorgonian and pennatulacean corals and sponges, likely due to enhanced surface productivity, benthic currents and seafloor topography. Rockfishes, including the commercially important Pacific ocean perch, Sebastes alutus, were associated with corals and sponges as well as with isolated boulders. Sculpins, poachers and pleuronectid flounders were also associated with corals in Pribilof Canyon, where corals were most abundant. Fishes likely use corals and sponges as sources of vertical relief, which may harbor prey as well as provide shelter from predators. Boulders may be equivalent habitat in this regard, but are sparse in the canyons, strongly suggesting that biogenic structure is important fish habitat. Evidence of disturbance to the benthos from fishing activities was observed in these remote canyons. Bottom trawling and other benthic fishing gear has been shown to damage corals and sponges that may be very slow to recover from such disturbance. Regulation of these destructive practices is key to conservation of benthic habitats in these canyons and the ecosystem services they provide.

Structure-forming corals and sponges and their use as fish habitat in Bering Sea submarine canyons.

Directory of Open Access Journals (Sweden)

Robert J Miller

Full Text Available Continental margins are dynamic, heterogeneous settings that can include canyons, seamounts, and banks. Two of the largest canyons in the world, Zhemchug and Pribilof, cut into the edge of the continental shelf in the southeastern Bering Sea. Here currents and upwelling interact to produce a highly productive area, termed the Green Belt, that supports an abundance of fishes and squids as well as birds and marine mammals. We show that in some areas the floor of these canyons harbors high densities of gorgonian and pennatulacean corals and sponges, likely due to enhanced surface productivity, benthic currents and seafloor topography. Rockfishes, including the commercially important Pacific ocean perch, Sebastes alutus, were associated with corals and sponges as well as with isolated boulders. Sculpins, poachers and pleuronectid flounders were also associated with corals in Pribilof Canyon, where corals were most abundant. Fishes likely use corals and sponges as sources of vertical relief, which may harbor prey as well as provide shelter from predators. Boulders may be equivalent habitat in this regard, but are sparse in the canyons, strongly suggesting that biogenic structure is important fish habitat. Evidence of disturbance to the benthos from fishing activities was observed in these remote canyons. Bottom trawling and other benthic fishing gear has been shown to damage corals and sponges that may be very slow to recover from such disturbance. Regulation of these destructive practices is key to conservation of benthic habitats in these canyons and the ecosystem services they provide.

Stresses in a submarine topography under ocean waves

Energy Technology Data Exchange (ETDEWEB)

Mei, C.C.; McTigue, D.F.

1984-01-01

The problem of submarine slope stability is of interest to both offshore engineering and geology. In an uneven topography, the weight above a horizontal plane induces two-dimensional variation in the static stress field. The action of wave pressure, which changes with depth, further introduces excess pore pressure and dynamic stresses in the sea bottom. In the present paper, we combine a simple analytical theory for the static stress by the present authors, and the recent solution by Mei and Foda for wave-induced stresses in a plane poro-elastic sea bed to account for mild bottom slope and wave shoaling, to obtain the effective stress field in a submarine topography under sea waves. Sample results are given for a ridge and a canyon. In particular the dynamic pore pressure and the combined static and dynamic effective stresses are presented. 10 references, 11 figures.

Sediment transport processes at the head of Halibut Canyon, Eastern Canada margin: An interplay between internal tides and dense shelf water cascading.

Science.gov (United States)

Puig, Pere; Greenan, Blair J. W.; Li, Michael Z.; Prescott, Robert H.; Piper, David J. W.

2013-04-01

To investigate the processes by which sediment is transported through a submarine canyon incised in a glaciated margin, the bottom boundary layer quadrapod RALPH was deployed at 276-m depth in the West Halibut Canyon (off Newfoundland) during winter 2008-2009. Two main sediment transport processes were identified throughout the deployment. Firstly, periodic increases of near-bottom suspended-sediment concentrations (SSC) were recorded associated with the up-canyon propagation of the semidiurnal internal tidal bore along the canyon axis, carrying fine sediment particles resuspended from deeper canyon regions. The recorded SSC peaks, lasting less than one hour, were observed sporadically and were linked to bottom intensified up-canyon flows concomitant with sharp drops in temperature. Secondly, sediment transport was also observed during events of intensified down-canyon current velocities that occurred during periods of sustained heat loss from surface waters, but were not associated with large storms. High-resolution velocity profiles throughout the water column during these events revealed that the highest current speeds (~1 m s-1) were centered several meters above the sea floor and corresponded to the region of maximum velocities of a gravity flow. Such flows had associated low SSC and cold water temperatures and have been interpreted as dense shelf water cascading events channelized along the canyon axis. Sediment transport during these events was largely restricted to bedload and saltation, producing winnowing of sands and fine sediments around larger gravel particles. Analysis of historical hydrographic data suggests that the origin of such gravity flows is not related to the formation of coastal dense waters advected towards the canyon head. Rather, the dense shelf waters appear to be generated around the outer shelf, where convection during winter is able to reach the sea floor and generate a pool of near-bottom dense water that cascades into the canyon

Gigantic oocytes in the deep sea black coral Dendrobathypathes grandis (Antipatharia) from the Mar del Plata submarine canyon area (southwestern Atlantic)

Science.gov (United States)

Lauretta, Daniel; Penchaszadeh, Pablo E.

2017-10-01

The black coral Dendrobathypathes grandis (Cnidaria: Antipatharia) is studied for the first time in the southwestern Atlantic off Argentina. This is the only antipatharian reported from the Atlantic between 35°S and 54°S. Eleven specimens were collected at depths of 819-2204 m during three expeditions to the Mar del Plata submarine canyon (2012-2013); seven were females. The species is gonochoric, and the polyps in female colonies contain up to nine oocytes per polyp, which can reach 1500 μm in diameter. In contrast, the largest oocyte currently reported for antipatharians is 500 μm, and usual diameters do not exceed 200 μm. These large oocytes have over 20 times more volume than the biggest oocyte reported, but over 800 times more volume when compared with the common oocyte size of the group. Sperm size and morphology is similar to previous data from other species. As in previous studies, neither embryos nor larvae were found in any specimens. This species was previously only reported from waters off South Georgia Island, and so these specimens expand the known distribution north by 1800 km.

Origin and biogeography of the deep-water Mediterranean Hydromedusae including the description of two new species collected in submarine canyons of Northwestern Mediterranean

Directory of Open Access Journals (Sweden)

J. M. Gili

1998-06-01

Full Text Available Two new species of hydromedusae (Foersteria antoniae and Cunina simplex are described from plankton collected in sediment traps placed in the Lacaze-Duthiers Submarine Canyon and along Banyuls-sur-Mer coast (northwestern Mediterranean. The Mediterranean hydromedusan deep-water fauna contains 41 species which represent 45.5 % of the world-wide deep-sea hydromedusae fauna (90 and 20% of the total number of Mediterranean hydromedusae (204. The Mediterranean deep-water hydromedusan fauna is characterised by a large percentage of holoplanktonic species (61%, mainly Trachymedusae. Nevertheless, contrary to the general opinion, the percentage of meroplanktonic species is equally high. The most original features of this fauna lies however in the importance of the number of endemic species (22% and in the fact that the majority of them are meroplanktonic Leptomedusae with a supposed bathybenthic stage. Some of the endemic species could still represent relics of the primitive Tethys fauna having survived to the Messinian crisis. The origin of the Mediterranean deep-water hydromedusan fauna is discussed and a general hypothesis is proposed.

Morphology, sedimentary features and evolution of a large palaeo submarine canyon in Qiongdongnan basin, Northern South China Sea

Science.gov (United States)

Li, Xiangquan; Fairweather, Luke; Wu, Shiguo; Ren, Jianye; Zhang, Hongjie; Quan, Xiayun; Jiang, Tao; Zhang, Cheng; Su, Ming; He, Yunlong; Wang, Dawei

2013-01-01

The large Miocene-aged palaeo canyon that extents through the Qiongdongnan basin (QDNB) and Yinggehai basin (YGHB) of Northern South China Sea has been of considerable interest both economically and scientifically over the past decade. Stemmed from this, significant research has been employed into understanding the mechanism for its existence, incision, and sedimentary fill, yet debate remains. In the first case the canyon itself is actually quite anomalous. Alone from the size (over 570 km in length and more than 8 km in width (Yuan et al., 2009)), which is considerably more than most ancient deep-water channels (REFS), the canyon's sedimentary fill is also distinctly different. Some explanations have been given to explain the canyon's origin and existence, these include increased sediment supply from the Red River which is genetically linked to uplift of the Tibetan Plateau, lowstand turbidite and mass-transport activity, reactivation and dextral displacement of the Red River Fault zone inducing erosive gravity-flows, regional tilt of the QDNB and YGHB, paleo-seafloor morphology and seal-level fluctuations. With the application of new data obtained from interpretations of a large number of 2D seismic profiles, core and well log data, and tectonic and sedimentary analysis this contribution aims to: (1) Present models to explain the Canyon's sedimentary fill and basin plain deposits, which provided significant understanding of processes pre-, syn- and post-incision and; (2) review the plausibility and likelihood of each of the controlling mechanisms, hoping to shed light on this controversial aspect. We conclude that the final erosive event that shaped the canyon is dated at 5.5 Ma. The Canyon's unusual fill is a product of variation in the interaction between turbidity currents and MTD that blocked the canyon's axis, and the reduction in gravity flow energy through time; and therefore the complete succession represents one major erosive and cut event at 5.5 Ma and

Repeat Mapping in the Lower Monterey Submarine Canyon Sheds Light on Morphological Change During Discrete Sediment Density Flow Events

Science.gov (United States)

Anderson, K.; Lundsten, E. M.; Caress, D. W.; Thomas, H. J.; Paull, C. K.; Maier, K. L.; Gales, J. A.; Gwiazda, R.; Talling, P.; Xu, J.; Parsons, D. R.

2017-12-01

The Coordinated Canyon Experiment (CCE), a multi-institutional collaboration effort, was designed to monitor the passage of sediment density flows along the axis of Monterey Canyon, offshore California, between 200 and 1850 m water depth. An array of moorings and sensors were deployed for three 6-month periods from October 2015 to April 2017. Aligned with the CCE deployments, repeat high-resolution multibeam bathymetric surveys of the Monterey Canyon floor were conducted with a mapping AUV (Autonomous Underwater Vehicle). The AUV carried a Reson 7125 multibeam echosounder (vertical precision of 0.15 m and horizontal resolution of 1.0 m). An inertial navigation system combined with a Doppler velocity logger allowed the AUV to fly pre-programmed grids at 3 knots, while maintaining an altitude of 50 m above the seafloor, to obtain a nominal line spacing of 130 m. The floor and lower flanks of the canyon between 200 to 540 m and 1350 to 1880 m water depths were mapped six times during the CCE. These repeat maps are subtracted to create bathymetry difference grids to show morphological change. Coupling the sensor observations with the bathymetric surveys, the CCE successfully documented sediment density flow events as well as the associated changes in seafloor morphology. Between repeat surveys, three sediment density flow events reached the lower canyon, extending to at least 1850 m water depth. On January 15, 2016, a particularly large density flow traveled more than 50 km down Monterey Canyon. Unlike in the upper canyon where this event caused wholesale reorganization of geomorphological features, changes to the lower canyon morphology involved a more moderate re-sculpting of the features. The effect of a sediment density flow of known magnitude and duration on the seafloor morphology has never been documented in a deep-sea setting before.

Megabenthic assemblages at the Hudson Canyon head (NW Atlantic margin): Habitat-faunal relationships

Science.gov (United States)

Pierdomenico, Martina; Gori, Andrea; Guida, Vincent G.; Gili, Josep-Maria

2017-09-01

. Such results are of particular significance in light of the recent action promoted by the Mid-Atlantic Fisheries Management Council, that restricts bottom trawling in most of the submarine canyons of the US Atlantic margin, including the Hudson Canyon, to protect cold-water corals from damage by fishing gear.

Submarine fans: A critical retrospective (1950–2015

Directory of Open Access Journals (Sweden)

G. Shanmugam

2016-04-01

Full Text Available When we look back the contributions on submarine fans during the past 65 years (1950–2015, the empirical data on 21 modern submarine fans and 10 ancient deep-water systems, published by the results of the First COMFAN (Committee on FANs Meeting (Bouma et al., 1985a, have remained the single most significant compilation of data on submarine fans. The 1970s were the “heyday” of submarine fan models. In the 21st century, the general focus has shifted from submarine fans to submarine mass movements, internal waves and tides, and contourites. The purpose of this review is to illustrate the complexity of issues surrounding the origin and classification of submarine fans. The principal elements of submarine fans, composed of canyons, channels, and lobes, are discussed using nine modern case studies from the Mediterranean Sea, the Equatorial Atlantic, the Gulf of Mexico, the North Pacific, the NE Indian Ocean (Bay of Bengal, and the East Sea (Korea. The Annot Sandstone (Eocene–Oligocene, exposed at Peira-Cava area, SE France, which served as the type locality for the “Bouma Sequence”, was reexamined. The field details are documented in questioning the validity of the model, which was the basis for the turbidite-fan link. The 29 fan-related models that are of conceptual significance, developed during the period 1970–2015, are discussed using modern and ancient systems. They are: (1 the classic submarine fan model with attached lobes, (2 the detached-lobe model, (3 the channel-levee complex without lobes, (4 the delta-fed ramp model, (5 the gully-lobe model, (6 the suprafan lobe model, (7 the depositional lobe model, (8 the fan lobe model, (9 the ponded lobe model, (10 the nine models based on grain size and sediment source, (11 the four fan models based on tectonic settings, (12 the Jackfork debrite model, (13 the basin-floor fan model, (14 supercritical and subcritical fans, and (15 the three types of fan reservoirs. Each model is unique

Turkish Straits System and Southern Black Sea: Exchange. Mixing and Shelf / Canyon Interactions

Science.gov (United States)

Özsoy, Emin; Gürses, Özgür; Tutsak, Ersin

2015-04-01

Based largely on an experiment employing high-resolution measurements carried out in June-July 2013 and re-interpretation of past experiments, the oceanographic variability of the exchange through the Turkish Straits System (TSS) and the interactions with the southern Black Sea are revealed through CTD, ADCP, oxygen and light transmission measurements. The exchange flow is primarily governed by the complex topography spanning two narrow straits, wide continental shelf regions, steep slopes and numerous canyons connecting deep basins. Water properties and currents in the high energy environment depends on the mosaic of fine-scale processes and pathways. The TSS, often approximated as a two-layer system has a hydraulically controlled, upper ocean and straits intensified regime, leading to surface jets and bottom plumes participating in mixing and renewal processes. The exit of the 'Mediterranean effluent' onto the Black Sea past a sill overflow from the Bosphorus passes through two subsequent hydraulic jumps and proceeds along a narrow canyon that veers to the west clear of the greater Bosphorus Canyon finally cascading down the few small canyons. A diffusive spread from the bottom vein of salty water reforms to the east and spills down the Bosphorus Canyon. The suspended particulate signature of the cascade, as well as its influence in hydrography is traced over the shelf and slope waters and through the numerous canyons into deep water where the reformed flow is found to sustain signatures of the past evolution of intrusive waters. An evaluation of the processes is given with reference to model development carried out in parallel to the analyses of the measurements.

A picture on the wall: innovative mapping reveals cold-water coral refuge in submarine canyon.

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Veerle A I Huvenne

Full Text Available Cold-water corals are azooxanthellate species found throughout the ocean at water depths down to 5000 m. They occur in patches, reefs or large mound structures up to 380 m high, and as ecosystem engineers create important habitats for a diverse fauna. However, the majority of these habitats are now within reach of deep-sea bottom trawling. Many have been severely damaged or are under threat, despite recent protection initiatives. Here we present a cold-water coral habitat type that so far has been overlooked--quite literally--and that has received minimal impact from human activities. Vertical and overhanging cliffs in deep-sea canyons, revealed using an innovative approach to marine habitat mapping, are shown to provide the perfect substratum for extensive cold-water coral-based communities. Typical canyon-related processes, including locally enhanced internal tides and focussed downslope organic carbon transport, provide favourable environmental conditions (current regime, food input to sustain the communities, even outside the optimal depth and density envelopes reported elsewhere in the NE Atlantic. Our findings show that deep-sea canyons can form natural refuges for faunal communities sensitive to anthropogenic disturbance, and have the potential to fulfil the crucial role of larval sources for the recolonisation of damaged sites elsewhere on the margin.

Seven years of geomorphic change in the head of Monterey Canyon, CA: Steady state equilibrium or monotonic change?

Science.gov (United States)

Smith, D. P.; Kvitek, R. G.; Ross, E.; Iampietro, P.; Paull, C. K.; Sandersfeld, M.

2010-12-01

The head of Monterey submarine canyon has been surveyed with high-precision multibeam sonar at least once each year since September 2002. This poster provides a summary of changes between September 2002 and September 2008. Data were collected with a variety of Reson mulitbeam sonar heads, and logged with an ISIS data acquisition system. Vessel attitude was corrected using an Applanix POS MV equipped with an auxillary C-Nav 2050 GPS receiver. Data were processed and filtered and cleaned in Caris HIPS. Depth changes for various time spans were determined through raster subtraction of pairs of 3-m resolution bathymetric grids in ArcMap. The depth change analyses focused on the canyon floor, except where a landslide occurred on a wall, and where obvious gullying near the headwall had occurred during the time of our study. Canyon walls were generally excluded from analysis. The analysis area was 1,414,240 sq meters. The gross changes between 2002 and 2008 include net erosion of 2,300,000 m^3 +/- 800,000 m^3 of material from the canyon. The annualized rate of net sediment loss from this time frame agrees within an order of magnitude with our previously published estimates from earlier (shorter) time frames, so the erosion events seem to be moderate magnitude and frequent, rather than infrequent and catastrophic. The greatest sediment loss appears to be from lateral erosion of channel-bounding terraces rather than deepening or scouring of the existing channel axis. A single landslide event that occurred in summer 2003 had an initial slide scar (void) volume of 71,000 m^3. The scar was observed to increase annually, and had grown to approximately 96,000 m^3 by 2008. The initial slide was too small to be tsunamigenic. In contrast to the monotonic canyon axis widening, the shoreward terminus of the canyon (canyon lip) appears to be in steady state equilibrium with sediment supply entering the canyon from the littoral zone. The lip position, indicated by the clearly defined

Repeat Mapping in Upper Monterey Canyon Captures the Effect of Sediment Transport Events of Known Magnitude and Duration on the Seafloor Morphology

Science.gov (United States)

Lundsten, E. M.; Anderson, K.; Caress, D. W.; Thomas, H. J.; Paull, C. K.; Maier, K. L.; Gwiazda, R.; Gales, J. A.; Talling, P.; Xu, J.; Parsons, D. R.

2017-12-01

As part of a multi-institution submarine canyon study, the Coordinated Canyon Experiment (CCE), high-resolution multibeam bathymetric surveys of the floor of Monterey Canyon, offshore California, were conducted to capture the changes in seafloor morphology directly related to the passage of sediment density flows documented during the study. The goals of this study were to monitor the passage of sediment density flows as they move through the axis of a submarine canyon in order to understand the velocity structure of these flows and to document the associated changes in seafloor morphology and the resultant deposits. The CCE consisted of an array of moorings and sensors deployed on the canyon floor during the 18-month period between October 2015 and April 2017. In addition, a mapping AUV (Autonomous Underwater Vehicle) repeatedly surveyed two sites along the canyon during the study. Differencing the repeat grids quantified the morphological changes directly related to specifically documented, individual flow events. The AUV carried a Reson 7125 multibeam echosounder (vertical precision of 0.15 m and horizontal resolution of 1.0 m). An inertial navigation system combined with a Doppler velocity logger allowed the AUV to fly pre-programmed grids at 3 knots while maintaining an altitude of 50 m above the seafloor and obtain a nominal line spacing of 130 m. The axial channel between 200 and 540 m water depth was surveyed six times. At least fifteen density flow events were captured by the array of CCE instruments within this AUV survey area. These events caused moorings as well as several large and small instruments to move down canyon significant distances at least 30 times. Difference grids show the canyon experienced erosion and deposition of up to +/- 3 m between surveys. The pair of surveys that straddle a sediment transport event on December 1, 2015 show the seafloor was altered only down to 420 m water depth, consistent with the observations on the CCE

Mechanisms of vegetation-induced channel narrowing of an unregulated canyon river: Results from a natural field-scale experiment

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Manners, Rebecca B.; Schmidt, John C.; Scott, Michael L.

2014-04-01

The lower Yampa River in Yampa Canyon, western Colorado serves as a natural, field-scale experiment, initiated when the invasive riparian plant, tamarisk (Tamarix spp.), colonized an unregulated river. In response to tamarisk's rapid invasion, the channel narrowed by 6% in the widest reaches since 1961. Taking advantage of this unique setting, we reconstructed the geomorphic and vegetation history in order to identify the key mechanisms for which, in the absence of other environmental perturbations, vegetation alters fluvial processes that result in a narrower channel. From our reconstruction, we identified a distinct similarity in the timing and magnitude of tamarisk encroachment and channel change, albeit with a lag in the channel response, thus suggesting tamarisk as the driving force. Within a decade of establishment, tamarisk effectively trapped sediment and, as a result, increased floodplain construction rates. Increasing tamarisk coverage over time also reduced the occurrence of floodplain stripping. Tamarisk recruitment was driven by both hydrologic and hydraulic variables, and the majority of tamarisk plants (84%) established below the stage of the 2-year flood. Thus, upon establishment nearly all plants regularly interact with the flow and sediment transport field. Our analyses were predicated on the hypothesis that the flow regime of the Yampa River was stationary, and that only the riparian vegetation community had changed. While not heavily impacted by water development, we determined that some aspects of the flow regime have shifted. However, this shift, which involved the clustering in time of extremely wet and dry years, did not influence fluvial processes directly. Instead these changes directly impacted riparian vegetation and changes in vegetation cover, in turn, altered fluvial processes. Today, the rate of channel change and new tamarisk recruitment is small. We believe that the rapid expansion of tamarisk and related floodplain construction

Giant landslides and turbidity currents in the Agadir Canyon Region, NW-Africa

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Krastel, Sebastian; Wynn, Russell B.; Stevenson, Christopher; Feldens, Peter; Mehringer, Lisa; Schürer, Anke

2017-04-01

Coring and drilling of the Moroccan Turbidite System off NW-Africa revealed a long sequence of turbidites, mostly sourced from the Moroccan continental margin and the volcanic Canary Islands. The largest individual flow deposits in the Moroccan Turbidite System contain sediment volumes >100 km3, although these large-scale events are relatively infrequent with a recurrence interval of 10,000 years (over the last 200,000 years). The largest siliciclastic flow in the last 200,000 years was the 'Bed 5 event', which transported 160 km3 of sediment up to 2000 km from the Agadir Canyon region to the southwest Madeira Abyssal Plain. While the Moroccan Turbidite System is extremely well investigated, almost no data from the source region, i.e. the Agadir Canyon, are available. Understanding why some submarine landslides remain as coherent blocks of sediment throughout their passage downslope, while others mix and disintegrate almost immediately after initial failure, is a major scientific challenge, which was addressed in the Agadir Canyon source region during RV Maria S. Merian Cruise MSM32 in late 2013. A major landslide area was identified 200 km south of the Agadir Canyon. A landslide was traced from this failure area to the Agadir Canyon. This landslide entered the canyon in about 2500 m water depth. Despite a significant increase in slope angle, the landslide did not disintegrate into a turbidity current when entering the canyon but moved on as landslide for at least another 200 km down the canyon. The age of the landslide ( 145 ka) does not correspond to any major turbidte deposit in the Moroccan Turbidite System, further supporting the fact that the landslide did not disintegrate into a major turbidity current. A core taken about 350 m above the thalweg in the head region of Agadir Canyon shows a single coarse-grained turbidite, which resembles the composition of the Bed 5 event in the Madeira Abyssal Plain. Hence, the Bed 5 turbidite originated as a failure in the

Currents, pressure, temperature, conductivity, salinity, and attenuation data collected from moorings during the Lydonia Canyon Dynamics Experiment deployed from platforms OCEANUS, LULU, and WHITEFOOT from October 24, 1980 to November 11, 1982 (NCEI Accession 0054154)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A major field experiment to determine the importance of submarine canyons in sediment transport along and across the continental margin. The experiment included...

Boulder emplacement and remobilisation by cyclone and submarine landslide tsunami waves near Suva City, Fiji

Science.gov (United States)

Lau, A. Y. Annie; Terry, James P.; Ziegler, Alan; Pratap, Arti; Harris, Daniel

2018-02-01

The characteristics of a reef-top boulder field created by a local submarine landslide tsunami are presented for the first time. Our examination of large reef-derived boulders deposited by the 1953 tsunami near Suva City, Fiji, revealed that shorter-than-normal-period tsunami waves generated by submarine landslides can create a boulder field resembling a storm boulder field due to relatively short boulder transport distances. The boulder-inferred 1953 tsunami flow velocity is estimated at over 9 m s- 1 at the reef edge. Subsequent events, for example Cyclone Kina (1993), appear to have remobilised some large boulders. While prior research has demonstrated headward retreat of Suva Canyon in response to the repeated occurrence of earthquakes over the past few millennia, our results highlight the lingering vulnerability of the Fijian coastlines to high-energy waves generated both in the presence (tsunami) and absence (storm) of submarine failures and/or earthquakes. To explain the age discrepancies of U-Th dated coral comprising the deposited boulders, we introduce a conceptual model showing the role of repeated episodes of tsunamigenic submarine landslides in removing reef front sections through collapse. Subsequent high-energy wave events transport boulders from exposed older sections of the reef front onto the reef where they are deposited as 'new' boulders, alongside freshly detached sections of the living reef. In similar situations where anachronistic deposits complicate the deposition signal, age-dating of the coral boulders should not be used as a proxy for determining the timing of the submarine landslides or the tsunamis that generated them.

Potential tsunamigenic hazard associated to submarine mass movement along the Ionian continental margin (Mediterranean Sea).

Science.gov (United States)

Ceramicola, S.; Tinti, S.; Praeg, D.; Zaniboni, F.; Planinsek, P.

2012-04-01

Submarine mass movements are natural geomorphic processes that transport marine sediment down continental slopes into deep-marine environments. Type of mass wasting include creep, slides, slump, debris flows, each with its own features and taking place over timescale from seconds to years. Submarine landslides can be triggered by a number of different causes, either internal (such as changes in physical chemical sediment properties) or external (e.g. earthquakes, volcanic activity, salt movements, sea level changes etc.). Landslides may mobilize sediments in such a way as to form an impulsive vertical displacement of a body of water, originating a wave or series of waves with long wavelengths and long periods called tsunamis ('harbor waves'). Over 600 km of continental margin has been investigated by OGS in the Ionian sea using geophysical data - morpho-bathymetry (Reson 8111, 8150) and sub-bottom profiles (7-10 KHz) - collected aboard the research vessel OGS Explora in the framework of the MAGIC Project (Marine Geohazard along the Italian Coasts), funded by the Italian Civil Protection. The objective of this project is the definition of elements that may constitute geological risk for coastal areas. Geophysical data allowed the recognition of four main types of mass wasting phenomena along the slopes of the ICM: 1) mass transport complexes (MTCs) within intra-slope basins. Seabed imagery show the slopes of all the seabed ridges to be marked by headwall scarps recording widespread failure, multiple debris flows in several basins indicate one or more past episodes of failure that may be linked to activity on the faults bounding the structural highs. 2) submarine landslide - a multiple failure event have been identified (Assi landslide) at about 6 km away from the coastline nearby Riace Marina. Headwall scars up to 50 m high across water depths of 700 to 1400 m, while sub-bottom profiles indicate stacked slide deposits at and near seabed. 4) canyon headwalls - in the

Calcareous nannoplankton and benthic foraminiferal assemblages from the Nazare Canyon (Portuguese continental margin): Preliminary results

International Nuclear Information System (INIS)

Guerreiro, C; Oliveira, A; Rodrigues, A; Rosa, F; Cachao, M; Fatela, F

2009-01-01

Submarine canyons are assumed to play an important role in oceanic/neritic circulation, marine productivity and sedimentary processes, acting as preferential conduits between the littoral and deep oceanic domain. Here we present first results of a comparative micropalaeontological study on calcareous nannoplankton and benthic foraminifera from surface sediments from the surroundings of the upper Nazare Canyon (Portuguese continental margin) and from the shelf north of the canyon. Regardless of the difficulty to distinguish taphonomical from (palaeo)ecological effects in such a complex and still poorly known marine system, the first results suggest that the canyon's hydro-sedimentary dynamic regime act as a prolongation of the shore/inner shelf hydrodynamic conditions towards west, preventing deposition and/or preservation of the smaller and fragile species of calcareous nannoplankton (e.g. E. huxleyi and G. ericsonii) and enhancing the record of the larger and more opportunistic ones (e.g. G. oceanica); and disturbing benthic foraminiferal productivity and/or diversity, or their preservation in the fossil record. Both calcareous nannoplankton and benthic foraminifera are more abundant off the canyon's domain, suggesting that its highly energetic thalweg conditions are probably filtering the fossil record in the sediment. Still, preliminary results suggest that the occurrence of persistent physical phenomena related with the canyon's morphology and proximity to the coast (e.g. solitary internal waves) may be locally promoting favourable conditions for calcareous nannoplankton, as shown by high values of nannoliths, chlorophyll a and 19' hexanoyloxyfucoxantine (unpublished data) north of the canyon's head. It is our goal to test this hypothesis in the near future by (a) studying multicore and surficial sediments from more recent surveys, and (b) calibrating the sediment results with water column data presently in process at the Institute of Oceanography (IO).

Calcareous nannoplankton and benthic foraminiferal assemblages from the Nazare Canyon (Portuguese continental margin): Preliminary results

Energy Technology Data Exchange (ETDEWEB)

Guerreiro, C; Oliveira, A; Rodrigues, A [Division of Marine Geology, Portuguese Hydrographic Institute (IH), Rua das Trinas 49, 1249-093 Lisboa (Portugal); Rosa, F [CIACOMAR, Algarve University, Av. 16 de Julho s/n 8700-311 Olhao (Portugal); Cachao, M; Fatela, F [Geology Center and Geology Department, FCUL, Bloco C6, 3o Piso, sala 6.3.57 Campo Grande 1749-016 Lisboa (Portugal)], E-mail: catarina.guerreiro@hidrografico.pt

2009-01-01

Submarine canyons are assumed to play an important role in oceanic/neritic circulation, marine productivity and sedimentary processes, acting as preferential conduits between the littoral and deep oceanic domain. Here we present first results of a comparative micropalaeontological study on calcareous nannoplankton and benthic foraminifera from surface sediments from the surroundings of the upper Nazare Canyon (Portuguese continental margin) and from the shelf north of the canyon. Regardless of the difficulty to distinguish taphonomical from (palaeo)ecological effects in such a complex and still poorly known marine system, the first results suggest that the canyon's hydro-sedimentary dynamic regime act as a prolongation of the shore/inner shelf hydrodynamic conditions towards west, preventing deposition and/or preservation of the smaller and fragile species of calcareous nannoplankton (e.g. E. huxleyi and G. ericsonii) and enhancing the record of the larger and more opportunistic ones (e.g. G. oceanica); and disturbing benthic foraminiferal productivity and/or diversity, or their preservation in the fossil record. Both calcareous nannoplankton and benthic foraminifera are more abundant off the canyon's domain, suggesting that its highly energetic thalweg conditions are probably filtering the fossil record in the sediment. Still, preliminary results suggest that the occurrence of persistent physical phenomena related with the canyon's morphology and proximity to the coast (e.g. solitary internal waves) may be locally promoting favourable conditions for calcareous nannoplankton, as shown by high values of nannoliths, chlorophyll a and 19' hexanoyloxyfucoxantine (unpublished data) north of the canyon's head. It is our goal to test this hypothesis in the near future by (a) studying multicore and surficial sediments from more recent surveys, and (b) calibrating the sediment results with water column data presently in process at the Institute of

Oceanographic data collected during the Atlantic Deep-Water Canyons: Pathways to the Abyss 2011 on NOAA Ship Nancy Foster in the North Atlantic Ocean from 2011-06-04 to 2011-06-17 (NODC Accession 0082240)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Submarine canyons are dominant features of the outer continental shelf and slope of the US East coast from Cape Hatteras to the Gulf of Maine. They are important...

Go big or die out: Bifurcation and bimodality in submarine sediment flow behaviour

Science.gov (United States)

Talling, P.; Paull, C. K.; Lintern, G.; Gwiazda, R.; Cartigny, M.; Hughes Clarke, J. E.; Xu, J.; Clare, M. A.; Parsons, D. R.; Simmons, S.; Maier, K. L.; Gales, J. A.; Hage, S.; McGann, M.; Pope, E.; Rosenberger, K. J.; Stacey, C.; Barry, J.; Lundsten, E. M.; Anderson, K.; O'Reilly, T. C.; Chapplow, N.; Vendettuoli, D.

2017-12-01

Submarine flows of sediment (turbidity currents) flush globally significant volumes of sediment and organic carbon into deep-sea basins. These flows create the largest sediment accumulations on Earth, which hold valuable oil and gas reserves. These flows affect global carbon burial, how deep-sea ecosystems function, and pose a hazard to offshore infrastructure. Only river systems transport such large amounts of sediment across such long distances. However, there are remarkably few direct measurements from active submarine flows, which is a stark contrast to >1 million direct observations from rivers. Here we present unusually detailed information on frequency, power and runout distance of multiple submarine flows at two contrasting locations. The first data set comes from Monterey Canyon, offshore California, which is fed by littoral cells. The second site is a river-fed delta in Bute Inlet, British Columbia. In both cases, the timing and runout distance of submarine flows was documented using instruments on multiple moorings placed along the 50-km long flow pathway. A striking observation is that flow behaviour and runout is strongly bimodal in both locations. Flows tend to either dissipate rapidly, or runout through the entire mooring arrays. We thus test whether i) the character of short or long runout flows can be distinguished at the first mooring and ii) whether long and short runout flows have different triggers. It has been proposed that submarine flows have two modes of behaviour; either eroding and accelerating, or depositing and dissipating. These field data support such a view of bifurcation and bimodality in flow behaviour. However, some short runout flows resemble their longer runout cousins at the first mooring, and there is no clear relationship between flow trigger and runout. Thus, some flows reach a point where their character is no longer dependent on their initial trigger or initial structure, but on factors acting along the flow pathway.

Effect of Topography on Subglacial Discharge and Submarine Melting During Tidewater Glacier Retreat

Science.gov (United States)

Amundson, J. M.; Carroll, D.

2018-01-01

To first order, subglacial discharge depends on climate, which determines precipitation fluxes and glacier mass balance, and the rate of glacier volume change. For tidewater glaciers, large and rapid changes in glacier volume can occur independent of climate change due to strong glacier dynamic feedbacks. Using an idealized tidewater glacier model, we show that these feedbacks produce secular variations in subglacial discharge that are influenced by subglacial topography. Retreat along retrograde bed slopes (into deep water) results in rapid surface lowering and coincident increases in subglacial discharge. Consequently, submarine melting of glacier termini, which depends on subglacial discharge and ocean thermal forcing, also increases during retreat into deep water. Both subglacial discharge and submarine melting subsequently decrease as glacier termini retreat out of deep water and approach new steady state equilibria. In our simulations, subglacial discharge reached peaks that were 6-17% higher than preretreat values, with the highest values occurring during retreat from narrow sills, and submarine melting increased by 14% for unstratified fjords and 51% for highly stratified fjords. Our results therefore indicate that submarine melting acts in concert with iceberg calving to cause tidewater glacier termini to be unstable on retrograde beds. The full impact of submarine melting on tidewater glacier stability remains uncertain, however, due to poor understanding of the coupling between submarine melting and iceberg calving.

Active normal faults and submarine landslides in the Keelung Shelf off NE Taiwan

Directory of Open Access Journals (Sweden)

Ching-Hui Tsai

2018-01-01

Full Text Available The westernmost Okinawa Trough back-arc basin is located to the north of the Ryukyu islands and is situated above the northward dipping Ryukyu subducted slab. In the northern continental margin of the Okinawa Trough, the continental slope between the Keelung Valley and the Mein-Hua Submarine Canyon shows a steep angle and future slope failures are expected. The question is how slope failures will proceed? A sudden deep-seated slump or landslide would probably cause local tsunami and hit northern coast of Taiwan. To understand the probable submarine landslides, we conducted multi-channel seismic reflection, sub-bottom profilers, and multi-beam bathymetry surveys off NE Taiwan. Two general trends of shallow crustal faults are observed. The NE-SW trending faults generally follow the main structural trend of the Taiwan mountain belt. These faults are products of inversion tectonics of reverse faults from the former collisional thrust faults to post-collisional normal faults. Another trend of roughly E-W faults is consistent with the current N-S extension of the southern Okinawa Trough. The fault offsets in the eastern portion of the study area are more pronounced. No obvious basal surface of sliding is found beneath the continental margin. We conclude that the movement of the submarine landslides in the Keelung Shelf off northeastern Taiwan could be in a spread type. The submarine landslides mainly occur in the continental slope area and it is more obvious in the east than in the west of the Keelung Shelf.

High resolution morphobathymetric analysis and short-term evolution of the upper part of the Capbreton submarine canyon (south-east Bay of Biscay - French Atlantic coast)

Science.gov (United States)

Gillet, Hervé; Mazières, Alaïs; Mulder, Thierry; Cremer, Michel

2013-04-01

The Capbreton Canyon stands out by its deep incision through continental shelf and slope and its present turbidite activity. The head of the canyon is anthropically disconnected from the Adour River since 1310 AD, but is located close enough to the coast to allow a direct supply by longshore drift. Sedimentary processes in upper part of the Capbreton Canyon are poorly documented. Several evidences, including sandy slide scars in the head, suggest that this area plays a major role in triggering downstream gravity currents). However, no modern sedimentary activity in the upper canyon had so far been evidenced. Our study is based on the analysis and comparison of several sets of multibeam bathymetric data acquired in 1998, 2010 and 2012 (up to 1.5 m resolution). The morphobathymetric analysis brought the following key observations: - The upper part of the canyon is characterised by a meandering talweg underlined by two kinds of terraces: (1) small elongated terraces standing only 10 to 15 m above the talweg axis and (2) large terraces standing 45 to 100 m above the talweg axis. - The regular 1° longitudinal slope of the talweg is interrupted by several 10 m high knickpoints. - The floor of the talweg shows some rough areas scattered with transversal bedforms similar to the sediment waves described in the Monterey Canyon upper part (Smith et al, 2005). The morphological evolutions in the upper part of the canyon over the last 14 years especially affect the floor of the talweg: - Between 1998 and 2010, we observe a downstream succession of accretion areas (up to 11m thick) and erosion areas (reaching -25 m). The largest and highest terraces remain stable over this period, whereas the smallest and lowest elongated terraces show active sedimentation (+5 to +8 m). - Difference between 2010 and 2012 DEMs reveals three localized erosion spots corresponding to 200 m backward stepping of the knickpoints. Such observation confirms the active headward erosion in this part of

Nuclear-powered submarines

International Nuclear Information System (INIS)

Curren, T.

1989-01-01

The proposed acquisition of nuclear-powered submarines by the Canadian Armed Forces raises a number of legitimate concerns, including that of their potential impact on the environment. The use of nuclear reactors as the propulsion units in these submarines merits special consideration. Radioactivity, as an environmental pollutant, has unique qualities and engenders particular fears among the general population. The effects of nuclear submarines on the environment fall into two distinct categories: those deriving from normal operations of the submarine (the chief concern of this paper), and those deriving from a reactor accident. An enormous body of data must exist to support the safe operation of nuclear submarines; however, little information on this aspect of the proposed submarine program has been made available to the Canadian public. (5 refs.)

Insights from field observations into controls on flow front speed in submarine sediment flows

Science.gov (United States)

Heerema, C.; Talling, P.; Cartigny, M.; Paull, C. K.; Gwiazda, R.; Clare, M. A.; Parsons, D. R.; Xu, J.; Simmons, S.; Maier, K. L.; Chapplow, N.; Gales, J. A.; McGann, M.; Barry, J.; Lundsten, E. M.; Anderson, K.; O'Reilly, T. C.; Rosenberger, K. J.; Sumner, E. J.; Stacey, C.

2017-12-01

Seafloor avalanches of sediment called turbidity currents are one of the most important processes for moving sediment across our planet. Only rivers carry comparable amounts of sediment across such large areas. Here we present some of the first detailed monitoring of these underwater flows that is being undertaken at a series of test sites. We seek to understand the factors that determine flow front speed, and how that speed varies with distance. This frontal speed is particularly important for predicting flow runout, and how the power of these hazardous flows varies with distance. First, we consider unusually detailed measurements of flow front speed defined by transit times between moorings and other tracked objects placed on the floor of Monterey Canyon offshore California in 2016-17. These measurements are then compared to flow front speeds measured using multiple moorings in Bute Inlet, British Columbia in 2016; and by cable breaks in Gaoping Canyon offshore Taiwan in 2006 and 2009. We seek to understand how flow front velocity is related to seafloor gradient, flow front thickness and density. It appears that the spatial evolution of frontal speed is similar in multiple flows, although their peak frontal velocities vary. Flow front velocity tends to increase rapidly initially before declining rather gradually over tens or even hundreds of kilometres. It has been proposed that submarine flows will exist in one of two states; either eroding and accelerating, or depositing sediment and dissipating. We conclude by discussing the implications of this global compilation of flow front velocities for understanding submarine flow behaviour.

Into the deep: A coarse-grained carbonate turbidite thalweg generated by gigantic submarine chutes

Science.gov (United States)

Mulder, Thierry; Gillet, Hervé; Reijmer, John; Droxler, André; cavailhes, Thibault; Hanquiez, Vincent; Fauquembergue, Kelly; Bujan, Stéphane; Blanck, David; bashah, Sara; Guiastrennec, Léa; Fabregas, Natacha; Recouvreur, Audrey; Seibert, Chloé

2017-04-01

New high-resolution multibeam mapping, in the Southeastern Bahamas, images in exquisite details the southern part of Exuma Sound, and its unchartered transition area to the deep abyssal plain of the Western North Atlantic bounded by the Bahama Escarpment (BE) between San Salvador Island and Samana Cay, referred here to the San Salvador abyssal plain. The transition area is locally referred to as Crooked Island Passage, loosely delineated by Crooked, Long, and Conception Islands, Rum and Samana Cays. Surprisingly in such a pure carbonate landscape, the newly established map reveals the detailed and complex morphology of a giant valley formed by numerous gravity flows originated in Exuma Sound itself, in addition to many secondary slope gullies and smaller tributaries draining the surrounding upper slopes. The valley referred here as the Exuma canyon system starts with a perched valley with low sinuosity, characterized by several flow restrictions and knickpoints initiated by the presence of drowned isolated platforms and merging tributaries. The valley abruptly transforms itself into a deep incised canyon, rivaling the depth of the Colorado Grand Canyon, through two major knickpoints with outsized chutes exceeding several hundred of meters in height, a total of 1600-1800 m. The sudden transformation of the wide valley into a deep narrow canyon, occurring when the flows incised deep into an underlying lower Cretaceous drowned carbonate platform, generates a huge hydraulic jump and creates an enormous plunge pool and related deposits with mechanisms comparable to the ones operating along giant subaerial waterfalls. The high kinetic flow energy, constrained by this narrow and deeply incised canyon, formed, when it is released at its mouth in the abyssal plain, a wide deep-sea channel with well-developed levees and fan, made of coarse-grained carbonate defined layers separated by fine carbonate sediments mixed with fine siliciclastics transported along the BE by the

Pharmacological Potential of Phylogenetically Diverse Actinobacteria Isolated from Deep-Sea Coral Ecosystems of the Submarine Avilés Canyon in the Cantabrian Sea.

Science.gov (United States)

Sarmiento-Vizcaíno, Aida; González, Verónica; Braña, Alfredo F; Palacios, Juan J; Otero, Luis; Fernández, Jonathan; Molina, Axayacatl; Kulik, Andreas; Vázquez, Fernando; Acuña, José L; García, Luis A; Blanco, Gloria

2017-02-01

Marine Actinobacteria are emerging as an unexplored source for natural product discovery. Eighty-seven deep-sea coral reef invertebrates were collected during an oceanographic expedition at the submarine Avilés Canyon (Asturias, Spain) in a range of 1500 to 4700 m depth. From these, 18 cultivable bioactive Actinobacteria were isolated, mainly from corals, phylum Cnidaria, and some specimens of phyla Echinodermata, Porifera, Annelida, Arthropoda, Mollusca and Sipuncula. As determined by 16S rRNA sequencing and phylogenetic analyses, all isolates belong to the phylum Actinobacteria, mainly to the Streptomyces genus and also to Micromonospora, Pseudonocardia and Myceligenerans. Production of bioactive compounds of pharmacological interest was investigated by high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) techniques and subsequent database comparison. Results reveal that deep-sea isolated Actinobacteria display a wide repertoire of secondary metabolite production with a high chemical diversity. Most identified products (both diffusible and volatiles) are known by their contrasted antibiotic or antitumor activities. Bioassays with ethyl acetate extracts from isolates displayed strong antibiotic activities against a panel of important resistant clinical pathogens, including Gram-positive and Gram-negative bacteria, as well as fungi, all of them isolated at two main hospitals (HUCA and Cabueñes) from the same geographical region. The identity of the active extracts components of these producing Actinobacteria is currently being investigated, given its potential for the discovery of pharmaceuticals and other products of biotechnological interest.

Sunken nuclear submarines

International Nuclear Information System (INIS)

Eriksen, V.O.

1990-01-01

The increasing number of accidents with nuclear submarines is a worriment to the general public. Five nuclear submarines are resting on the bottom of the North Atlantic. Design information on nuclear propulsion plants for submarines is classified. The author describes a potential generic nuclear submarine propulsion plant. Design information from the civilian nuclear industry, nuclear power plants, research reactors, nuclear cargo vessels and nuclear propelled icebreakers are used for illustration of relevant problems. A survey is given of nuclear submarines. Factors influencing the accident risks and safety characteristics of nuclear submarines are considered, and potential accident scenarios are described. The fission product content of the nuclear plant can be estimated, '' source terms'' can be guessed and potential release rates can be judged. The mechanisms of dispersion in the oceans is reviewed and compared with the dumping of radioactive waste in the Atlantic and other known releases. 46 refs., 49 figs., 14 tabs

Influence of the submarine orography on the distribution of long-lived radionuclides in the Palomares marine ecosystem

International Nuclear Information System (INIS)

Gasco, C.; Anton, M.P.

1997-01-01

To trace the consequences of the Palomares accident which occurred in southeastern Spain in 1966, a number of studies were performed upon sediments collected in the adjacent marine ecosystem in 1985. The research revealed a land-to-sea transport of part of the transuranics residual contamination still remaining in the affected area after the clean-up operations. The transfer routes to the Mediterranean sea (via river flooding and airborne relocation) were elucidated through the reconstruction of the sediment cores' depositional history. Present investigations focus on the distribution of Pu, Am and Cs along the complex system of submarine canyons shaping the orography of the Palomares marine environment. Marine samples were collected in 1991 to evaluate the possible removal of the radionuclides deposited in the continental shelf towards the deep sea, favoured by the strong turbidity currents and/or the topography of the canyon itself. (Author)

Sedimentation in Rio La Venta Canyon in Netzahualcoyotl Reservoir, Chiapas, Mexico

Science.gov (United States)

Juan Antonio de la Fuente; Tom Lisle; Jose Velasquez; Bonnie L. Allison; Alisha Miller

2000-01-01

Sedimentation of Rio La Venta as it enters the Netzahualcoyotl Reservoir in Chiapas, Mexico, threatens a unique part of the aquatic ecosystem. Rio La Venta enters the reservoir via a narrow canyon about 16 km long with spectacular, near-vertical limestone bluffs up to 320 m high and inhabited by the flora and fauna of a pristine tropical forest.

Megafauna of vulnerable marine ecosystems in French mediterranean submarine canyons: Spatial distribution and anthropogenic impacts

OpenAIRE

Fabri, Marie-claire; Pedel, Laura; Beuck, L.; Galgani, Francois; Hebbeln, D.; Freiwald, A.

2014-01-01

Vulnerable Marine Ecosystems (VME) in the deep Mediterranean Sea have been identified by the General Fisheries Commission for the Mediterranean as consisting of communities of Scleractinia (Lophelia pertusa and Madrepora oculata), Pennatulacea (Funiculina quadrangularis) and Alcyonacea (Isidella elongata). This paper deals with video data recorded in the heads of French Mediterranean canyons. Quantitative observations were extracted from 101 video films recorded during the MEDSEACAN cruise in...

Mineral resources of the Desolation Canyon, Turtle Canyon, and Floy Canyon Wilderness Study Areas, Carbon Emery, and Grand counties, Utah

International Nuclear Information System (INIS)

Cashion, W.B.; Kilburn, J.E.; Barton, H.N.; Kelley, K.D.; Kulik, D.M.; McDonnell, J.R.

1990-09-01

This paper reports on the Desolation Canyon, Turtle Canyon, and Floy Canyon Wilderness Study Areas which include 242,000 acres, 33,690 acres, and 23,140 acres. Coal deposits underlie all three study areas. Coal zones in the Blackhawk and Nelsen formations have identified bituminous coal resources of 22 million short tons in the Desolation Canyon Study Area, 6.3 million short tons in the Turtle Canyon Study Area, and 45 million short tons in the Floy Canyon Study Area. In-place inferred oil shale resources are estimated to contain 60 million barrels in the northern part of the Desolation Canyon area. Minor occurrences of uranium have been found in the southeastern part of the Desolation Canyon area and in the western part of the Floy Canyon area. Mineral resource potential for the study areas is estimated to be for coal, high for all areas, for oil and gas, high for the northern tract of the Desolation Canyon area and moderate for all other tracts, for bituminous sandstone, high for the northern part of the Desolation Canyon area, and low for all other tracts, for oil shale, low in all areas, for uranium, moderate for the Floy Canyon area and the southeastern part of the Desolation Canyon area and low for the remainder of the areas, for metals other than uranium, bentonite, zeolites, and geothermal energy, low in all areas, and for coal-bed methane unknown in all three areas

On the pollutant removal, dispersion, and entrainment over two-dimensional idealized street canyons

Science.gov (United States)

Liu, Chun-Ho; Wong, Colman C. C.

2014-01-01

Pollutant dispersion over urban areas is not that well understood, in particular at the street canyon scale. This study is therefore conceived to examine how urban morphology modifies the pollutant removal, dispersion, and entrainment over urban areas. An idealized computational domain consisting of 12 two-dimensional (2D) identical street canyons of unity aspect ratio is employed. The large-eddy simulation (LES) is used to calculate the turbulent flows and pollutant transport in the urban boundary layer (UBL). An area source of uniform pollutant concentration is applied on the ground of the first street canyon. A close examination on the roof-level turbulence reveals patches of low-speed air masses in the streamwise flows and narrow high-speed downdrafts in the shear layer. Different from the flows over a smooth surface, the turbulence intensities are peaked near the top of the building roughness. The pollutant is rather uniformly distributed inside a street canyon but disperses quickly in the UBL over the buildings. Partitioning the vertical pollutant flux into its mean and turbulent components demystifies that the pollutant removal is mainly governed by turbulence. Whereas, mean wind carries pollutant into and out of a street canyon simultaneously. In addition to wind speed promotion, turbulent mixing is thus required to dilute the ground-level pollutants, which are then removed from the street canyon to the UBL. Atmospheric flows slow down rapidly after the leeward buildings, leading to updrafts carrying pollutants away from the street canyons (the basic pollutant removal mechanism).

Deep-Sea, Deep-Sequencing: Metabarcoding Extracellular DNA from Sediments of Marine Canyons.

Directory of Open Access Journals (Sweden)

Magdalena Guardiola

Full Text Available Marine sediments are home to one of the richest species pools on Earth, but logistics and a dearth of taxonomic work-force hinders the knowledge of their biodiversity. We characterized α- and β-diversity of deep-sea assemblages from submarine canyons in the western Mediterranean using an environmental DNA metabarcoding. We used a new primer set targeting a short eukaryotic 18S sequence (ca. 110 bp. We applied a protocol designed to obtain extractions enriched in extracellular DNA from replicated sediment corers. With this strategy we captured information from DNA (local or deposited from the water column that persists adsorbed to inorganic particles and buffered short-term spatial and temporal heterogeneity. We analysed replicated samples from 20 localities including 2 deep-sea canyons, 1 shallower canal, and two open slopes (depth range 100-2,250 m. We identified 1,629 MOTUs, among which the dominant groups were Metazoa (with representatives of 19 phyla, Alveolata, Stramenopiles, and Rhizaria. There was a marked small-scale heterogeneity as shown by differences in replicates within corers and within localities. The spatial variability between canyons was significant, as was the depth component in one of the canyons where it was tested. Likewise, the composition of the first layer (1 cm of sediment was significantly different from deeper layers. We found that qualitative (presence-absence and quantitative (relative number of reads data showed consistent trends of differentiation between samples and geographic areas. The subset of exclusively benthic MOTUs showed similar patterns of β-diversity and community structure as the whole dataset. Separate analyses of the main metazoan phyla (in number of MOTUs showed some differences in distribution attributable to different lifestyles. Our results highlight the differentiation that can be found even between geographically close assemblages, and sets the ground for future monitoring and conservation

Submarine Medicine Team

Data.gov (United States)

Federal Laboratory Consortium — The Submarine Medicine Team conducts basic and applied research on biomedical aspects of submarine and diving environments. It focuses on ways to optimize the health...

Metazoan meiofauna in deep-sea canyons and adjacent open slopes: A large-scale comparison with focus on the rare taxa

Science.gov (United States)

Bianchelli, S.; Gambi, C.; Zeppilli, D.; Danovaro, R.

2010-03-01

Metazoan meiofaunal abundance, total biomass, nematode size and the richness of taxa were investigated along bathymetric gradients (from the shelf break down to ca. 5000-m depth) in six submarine canyons and on five adjacent open slopes of three deep-sea regions. The investigated areas were distributed along >2500 km, on the Portuguese to the Catalan and South Adriatic margins. The Portuguese and Catalan margins displayed the highest abundances, biomass and richness of taxa, while the lowest values were observed in the Central Mediterranean Sea. The comparison between canyons and the nearby open slopes showed the lack of significant differences in terms of meiofaunal abundance and biomass at any sampling depth. In most canyons and on most slopes, meiofaunal variables did not display consistent bathymetric patterns. Conversely, we found that the different topographic features were apparently responsible for significant differences in the abundance and distribution of the rare meiofaunal taxa (i.e. taxa accounting for Priapulida, Holothuroidea, Ascidiacea and Cnidaria, were encountered exclusively on open slopes, while others (including the Tanaidacea and Echinodea larvae) were found exclusively in canyons sediments. Results reported here indicate that, at large spatial scales, differences in deep-sea meiofaunal abundance and biomass are not only controlled by the available food sources, but also by the region or habitat specific topographic features, which apparently play a key role in the distribution of rare benthic taxa.

Sediment concentrations, flow conditions, and downstream evolution of two turbidity currents, Monterey Canyon, USA

Science.gov (United States)

Xu, Jingping; Octavio E. Sequeiros,; Noble, Marlene A.

2014-01-01

The capacity of turbidity currents to carry sand and coarser sediment from shallow to deep regions in the submarine environment has attracted the attention of researchers from different disciplines. Yet not only are field measurements of oceanic turbidity currents a rare achievement, but also the data that have been collected consist mostly of velocity records with very limited or no suspended sediment concentration or grain size distribution data. This work focuses on two turbidity currents measured in Monterey Canyon in 2002 with emphasis on suspended sediment from unique samples collected within the body of these currents. It is shown that concentration and grain size of the suspended material, primarily controlled by the source of the gravity flows and their interaction with bed material, play a significant role in shaping the characteristics of the turbidity currents as they travel down the canyon. Before the flows reach their normal or quasi-steady state, which is defined by bed slope, bed roughness, and suspended grain size, they might pass through a preliminary adjustment stage where they are subject to capacity-driven deposition, and release heavy material in excess. Flows composed of fine (silt/clay) sediments tend to be thicker than those with sands. The measured velocity and concentration data confirm that flow patterns differ between the front and body of turbidity currents and that, even after reaching normal state, the flow regime can be radically disrupted by abrupt changes in canyon morphology.

Marine litter in the upper São Vicente submarine canyon (SW Portugal): Abundance, distribution, composition and fauna interactions.

Science.gov (United States)

Oliveira, Frederico; Monteiro, Pedro; Bentes, Luis; Henriques, Nuno Sales; Aguilar, Ricardo; Gonçalves, Jorge M S

2015-08-15

Marine litter has become a worldwide environmental problem, tainting all ocean habitats. The abundance, distribution and composition of litter and its interactions with fauna were evaluated in the upper S. Vicente canyon using video images from 3 remote operated vehicle exploratory dives. Litter was present in all dives and the abundance was as high as 3.31 items100m(-1). Mean abundance of litter over rock bottom was higher than on soft substrate. Mean litter abundance was slightly higher than reported for other canyons on the Portuguese margin, but lower in comparison to more urbanized coastal areas of the world. Lost fishing gear was the prevalent type of litter, indicating that the majority of litter originates from maritime sources, mainly fishing activity. Physical contact with sessile fauna and entanglement of specimens were the major impacts of lost fishing gear. Based on the importance of this region for the local fishermen, litter abundance is expected to increase. Copyright © 2015 Elsevier Ltd. All rights reserved.

Geologic siting considerations for the disposal of radioactive waste into submarine geologic formations

International Nuclear Information System (INIS)

Hollister, C.D.

1979-01-01

The most desirable characteristics of the host medium are: (1) low permeability and high Kd; (2) ability to self heal, i.e., be visco-elastic in response to dynamic stress; (3) stability under predicted thermal loading; (4) a low content of organic matter, i.e., be well oxidized. The submarine geologic formation that appears to best satisfy the above criteria is abyssal red clay. Depending on organic interactions and permeability considerations, light brown deep-sea clays with 20 to 40% CaCO 3 also may be suitable. Increasingly organic-rich, more permeable biogenic oozes appear less suitable, with turbidite sands and silts least desirable of all. Ocean regions excluded at the present time are: (1) areas less than 4000 meters deep; (2) the continental margin including fans, deltas, aprons, cones; (3) proximal portions of abyssal plains; (4) all fracture zone abyssal plains; (5) all submarine canyon-levee systems; (6) areas covered with less than 50 meters of sediment; (7) areas greater than 100 nautical miles from plate boundaries; (8) areas with ice-rafted debris; (9) major shipping lanes, cable routes and defense installations; (10) seafloor regions below areas of high biological productivity; and (11) approximately one third of the world's ocean floor satisfy these criteria

The 2006 Pingtung Earthquake Doublet Triggered Seafloor Liquefaction: Revisiting the Evidence with Ultra-High-Resolution Seafloor Mapping

Science.gov (United States)

Su, C. C.; Chen, T. T.; Paull, C. K.; Gwiazda, R.; Chen, Y. H.; Lundsten, E. M.; Caress, D. W.; Hsu, H. H.; Liu, C. S.

2017-12-01

Since Heezen and Ewing's (1952) classic work on the 1929 Grand Banks earthquake, the damage of submarine cables have provided critical information on the nature of seafloor mass movements or sediment density flows. However, the understanding of the local conditions that lead to particular seafloor failures earthquakes trigger is still unclear. The Decemeber 26, 2006 Pingtung earthquake doublet which occurred offshore of Fangliao Township, southwestern Taiwan damaged 14 submarine cables between Gaoping slope to the northern terminus of the Manila Trench. Local fisherman reported disturbed waters at the head of the Fangliao submarine canyon, which lead to conjectures that eruptions of mud volcanoes which are common off the southwestern Taiwan. Geophysical survey were conducted to evaluate this area which revealed a series of faults, liquefied strata, pockmarks and acoustically transparent sediments with doming structures which may relate to the submarine groundwater discharge. Moreover, shipboard multi-beam bathymetric survey which was conducted at the east of Fangliao submarine canyon head shows over 10 km2 area with maximum depth around 40 m of seafloor subsidence after Pingtung earthquake. The north end of the subsidence is connected to the Fangliao submarine canyon where the first cable failed after Pingtung earthquake. The evidences suggests the earthquake triggered widespeard liquefaction and generated debris flows within Fangliao submarine canyon. In May 2017, an IONTU-MBARI Joint Survey Cruise (OR1-1163) was conducted on using MBARI Mapping AUV and miniROV to revisit the area where the cable damaged after Pingtung earthquake. From newly collected ultra-high-resolution (1-m lateral resolution) bathymetry data, the stair-stepped morphology is observed at the edge of canyon. The comet-shaped depressions are located along the main headwall of the seafloor failure. The new detailed bathymetry reveal details which suggest Fangliao submarine canyon head is

Diablo Canyon

International Nuclear Information System (INIS)

Bindon, F.J.L.

1986-01-01

The paper traces the history of Diablo Canyon nuclear power station, California, which took 18 years to reach full-power testing from the planning stage. The major delays during the construction are outlined, as well as the costs of Diablo Canyon. (UK)

Integrated Web-Based Immersive Exploration of the Coordinated Canyon Experiment Data using Open Source STOQS Software

Science.gov (United States)

McCann, M. P.; Gwiazda, R.; O'Reilly, T. C.; Maier, K. L.; Lundsten, E. M.; Parsons, D. R.; Paull, C. K.

2017-12-01

The Coordinated Canyon Experiment (CCE) in Monterey Submarine Canyon has produced a wealth of oceanographic measurements whose analysis will improve understanding of turbidity current processes. Exploration of this data set, consisting of over 60 parameters from 15 platforms, is facilitated by using the open source Spatial Temporal Oceanographic Query System (STOQS) software (https://github.com/stoqs/stoqs). The Monterey Bay Aquarium Research Institute (MBARI) originally developed STOQS to help manage and visualize upper water column oceanographic measurements, but the generality of its data model permits effective use for any kind of spatial/temporal measurement data. STOQS consists of a PostgreSQL database and server-side Python/Django software; the client-side is jQuery JavaScript supporting AJAX requests to update a single page web application. The User Interface (UI) is optimized to provide a quick overview of data in spatial and temporal dimensions, as well as in parameter, platform, and data value space. A user may zoom into any feature of interest and select it, initiating a filter operation that updates the UI with an overview of all the data in the new filtered selection. When details are desired, radio buttons and checkboxes are selected to generate a number of different types of visualizations. These include color-filled temporal section and line plots, parameter-parameter plots, 2D map plots, and interactive 3D spatial visualizations. The Extensible 3D (X3D) standard and X3DOM JavaScript library provide the technology for presenting animated 3D data directly within the web browser. Most of the oceanographic measurements from the CCE (e.g. mooring mounted ADCP and CTD data) are easily visualized using established methods. However, unified integration and multiparameter display of several concurrently deployed sensors across a network of platforms is a challenge we hope to solve. Moreover, STOQS also allows display of data from a new instrument - the

Hudson Canyon benthic habitats characterization and mapping by integrated analysis of multidisciplinary data

Science.gov (United States)

Pierdomenico, Martina; Guida, Vincent G.; Rona, Peter A.; Macelloni, Leonardo; Scranton, Mary I.; Asper, Vernon; Diercks, Arne

2013-04-01

Hudson Canyon, about 180 km SE of New York City, is the largest eastern U.S. submarine canyon and is under consideration for HAPC (Habitat Area of Particular Concern) status, representing a fisheries and biodiversity hot spot. Interest in the area, within the perspective of ecosystem based management, marine spatial planning, habitat and species conservation, led to a joint project between NOAA Northeast Fisheries, U.S. Geological Survey (USGS), Mississippi Mineral Research Institute (MMRI), National Institute for Undersea Science and Technology (NIUST), Stony Brook and Rutgers Universities for the study of benthic habitats, that includes the assembly of existing data with newly collected ones: acoustic mapping, visual ground-truthing, hydrographic, sedimentological, and trawl data collections. Acoustic mapping, performed using AUV-mounted multibeam sonar, provided ultra-high resolution bathymetric and backscatter imagery (3m and 1m respectively) at all water depths for identification of geomorphological features and for the characterization of surficial sediments along the two thirds of the shelf portion of the canyon. Identification of benthic and demersal communities was accomplished by visual ground thruthing with underwater vehicle video and still cameras, and from trawl catch data. A CTD-rosette sampler provided water column salinity-temperature profiles and water samples for dissolved methane analysis in the vicinity of suspected bottom sources. Analysis of data revealed a complex of topographic structures and hydrological patterns that provide a wide range of physical habitats in a relatively small area. A mosaic of sandy and muddy substrates, gravel beds, rock outcrops, and semilithified clay outcrops host rich and varied faunal assemblages, including deepwater corals and sponge communities. Pockmark fields, occurring below 300 m depth, suggest that methane-based chemosynthetic carbonate deposition contributes to creation of specific hard bottom habitats

Submarine hydrodynamics

CERN Document Server

Renilson, Martin

2015-01-01

This book adopts a practical approach and presents recent research together with applications in real submarine design and operation. Topics covered include hydrostatics, manoeuvring, resistance and propulsion of submarines. The author briefly reviews basic concepts in ship hydrodynamics and goes on to show how they are applied to submarines, including a look at the use of physical model experiments. The issues associated with manoeuvring in both the horizontal and vertical planes are explained, and readers will discover suggested criteria for stability, along with rudder and hydroplane effectiveness. The book includes a section on appendage design which includes information on sail design, different arrangements of bow planes and alternative stern configurations. Other themes explored in this book include hydro-acoustic performance, the components of resistance and the effect of hull shape. Readers will value the author’s applied experience as well as the empirical expressions that are presented for use a...

California State Waters Map Series—Monterey Canyon and vicinity, California

Science.gov (United States)

Dartnell, Peter; Maier, Katherine L.; Erdey, Mercedes D.; Dieter, Bryan E.; Golden, Nadine E.; Johnson, Samuel Y.; Hartwell, Stephen R.; Cochrane, Guy R.; Ritchie, Andrew C.; Finlayson, David P.; Kvitek, Rikk G.; Sliter, Ray W.; Greene, H. Gary; Davenport, Clifton W.; Endris, Charles A.; Krigsman, Lisa M.; Dartnell, Peter; Cochran, Susan A.

2016-06-10

IntroductionIn 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within the 3-nautical-mile limit of California’s State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, and visualization of swath bathymetry data, acoustic backscatter, seafloor video, seafloor photography, high-resolution seismic-reflection profiles, and bottom-sediment sampling data. The map products display seafloor morphology and character, identify potential marine benthic habitats, and illustrate both the surficial seafloor geology and shallow subsurface geology.The Monterey Canyon and Vicinity map area lies within Monterey Bay in central California. Monterey Bay is one of the largest embayments along the west coast of the United States, spanning 36 km from its northern to southern tips (in Santa Cruz and Monterey, respectively) and 20 km along its central axis. Not only does it contain one of the broadest sections of continental shelf along California’s coast, it also contains Monterey Canyon, one of the largest and deepest submarine canyons in the world. Note that the California’s State Waters limit extends farther offshore between Santa Cruz and Monterey so that it encompasses all of Monterey Bay.The coastal area within the map area is lightly populated. The community of Moss Landing (population, 204) hosts the largest commercial fishing fleet in Monterey Bay in its harbor. The map area also includes parts of the cities of Marina (population, about 20,000) and Castroville (population, about 6,500). Fertile lowlands of the Salinas River and Pajaro River valleys largely occupy the inland part of the map area, and land use is primarily agricultural.The offshore part of the map area lies completely within the Monterey Bay National Marine Sanctuary. The

To the problem of utilization of nuclear submarines

International Nuclear Information System (INIS)

Tarakanov, E.; Larin, V.

1999-01-01

Paper discusses a concept of step-by-step utilization of nuclear submarines in Russia. By the late 2000 minimum 160 nuclear submarines with over 300 nuclear reactors should be removed. Unloading of spent nuclear fuel from reactors, dismounting of nuclear submarines, efforts to arrange storage facilities for liquid and solid radioactive waste are the main steps of nuclear submarine utilization. Under the rates of nuclear submarine utilization being as they are, the utilization of 160 nuclear submarines will take about 30 years. Paper analyzes the alternative variants of nuclear submarine utilization and discusses the social and ecological aspects of utilization of nuclear submarines [ru

Changes in body composition of submarine crew during prolonged submarine deployment

Directory of Open Access Journals (Sweden)

Sourabh Bhutani

2015-01-01

Discussion: Increased body fat along with lack of physical activity can lead to development of lifestyle disorders in submarine crew. These crew members need to be actively encouraged to participate in physical activity when in harbour. In addition dieting program specifically to encourage reduced fat consumption needs to be instituted in submarines during sorties at sea.

Submarine Salt Karst Terrains

Directory of Open Access Journals (Sweden)

Nico Augustin

2016-06-01

Full Text Available Karst terrains that develop in bodies of rock salt (taken as mainly of halite, NaCl are special not only for developing in one of the most soluble of all rocks, but also for developing in one of the weakest rocks. Salt is so weak that many surface-piercing salt diapirs extrude slow fountains of salt that that gravity spread downslope over deserts on land and over sea floors. Salt fountains in the deserts of Iran are usually so dry that they flow at only a few cm/yr but the few rain storms a decade so soak and weaken them that they surge at dm/day for a few days. We illustrate the only case where the rates at which different parts of one of the many tens of subaerial salt karst terrains in Iran flows downslope constrains the rates at which its subaerial salt karst terrains form. Normal seawater is only 10% saturated in NaCl. It should therefore be sufficiently aggressive to erode karst terrains into exposures of salt on the thousands of known submarine salt extrusions that have flowed or are still flowing over the floors of hundreds of submarine basins worldwide. However, we know of no attempt to constrain the processes that form submarine salt karst terrains on any of these of submarine salt extrusions. As on land, many potential submarine karst terrains are cloaked by clastic and pelagic sediments that are often hundreds of m thick. Nevertheless, detailed geophysical and bathymetric surveys have already mapped likely submarine salt karst terrains in at least the Gulf of Mexico, and the Red Sea. New images of these two areas are offered as clear evidence of submarine salt dissolution due to sinking or rising aggressive fluids. We suggest that repeated 3D surveys of distinctive features (± fixed seismic reflectors of such terrains could measure any downslope salt flow and thus offer an exceptional opportunity to constrain the rates at which submarine salt karst terrains develop. Such rates are of interest to all salt tectonicians and the many

Russian nuclear-powered submarine decommissioning

International Nuclear Information System (INIS)

Bukharin, O.; Handler, J.

1995-01-01

Russia is facing technical, economic and organizational difficulties in dismantling its oversized and unsafe fleet of nuclear powered submarines. The inability of Russia to deal effectively with the submarine decommissioning crisis increases the risk of environmental disaster and may hamper the implementation of the START I and START II treaties. This paper discusses the nuclear fleet support infrastructure, the problems of submarine decommissioning, and recommends international cooperation in addressing these problems

What the submarine is

Energy Technology Data Exchange (ETDEWEB)

Liuzzi, A

1972-03-01

A short review of submarine problems and design is presented. Included are trim and stability concepts; propulsion and steering gears (surface and submerged); batteries on a conventional (diesel) submarine; optical and electronic sensing equipments; and an outline of new hull designs and shipbuilding methods.

Low cost submarine robot

Directory of Open Access Journals (Sweden)

Ponlachart Chotikarn

2010-10-01

Full Text Available A submarine robot is a semi-autonomous submarine robot used mainly for marine environmental research. We aim todevelop a low cost, semi-autonomous submarine robot which is able to travel underwater. The robot’s structure was designedand patented using a novel idea of the diving system employing a volume adjustment mechanism to vary the robot’s density.A light weight, flexibility and small structure provided by PVC can be used to construct the torpedo-liked shape robot.Hydraulic seal and O-ring rubbers are used to prevent water leaking. This robot is controlled by a wired communicationsystem.

Flow in bedrock canyons.

Science.gov (United States)

Venditti, Jeremy G; Rennie, Colin D; Bomhof, James; Bradley, Ryan W; Little, Malcolm; Church, Michael

2014-09-25

Bedrock erosion in rivers sets the pace of landscape evolution, influences the evolution of orogens and determines the size, shape and relief of mountains. A variety of models link fluid flow and sediment transport processes to bedrock incision in canyons. The model components that represent sediment transport processes are increasingly well developed. In contrast, the model components being used to represent fluid flow are largely untested because there are no observations of the flow structure in bedrock canyons. Here we present a 524-kilometre, continuous centreline, acoustic Doppler current profiler survey of the Fraser Canyon in western Canada, which includes 42 individual bedrock canyons. Our observations of three-dimensional flow structure reveal that, as water enters the canyons, a high-velocity core follows the bed surface, causing a velocity inversion (high velocities near the bed and low velocities at the surface). The plunging water then upwells along the canyon walls, resulting in counter-rotating, along-stream coherent flow structures that diverge near the bed. The resulting flow structure promotes deep scour in the bedrock channel floor and undercutting of the canyon walls. This provides a mechanism for channel widening and ensures that the base of the walls is swept clear of the debris that is often deposited there, keeping the walls nearly vertical. These observations reveal that the flow structure in bedrock canyons is more complex than assumed in the models presently used. Fluid flow models that capture the essence of the three-dimensional flow field, using simple phenomenological rules that are computationally tractable, are required to capture the dynamic coupling between flow, bedrock erosion and solid-Earth dynamics.

2010 Pacific Gas and Electric Diablo Canyon Power Plant (DCPP): Diablo Canyon, CA Central Coast

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Diablo Canyon Power Plant (DCPP) LiDAR and Imagery datasets are comprised of three separate LiDAR surveys: Diablo Canyon (2010), Diablo Canyon (2010), and San...

Analysis of SSN 688 Class Submarine Maintenance Delays

Science.gov (United States)

2017-06-01

Simplified Notional Submarine FRP (Independent Deployer) ..................11  Figure 8.  Evolution of Los Angeles Class Submarine Notional...Number TFP Technical Foundation Paper URO Unrestricted Operations xv ACKNOWLEDGMENTS I would like to thank my lead advisor, Professor Nick Dew...only on Los Angeles (SSN 688)-class submarines. Being the higher quantity and older generation submarine hull type, the Los Angeles class submarine

Pollutant Removal, Dispersion and Entrainment over Two-Dimensional Idealized Street Canyons: an LES Approach

Science.gov (United States)

Wong, C.; Liu, C.

2010-12-01

Unlike pollutant transport over flat terrain, the mechanism and plume dispersion over urban areas is not well known. This study is therefore conceived to examine how urban morphology modifies the pollutant transport over urban areas. The computational domain and boundary condition used in this study is shown in Figure 1. The LES shows that inside the street canyon, the ground-level pollutants are carried to roof-level by the re-circulating flow, which are then removed from the street canyon to the UBL. Right above the roof level, narrow high-speed air masses in the streamwise flows and intensive downdrafts have been found in the shear layer. Different from the flows over a smooth surface, the maximum turbulence intensities descend that are peaked near the top of the building roughness. The pollutant is rather uniformly distributed inside a street canyon but disperses rapidly over the buildings exhibiting a Gaussian-plume form in the UBL. The mean component of vertical pollutant flux shows that the mean wind contributes to pollutant removal and entrainment simultaneously. Whereas, the fluctuating component demystifies that pollutant removal is mainly governed by atmospheric turbulence. Over the roof level, atmospheric flows slow down rapidly in the wake behind leeward building, suggesting the momentum entrainment into the street canyons. The decelerating streamwise flows in turn lead to upward flows carrying pollutants away from the street canyons, illustrating the basic pollutant removal mechanism in the skimming flow regime. Figure 1: Computational domain and boundary conditions Figure 2: Ensemble average vertical pollutant flux along the roof level. (a). Mean component; (b). turbulent component.

Suspended sediment dynamics in a large-scale turbidity current: Direct measurements from the deep-water Congo Canyon

Science.gov (United States)

Simmons, S.; Azpiroz, M.; Cartigny, M.; Clare, M. A.; Parsons, D. R.; Sumner, E.; Talling, P. J.

2016-12-01

Turbidity currents that transport sediment to the deep ocean deposit a greater volume of sediment than any other process on Earth. To date, only a handful of studies have directly measured turbidity currents, with flow durations ranging from a few minutes to a few hours. Our understanding of turbidity current dynamics is therefore largely derived from scaled laboratory experiments and numerical modelling. Recent years have seen the first field-scale measurements of depth-resolved velocity profiles, but sediment concentration (a key parameter for turbidity currents) remains elusive. Here, we present high resolution measurements of deep-water turbidity currents from the Congo Canyon; one of the world's largest submarine canyons. Direct measurements using acoustic Doppler current profilers (ADCPs) show that flows can last for many days, rather than hours as seen elsewhere, and provide the first quantification of concentration and grain size within deep-water turbidity currents.Velocity and backscatter were measured at 5 second intervals by an ADCP suspended 80 m above the canyon floor, at 2000 m water depth. A novel inversion method using multiple ADCP frequencies enabled quantification of sediment concentration and grain size within the flows. We identify high concentrations of coarse sediment within a thin frontal cell, which outruns a thicker, trailing body. Thus, the flows grow in length while propagating down-canyon. This is distinct from classical models and other field-scale measurements of turbidity currents. The slow-moving body is dominated by suspended fine-grained sediment. The body mixes with the surrounding fluid leaving diffuse clouds of sediment that persist for days after initial entrainment. Ambient tidal flow also controls the mixing within the body and the surrounding fluid. Our results provide a new quantification of suspended sediment within flows and the interaction with the surrounding fluid.

Formative flow in bedrock canyons

Science.gov (United States)

Venditti, J. G.; Kwoll, E.; Rennie, C. D.; Church, M. A.

2017-12-01

In alluvial channels, it is widely accepted that river channel configuration is set by a formative flow that represents a balance between the magnitude and frequency of flood flows. The formative flow is often considered to be one that is just capable of filling a river channel to the top of its banks. Flows much above this formative flow are thought to cause substantial sediment transport and rearrange the channel morphology to accommodate the larger flow. This idea has recently been extended to semi-alluvial channels where it has been shown that even with bedrock exposed, the flows rarely exceed that required to entrain the local sediment cover. What constitutes a formative flow in a bedrock canyon is not clear. By definition, canyons have rock walls and are typically incised vertically, removing the possibility of the walls being overtopped, as can occur in an alluvial channel at high flows. Canyons are laterally constrained, have deep scour pools and often have width to maximum depth ratios approaching 1, an order of magnitude lower than alluvial channels. In many canyons, there are a sequence of irregularly spaced scour pools. The bed may have intermittent or seasonal sediment cover, but during flood flows the sediment bed is entrained leaving a bare bedrock channel. It has been suggested that canyons cut into weak, well-jointed rock may adjust their morphology to the threshold for block plucking because the rock bed is labile during exceptionally large magnitude flows. However, this hypothesis does not apply to canyons cut into massive crystalline rock where abrasion is the dominant erosion process. Here, we argue that bedrock canyon morphology is adjusted to a characteristic flow structure developed in bedrock canyons. We show that the deeply scoured canyon floor is adjusted to a velocity inversion that is present at low flows, but gets stronger at high flows. The effect is to increase boundary shear stresses along the scour pool that forms in constricted

Grand Canyon Monitoring and Research Center

Science.gov (United States)

Hamill, John F.

2009-01-01

The Grand Canyon of the Colorado River, one of the world's most spectacular gorges, is a premier U.S. National Park and a World Heritage Site. The canyon supports a diverse array of distinctive plants and animals and contains cultural resources significant to the region's Native Americans. About 15 miles upstream of Grand Canyon National Park sits Glen Canyon Dam, completed in 1963, which created Lake Powell. The dam provides hydroelectric power for 200 wholesale customers in six western States, but it has also altered the Colorado River's flow, temperature, and sediment-carrying capacity. Over time this has resulted in beach erosion, invasion and expansion of nonnative species, and losses of native fish. Public concern about the effects of Glen Canyon Dam operations prompted the passage of the Grand Canyon Protection Act of 1992, which directs the Secretary of the Interior to operate the dam 'to protect, mitigate adverse impacts to, and improve values for which Grand Canyon National Park and Glen Canyon National Recreation Area were established...' This legislation also required the creation of a long-term monitoring and research program to provide information that could inform decisions related to dam operations and protection of downstream resources.

Wintertime Boundary Layer Structure in the Grand Canyon.

Science.gov (United States)

Whiteman, C. David; Zhong, Shiyuan; Bian, Xindi

1999-08-01

Wintertime temperature profiles in the Grand Canyon exhibit a neutral to isothermal stratification during both daytime and nighttime, with only rare instances of actual temperature inversions. The canyon warms during daytime and cools during nighttime more or less uniformly through the canyon's entire depth. This weak stability and temperature structure evolution differ from other Rocky Mountain valleys, which develop strong nocturnal inversions and exhibit convective and stable boundary layers that grow upward from the valley floor. Mechanisms that may be responsible for the different behavior of the Grand Canyon are discussed, including the possibility that the canyon atmosphere is frequently mixed to near-neutral stratification when cold air drains into the top of the canyon from the nearby snow-covered Kaibab Plateau. Another feature of canyon temperature profiles is the sharp inversions that often form near the canyon rims. These are generally produced when warm air is advected over the canyon in advance of passing synoptic-scale ridges.Wintertime winds in the main canyon are not classical diurnal along-valley wind systems. Rather, they are driven along the canyon axis by the horizontal synoptic-scale pressure gradient that is superimposed along the canyon's axis by passing synoptic-scale weather disturbances. They may thus bring winds into the canyon from either end at any time of day.The implications of the observed canyon boundary layer structure for air pollution dispersion are discussed.

Evidence for submarine landslides and continental slope erosion related to fault reactivation during the last glaciation offshore eastern Canada

Science.gov (United States)

Saint-Ange, F.; Campbell, C.; MacKillop, K.; Mosher, D. C.; Piper, D. J.; Roger, J.

2012-12-01

Many studies have proposed that reactivation of dormant faults during deglaciation is a source of neotectonic activity in glaciated regions, but few have demonstrated the relationship to submarine landslides. In this study, seabed morphology and shallow geology of the outer continental margin adjacent to the Charlie Gibbs Fracture Zone off Newfoundland, Canada was investigated for evidence of this relationship. The glacial history and morphology of the margin suggest that the entire continental shelf in the area, coincident with major continental crustal lineaments, was ice-covered during the Last glacial cycle, and transverse troughs delineate the paleo-icestream drainage patterns. A recent investigation of Notre Dame Trough revealed the existence of large sediment failures on the shelf. The current study investigates complex seafloor erosion and widespread mass transport deposition (MTD) on the continental slope seaward of Notre Dame Trough, using recently-acquired high resolution seismic reflection data and piston cores. The new data reveal that a trough mouth fan (TMF) is present on the slope seaward of Notre Dame Trough. The Notre Dame TMF is characterized by a succession of stacked debris flows, but does not show a lobate shape in plan view like other classic TMFs. Instead, the Notre Dame TMF has abruptly-truncated margins suggesting post-depositional failure and erosion of the fan deposits. Seismic reflection data show that the locations of the failures along the TMF margin are coincident with a set of shallow faults; however the current dataset does not image the deeper portion of the faults. On the upper slope immediately south of the TMF, a narrow and deeply incised canyon is located along-trend with the Notre Dame Trough. The location of this canyon appears to be controlled by a fault. Downslope from this canyon, along the southern margin of the TMF, a 25 km wide, flat-floored, U-shaped valley was eroded into a succession of stacked MTD-filled channels

Integrated study of Mediterranean deep canyons: Novel results and future challenges

Science.gov (United States)

Canals, M.; Company, J. B.; Martín, D.; Sànchez-Vidal, A.; Ramírez-Llodrà, E.

2013-11-01

This volume compiles a number of scientific papers resulting from a sustained multidisciplinary research effort of the deep-sea ecosystem in the Mediterranean Sea. This started 20 years ago and peaked over the last few years thanks to a number of Spanish and European projects such as PROMETEO, DOS MARES, REDECO, GRACCIE, HERMES, HERMIONE and PERSEUS, amongst others. The geographic focus of most papers is on the NW Mediterranean Sea including the Western Gulf of Lion and the North Catalan margin, with a special attention to submarine canyons, in particular the Blanes and Cap de Creus canyons. This introductory article to the Progress in Oceanography special issue on “Mediterranean deep canyons” provides background information needed to better understand the individual papers forming the volume, comments previous reference papers related to the main topics here addressed, and finally highlights the existing relationships between atmospheric forcing, oceanographic processes, seafloor physiography, ecosystem response, and litter and chemical pollution. This article also aims at constituting a sort of glue, in terms of existing knowledge and concepts and novel findings, linking together the other twenty papers in the volume, also including some illustrative figures. The main driving ideas behind this special issue, particularly fitting to the study area of the NW Mediterranean Sea, could be summarized as follows: (i) the atmosphere and the deep-sea ecosystem are connected through oceanographic processes originating in the coastal area and the ocean surface, which get activated at the occasion of high-energy events leading to fast transfers of matter and energy to the deep; (ii) shelf indented submarine canyons play a pivotal role in such transfers, which involve dense water, sedimentary particles, organic matter, litter and chemical pollutants; (iii) lateral inputs (advection) from the upper continental margin contributes significantly to the formation of

A Numerical Study of the Temperature Reduction by Water Spray Systems within Urban Street Canyons

Directory of Open Access Journals (Sweden)

Ying-Chen Lee

2018-04-01

Full Text Available To reduce energy demand (both fossil fuel and renewable energy for cooling the urban heat island environment, some solutions have been studied. Among these methods, the water spray system is considered more flexible due to its dynamic controls. This study investigated the cooling effect of water spray systems in the street canyon under different aspect ratios and high relative humidity environments using a computational fluid dynamics model. This model was validated with water channel and wind tunnel experiments. The results showed that the most effective cooling area was the area just under the spray nozzles. However, in a narrow street canyon, people in the middle of the street may feel the cooling effect because of the dispersion and accumulation of the cooled air. Our simulations demonstrated that air under the nozzles was saturated and this revealed that under drier conditions the water spray systems will have higher cooling performance. We also found that using large water droplets created a wider cooling area in the middle of the street canyon, and this phenomenon was not changed much if the nozzle height was increased from 2.5 m to 3.5 m.

Street canyon aerosol pollutant transport measurements.

Science.gov (United States)

Longley, I D; Gallagher, M W; Dorsey, J R; Flynn, M; Bower, K N; Allan, J D

2004-12-01

Current understanding of dispersion in street canyons is largely derived from relatively simple dispersion models. Such models are increasingly used in planning and regulation capacities but are based upon a limited understanding of the transport of substances within a real canyon. In recent years, some efforts have been made to numerically model localised flow in idealised canyons (e.g., J. Appl. Meteorol. 38 (1999) 1576-89) and stepped canyons (Assimakopoulos V. Numerical modelling of dispersion of atmospheric pollution in and above urban canopies. PhD thesis, Imperial College, London, 2001) but field studies in real canyons are rare. To further such an understanding, a measurement campaign has been conducted in an asymmetric street canyon with busy one-way traffic in central Manchester in northern England. The eddy correlation method was used to determine fluxes of size-segregated accumulation mode aerosol. Measurements of aerosol at a static location were made concurrently with measurements on a platform lift giving vertical profiles. Size-segregated measurements of ultrafine and coarse particle concentrations were also made simultaneously at various heights. In addition, a small mobile system was used to make measurements of turbulence at various pavement locations within the canyon. From this data, various features of turbulent transport and dispersion in the canyon will be presented. The concentration and the ventilation fluxes of vehicle-related aerosol pollutants from the canyon will be related to controlling factors. The results will also be compared with citywide ventilation data from a separate measurement campaign conducted above the urban canopy.

Geohydrology of White Rock Canyon of the Rio Grande from Otowi to Frijoles Canyon

International Nuclear Information System (INIS)

Purtymun, W.D.; Peters, R.J.; Owens, J.W.

1980-12-01

Twenty-seven springs discharge from the Totavi Lentil and Tesuque Formation in White Rock Canyon. Water generally acquires its chemical characteristics from rock units that comprise the spring aquifer. Twenty-two of the springs are separated into three groups of similar aquifer-related chemical quality. The five remaining springs make up a fourth group with a chemical quality that differs due to localized conditions in the aquifer. Localized conditions may be related to recharge or discharge in or near basalt intrusion or through faults. Streams from Pajarito, Ancho, and Frijoles Canyons discharge into the Rio Grande in White Rock Canyon. The base flow in the streams is from springs. Sanitary effluent in Mortandad Canyon from the treatment plant at White Rock also reaches the Rio Grande

78 FR 48670 - Boulder Canyon Project

Science.gov (United States)

2013-08-09

... DEPARTMENT OF ENERGY Western Area Power Administration Boulder Canyon Project AGENCY: Western Area... Canyon Project (BCP) electric service provided by the Western Area Power Administration (Western). The... INFORMATION: Hoover Dam, authorized by the Boulder Canyon Project Act (45 Stat. 1057, December 21, 1928), sits...

77 FR 48151 - Boulder Canyon Project

Science.gov (United States)

2012-08-13

... DEPARTMENT OF ENERGY Western Area Power Administration Boulder Canyon Project AGENCY: Western Area... Canyon Project (BCP) electric service provided by the Western Area Power Administration (Western). The... INFORMATION: Hoover Dam, authorized by the Boulder Canyon Project Act (45 Stat. 1057, December 21, 1928), sits...

Seasonal monitoring of deep-sea megabenthos in Barkley Canyon cold seep by internet operated vehicle (IOV.

Directory of Open Access Journals (Sweden)

Carolina Doya

Full Text Available Knowledge of the processes shaping deep-sea benthic communities at seasonal scales in cold-seep environments is incomplete. Cold seeps within highly dynamic regions, such as submarine canyons, where variable current regimes may occur, are particularly understudied. Novel Internet Operated Vehicles (IOVs, such as tracked crawlers, provide new techniques for investigating these ecosystems over prolonged periods. In this study a benthic crawler connected to the NEPTUNE cabled infrastructure operated by Ocean Networks Canada was used to monitor community changes across 60 m2 of a cold-seep area of the Barkley Canyon, North East Pacific, at ~890 m depth within an Oxygen Minimum Zone (OMZ. Short video-transects were run at 4-h intervals during the first week of successive calendar months, over a 14 month period (February 14th 2013 to April 14th 2014. Within each recorded transect video megafauna abundances were computed and changes in environmental conditions concurrently measured. The responses of fauna to environmental conditions as a proxy of seasonality were assessed through analysis of abundances in a total of 438 video-transects (over 92 h of total footage. 7698 fauna individuals from 6 phyla (Cnidaria, Ctenophora, Arthropoda, Echinodermata, Mollusca, and Chordata were logged and patterns in abundances of the 7 most abundant taxa (i.e. rockfish Sebastidae, sablefish Anoplopoma fimbria, hagfish Eptatretus stoutii, buccinids (Buccinoidea, undefined small crabs, ctenophores Bolinopsis infundibulum, and Scyphomedusa Poralia rufescens were identified. Patterns in the reproductive behaviour of the grooved tanner crab (Chionnecetes tanneri were also indicated. Temporal variations in biodiversity and abundance in megabenthic fauna was significantly influenced by variabilities in flow velocity flow direction (up or down canyon, dissolved oxygen concentration and month of study. Also reported here for the first time are transient mass aggregations of

Arctic Submarine Slope Stability

Science.gov (United States)

Winkelmann, D.; Geissler, W.

2010-12-01

Submarine landsliding represents aside submarine earthquakes major natural hazard to coastal and sea-floor infrastructure as well as to coastal communities due to their ability to generate large-scale tsunamis with their socio-economic consequences. The investigation of submarine landslides, their conditions and trigger mechanisms, recurrence rates and potential impact remains an important task for the evaluation of risks in coastal management and offshore industrial activities. In the light of a changing globe with warming oceans and rising sea-level accompanied by increasing human population along coasts and enhanced near- and offshore activities, slope stability issues gain more importance than ever before. The Arctic exhibits the most rapid and drastic changes and is predicted to change even faster. Aside rising air temperatures, enhanced inflow of less cooled Atlantic water into the Arctic Ocean reduces sea-ice cover and warms the surroundings. Slope stability is challenged considering large areas of permafrost and hydrates. The Hinlopen/Yermak Megaslide (HYM) north of Svalbard is the first and so far only reported large-scale submarine landslide in the Arctic Ocean. The HYM exhibits the highest headwalls that have been found on siliciclastic margins. With more than 10.000 square kilometer areal extent and app. 2.400 cubic kilometer of involved sedimentary material, it is one of the largest exposed submarine slides worldwide. Geometry and age put this slide in a special position in discussing submarine slope stability on glaciated continental margins. The HYM occurred 30 ka ago, when the global sea-level dropped by app. 50 m within less than one millennium due to rapid onset of global glaciation. It probably caused a tsunami with circum-Arctic impact and wave heights exceeding 130 meters. The HYM affected the slope stability field in its neighbourhood by removal of support. Post-megaslide slope instability as expressed in creeping and smaller-scaled slides are

Assessment of submarine landslides hazard through geotechnical and rheological analysis of sediments on the French Atlantic continental slope

Science.gov (United States)

Toucanne, S.; Howlett, S.; Garziglia, S.; Silva Jacinto, R.; Courgeon, S.; Sabine, M.; Riboulot, V.; Marsset, B.

2016-12-01

In the aftermath of the devastating tsunami on the Japanese coast in 2011, a French multi-partnership project called TANDEM has been launched to assess the impact of tsunamis generated or propagated in the vicinity of French Channel and Atlantic coastlines. Tsunami are usually generated by earthquakes, but can also be triggered by submarine landslides. This study focuses on submarine landslides along the French Atlantic continental slope using data that were mainly collected in August 2015 during the GITAN cruise (R/V Pourquoi Pas?). Following geomorphological, geophysical and sedimentological analysis of the Bay of Biscay, efforts were oriented towards the determination of the sediment properties controlling landslide dynamics from in situ and laboratory measurements. Preliminary results show over 700 landslide scars on the French Atlantic continental slope, with most of them occurring between 400 and 1000m water depth and in canyon environments. The Plio-Quaternary sediments draping the majority of the Bay of Biscay are generally normally consolidated and composed of high plasticity clays. They show similar geomechanical properties throughout the area studied, with linear evolutions with depth and good reproducibility for rheological parameters such as Storage and Loss modulus. These similarities allow to extend geotechnical and rheological models to a regional scale in the Bay of Biscay. Our multi-disciplinary approach will provide the tools to assess continental slope failures and submarine landslides generation. Finally, we will aim to qualify and quantify the volumes and flow properties of sediment transported obtained through slope-stability modeling on SAMU-3D and rheology modelling on Nixes-SPH. These results will provide the TANDEM actors with the information necessary to simulate tsunami wave generation.

Environmental assessment: Davis Canyon site, Utah

International Nuclear Information System (INIS)

1986-05-01

In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. These evaluations were reported in draft environmental assessments (EAs), which were issued for public review and comment. After considering the comments received on the draft EAs, the DOE prepared the final EA. The Davis Canyon site is in the Paradox Basin, which is one of five distinct geohydrologic settings considered for the first repository. This setting contains one other potentially acceptable site -- the Lavender Canyon site. Although the Lavender Canyon site is suitable for site characterization, the DOE has concluded that the Davis Canyon site is the preferred site in the Paradox Basin. On the basis of the evaluations reported in this EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. Furthermore, the DOE has fond that the site is suitable for site characterization because the evidence does not support a conclusion that the site will not be able to meet each of the qualifying conditions specified in the guidelines. On the basis of these findings, the DOE is nominating the Davis Canyon site as one of five sites suitable for characterization. 181 figs., 175 tabs

Environmental assessment: Davis Canyon site, Utah

Energy Technology Data Exchange (ETDEWEB)

none,

1986-05-01

In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high- level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. These evaluations were reported in draft environmental assessments (EAs), which were issued for public review and comment. After considering the comments received on the draft EAs, the DOE prepared the final EA. The Davis Canyon site is in the Paradox Basin, which is one of five distinct geohydrologic settings considered for the first repository. This setting contains one other potentially acceptable site -- the Lavender Canyon site. Although the Lavender Canyon site is suitable for site characterization, the DOE has concluded that the Davis Canyon site is the preferred site in the Paradox Basin. On the basis of the evaluations reported in this EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. Furthermore, the DOE has found that the site is suitable for site characterization because the evidence does not support a conclusion that the site will not be able to meet each of the qualifying conditions specified in the guidelines. On the basis of these findings, the DOE is nominating the Davis Canyon site as one of the five sites suitable for characterization.

Environmental assessment: Davis Canyon site, Utah

Energy Technology Data Exchange (ETDEWEB)

none,

1986-05-01

In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. These evaluations were reported in draft environmental assessments (EAs), which were issued for public review and comment. After considering the comments received on the draft EAs, the DOE prepared the final EA. The Davis Canyon site is in the Paradox Basin, which is one of five distinct geohydrologic settings considered for the first repository. This setting contains one other potentially acceptable site -- the Lavender Canyon site. Although the Lavender Canyon site is suitable for site characterization, the DOE has concluded that the Davis Canyon site is the preferred site in the Paradox Basin. On the basis of the evaluations reported in this EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. Furthermore, the DOE has fond that the site is suitable for site characterization because the evidence does not support a conclusion that the site will not be able to meet each of the qualifying conditions specified in the guidelines. On the basis of these findings, the DOE is nominating the Davis Canyon site as one of five sites suitable for characterization. 181 figs., 175 tabs.

Environmental assessment: Davis Canyon site, Utah

Energy Technology Data Exchange (ETDEWEB)

none,

1986-05-01

In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. These evaluations were reported in draft environmental assessments (EAs), which were issued for public review and comment. After considering the comments received on the draft EAs, the DOE prepared the final EA. The Davis Canyon site is in the Paradox Basin, which is one of five distinct geohydrologic settings considering for the first repository. This setting contains one other potentially acceptable site -- the Lavender Canyon site. Although the Lavender Canyon site is suitable for site characterization, the DOE has concluded that the Davis Canyon site is the preferred site in the Paradox Basin. On the basis of the evaluations reported in this EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. Furthermore, the DOE has found that the site is suitable for site characterization because the evidence does not support a conclusion that the site will not be able to meet each of the qualifying conditions specified in the guidelines. On the basis of these findings, the DOE is nominating the Davis Canyon site as one of five sites suitable for characterization.

Environmental assessment: Davis Canyon site, Utah

International Nuclear Information System (INIS)

1986-05-01

In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. These evaluations were reported in draft environmental assessments (EAs), which were issued for public review and comment. After considering the comments received on the draft EAs, the DOE prepared the final EA. The Davis Canyon site is in the Paradox Basin, which is one of five distinct geohydrologic settings considering for the first repository. This setting contains one other potentially acceptable site -- the Lavender Canyon site. Although the Lavender Canyon site is suitable for site characterization, the DOE has concluded that the Davis Canyon site is the preferred site in the Paradox Basin. On the basis of the evaluations reported in this EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. Furthermore, the DOE has found that the site is suitable for site characterization because the evidence does not support a conclusion that the site will not be able to meet each of the qualifying conditions specified in the guidelines. On the basis of these findings, the DOE is nominating the Davis Canyon site as one of five sites suitable for characterization

Environmental assessment: Davis Canyon site, Utah

International Nuclear Information System (INIS)

1986-05-01

In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high- level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. These evaluations were reported in draft environmental assessments (EAs), which were issued for public review and comment. After considering the comments received on the draft EAs, the DOE prepared the final EA. The Davis Canyon site is in the Paradox Basin, which is one of five distinct geohydrologic settings considered for the first repository. This setting contains one other potentially acceptable site -- the Lavender Canyon site. Although the Lavender Canyon site is suitable for site characterization, the DOE has concluded that the Davis Canyon site is the preferred site in the Paradox Basin. On the basis of the evaluations reported in this EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. Furthermore, the DOE has found that the site is suitable for site characterization because the evidence does not support a conclusion that the site will not be able to meet each of the qualifying conditions specified in the guidelines. On the basis of these findings, the DOE is nominating the Davis Canyon site as one of the five sites suitable for characterization

Sedimentation in Rio La Venta Canyon in Netzahualcoyotl Reservoir, Chiapas, Mexico

Science.gov (United States)

de La Fuente, J. A.; Lisle, T.; Velasquez, J.; Allison, B. L.; Miller, A.

2002-12-01

Sedimentation of Rio La Venta as it enters the Netzahualcoyotl Reservoir in Chiapas, Mexico, threatens a unique part of the aquatic ecosystem. Rio La Venta enters the reservoir via a narrow canyon about 16 km long with spectacular, near-vertical limestone bluffs up to 320 m high and inhabited by the flora and fauna of a pristine tropical forest. Karst terrain underlies most of the Rio La Venta basin in the vicinity of the reservoir, while deeply weathered granitic terrain underlies the Rio Negro basin, and the headwaters of the Rio La Venta to the south. The Rio Negro joins Rio La Venta 3 km downstream of the upper limit of the reservoir and delivers the bulk of the total clastic sediment (mostly sand and finer material). The canyon and much of the contributing basin lie within the Reserva de la Biosfera, Selva El Ocote, administered by the Comision Nacional de Areas Naturales Protegidas, part of the Secretaria de Medioambiente y Recursos Naturales. The Klamath National Forest Forest has cooperated with its Mexican counterparts since 1993 in natural resource management, neo-tropical bird inventories, wildfire management, and more recently in watershed analyses. Rates of sedimentation are estimated from bathymetric surveys conducted in March, 2002. A longitudinal profile down the inundated canyon during a high reservoir level shows an inflection from a slope of 0.0017 to one of 0.0075 at 7.2 km downstream of the mouth of Rio Negro. The bed elevation at this point corresponds to the lowest reservoir level, suggesting that the gentler sloping bed upstream is formed by fluvial processes during drawdown and that downstream by pluvial processes. Using accounts that boats could access Rio Negro during low water levels in 1984, we estimate an annual sedimentation rate of roughly 3 million cubic meters per year. This suggests that boats might no longer be able to access the most spectacular section of canyon upstream of Rio Negro within a decade, depending on how the

Hydrogeology of Middle Canyon, Oquirrh Mountains, Tooele County, Utah

Science.gov (United States)

Gates, Joseph Spencer

1963-01-01

Geology and climate are the principal influences affecting the hydrology of Middle Canyon, Tooele County, Utah. Reconnaissance in the canyon indicated that the geologic influences on the hydrology may be localized; water may be leaking through fault and fracture zones or joints in sandstone and through solution openings in limestone of the Oquirrh formation of Pennsylvanian and Permian age. Surficial deposits of Quaternary age serve as the main storage material for ground water in the canyon and transmit water from the upper canyon to springs and drains at the canyon mouth. The upper canyon is a more important storage area than the lower canyon because the surficial deposits are thicker, and any zones of leakage in the underlying bedrock of the upper canyon probably would result in greater leakage than would similar outlets in the lower canyon.The total annual discharge from Middle Canyon, per unit of precipitation, decreased between 1910 and 1939. Similar decreases occurred in Parleys Canyon in the nearby Wasatch Range and in other drainage basins in Utah, and it is likely that most of the decrease in discharge from Middle Canyon and other canyons in Utah is due to a change in climate.Chemical analyses of water showed that the high content of sulfate and other constituents in the water from the Utah Metals tunnel, which drains into Middle Canyon, does not have a significant effect on water quality at the canyon mouth. This suggests that much of the tunnel water is lost from the channel by leakage, probably in the upper canyon, during the dry part of the year.Comparison of the 150 acre-feet of water per square mile of drainage area discharged by Middle Canyon in 1947 with the 623 and 543 acre-feet per square mile discharged in 1948 by City Creek and Mill Creek Canyons, two comparable drainage basins in the nearby Wasatch Range, also suggests that there is leakage in Middle Canyon.A hydrologic budget of the drainage basin results in an estimate that about 3,000 acre

Late Holocene earthquake history of the Brigham City segment of the Wasatch fault zone at the Hansen Canyon, Kotter Canyon, and Pearsons Canyon trench sites, Box Elder County, Utah

Science.gov (United States)

DuRoss, Christopher B.; Personius, Stephen F.; Crone, Anthony J.; McDonald, Greg N.; Briggs, Richard W.

2012-01-01

Of the five central segments of the Wasatch fault zone (WFZ) having evidence of recurrent Holocene surface-faulting earthquakes, the Brigham City segment (BCS) has the longest elapsed time since its most recent surface-faulting event (~2.1 kyr) compared to its mean recurrence time between events (~1.3 kyr). Thus, the BCS has the highest time-dependent earthquake probability of the central WFZ. We excavated trenches at three sites––the Kotter Canyon and Hansen Canyon sites on the north-central BCS and Pearsons Canyon site on the southern BCS––to determine whether a surface-faulting earthquake younger than 2.1 ka occurred on the BCS. Paleoseismic data for Hansen Canyon and Kotter Canyon confirm that the youngest earthquake on the north-central BCS occurred before 2 ka, consistent with previous north-central BCS investigations at Bowden Canyon and Box Elder Canyon. At Hansen Canyon, the most recent earthquake is constrained to 2.1–4.2 ka and had 0.6–2.5 m of vertical displacement. At Kotter Canyon, we found evidence for two events at 2.5 ± 0.3 ka and 3.5 ± 0.3 ka, with an average displacement per event of 1.9–2.3 m. Paleoseismic data from Pearsons Canyon, on the previously unstudied southern BCS, indicate that a post-2 ka earthquake ruptured this part of the segment. The Pearsons Canyon earthquake occurred at 1.2 ± 0.04 ka and had 0.1–0.8 m of vertical displacement, consistent with our observation of continuous, youthful scarps on the southern 9 km of the BCS having 1–2 m of late Holocene(?) surface offset. The 1.2-ka earthquake on the southern BCS likely represents rupture across the Weber–Brigham City segment boundary from the penultimate Weber-segment earthquake at about 1.1 ka. The Pearsons Canyon data result in a revised length of the BCS that has not ruptured since 2 ka (with time-dependent probability implications), and provide compelling evidence of at least one segment-boundary failure and multi-segment rupture on the central WFZ. Our

Anaerobic methanotrophic communities thrive in deep submarine permafrost.

Science.gov (United States)

Winkel, Matthias; Mitzscherling, Julia; Overduin, Pier P; Horn, Fabian; Winterfeld, Maria; Rijkers, Ruud; Grigoriev, Mikhail N; Knoblauch, Christian; Mangelsdorf, Kai; Wagner, Dirk; Liebner, Susanne

2018-01-22

Thawing submarine permafrost is a source of methane to the subsurface biosphere. Methane oxidation in submarine permafrost sediments has been proposed, but the responsible microorganisms remain uncharacterized. We analyzed archaeal communities and identified distinct anaerobic methanotrophic assemblages of marine and terrestrial origin (ANME-2a/b, ANME-2d) both in frozen and completely thawed submarine permafrost sediments. Besides archaea potentially involved in anaerobic oxidation of methane (AOM) we found a large diversity of archaea mainly belonging to Bathyarchaeota, Thaumarchaeota, and Euryarchaeota. Methane concentrations and δ 13 C-methane signatures distinguish horizons of potential AOM coupled either to sulfate reduction in a sulfate-methane transition zone (SMTZ) or to the reduction of other electron acceptors, such as iron, manganese or nitrate. Analysis of functional marker genes (mcrA) and fluorescence in situ hybridization (FISH) corroborate potential activity of AOM communities in submarine permafrost sediments at low temperatures. Modeled potential AOM consumes 72-100% of submarine permafrost methane and up to 1.2 Tg of carbon per year for the total expected area of submarine permafrost. This is comparable with AOM habitats such as cold seeps. We thus propose that AOM is active where submarine permafrost thaws, which should be included in global methane budgets.

Monitoring of radioactivity at the Russian nuclear submarine Kursk

International Nuclear Information System (INIS)

Amundsen, I.; Lind, B.

2002-01-01

In the morning of August 12th 2000, a Russian submarine accident occurred in international waters east of Rybatschi Peninsula in the Barents Sea about 250 km from Norway. The submarine, a Russian Oscar class II attack submarine, sunk to 116 meters depth at the position 69 deg. 36,99N, 37 deg. 34,50E. The submarine 'Kursk' is 154 meters long, equipped with two pressurised water reactors and the submerged displacement is 24000 tons. Each reactor has a thermal effect or 190 megawatt, or less than 10% of a typical nuclear power plant reactor. The submarines in Oscar-II class is one of the largest and most capable in the Russian Northern Fleet. No indications of leakage from the submarine have so far been observed during the monitoring expeditions. Elevated levels of radioactivity have note been detected in any dose-rate readings or at any of the measurements of environmental samples taken close to Kursk. Furthermore, no increased levels were measured on bits and pieces from the submarine or from water sampled inside the submarine. A more comprehensive report covering experience and monitoring results from the two expeditions term and impact assessments of possible future releases from Kursk. (LN)

Addressing submarine geohazards through scientific drilling

Science.gov (United States)

Camerlenghi, A.

2009-04-01

Natural submarine geohazards (earthquakes, volcanic eruptions, landslides, volcanic island flank collapses) are geological phenomena originating at or below the seafloor leading to a situation of risk for off-shore and on-shore structures and the coastal population. Addressing submarine geohazards means understanding their spatial and temporal variability, the pre-conditioning factors, their triggers, and the physical processes that control their evolution. Such scientific endeavour is nowadays considered by a large sector of the international scientific community as an obligation in order to contribute to the mitigation of the potentially destructive societal effects of submarine geohazards. The study of submarine geohazards requires a multi-disciplinary scientific approach: geohazards must be studied through their geological record; active processes must be monitored; geohazard evolution must be modelled. Ultimately, the information must be used for the assessment of vulnerability, risk analysis, and development of mitigation strategies. In contrast with the terrestrial environment, the oceanic environment is rather hostile to widespread and fast application of high-resolution remote sensing techniques, accessibility for visual inspection, sampling and installation of monitoring stations. Scientific Drilling through the IODP (including the related pre site-survey investigations, sampling, logging and in situ measurements capability, and as a platform for deployment of long term observatories at the surface and down-hole) can be viewed as the centre of gravity of an international, coordinated, multi-disciplinary scientific approach to address submarine geohazards. The IODP Initial Science Plan expiring in 2013 does not address openly geohazards among the program scientific objectives. Hazards are referred to mainly in relation to earthquakes and initiatives towards the understanding of seismogenesis. Notably, the only drilling initiative presently under way is the

Separations canyon decontamination facilities

International Nuclear Information System (INIS)

Hershey, J.H.

1975-01-01

Highly radioactive process equipment is decontaminated at the Savannah River Plant in specially equipped areas of the separations canyon building so that direct mechanical repairs or alterations can be made. Using these facilities it is possible to decontaminate and repair equipment such as 10- x 11-ft storage tanks, 8- x 8-ft batch evaporator pots and columns, 40-in. Bird centrifuges, canyon pumps and agitators, and various canyon piping systems or ''jumpers.'' For example, centrifuge or evaporator pots can be decontaminated and rebuilt for about 60 percent of the 1974 replacement cost. The combined facilities can decontaminate and repair 6 to 10 pieces of major equipment per year. Decontamination time varies with type of equipment and radioactivity levels encountered

Separations canyon decontamination facilities

International Nuclear Information System (INIS)

Hershey, J.H.

1975-05-01

Highly radioactive process equipment is decontaminated at the Savannah River Plant in specially equipped areas of the separations canyon buildings so that direct mechanical repairs or alterations can be made. Using these facilities it is possible to decontaminate and repair equipment such as 10- x 11-ft storage tanks, 8- x 8-ft batch evaporator pots and columns, 40-in. Bird centrifuges, canyon pumps and agitators, and various canyon piping systems or ''jumpers.'' For example, centrifuge or evaporator pots can be decontaminated and rebuilt for about 60 percent of the 1974 replacement cost. The combined facilities can decontaminate and repair 6 to 10 pieces of major equipment per year. Decontamination time varies with type of equipment and radioactivity levels encountered. (U.S.)

How well do basic models describe the turbidity currents coming down Monterey and Congo Canyon?

Science.gov (United States)

Cartigny, M.; Simmons, S.; Heerema, C.; Xu, J. P.; Azpiroz, M.; Clare, M. A.; Cooper, C.; Gales, J. A.; Maier, K. L.; Parsons, D. R.; Paull, C. K.; Sumner, E. J.; Talling, P.

2017-12-01

Turbidity currents rival rivers in their global capacity to transport sediment and organic carbon. Furthermore, turbidity currents break submarine cables that now transport >95% of our global data traffic. Accurate turbidity current models are thus needed to quantify their transport capacity and to predict the forces exerted on seafloor structures. Despite this need, existing numerical models are typically only calibrated with scaled-down laboratory measurements due to the paucity of direct measurements of field-scale turbidity currents. This lack of calibration thus leaves much uncertainty in the validity of existing models. Here we use the most detailed observations of turbidity currents yet acquired to validate one of the most fundamental models proposed for turbidity currents, the modified Chézy model. Direct measurements on which the validation is based come from two sites that feature distinctly different flow modes and grain sizes. The first are from the multi-institution Coordinated Canyon Experiment (CCE) in Monterey Canyon, California. An array of six moorings along the canyon axis captured at least 15 flow events that lasted up to hours. The second is the deep-sea Congo Canyon, where 10 finer grained flows were measured by a single mooring, each lasting several days. Moorings captured depth-resolved velocity and suspended sediment concentration at high resolution (turbidity currents; the modified Chézy model. This basic model has been very useful for river studies over the past 200 years, as it provides a rapid estimate of how flow velocity varies with changes in river level and energy slope. Chézy-type models assume that the gravitational force of the flow equals the friction of the river-bed. Modified Chézy models have been proposed for turbidity currents. However, the absence of detailed measurements of friction and sediment concentration within full-scale turbidity currents has forced modellers to make rough assumptions for these parameters. Here

What threat do turbidity currents and submarine landslides pose to submarine telecommunications cable infrastructure?

Science.gov (United States)

Clare, Michael; Pope, Edward; Talling, Peter; Hunt, James; Carter, Lionel

2016-04-01

The global economy relies on uninterrupted usage of a network of telecommunication cables on the seafloor. These submarine cables carry ~99% of all trans-oceanic digital data and voice communications traffic worldwide, as they have far greater bandwidth than satellites. Over 9 million SWIFT banks transfers alone were made using these cables in 2004, totalling 7.4 trillion of transactions per day between 208 countries, which grew to 15 million SWIFT bank transactions last year. We outline the challenge of why, how often, and where seafloor cables are broken by natural causes; primarily subsea landslides and sediment flows (turbidity currents and also debris flows and hyperpycnal flows). These slides and flows can be very destructive. As an example, a sediment flow in 1929 travelled up to 19 m/s and broke 11 cables in the NE Atlantic, running out for ~800 km to the abyssal ocean. The 2006 Pingtung earthquake triggered a sediment flow that broke 22 cables offshore Taiwan over a distance of 450 km. Here, we present initial results from the first statistical analysis of a global database of cable breaks and causes. We first investigate the controls on frequency of submarine cable breaks in different environmental and geological settings worldwide. We assess which types of earthquake pose a significant threat to submarine cable networks. Meteorological events, such as hurricanes and typhoons, pose a significant threat to submarine cable networks, so we also discuss the potential impacts of future climate change on the frequency of such hazards. We then go on to ask what are the physical impacts of submarine sediment flows on submerged cables? A striking observation from past cable breaks is sometimes cables remain unbroken, whilst adjacent cables are severed (and record powerful flows travelling at up to 6 m/s). Why are some cables broken, but neighbouring cables remain intact? We provide some explanations for this question, and outline the need for future in

Influence of Anchoring on Burial Depth of Submarine Pipelines.

Science.gov (United States)

Zhuang, Yuan; Li, Yang; Su, Wei

2016-01-01

Since the beginning of the twenty-first century, there has been widespread construction of submarine oil-gas transmission pipelines due to an increase in offshore oil exploration. Vessel anchoring operations are causing more damage to submarine pipelines due to shipping transportation also increasing. Therefore, it is essential that the influence of anchoring on the required burial depth of submarine pipelines is determined. In this paper, mathematical models for ordinary anchoring and emergency anchoring have been established to derive an anchor impact energy equation for each condition. The required effective burial depth for submarine pipelines has then been calculated via an energy absorption equation for the protection layer covering the submarine pipelines. Finally, the results of the model calculation have been verified by accident case analysis, and the impact of the anchoring height, anchoring water depth and the anchor weight on the required burial depth of submarine pipelines has been further analyzed.

Tsunami run-up and inundation along the coast of Sabah and Sarawak, Malaysia due to a potential Brunei submarine mass failure.

Science.gov (United States)

Tan, Wai Kiat; Teh, Su Yean; Koh, Hock Lye

2017-07-01

Submarine landslides, also known as submarine mass failures (SMFs), are major natural marine disasters that could critically damage coastal facilities such as nuclear power plants and oil and gas platforms. It is therefore essential to investigate submarine landslides for potential tsunami hazard assessment. Three-dimensional seismic data from offshore Brunei have revealed a giant seabed mass deposited by a previous SMF. The submarine mass extends over 120 km from the continental slope of the Baram Canyon at 200 m water depth to the deep basin floor of the Northwest Borneo Trough. A suite of in-house two-dimensional depth-averaged tsunami simulation model TUNA (Tsunami-tracking Utilities and Application) is developed to assess the vulnerability of coastal communities in Sabah and Sarawak subject to potential SMF tsunami. The submarine slide is modeled as a rigid body moving along a planar slope with the center of mass motion parallel to the planar slope and subject to external forces due to added mass, gravity, and dissipation. The nonlinear shallow water equations are utilized to simulate tsunami propagation from deepwater up to the shallow offshore areas. A wetting-drying algorithm is used when a tsunami wave reaches the shoreline to compute run up of tsunami along the shoreline. Run-up wave height and inundation maps are provided for seven densely populated locations in Sabah and Sarawak to highlight potential risks at each location, subject to two scenarios of slide slopes: 2° and 4°. The first wave may arrive at Kudat as early as 0.4 h after the SMF, giving local communities little time to evacuate. Over a small area, maximum inundated depths reaching 20.3 m at Kudat, 26.1 m at Kota Kinabalu, and 15.5 m at Miri are projected, while the maximum inundation distance of 4.86 km is expected at Miri due to its low-lying coast. In view of the vulnerability of some locations to the SMF tsunami, it is important to develop and implement community resilience

Investigation of the shelf break and continental slope in the Western part of the Black Sea using acoustic methods

Science.gov (United States)

Dutu, F.; Ion, G.; Jugaru Tiron, L.

2009-04-01

The Black Sea is a large marginal sea surrounded by a system of Alpine orogenic chains, including the Balkanides-Pontides, Caucasus, Crimea and North Dobrogea located to the south, northeast, north and northwest, respectively (Dinu et al., 2005). The north-western part of the Black Sea is the main depocentre for sediment supply from Central Europe via the Danube River, but also from Eastern Europe through the Ukrainian rivers Dniepr, Dniestr and Southern Bug (Popescu et al., 2004). The shelfbreak is located at water depths of 120-140 m southward of the Danube Canyon, and up to 170 m northward of the canyon possibly due to recent faulting which is very common in this area. The continental slope is dissected by numerous canyons, each of which is fed by several tributaries. The Danube Canyon (also known as Viteaz Canyon) is a large shelf-indenting canyon located in the north-western Black Sea and connected to the youngest channel-levee system of the Danube Fan (Popescu et al., 2004). The acoustic methods are a useful way for investigate the shelf break and the continental slope giving us information about landslides on the continental slope, the topography of the investigated area, the sedimentary zones affected by instability and to quantify the geometry of the underwater landslides. The measurements made on the continental slope from north-western part of the Black Sea gave us the possibility to make a digital terrain model. After processing the data the model offer information about the main access ways of the sediments through gravitational slide on the submarines canyons, with forming of turbidity currents, debris flows and also other transport/transformation phenomena of the sediments on the continental slope like submarine landslides and submarine collapse. References Dinu, C., Wong, H.K., Tambrea, D., Matenco, L., 2005. Stratigraphic and structural characteristics of the Romanian Black Sea shelf. Tectonophysics 410, 417-435. Popescu, I., Lericolais, G., Panin

Influence of Anchoring on Burial Depth of Submarine Pipelines.

Directory of Open Access Journals (Sweden)

Yuan Zhuang

Full Text Available Since the beginning of the twenty-first century, there has been widespread construction of submarine oil-gas transmission pipelines due to an increase in offshore oil exploration. Vessel anchoring operations are causing more damage to submarine pipelines due to shipping transportation also increasing. Therefore, it is essential that the influence of anchoring on the required burial depth of submarine pipelines is determined. In this paper, mathematical models for ordinary anchoring and emergency anchoring have been established to derive an anchor impact energy equation for each condition. The required effective burial depth for submarine pipelines has then been calculated via an energy absorption equation for the protection layer covering the submarine pipelines. Finally, the results of the model calculation have been verified by accident case analysis, and the impact of the anchoring height, anchoring water depth and the anchor weight on the required burial depth of submarine pipelines has been further analyzed.

Enhancing Submarine Operational Relevance: A Leadership Challenge

National Research Council Canada - National Science Library

Daigle, Jr, Michael J

2008-01-01

.... This vision of submarine operations must change. As the military continues to shift to operations focused on joint capabilities, the submarine force must break from the closed, protective, and risk averse culture of its past and push forward...

The fluorescent tracer experiment on Holiday Beach near Mugu Canyon, Southern California

Science.gov (United States)

Kinsman, Nicole; Xu, J. P.

2012-01-01

After revisiting sand tracer techniques originally developed in the 1960s, a range of fluorescent coating formulations were tested in the laboratory. Explicit steps are presented for the preparation of the formulation evaluated to have superior attributes, a thermoplastic pigment/dye in a colloidal mixture with a vinyl chloride/vinyl acetate copolymer. In September 2010, 0.59 cubic meters of fluorescent tracer material was injected into the littoral zone about 4 kilometers upcoast of Mugu submarine canyon in California. The movement of tracer was monitored in three dimensions over the course of 4 days using manual and automated techniques. Detailed observations of the tracer's behavior in the coastal zone indicate that this tracer successfully mimicked the native beach sand and similar methods could be used to validate models of tracer movement in this type of environment. Recommendations including how to time successful tracer studies and how to scale the field of view of automated camera systems are presented along with the advantages and disadvantages of the described tracer methodology.

A Gradually Varied Approach to Model Turbidity Currents in Submarine Channels

Science.gov (United States)

Bolla Pittaluga, M.; Frascati, A.; Falivene, O.

2018-01-01

We develop a one-dimensional model to describe the dynamics of turbidity current flowing in submarine channels. We consider the flow as a steady state polydisperse suspension accounting for water detrainment from the clear water-turbid interface, for spatial variations of the channel width and for water and sediment lateral overspill from the channel levees. Moreover, we account for sediment exchange with the bed extending the model to deal with situations where the current meets a nonerodible bed. Results show that when water detrainment is accounted for, the flow thickness becomes approximately constant proceeding downstream. Similarly, in the presence of channel levees, the flow tends to adjust to channel relief through the lateral loss of water and sediment. As more mud is spilled above the levees relative to sand, the flow becomes more sand rich proceeding downstream when lateral overspill is present. Velocity and flow thickness predicted by the model are then validated by showing good agreement with laboratory observations. Finally, the model is applied to the Monterey Canyon bathymetric data matching satisfactorily the December 2002 event field measurements and predicting a runout length consistent with observations.

Relationship between work stress and health in submariners

Directory of Open Access Journals (Sweden)

Nan-nan JIANG

2013-09-01

Full Text Available Objective　To explore the relationship between work stress and health in submariners. Methods　In April 2008, 272 submariners trained in a navy base were selected as study subjects by random group sampling method, and tested by primary personal information questionnaire, self-rated health measurement scale (SRHMS, self-developed submariners' work stressors questionnaire, and work stress self-rated scale. Physical health, mental health and social health of submariners were analyzed, and scores were compared with the norm of reference scores. Correlations were analyzed respectively between 10 items of submariners' general information (including age, length of military service, education degree, years at the present post, times of receiving awards, on-duty hours, off-duty hours, hours of sleep, lost days of leave, positive attitude to work and their physical health score, mental health score, social health score, total health score, as well as between 15 submariners' work stressors (including workrelated risks, diet problems, high temperature, humidity and noise in workplace, shortage of clean clothes, illness, losing contact with outside, lack of information about the task, lacking supports from family members, relationship problems, lack of involvement in task decisions, boring and dull work, on duty, heavy work, high quality of work, coping with unexpected threat and their physical health score, mental health score, social health score and total health score. Results　No significant difference was found between submariners' SRHMS total score and the normal referenced score (t=0.56, P>0.05, but the physical health score and mental health score were significantly lower than normal referenced scores respectively (t=–2.172, P<0.05; t=–3.299, P<0.01, and the social health score was significantly higher than normal referenced score (t=9.331, P<0.001. The age, length of military service, years at present post of submariners were related

236-Z canyon utilization study

International Nuclear Information System (INIS)

Dixon, D.R.

1977-01-01

The 236-Z canyon contains equipment for repurification of plutonium and recovery of plutonium from scrap material. To meet production requirements of Fast Flux Test Facility/Clinch River Breeder Reactor oxide with the existing plant, several new pieces of equipment will be needed in the future. More storage space and a better accountability system are needed to support this increased production. The available canyon space needs to be utilized to its fullest in order to accommodate the new equipment. The purpose of this document is to identify the new pieces of equipment, show how they fit into the flowsheet, and locate them in the canyon

Submarine Landslides: What we Know and Where we are Going!

Science.gov (United States)

Moscardelli, L. G.; Mountjoy, J. J.; Micallef, A.; Strasser, M.; Vanneste, M.; Chaytor, J. D.; Mosher, D.; Krastel, S.; Lo Iacono, C.; Yamada, Y.

2015-12-01

Submarine landslides and other gravity-induced movements can disrupt very large areas of continental margins resulting in long-term seafloor morphologic change and multi-scale mass transport deposits (MTDs). Potential consequences of submarine landslides include damage to seabed infrastructure, offshore facilities, as well as generation or enhancement of tsunamis. MTDs are common on the modern seafloor and within the stratigraphic record. Slides, slumps and debris flows can be constituents of MTDs and can co-occur in the same event or depositional unit. Recent research indicates that relationships exist between MTD geological setting, causal mechanisms, and geometries. Quantitative data analysis suggests that MTD morphometric parameters can be used to link these three parameters. Despite many advances in this field, it still remains unclear how to definitively identify pre-conditioning factors and triggers of submarine landslides in modern slopes, and how submarine landslides evolve after initiation. In addition, new questions regarding the interaction between submarine landslides and active marine processes, such as bottom currents and fluid flow, have emerged.One of the mandates of the S4SLIDE (IGCP-640) project, a joint endeavor of UNESCO and IGCP that represents the broad field of submarine landslide research, is to facilitate interactions at an international level among scientists, industry and government representatives to advance our knowledge on a number of outstanding science questions: (i) What is the nature of the interaction between current-controlled sedimentation and submarine landslides? (ii) What role do transient turbulent-laminar flows play in the formation of submarine landslides? (iii) Do climatic variations control the occurrence of submarine landslides? (iv) What is the economic significance of submarine landslides? (v) Do we understand the hazards that submarine landslides pose to the environment and to humans? This presentation will cover

Ventilation Processes in a Three-Dimensional Street Canyon

Science.gov (United States)

Nosek, Štěpán; Kukačka, Libor; Kellnerová, Radka; Jurčáková, Klára; Jaňour, Zbyněk

2016-05-01

The ventilation processes in three different street canyons of variable roof geometry were investigated in a wind tunnel using a ground-level line source. All three street canyons were part of an urban-type array formed by courtyard-type buildings with pitched roofs. A constant roof height was used in the first case, while a variable roof height along the leeward or windward walls was simulated in the two other cases. All street-canyon models were exposed to a neutrally stratified flow with two approaching wind directions, perpendicular and oblique. The complexity of the flow and dispersion within the canyons of variable roof height was demonstrated for both wind directions. The relative pollutant removals and spatially-averaged concentrations within the canyons revealed that the model with constant roof height has higher re-emissions than models with variable roof heights. The nomenclature for the ventilation processes according to quadrant analysis of the pollutant flux was introduced. The venting of polluted air (positive fluctuations of both concentration and velocity) from the canyon increased when the wind direction changed from perpendicular to oblique, irrespective of the studied canyon model. Strong correlations (>0.5) between coherent structures and ventilation processes were found at roof level, irrespective of the canyon model and wind direction. This supports the idea that sweep and ejection events of momentum bring clean air in and detrain the polluted air from the street canyon, respectively.

Late Holocene sea ice conditions in Herald Canyon, Chukchi Sea

Science.gov (United States)

Pearce, C.; O'Regan, M.; Rattray, J. E.; Hutchinson, D. K.; Cronin, T. M.; Gemery, L.; Barrientos, N.; Coxall, H.; Smittenberg, R.; Semiletov, I. P.; Jakobsson, M.

2017-12-01

Sea ice in the Arctic Ocean has been in steady decline in recent decades and, based on satellite data, the retreat is most pronounced in the Chukchi and Beaufort seas. Historical observations suggest that the recent changes were unprecedented during the last 150 years, but for a longer time perspective, we rely on the geological record. For this study, we analyzed sediment samples from two piston cores from Herald Canyon in the Chukchi Sea, collected during the 2014 SWERUS-C3 Arctic Ocean Expedition. The Herald Canyon is a local depression across the Chukchi Shelf, and acts as one of the main pathways for Pacific Water to the Arctic Ocean after entering through the narrow and shallow Bering Strait. The study site lies at the modern-day seasonal sea ice minimum edge, and is thus an ideal location for the reconstruction of past sea ice variability. Both sediment cores contain late Holocene deposits characterized by high sediment accumulation rates (100-300 cm/kyr). Core 2-PC1 from the shallow canyon flank (57 m water depth) is 8 meter long and extends back to 4200 cal yrs BP, while the upper 3 meters of Core 4-PC1 from the central canyon (120 mwd) cover the last 3000 years. The chronologies of the cores are based on radiocarbon dates and the 3.6 ka Aniakchak CFE II tephra, which is used as an absolute age marker to calculate the marine radiocarbon reservoir age. Analysis of biomarkers for sea ice and surface water productivity indicate stable sea ice conditions throughout the entire late Holocene, ending with an abrupt increase of phytoplankton sterols in the very top of both sediment sequences. The shift is accompanied by a sudden increase in coarse sediments (> 125 µm) and a minor change in δ13Corg. We interpret this transition in the top sediments as a community turnover in primary producers from sea ice to open water biota. Most importantly, our results indicate that the ongoing rapid ice retreat in the Chukchi Sea of recent decades was unprecedented during the

Origin, evolution and sedimentary processes associated with a late Miocene submarine landslide, southeast Spain

Science.gov (United States)

Sola, F.; Puga-Bernabéu, Á.; Aguirre, J.; Braga, J. C.

2018-02-01

A submarine landslide, the Alhama de Almería Slide, influenced late Tortonian and early Messinian (late Miocene) sedimentary processes in the vicinity of Alhama de Almería in southeast Spain. Its 220-m-high headscarp and deposits are now subaerially exposed. The landslide occurred at the northern slope of the antecedent relief of the present-day Sierra de Gádor mountain range. This is a large antiform trending east-west to east-northeast-west-southwest, which has been uplifting since the late Miocene due to convergence of the African and Eurasian plates. During the Tortonian, this relief was an island separated from the Iberian Peninsula mainland by the Alpujarra corridor, a small and narrow intermontane basin of the Betic Cordillera in the western Mediterranean Sea. The materials involved in the slope failure were Triassic dolostones and phyllites from the metamorphic Alpujárride Complex and Tortonian marine conglomerates, sandstones, and marls that formed an initial sedimentary cover on the basement rocks. Coherent large masses of metamorphic rocks and Miocene deposits at the base of the headscarp distally change to chaotic deposits of blocks of different lithologies embedded in upper Tortonian marine marls, and high-strength cohesive debrites. During downslope sliding, coherent carbonate blocks brecciated due to their greater strength. Phyllites disintegrated, forming a cohesive matrix that engulfed and/or sustained the carbonate blocks. Resedimented, channelized breccias were formed by continuing clast collision, bed fragmentation, and disaggregation of the failed mass. The conditions leading to rock/sediment failure were favoured by steep slopes and weak planes at the contact between the basement carbonates and phyllites. Displacement of collapsed rocks created a canyon-like depression at the southeast edge of the landslide. This depression funnelled sediment gravity flows that were generated upslope, promoting local thick accumulations of sediments during

Environmental assessment overview, Davis Canyon site, Utah

International Nuclear Information System (INIS)

1986-05-01

In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. The Davis Canyon site is in the Paradox Basin, which is one of five distinct geohydrologic settings considered for the first repository. On the basis of the evaluations reported in this EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. On the basis of these findings, the DOE is nominating the Davis Canyon site as one of five sites suitable for characterization. 3 figs

Preliminary report on the geology and hydrology of Mortandad Canyon near Los Alamos, New Mexico, with reference to disposal of liquid low-level radioactive waste

Science.gov (United States)

Baltz, E.H.; Abrahams, J.H.; Purtyman, W.D.

1963-01-01

The U.S. Geological Survey, in cooperation with the U.S. Atomic Energy Commission and the Los Alamos Scientific Laboratory, selected the upper part of Mortandad Canyon near Los Alamos, New Mexico for a site for disposal of treated liquid low-level radioactive waste. This report summarizes the part of a study of the geology and hydrology that was done from October 1960 through June 1961. Additional work is being continued. Mortandad Canyon is a narrow east-southeast-trending canyon about 9? miles long that heads on the central part of the Pajarito Plateau at an altitude of about 7,340 feet. The canyon is tributary to the Rio Grande. The drainage area of the part of Mortandad Canyon that was investigated is about 2 square miles, and the total drainage area is about 4.9 square miles. The Pajarito Plateau is capped by the Bandelier Tuff of Pleistocene age. Mortandad Canyon is cut in the Bandelier, and alluvium covers the floor of the canyon to depths ranging from less than 1 foot to as much as 100 feet. The Bandelier is underlain by silt, sand, conglomerate, and interbedded basalt of the Santa Fe Group of Miocene, Pliocene, and Pleistocene(?) age. Some ground water is perched in the alluvium in the canyon; however, the top of the main aquifer is in the Santa Fe Group at a depth of about 990 feet below the canyon floor. Joints in the Bandelier Tuff probably were caused by shrinkage of the tuff during cooling. The joints range in width from hairline cracks to fissures several inches wide. Water can infiltrate along the open joints where the Bandelier is at the surface; however, soil, alluvial fill, and autochthonous clay inhibit infiltration on the tops of mesas and probably in the alluvium-floored canyons also. Thirty-three test holes, each less than 100 feet deep, were drilled in 10 lies across Mortandad Canyon from the western margin of the study area to just west of the Los Alamos-Santa Fe County line. Ten of the holes were cased for observation wells to measure

Turbulence and Air Exchange in a Two-Dimensional Urban Street Canyon Between Gable Roof Buildings

Science.gov (United States)

Garau, Michela; Badas, Maria Grazia; Ferrari, Simone; Seoni, Alessandro; Querzoli, Giorgio

2018-04-01

We experimentally investigate the effect of a typical building covering: the gable roof, on the flow and air exchange in urban canyons. In general, the morphology of the urban canopy is very varied and complex, depending on a large number of factors, such as building arrangement, or the morphology of the terrain. Therefore we focus on a simple, prototypal shape, the two-dimensional canyon, with the aim of elucidating some fundamental phenomena driving the street-canyon ventilation. Experiments are performed in a water channel, over an array of identical prismatic obstacles representing an idealized urban canopy. The aspect ratio, i.e. canyon-width to building-height ratio, ranges from 1 to 6. Gable roof buildings with 1:1 pitch are compared with flat roofed buildings. Velocity is measured using a particle-image-velocimetry technique with flow dynamics discussed in terms of mean flow and second- and third-order statistical moments of the velocity. The ventilation is interpreted by means of a simple well-mixed box model and the outflow rate and mean residence time are computed. Results show that gable roofs tend to delay the transition from the skimming-flow to the wake-interference regime and promote the development of a deeper and more turbulent roughness layer. The presence of a gable roof significantly increases the momentum flux, especially for high packing density. The air exchange is improved compared to the flat roof buildings, and the beneficial effect is more significant for narrow canyons. Accordingly, for unit aspect ratio gable roofs reduce the mean residence time by a factor of 0.37 compared to flat roofs, whereas the decrease is only by a factor of 0.9 at the largest aspect ratio. Data analysis indicates that, for flat roof buildings, the mean residence time increases by 30% when the aspect ratio is decreased from 6 to 2, whereas this parameter is only weakly dependent on aspect ratio in the case of gable roofs.

Chemical environments of submarine hydrothermal systems

Science.gov (United States)

Shock, Everett L.

1992-01-01

Perhaps because black-smoker chimneys make tremendous subjects for magazine covers, the proposal that submarine hydrothermal systems were involved in the origin of life has caused many investigators to focus on the eye-catching hydrothermal vents. In much the same way that tourists rush to watch the spectacular eruptions of Old Faithful geyser with little regard for the hydrology of the Yellowstone basin, attention is focused on the spectacular, high-temperature hydrothermal vents to the near exclusion of the enormous underlying hydrothermal systems. Nevertheless, the magnitude and complexity of geologic structures, heat flow, and hydrologic parameters which characterize the geyser basins at Yellowstone also characterize submarine hydrothermal systems. However, in the submarine systems the scale can be considerably more vast. Like Old Faithful, submarine hydrothermal vents have a spectacular quality, but they are only one fascinating aspect of enormous geologic systems operating at seafloor spreading centers throughout all of the ocean basins. A critical study of the possible role of hydrothermal processes in the origin of life should include the full spectrum of probable environments. The goals of this chapter are to synthesize diverse information about the inorganic geochemistry of submarine hydrothermal systems, assemble a description of the fundamental physical and chemical attributes of these systems, and consider the implications of high-temperature, fluid-driven processes for organic synthesis. Information about submarine hydrothermal systems comes from many directions. Measurements made directly on venting fluids provide useful, but remarkably limited, clues about processes operating at depth. The oceanic crust has been drilled to approximately 2.0 km depth providing many other pieces of information, but drilling technology has not allowed the bore holes and core samples to reach the maximum depths to which aqueous fluids circulate in oceanic crust. Such

Monitoring of the nuclear submarine Komsomolets

Energy Technology Data Exchange (ETDEWEB)

Heldal, Hilde E.; Flo, Janita K.; Liebig, Penny L. [Institute of Marine Research, P. O. Box 1870 Nordnes, N-5817 Bergen (Norway); Gaefvert, Torbjoern; Rudjord, Anne Liv [Norwegian Radiation Protection Authority, P.O. Box 55, N-1332 Oesteraas (Norway); Gwynn, Justin P. [Norwegian Radiation Protection Authority, The Fram Centre, N-9296 Tromsoe (Norway)

2014-07-01

The Soviet nuclear submarine Komsomolets sank on the 7 April 1989, 180 km southwest of Bear Island in the Norwegian Sea to a depth of about 1655 m. The submarine contains one nuclear reactor containing long-lived radionuclides such as cesium-137 ({sup 137}Cs) along with other fission and activation products, in addition to 2 mixed uranium/plutonium nuclear warheads containing weapons grade plutonium. Although several model studies have shown that a radioactive leakage from Komsomolets will have insignificant impact on fish and other marine organisms, there are still public concerns about the condition of the submarine and the potential for radioactive leakage. In order to document the contamination levels and to meet public concerns, monitoring of radioactive contamination in the area adjacent to the submarine has been ongoing since 1993. Samples of bottom seawater and sediments have been collected annually by the Institute of Marine Research (IMR) and have been analysed for {sup 137}Cs and plutonium-239,240 ({sup 239,240}Pu). So far, activity concentrations in the samples have been comparable to levels found in other samples from the Norwegian and Barents Seas. During sampling from R/V 'G. O. Sars' in April 2013, an area of about 1 km{sup 2} of the seabed around Komsomolets was mapped to precisely locate the submarine using a Kongsberg EM302 multibeam echo sounder, a Simrad EK60 single beam echo sounder and an Olex 3D bottom-mapping system. For sediment sampling, a Simrad MST342 mini-transponder was attached to a Smoegen box corer to allow for precise positioning of the corer. With the aid of the Kongsberg HiPAP (High Precision Acoustic Positioning) system, 4 box cores were collected around the submarine at a distance of 10 to 20 m. In addition, one box core was collected from a reference station about 100 m upstream of the submarine. Surface sediments and sediment cores were collected from the box cores taken at each sampling location. Sediment cores

Modeling the Effect of Wider Canyons on Urban Heating

Directory of Open Access Journals (Sweden)

Rizwan Ahmed Memon

2011-04-01

Full Text Available The k-? turbulence model is adopted in this study to simulate the impact of street canyon AR (Aspect Ratios on heating within street canyon. The two-dimensional model was validated for RANS (Reynolds Averaged Navier Stokes and energy transport equations. The validation process confirms that the results of the model for airtemperature and wind speed could be trusted. The application of the said model is carried out to ideal street canyons of ARs (ratio of building-height-to-street-width from 0.4 to 2 with the same boundary conditions. Notably, street canyon aspect ratio was calculated by varying the street width while keeping the building height constant. Results show that the weighted-average-air-temperature within AR 0.4 was around 0.8% (i.e. 2.4K higher than that within AR 2.0. Conversely, there was strong correlation (i.e., R2>0.9 between air temperature within the street canyon and street canyon AR. Results demonstrate stronger influence of vertical velocity on heating within street canyon. Evidently, increased vertical velocity decreased the temperatures. Conversely, temperatures were higher along the leeward side of the canyon in lower ARs.

Improved Submariner Eyewear for Routine Wear and Emergency Equipment Use Underway

Science.gov (United States)

2010-01-15

information. 2.0 DESCRIPTION Naval Submarine Medical Research Laboratory (NSMRL) is seeking information from the eyewear industry that will provide...Improved Submariner Eyewear for Routine Wear and Emergency Equipment Use Underway by Alison America, MA Wayne G. Horn, MD...Submariner Eyewear for Routine Wear and Emergency Equipment Use Underway 50818 Alison America, MA Wayne G. Horn, MD Naval Submarine Medical Research

VICTORIA Class Submarine Human-in-the-Loop Experimentation Plan

Science.gov (United States)

2014-06-01

1472G. VICTORIA Class Submarine Human-in-the-Loop Experimentation Plan and Preliminary Results © Her Majesty the Queen in Right of...19 th International Command and Control Research and Technology Symposium Title: VICTORIA Class Submarine Human-in-the-Loop...TYPE 3. DATES COVERED 00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE VICTORIA Class Submarine Human-in-the-Loop Experimentation Plan 5a. CONTRACT

First Survey For Submarine Hydrothermal Vents In NE Sulawesi, Indonesia

Science.gov (United States)

McConachy, T.; Binns, R.; Permana, H.

2001-12-01

The IASSHA-2001 cruise (Indonesia-Australia Survey for Submarine Hydrothermal Activity) was successfully conducted from June 1 to June 29 on board Baruna Jaya VIII. Preliminary results are reported of the first expedition to locate and study submarine hydrothermal activity in north east Sulawesi. Leg A focussed on Tomini Bay, a virtually unexplored Neogene sedimentary basin. Its objective was to test whether modern sediment-hosted hydrothermal activity occurred on the sea floor. The results of new bathymetric mapping, sediment coring and CTD/transmissometer hydrocasts negate the likely presence in central Tomini Bay of large-scale modern analogues of hydrothermal massive sulfide environments involving hydrothermal venting of basinal or magma-derived fluids into reduced sediments. It is possible that the "heat engine" required to drive circulation of basinal and hydrothermal fluids is today too weak. Surveys around Colo volcano indicate that it may be in its final stage of evolution. Leg B studied the arc and behind-arc sectors of the Sangihe volcanic island chain extending northwards from Quaternary volcanoes on the northeastern tip of Sulawesi's North Arm, near Manado. West of the main active chain and extending northwards from Manado there is a subparallel ridge surmounted by a number of high (>2000 m) seamounts of uncertain age. Fifteen relatively high-standing submarine edifices were crossed during this leg, of which nine were tested for hydrothermal activity by hydrocast and dredging. Eight sites were known from previous bathymetric surveys, and seven are new discoveries made by narrow-beam or multibeam echo sounding. Two submarine edifices at least 1000 m high were discovered in the strait immediately north of Awu volcano on Sangihe Island. One, with crest at 206 m, is surrounded by a circular platform 300m deep which we infer to be a foundered fringing reef to a formerly emergent island. The other, lacking such a platform, appears relatively young and may be

76 FR 56430 - Boulder Canyon Project

Science.gov (United States)

2011-09-13

... DEPARTMENT OF ENERGY Western Area Power Administration Boulder Canyon Project AGENCY: Western Area... Project (BCP) electric service provided by the Western Area Power Administration (Western). The Rates will... by the Boulder Canyon Project Act (45 Stat. 1057, December 21, 1928), sits on the Colorado River...

Index of Submarine Medical Officer’s Qualification Theses 1944-1974

Science.gov (United States)

1976-04-01

USING HYPOTHERMIA AND HYPERBARIC CXYGENATI 1972-3011 0 A CASE REPO+ HYPOBARIC HYPOXIA ABOARD A SUBMERGED SUBMARINE 1972-0014 THE EFFECTS OF ACUTE HYPOXIA...G009 LEVEL. VENTILATORY DYNAMICS UNDER HYPERBARIC STATES.= SUBMARINE MEDICAL QUALIFICATION THESES U. So NAVAL SJBMARINE MEDICAL CENTER SUBMARINE BASE...CONNECTICUT. 23 OCT 62 StJRL ____________ 1962-0019 WOO3D W.- - ____ VENTILATORY DYNAMICS UNDER HYPERBARIC STATES.= SUBMARINE MEDICAL QUALIFICATION THESES

Pollutant Dilution and Diffusion in Urban Street Canyon Neighboring Streets

Science.gov (United States)

Sun, Z.; Fu, Zh. M.

2011-09-01

In the present study we investigated the airflow patterns and air quality of a series of typical street canyon combinations, developed a mass balance model to determine the local pollutant dilution rate, and discuss the impact of upstream canyon on the air quality of downstream canyon. The results indicated that the geometrical size of upstream and downstream buildings have significant impacts on the ambient airflow patterns. The pollution distribution within the canyons varies with different building combinations and flow patterns. Within the upstream canyon, pollution always accumulates to the low building side for non-symmetrical canyon, and for symmetrical canyon high level of pollution occurs at the leeward side. The height of the middle and downstream buildings can evidently change the pollutant dispersion direction during the transport process. Within the polluted canyon, the pollutant dilution rate (PDR) also varies with different street canyon combinations. The highest PDR is observed when the upstream buildings are both low buildings no matter the height of downstream building. However, the two cases are likely to contribution pollution to the downstream canyon. The H-L-H combination is mostly against local pollution remove, while the L-H-L case is considered the best optimistic building combination with both the ability of diluting local pollution and not remarkably decreasing air quality of downstream canyon. The current work is expected instructive for city designers to optimize traffic patterns under typical existing geometry or in the development of urban geometry modification for air quality control.

33 CFR 165.1302 - Bangor Naval Submarine Base, Bangor, WA.

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Bangor Naval Submarine Base... Bangor Naval Submarine Base, Bangor, WA. (a) Location. The following is a security zone: The waters of... States Naval vessels. (ii) Vessels that are performing work at Naval Submarine Base Bangor pursuant to a...

Early benthic successional processes at implanted substrates in Barkley Submarine Canyon affected by a permanent oxygen minimum zone

Science.gov (United States)

Cabrera De Leo, F.; Smith, C. R.; Levin, L. A.; Fleury, A.; Aguzzi, J.

2016-02-01

With the advent of cabled observatories scientists are now able to have a permanent presence in the deep-seafloor, being able to reveal previously unseen faunal behavior as well as to track long-term changes in biodiversity and ecosystem function. The Ocean Networks Canada 800-km loop seafloor observatory array (NEPTUNE) located in the NE Pacific has instruments measuring a variety of environmental variables ranging from temperature, salinity, oxygen, currents, turbidity, fluorescence, etc, at multiple and very high temporal resolution scales. High-definition video cameras also monitor benthic communities in multiple deep-sea habitats, all at some extent influenced by an oxygen minimum zone (OMZ). In the present study, whale-bone and wood substrates are being used to evaluate bathymetric, regional and inter-basin variations in benthic biodiversity and connectivity, as well as interactions between biodiversity and ecosystem function. In May of 2014 three humpback whale (Megaptera novaeangliae) rib sections, one 20x20x10 cm block of Douglas Fir (Pseudotsunga meniziesii), and a 30x30x30 block of authigenic carbonate were placed with the use of an ROV at 890 m depth inside Barkley Canyon. The substrate packages were placed concentrically, 45-cm away from a HD video camera. Five-minute videos were captured at 2-hr intervals. Preliminary data analysis from 8 months of deployment showed very distinct early community succession patterns between the two organic substrates (bones and wood) and the authigenic carbonate. Whalebones and wood showed amphipod (Orchomene obtusa) abundance peaks mostly contained during the first 60 days after deployment; Amphipod peak abundance rapid decline coincides with rapid growth of bacterial mat on whalebone and wood surfaces. Low abundance, species richness and substrate degradation rates are in agreement with a low oxygen environment of the OMZ in the canyon. Despite the early stages of data analysis, this experiment demonstrates how

76 FR 8359 - Boulder Canyon Project

Science.gov (United States)

2011-02-14

... DEPARTMENT OF ENERGY Western Area Power Administration Boulder Canyon Project AGENCY: Western Area... Western Area Power Administration (Western) is proposing an adjustment to the Boulder Canyon Project (BCP... Reclamation Project Act of 1939 (43 U.S.C. 485h(c)), and other acts that specifically apply to the project...

Recreational impacts on Colorado River beaches in Glen Canyon, Arizona

Science.gov (United States)

Carothers, Steven W.; Johnson, Robert A.; Dolan, Robert

1984-07-01

Recreational impact was measured on eight beaches in Glen Canyon National Recreation Area and 15 beaches in Grand Canyon National Park using permanently located transects and plots. Recreational impact indices included densities of human trash and charcoal and a measure of sand discoloration due to charcoal. Significant increases in the indices occurred on several Glen Canyon beaches over a seven-month period. Sand discoloration became significantly higher over all Glen Canyon beaches during the same time period. All indices were significantly higher in Glen Canyon than on similar Grand Canyon beaches. These differences are probably due to differences in: (a) level of impacts tolerated by the respective management regimes and, (b) in the number of user days among the two National Park Service administrative units. Management alternatives are presented for reversing the present trends of recreational impact on Glen Canyon beaches.

Phase 1 Final Report: Titan Submarine

Science.gov (United States)

Oleson, Steven R.; Lorenz, Ralph D.; Paul, Michael V.

2015-01-01

The conceptual design of a submarine for Saturn's moon Titan was a funded NASA Innovative Advanced Concepts (NIAC) Phase 1 for 2014. The proposal stated the desire to investigate what science a submarine for Titan's liquid hydrocarbon seas might accomplish and what that submarine might look like. Focusing on a flagship class science system (100 kg), it was found that a submersible platform can accomplish extensive science both above and below the surface of the Kraken Mare. Submerged science includes mapping using side-looking sonar, imaging and spectroscopy of the lake, as well as sampling of the lake's bottom and shallow shoreline. While surfaced, the submarine will not only sense weather conditions (including the interaction between the liquid and atmosphere) but also image the shoreline, as much as 2 km inland. This imaging requirement pushed the landing date to Titan's next summer period (2047) to allow for lighted conditions, as well as direct-to-Earth communication, avoiding the need for a separate relay orbiter spacecraft. Submerged and surfaced investigation are key to understanding both the hydrological cycle of Titan as well as gather hints to how life may have begun on Earth using liquid, sediment, and chemical interactions. An estimated 25 Mb of data per day would be generated by the various science packages. Most of the science packages (electronics at least) can be safely kept inside the submarine pressure vessel and warmed by the isotope power system.The baseline 90-day mission would be to sail submerged and surfaced around and through Kraken Mare investigating the shoreline and inlets to evaluate the sedimentary interaction both on the surface and then below. Depths of Kraken have yet to be sensed (Ligeia to the north is thought to be 200 m (656 ft) deep), but a maximum depth of 1,000 m (3,281 ft) for Kraken Mare was assumed for the design). The sub would spend 20 d at the interface between Kraken Mare and Ligeia Mare for clues to the drainage of

78 FR 7775 - Boulder Canyon Project

Science.gov (United States)

2013-02-04

... DEPARTMENT OF ENERGY Western Area Power Administration Boulder Canyon Project AGENCY: Western Area...), is proposing an adjustment to the Boulder Canyon Project (BCP) electric service base charge and rates... subsequent laws, particularly section 9(c) of the Reclamation Project Act of 1939 (43 U.S.C. 485h(c)); and...

77 FR 2533 - Boulder Canyon Project

Science.gov (United States)

2012-01-18

... DEPARTMENT OF ENERGY Western Area Power Administration Boulder Canyon Project AGENCY: Western Area...), is proposing an adjustment to the Boulder Canyon Project (BCP) electric service base charge and rates...) of the Reclamation Project Act of 1939 (43 U.S.C. 485h(c)); and other acts that specifically apply to...

Deepwater Canyons 2013: Pathways to the Abyss

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Leg I focused on biological objectives in Norfolk Canyon, with some sampling in Baltimore Canyon. Leg II focused on archaeological targets in and around the Norfolk...

Submarine films as narratives of masculinity

OpenAIRE

MacDonald, Alex

2002-01-01

The research for this thesis is on representations of masculinity in Anglo-American submarine films since 1943. The discussion will draw on relevant work on the representation of masculinity and popular cinema in film and cultural studies. In particular, the thesis will account for the notion of hegemony in relation to masculinity in the submarine film. Further, the notion of hegemonic masculinity will be addressed in terms of four key claims. These are as follows: that relations between grou...

Effects of canyon geometry on the distribution of traffic-related air pollution in a large urban area: Implications of a multi-canyon air pollution dispersion model

Science.gov (United States)

Fu, Xiangwen; Liu, Junfeng; Ban-Weiss, George A.; Zhang, Jiachen; Huang, Xin; Ouyang, Bin; Popoola, Olalekan; Tao, Shu

2017-09-01

Street canyons are ubiquitous in urban areas. Traffic-related air pollutants in street canyons can adversely affect human health. In this study, an urban-scale traffic pollution dispersion model is developed considering street distribution, canyon geometry, background meteorology, traffic assignment, traffic emissions and air pollutant dispersion. In the model, vehicle exhausts generated from traffic flows first disperse inside street canyons along the micro-scale wind field generated by computational fluid dynamics (CFD) model. Then, pollutants leave the street canyon and further disperse over the urban area. On the basis of this model, the effects of canyon geometry on the distribution of NOx and CO from traffic emissions were studied over the center of Beijing. We found that an increase in building height leads to heavier pollution inside canyons and lower pollution outside canyons at pedestrian level, resulting in higher domain-averaged concentrations over the area. In addition, canyons with highly even or highly uneven building heights on each side of the street tend to lower the urban-scale air pollution concentrations at pedestrian level. Further, increasing street widths tends to lead to lower pollutant concentrations by reducing emissions and enhancing ventilation simultaneously. Our results indicate that canyon geometry strongly influences human exposure to traffic pollutants in the populated urban area. Carefully planning street layout and canyon geometry while considering traffic demand as well as local weather patterns may significantly reduce inhalation of unhealthy air by urban residents.

The Ministry of Dilemmas [decommissioning nuclear submarines

International Nuclear Information System (INIS)

Peden, W.

1995-01-01

A consultant for Greenpeace, the anti-nuclear campaigners, looks at the United Kingdom Government's problems with decommissioning of its nuclear submarine fleet as the vessels become obsolete, and at the transport and storage of spent fuels from the submarine's propulsion reactors. It is argued that no proper plans exist to decommission the vessels safely. The Ministry of Defence sites such as Rosyth and Devonport are immune from inspection by regulatory bodies, so there is no public knowledge of any potential radioactive hazards from the stored out-of-service carcasses, floating in dock, awaiting more active strategies. The author questions the wisdom of building new nuclear submarines, when no proper program exists to decommission existing vessels and their operational waste. (U.K.)

Modeling Submarine Lava Flow with ASPECT

Science.gov (United States)

Storvick, E. R.; Lu, H.; Choi, E.

2017-12-01

Submarine lava flow is not easily observed and experimented on due to limited accessibility and challenges posed by the fast solidification of lava and the associated drastic changes in rheology. However, recent advances in numerical modeling techniques might address some of these challenges and provide unprecedented insight into the mechanics of submarine lava flow and conditions determining its wide-ranging morphologies. In this study, we explore the applicability ASPECT, Advanced Solver for Problems in Earth's ConvecTion, to submarine lava flow. ASPECT is a parallel finite element code that solves problems of thermal convection in the Earth's mantle. We will assess ASPECT's capability to model submarine lava flow by observing models of lava flow morphology simulated with GALE, a long-term tectonics finite element analysis code, with models created using comparable settings and parameters in ASPECT. From these observations we will contrast the differing models in order to identify the benefits of each code. While doing so, we anticipate we will learn about the conditions required for end-members of lava flow morphology, for example, pillows and sheet flows. With ASPECT specifically we focus on 1) whether the lava rheology can be implemented; 2) how effective the AMR is in resolving morphologies of the solidified crust; 3) whether and under what conditions the end-members of the lava flow morphologies, pillows and sheets, can be reproduced.

Characteristics of flow and reactive pollutant dispersion in urban street canyons

Science.gov (United States)

Park, Soo-Jin; Kim, Jae-Jin; Kim, Minjoong J.; Park, Rokjin J.; Cheong, Hyeong-Bin

2015-05-01

In this study, the effects of aspect ratio defined as the ratio of building height to street width on the dispersion of reactive pollutants in street canyons were investigated using a coupled CFD-chemistry model. Flow characteristics for different aspect ratios were analyzed first. For each aspect ratio, six emission scenarios with different VOC-NOX ratios were considered. One vortex was generated when the aspect ratio was less than 1.6 (shallow street canyon). When the aspect ratio was greater than 1.6 (deep street canyon), two vortices were formed in the street canyons. Comparing to previous studies on two-dimensional street canyons, the vortex center is slanted toward the upwind building and reverse and downward flows are dominant in street canyons. Near the street bottom, there is a marked difference in flow pattern between in shallow and deep street canyons. Near the street bottom, reverse and downward flows are dominant in shallow street canyon and flow convergence exists near the center of the deep street canyons, which induces a large difference in the NOX and O3 dispersion patterns in the street canyons. NOX concentrations are high near the street bottom and decreases with height. The O3 concentrations are low at high NO concentrations near the street bottom because of NO titration. At a low VOC-NOX ratio, the NO concentrations are sufficiently high to destroy large amount of O3 by titration, resulting in an O3 concentration in the street canyon much lower than the background concentration. At high VOC-NOX ratios, a small amount of O3 is destroyed by NO titration in the lower layer of the street canyons. However, in the upper layer, O3 is formed through the photolysis of NO2 by VOC degradation reactions. As the aspect ratio increases, NOX (O3) concentrations averaged over the street canyons decrease (increase) in the shallow street canyons. This is because outward flow becomes strong and NOX flux toward the outsides of the street canyons increases

'Good Hunting': German submarine offensives and South African ...

African Journals Online (AJOL)

By the latter half of 1942, the High Command of the German U-boats (BdU) realised that the 'sinking results' of the North Atlantic had decreased immensely. The successes of the Allied anti-submarine operations in the North Atlantic precluded the successful employment of the German submarines in said waters.

Geomorphology, acoustic backscatter, and processes in Santa Monica Bay from multibeam mapping.

Science.gov (United States)

Gardner, James V; Dartnell, Peter; Mayer, Larry A; Hughes Clarke, John E

2003-01-01

Santa Monica Bay was mapped in 1996 using a high-resolution multibeam system, providing the first substantial update of the submarine geomorphology since the initial compilation by Shepard and Emery [(1941) Geol. Soc. Amer. Spec. Paper 31]. The multibeam mapping generated not only high-resolution bathymetry, but also coregistered, calibrated acoustic backscatter at 95 kHz. The geomorphology has been subdivided into six provinces; shelf, marginal plateau, submarine canyon, basin slope, apron, and basin. The dimensions, gradients, and backscatter characteristics of each province is described and related to a combination of tectonics, climate, sea level, and sediment supply. Fluctuations of eustatic sea level have had a profound effect on the area; by periodically eroding the surface of Santa Monica plateau, extending the mouth of the Los Angeles River to various locations along the shelf break, and by connecting submarine canyons to rivers. A wetter glacial climate undoubtedly generated more sediment to the rivers that then transported the increased sediment load to the low-stand coastline and canyon heads. The trends of Santa Monica Canyon and several bathymetric highs suggest a complex tectonic stress field that has controlled the various segments. There is no geomorphic evidence to suggest Redondo Canyon is fault controlled. The San Pedro fault can be extended more than 30 km to the northwest by the alignment of a series of bathymetric highs and abrupt changes in direction of channel thalwegs.

77 FR 22801 - Glen Canyon Dam Adaptive Management Work Group

Science.gov (United States)

2012-04-17

... DEPARTMENT OF THE INTERIOR Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group...). SUMMARY: The Glen Canyon Dam Adaptive Management Work Group (AMWG) makes recommendations to the Secretary..., the AMWG, a technical work group, a Grand Canyon Monitoring and Research Center, and independent...

Modelling the air flow in symmetric and asymmetric street canyons

Energy Technology Data Exchange (ETDEWEB)

Santiago, J.L.; Martin, F. [Research Center for Energy, Environment and Technology (CIEMAT), Madrid (Spain). Fossil Fuels Dept., Numerical Simulation and Modelling Program

2004-07-01

In recent years a large amount of research has been conducted on urban scale and street canyon. Control of air quality inside cities is important for human health. To achieve this objective, street canyon modelling plays a significant role. Pollutant dispersion inside canyons are determined by wind flow around this complex geometry. Experimental investigations have been made by means of field measurements such as Vachon, G. et al. or wind tunnel experiences as Meroney, R.N. et al. or Kastner-Klein, P. and E.J. Plate. In many of these researches, they have used CFD models in several configurations, for instance Assimakopoulos, V.D. et al. or Sini, J.-F. et al. These models are based on a numerical resolution of Navier-Stokes equations with a turbulence closure. In this study, the aim is contribute to the understanding of air circulation inside street canyons. In order to achieve this purpose, several configurations of canyons are investigated. Two-dimensional sequences of real-scale street canyons (order to obstacles height is meters) with different features (symmetric canyons and asymmetric canyons forming step-up and step-down notch configurations) are simulated. These general configurations are modified to investigate some parameters such as aspect ratio, W/H, where W is the width of street and H is the height of buildings. Flows with high Reynolds numbers are modelling. FLUENT CFD software is used. (orig.)

Crossing fitness canyons by a finite population

Science.gov (United States)

Saakian, David B.; Bratus, Alexander S.; Hu, Chin-Kun

2017-06-01

We consider the Wright-Fisher model of the finite population evolution on a fitness landscape defined in the sequence space by a path of nearly neutral mutations. We study a specific structure of the fitness landscape: One of the intermediate mutations on the mutation path results in either a large fitness value (climbing up a fitness hill) or a low fitness value (crossing a fitness canyon), the rest of the mutations besides the last one are neutral, and the last sequence has much higher fitness than any intermediate sequence. We derive analytical formulas for the first arrival time of the mutant with two point mutations. For the first arrival problem for the further mutants in the case of canyon crossing, we analytically deduce how the mean first arrival time scales with the population size and fitness difference. The location of the canyon on the path of sequences has a crucial role. If the canyon is at the beginning of the path, then it significantly prolongs the first arrival time; otherwise it just slightly changes it. Furthermore, the fitness hill at the beginning of the path strongly prolongs the arrival time period; however, the hill located near the end of the path shortens it. We optimize the first arrival time by applying a nonzero selection to the intermediate sequences. We extend our results and provide a scaling for the valley crossing time via the depth of the canyon and population size in the case of a fitness canyon at the first position. Our approach is useful for understanding some complex evolution systems, e.g., the evolution of cancer.

[Effect of greenbelt on pollutant dispersion in street canyon].

Science.gov (United States)

Xu, Wei-Jia; Xing, Hong; Yu, Zhi

2012-02-01

The effect feature of greenbelt on flow field and pollutant dispersion in urban street canyon was researched. The greenbelt was assumed as uniform porous media and its aerodynamics property defined by the pressure loss coefficient. Subsequently, the pollutant dispersion in the street canyon of which there was greenbelt in the middle was simulated with the steady-state standard kappa-epsilon turbulence model and species transport equation. The simulated results agreed well with the wind-tunnel data. Compared with the treeless case, it finds that the street canyon contain a clockwise vortex, the pollutant concentration of the leeward was several times than the windward and the growth rate of pollutant concentration was 46.0%. The further simulation for the impact of tree crown position on the airflow and pollutant dispersion finds that the height of major vortex center in the street canyon increases with the height of tree crown and gradually closes the top of windward building This causes that the average wind speed in the street canyon decreases. Especially when the top of tree crown over the roof and hinder the air flow above the street canyon, the average pollutant concentration increases with the height of tree crown rapidly.

Modern landscape processes affecting archaeological sites along the Colorado River corridor downstream of Glen Canyon Dam, Glen Canyon National Recreation Area, Arizona

Science.gov (United States)

East, Amy E.; Sankey, Joel B.; Fairley, Helen C.; Caster, Joshua J.; Kasprak, Alan

2017-08-29

The landscape of the Colorado River through Glen Canyon National Recreation Area formed over many thousands of years and was modified substantially after the completion of Glen Canyon Dam in 1963. Changes to river flow, sediment supply, channel base level, lateral extent of sedimentary terraces, and vegetation in the post-dam era have modified the river-corridor landscape and have altered the effects of geologic processes that continue to shape the landscape and its cultural resources. The Glen Canyon reach of the Colorado River downstream of Glen Canyon Dam hosts many archaeological sites that are prone to erosion in this changing landscape. This study uses field evaluations from 2016 and aerial photographs from 1952, 1973, 1984, and 1996 to characterize changes in potential windblown sand supply and drainage configuration that have occurred over more than six decades at 54 archaeological sites in Glen Canyon and uppermost Marble Canyon. To assess landscape change at these sites, we use two complementary geomorphic classification systems. The first evaluates the potential for aeolian (windblown) transport of river-derived sand from the active river channel to higher elevation archaeological sites. The second identifies whether rills, gullies, or arroyos (that is, overland drainages that erode the ground surface) exist at the archaeological sites as well as the geomorphic surface, and therefore the relative base level, to which those flow paths drain. Results of these assessments are intended to aid in the management of irreplaceable archaeological resources by the National Park Service and stakeholders of the Glen Canyon Dam Adaptive Management Program.

Introduction to the special issue on submarine geohazard records and potential seafloor instability

Directory of Open Access Journals (Sweden)

Song-Chuen Chen Jia-Jyun Dong

2018-01-01

Full Text Available Submarine landslides frequently occur in passive continental margins or active margins (Hampton et al. 1996; Wynn et al. 2000; Mienert et al. 2002; Korup et al. 2007; Twichell et al. 2009; Cukur et al. 2016. Submarine landslides have been studied extensively not only for scientific research but also for submarine geohazards. Submarine landslides could jeopardize marine infrastructures, such as offshore drilling platforms or submarine telecommunication cables, and could even trigger disastrous tsunamis (Bondevik et al. 2005; Harbitz et al. 2006; Hornbach et al. 2007, 2008; Hsu et al. 2008; Su et al. 2012; Tappin et al. 2014; Li et al. 2015. For instance, one disastrous tsunami hitting the coastal area of southwestern Taiwan in 1781 or 1782 was reported (Chen 1830; Hsu 1983; the tsunami event was probably generated by submarine landslides in the offshore area of southwestern Taiwan (Li et al. 2015. Moreover, several submarine landslides triggered by the 2006 Pingtung earthquake have induced turbidity currents off southwest Taiwan and destroyed about 14 submarine telecommunication cables off SW Taiwan (Hsu et al. 2008. The area of southwest Taiwan currently has a dense population (more than 3 million people in total, one deep-water Kaohsiung Port, several tanks of liquefied natural gas and a nuclear power plant on the coast (Fig. 1. Numerous submarine telecommunication cables exist off SW Taiwan. If a considerable tsunami event would hit again the costal area of SW Taiwan, the damage could very serious. Likewise, there are two nuclear power plants on the coast of northern Taiwan (Fig. 2, and the population in northern Taiwan has more than 10 million people. Submarine telecommunication cables also exist off northern Taiwan. In any case, it is important to understand the status of seafloor stability in the offshore areas of SW and NE Taiwan. For that, this special issue of submarine geohazard records and potential seafloor instability is aimed to

Operational Planning for Theater Anti-Submarine Warfare

Science.gov (United States)

2017-03-01

or P-8 as a supplementary platform to a ship or sub and never assigned to search alone . This thesis allows the MPRA to search alone and has 10 a...Marina, I will truly miss sitting in class with you guys wondering what a basis is. Finally, to my dog, Dougie: thank you for not eating my homework...can have trouble searching and tracking one submarine, let alone multiple submarines in different regions or mission areas. B. LITERATURE REVIEW

Fracture propagation in gas pipelines - relevance to submarine lines

Energy Technology Data Exchange (ETDEWEB)

Fearnehough, G D [British Gas Corp., Newcastle upon Tyne. Engineering Research Station

1976-09-01

This paper reviews the factors which control fracture propagation in pipes and suggests how they are influenced by submarine environments. If fracture arrest capability is required then these factors should be considered in terms of the design philosophy and the maximum tolerable length of fracture which can be repaired. The paper shows that brittle fracture characteristics of submarine pipelines are probably similar to land based lines and fracture arrest can only be guaranteed by appropriate material toughness specification. Resistance to ductile fracture propagation in submarine lines is enhanced by lower design stresses, thicker pipe, concrete coating and the effect of hydrostatic head on gas dynamics. However, additional factors due to submarine design can be deleterious viz: uncertainty about backfill integrity and a tendency of thicker steels to low fracture resistance arising from 'separation' formation. Attention is drawn to problems which may arise with transportation of gases rich in hydrocarbons and the use of mechanical methods of fracture arrest.

H Canyon Processing In Correlation With FH Analytical Labs

International Nuclear Information System (INIS)

Weinheimer, E.

2012-01-01

Management of radioactive chemical waste can be a complicated business. H Canyon and F/H Analytical Labs are two facilities present at the Savannah River Site in Aiken, SC that are at the forefront. In fact H Canyon is the only large-scale radiochemical processing facility in the United States and this processing is only enhanced by the aid given from F/H Analytical Labs. As H Canyon processes incoming materials, F/H Labs provide support through a variety of chemical analyses. Necessary checks of the chemical makeup, processing, and accountability of the samples taken from H Canyon process tanks are performed at the labs along with further checks on waste leaving the canyon after processing. Used nuclear material taken in by the canyon is actually not waste. Only a small portion of the radioactive material itself is actually consumed in nuclear reactors. As a result various radioactive elements such as Uranium, Plutonium and Neptunium are commonly found in waste and may be useful to recover. Specific processing is needed to allow for separation of these products from the waste. This is H Canyon's specialty. Furthermore, H Canyon has the capacity to initiate the process for weapons-grade nuclear material to be converted into nuclear fuel. This is one of the main campaigns being set up for the fall of 2012. Once usable material is separated and purified of impurities such as fission products, it can be converted to an oxide and ultimately turned into commercial fuel. The processing of weapons-grade material for commercial fuel is important in the necessary disposition of plutonium. Another processing campaign to start in the fall in H Canyon involves the reprocessing of used nuclear fuel for disposal in improved containment units. The importance of this campaign involves the proper disposal of nuclear waste in order to ensure the safety and well-being of future generations and the environment. As processing proceeds in the fall, H Canyon will have a substantial

Submarine landslides on the north continental slope of the South China Sea

Science.gov (United States)

Wang, Weiwei; Wang, Dawei; Wu, Shiguo; Völker, David; Zeng, Hongliu; Cai, Guanqiang; Li, Qingping

2018-02-01

Recent and paleo-submarine landslides are widely distributed within strata in deep-water areas along continental slopes, uplifts, and carbonate platforms on the north continental margin of the South China Sea (SCS). In this paper, high-resolution 3D seismic data and multibeam data based on seismic sedimentology and geomorphology are employed to assist in identifying submarine landslides. In addition, deposition models are proposed that are based on specific geological structures and features, and which illustrate the local stress field over entire submarine landslides in deep-water areas of the SCS. The SCS is one of the largest fluvial sediment sinks in enclosed or semi-enclosed marginal seas worldwide. It therefore provides a set of preconditions for the formation of submarine landslides, including rapid sediment accumulation, formation of gas hydrates, and fluid overpressure. A new concept involving temporal and spatial analyses is tested to construct a relationship between submarine landslides and different time scale trigger mechanisms, and three mechanisms are discussed in the context of spatial scale and temporal frequency: evolution of slope gradient and overpressure, global environmental changes, and tectonic events. Submarine landslides that are triggered by tectonic events are the largest but occur less frequently, while submarine landslides triggered by the combination of slope gradient and over-pressure evolution are the smallest but most frequently occurring events. In summary, analysis shows that the formation of submarine landslides is a complex process involving the operation of different factors on various time scales.

CODASC : a database for the validation of street canyon dispersion models

OpenAIRE

Gromke, C.B.

2013-01-01

CODASC stands for Concentration Data of Street Canyons (CODASC 2008, www.codasc.de). It is a database which provides traffic pollutant concentrations in urban street canyons obtained from wind-tunnel dispersion experiments. CODASC comprises concentration data of street canyons with different aspect ratios subjected to various wind directions and also for street canyons with tree-avenues. The database includes concentration data of tree-avenue configurations of different tree arrangement, tree...

Dispersion and photochemical evolution of reactive pollutants in street canyons

Science.gov (United States)

Kwak, Kyung-Hwan; Baik, Jong-Jin; Lee, Kwang-Yeon

2013-05-01

Dispersion and photochemical evolution of reactive pollutants in street canyons with canyon aspect ratios of 1 and 2 are investigated using a computational fluid dynamics (CFD) model coupled with the carbon bond mechanism IV (CBM-IV). Photochemical ages of NOx and VOC are expressed as a function of the NO2-to-NOx and toluene-to-xylene ratios, respectively. These are found to be useful for analyzing the O3 and OH oxidation processes in the street canyons. The OH oxidation process (O3 oxidation process) is more pronounced in the upper (lower) region of the street canyon with a canyon aspect ratio of 2, which is characterized by more (less) aged air. In the upper region of the street canyon, O3 is chemically produced as well as transported downward across the roof level, whereas O3 is chemically reduced in the lower region of the street canyon. The O3 chemical production is generally favorable when the normalized photochemical ages of NOx and VOC are larger than 0.55 and 0.28, respectively. The sensitivities of O3 chemical characteristics to NOx and VOC emission rates, photolysis rate, and ambient wind speed are examined for the lower and upper regions of the street canyon with a canyon aspect ratio of 2. The O3 concentration and the O3 chemical production rate divided by the O3 concentration increase as the NOx emission rate decreases and the VOC emission rate and photolysis rate increase. The O3 concentration is less sensitive to the ambient wind speed than to other factors considered. The relative importance of the OH oxidation process compared to the O3 oxidation process increases with increasing NOx emission rate and photolysis rate and decreasing VOC emission rate. In this study, both O3 and OH oxidation processes are found to be important in street-canyon scale chemistry. The methodology of estimating the photochemical ages can potentially be adopted to neighborhood scale chemistry.

Populating a Control Point Database: A cooperative effort between the USGS, Grand Canyon Monitoring and Research Center and the Grand Canyon Youth Organization

Science.gov (United States)

Brown, K. M.; Fritzinger, C.; Wharton, E.

2004-12-01

The Grand Canyon Monitoring and Research Center measures the effects of Glen Canyon Dam operations on the resources along the Colorado River from Glen Canyon Dam to Lake Mead in support of the Grand Canyon Adaptive Management Program. Control points are integral for geo-referencing the myriad of data collected in the Grand Canyon including aerial photography, topographic and bathymetric data used for classification and change-detection analysis of physical, biologic and cultural resources. The survey department has compiled a list of 870 control points installed by various organizations needing to establish a consistent reference for data collected at field sites along the 240 mile stretch of Colorado River in the Grand Canyon. This list is the foundation for the Control Point Database established primarily for researchers, to locate control points and independently geo-reference collected field data. The database has the potential to be a valuable mapping tool for assisting researchers to easily locate a control point and reduce the occurrance of unknowingly installing new control points within close proximity of an existing control point. The database is missing photographs and accurate site description information. Current site descriptions do not accurately define the location of the point but refer to the project that used the point, or some other interesting fact associated with the point. The Grand Canyon Monitoring and Research Center (GCMRC) resolved this problem by turning the data collection effort into an educational exercise for the participants of the Grand Canyon Youth organization. Grand Canyon Youth is a non-profit organization providing experiential education for middle and high school aged youth. GCMRC and the Grand Canyon Youth formed a partnership where GCMRC provided the logistical support, equipment, and training to conduct the field work, and the Grand Canyon Youth provided the time and personnel to complete the field work. Two data

SCICEX: Submarine Arctic Science Program

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Submarine Arctic Science Program, SCICEX, is a federal interagency collaboration among the operational Navy, research agencies, and the marine research community...

Strategic guidelines for street canyon geometry to achieve sustainable street air quality

Energy Technology Data Exchange (ETDEWEB)

Chan, Andy T.; So, Ellen S.P.; Samad, Subash C. [Hong Kong Univ., Dept. of Mechanical Engineering, Hong Kong (China)

2001-08-01

This paper is concerned with the motion of air within the urban street canyon and is directed towards a deeper understanding of pollutant dispersion with respect to various simple canyon geometries and source positions. Taking into account the present days typical urban configurations, three principal flow regimes 'isolated roughness flow', 'skimming flow' and 'wake interference flow' (Boundary Layer Climates, 2nd edition, Methuen, London) and their corresponding pollutant dispersion characteristics are studied for various canopies aspect ratios, namely relative height (h{sub 2}/H{sub 1}), canyon height to width ratio (h/w) and canyon length to height ratio (l/h). A field-size canyon has been analysed through numerical simulations using the standard k-{sup {epsilon}} turbulence closure model. It is found that the pollutant transport and diffusion is strongly dependent upon the type of flow regime inside the canyon and exchange between canyon and the above roof air. Some rules of thumbs have been established to get urban canyon geometries for efficient dispersion of pollutants. (Author)

Meta-Analysis of Data from the Submarine Ventilation Doctrine Test Program

National Research Council Canada - National Science Library

Hoover, J

1998-01-01

.... The Submarine Ventilation Doctrine Test Program was developed to address submarine-specific issues regarding the use of ventilation systems to control smoke and heat movement, maintain habitability...

Displaying Uncertainty: A Comparison Between Submarine Subject Matter Experts

Science.gov (United States)

2007-03-01

known as the “submarine capital of the world” and is the home for many of the schools relating to the submarine service. The administering officer for...and Woods, D. D. (1988). Aiding Human Performance: I. Cognitive Analysis, Le Travail Humain 51(1), 39-64. Roth, E. M., Patterson, E. S., and Mumaw

Geologic map and upper Paleozoic stratigraphy of the Marble Canyon area, Cottonwood Canyon quadrangle, Death Valley National Park, Inyo County, California

Science.gov (United States)

Stone, Paul; Stevens, Calvin H.; Belasky, Paul; Montañez, Isabel P.; Martin, Lauren G.; Wardlaw, Bruce R.; Sandberg, Charles A.; Wan, Elmira; Olson, Holly A.; Priest, Susan S.

2014-01-01

This geologic map and pamphlet focus on the stratigraphy, depositional history, and paleogeographic significance of upper Paleozoic rocks exposed in the Marble Canyon area in Death Valley National Park, California. Bedrock exposed in this area is composed of Mississippian to lower Permian (Cisuralian) marine sedimentary rocks and the Jurassic Hunter Mountain Quartz Monzonite. These units are overlain by Tertiary and Quaternary nonmarine sedimentary deposits that include a previously unrecognized tuff to which we tentatively assign an age of late middle Miocene (~12 Ma) based on tephrochronologic analysis, in addition to the previously recognized Pliocene tuff of Mesquite Spring. Mississippian and Pennsylvanian rocks in the Marble Canyon area represent deposition on the western continental shelf of North America. Mississippian limestone units in the area (Tin Mountain, Stone Canyon, and Santa Rosa Hills Limestones) accumulated on the outer part of a broad carbonate platform that extended southwest across Nevada into east-central California. Carbonate sedimentation was interrupted by a major eustatic sea-level fall that has been interpreted to record the onset of late Paleozoic glaciation in southern Gondwana. Following a brief period of Late Mississippian clastic sedimentation (Indian Springs Formation), a rise in eustatic sea level led to establishment of a new carbonate platform that covered most of the area previously occupied by the Mississippian platform. The Pennsylvanian Bird Spring Formation at Marble Canyon makes up the outer platform component of ten third-order (1 to 5 m.y. duration) stratigraphic sequences recently defined for the regional platform succession. The regional paleogeography was fundamentally changed by major tectonic activity along the continental margin beginning in middle early Permian time. As a result, the Pennsylvanian carbonate shelf at Marble Canyon subsided and was disconformably overlain by lower Permian units (Osborne Canyon and

History of Military Psychology at the U. S. Naval Submarine Medical Research Laboratory

Science.gov (United States)

1979-10-23

the first nuclear submarine, were gigantic increases in the environmental demands imposed upon the submarine crewmembers. Some of these changes had to...urgency for an empirical determination of the maximum duration a submarine could remain submerged before debilitative symptoms appeared in significant

CODASC : a database for the validation of street canyon dispersion models

NARCIS (Netherlands)

Gromke, C.B.

2013-01-01

CODASC stands for Concentration Data of Street Canyons (CODASC 2008, www.codasc.de). It is a database which provides traffic pollutant concentrations in urban street canyons obtained from wind-tunnel dispersion experiments. CODASC comprises concentration data of street canyons with different aspect

Is Canyon Width a Diagnostic Indicator of the Discharge of Megafloods on Earth and Mars?

Science.gov (United States)

Lapotre, M. G.; Lamb, M. P.

2013-12-01

On Earth, large floods have carved steep-walled and amphitheater-headed canyons from the Pleistocene (e.g. Box Canyon, ID) through the Holocene (e.g. Asbyrgi Canyon, Iceland), to historic times (e.g. Canyon Lake Gorge, TX). The geologic record on Mars suggests that similar floods have carved canyons by waterfall retreat about 3.5 billion years ago, when the red planet was wetter and possibly warmer. We currently lack robust paleo-hydraulic tools to reconstruct the discharge of ancient floods, especially on Mars where sediment sizes are obscured from observation. To address this issue, we hypothesize that the width of canyon escarpment is controlled by the hydraulics of the canyon-carving flood due to focusing of the flood into the canyon head. We compiled field data from multiple canyons and floods on Earth and Mars and show that there is a correlation between estimated flood discharge and canyon headwall width. To explore what sets this relationship, we identified five important parameters using dimensional analysis: the Froude number, the ratio of backwater length to canyon length, the ratio of backwater length to flood width, the ratio of canyon width to flood width, and the topographic slope upstream of the canyon. We used the hydraulic numerical modeling suite ANUGA to simulate overland flow over different canyon geometries and flood parameters to systematically explore the relative bed shear stresses along the canyon rim as a metric for flow focusing. Results show that canyons that exceed a certain length, scaling with the hydraulic backwater length, have shear stresses at their heads that are significantly higher than near the canyon mouth. Shear stresses along the rim of the canyon sidewalls are limited, in comparison to stresses along the canyon head, when the flood width is of the order of the backwater length. Flow focusing only occurs for subcritical flow. Together, these results suggest that canyons may only grow from a perturbation that is large

Situation awareness measures for simulated submarine track management.

Science.gov (United States)

Loft, Shayne; Bowden, Vanessa; Braithwaite, Janelle; Morrell, Daniel B; Huf, Samuel; Durso, Francis T

2015-03-01

The aim of this study was to examine whether the Situation Present Assessment Method (SPAM) and the Situation Awareness Global Assessment Technique (SAGAT) predict incremental variance in performance on a simulated submarine track management task and to measure the potential disruptive effect of these situation awareness (SA) measures. Submarine track managers use various displays to localize and track contacts detected by own-ship sensors. The measurement of SA is crucial for designing effective submarine display interfaces and training programs. Participants monitored a tactical display and sonar bearing-history display to track the cumulative behaviors of contacts in relationship to own-ship position and landmarks. SPAM (or SAGAT) and the Air Traffic Workload Input Technique (ATWIT) were administered during each scenario, and the NASA Task Load Index (NASA-TLX) and Situation Awareness Rating Technique were administered postscenario. SPAM and SAGAT predicted variance in performance after controlling for subjective measures of SA and workload, and SA for past information was a stronger predictor than SA for current/future information. The NASA-TLX predicted performance on some tasks. Only SAGAT predicted variance in performance on all three tasks but marginally increased subjective workload. SPAM, SAGAT, and the NASA-TLX can predict unique variance in submarine track management performance. SAGAT marginally increased subjective workload, but this increase did not lead to any performance decrement. Defense researchers have identified SPAM as an alternative to SAGAT because it would not require field exercises involving submarines to be paused. SPAM was not disruptive, but it is potentially problematic that SPAM did not predict variance in all three performance tasks. © 2014, Human Factors and Ergonomics Society.

Risk factors for dermatitis in submariners during a submerged patrol: an observational cohort study.

Science.gov (United States)

Flaxman, Amy; Allen, Elizabeth; Lindemann, Claudia; Yamaguchi, Yuko; O'Shea, Matthew K; Fallowfield, Joanne L; Lindsay, Michael; Gunner, Frances; Knox, Kyle; Wyllie, David H

2016-06-02

The aim of this pilot study was to determine risk factors, including Staphylococcus aureus nasal carriage, for dermatitis in submariners during a submarine patrol. 36 submariners undertaking a submerged 6-week patrol participated in the study. Severity of dermatitis and its impact was assessed using visual analogue scales and questionnaires at baseline and weekly throughout the patrol. S. aureus carriage levels in submariners were determined by nasal swabbing at baseline and shortly before disembarking the submarine. Occurrence of any skin or soft tissue infections (SSTI) were reported to the medical officer and swabs of the area were taken for subsequent analysis. S. aureus carriers were significantly more likely than non-carriers to have previously received treatment for a cutaneous abscess (39% vs 5%, OR=13 (95% CI 1.3 to 130)) with a trend to being submariners longer (p=0.051). Skin scores at baseline and on patrol were not significantly associated with carriage status. Higher dermatitis scores were observed in those who had been submariners longer (p=0.045). Smoking and allergies were not found to be linked to carriage status or skin health score in this cohort. This small pilot study investigates S. aureus carriage status and skin health in submariners. Length of submarine service but not S. aureus carriage was identified as a risk factor for worsening skin health in this small cohort during a 6-week patrol. This does not support S. aureus decolonisation to improve skin health in this population. Further investigation into causes of dermatitis in submariners is required. This data supports a better understanding of the potential impact of exposure to environmental factors that could affect skin health in submariners. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Late-stage development of the Bryant Canyon turbidite pathway on the Louisiana continental slope

Science.gov (United States)

Twichell, David C.; Nelson, Hans; Damuth, John E.

2000-01-01

GLORIA sidescan imagery, multibeam bathymetry, seismic profiles, and piston cores (3–5 m penetration) reveal the near-surface geology of the Bryant Canyon turbidite pathway on the continental margin of Louisiana. This pathway extends from the continental shelf edge, across the continental slope, to a deep-sea fan on the continental rise. The pathway is narrow (thalweg no longer has a continuous down-slope gradient. Some mini-basin floors along the pathway are now more than 500 m deeper than their basin’s spill point. We propose a 6-stage conceptual model to explain our observations for the evolution of a mini-basin along this turbidite pathway. In this model, an active channel feeds sand to a mini-basin (Stabe B). Once the mini-basin is filled, the sand deposit is entrenched by a bypass channel (Stage C). When the turbidite system shuts off, salt migration oversteepens the mini-basin walls (Stage D) which collapse and create a layer of mass-transport deposits on the mini-basin floor (Stage E). The depositional succession is capped by a layer of highstand hemipelagic drape (Stage F). The Bryant Canyon turbidite pathway provides a recent example of a large turbidite pathway in the Gulf of Mexico that crosses an area of active salt tectonics thus providing a conceptual model for older systems in similar settings. In Bryant Canyon, thick turbidite sands presumably are found in mini-basins however, they are sealed by thick, fine-grained, mass-transport deposits which terminate mini-basin turbidite deposition cycles. The importance of mass-transport deposits in basins along this turbidite pathway is in startling contrast to the Trinity-Brazos pathway whose shallow subsurface expression is virtually free of mass-transport deposits and has undergone minimal deformation by salt movement.

Submarines, spacecraft and exhaled breath.

Science.gov (United States)

Pleil, Joachim D; Hansel, Armin

2012-03-01

Foreword The International Association of Breath Research (IABR) meetings are an eclectic gathering of researchers in the medical, environmental and instrumentation fields; our focus is on human health as assessed by the measurement and interpretation of trace chemicals in human exhaled breath. What may have escaped our notice is a complementary field of research that explores the creation and maintenance of artificial atmospheres practised by the submarine air monitoring and air purification (SAMAP) community. SAMAP is comprised of manufacturers, researchers and medical professionals dealing with the engineering and instrumentation to support human life in submarines and spacecraft (including shuttlecraft and manned rockets, high-altitude aircraft, and the International Space Station (ISS)). Here, the immediate concerns are short-term survival and long-term health in fairly confined environments where one cannot simply 'open the window' for fresh air. As such, one of the main concerns is air monitoring and the main sources of contamination are CO(2) and other constituents of human exhaled breath. Since the inaugural meeting in 1994 in Adelaide, Australia, SAMAP meetings have been held every two or three years alternating between the North American and European continents. The meetings are organized by Dr Wally Mazurek (a member of IABR) of the Defense Systems Technology Organization (DSTO) of Australia, and individual meetings are co-hosted by the navies of the countries in which they are held. An overriding focus at SAMAP is life support (oxygen availability and carbon dioxide removal). Certainly, other air constituents are also important; for example, the closed environment of a submarine or the ISS can build up contaminants from consumer products, cooking, refrigeration, accidental fires, propulsion and atmosphere maintenance. However, the most immediate concern is sustaining human metabolism: removing exhaled CO(2) and replacing metabolized O(2). Another

An Air Quality Assessment Onboard an Oberon Class Submarine: HMCS Okanagan

National Research Council Canada - National Science Library

Severs, Y

2000-01-01

... submarine to determine if the atmosphere complied with Air Purification Standard BR 1326. The objective of the study was to obtain information to assist in developing plans for future submarine air quality management...

An air quality assessment onboard an Oberon class submarine : HMCS Okanagan

International Nuclear Information System (INIS)

Severs, Y.D.; Sabiston, B.H.

2000-09-01

The Defence and Civil Institute of Environmental Medicine (DCIEM) re-examined the air quality on an Oberon class submarine, the HMCS Okanagan, to determine if the atmosphere complied with Air Purification Standard BR 1326. The main objective of the assessment was to help in the development of future submarine air quality management. The information obtained from the Oberon class submarine could be readily applied to the Victoria class submarines. The assessment involved a trial aboard an Oberon under patrol conditions. The functional and detection capabilities of analytical air monitoring instruments were assessed for a 24-hour period to obtain data regarding the contaminants onboard the submarine. A profile of carbon dioxide accumulation and oxygen consumption was determined. This was followed by an assessment of the effectiveness of air purification such as carbon dioxide scrubbing, oxygen generation and snorting. Carbon monoxide was also monitored and carboxyhemoglobin was measured in both smokers and non-smokers. In order to determine if the sanitary or electrical systems, or engine exhaust posed any danger, ammonia, ozone and nitrous compounds were also measured. In addition, hydrogen, arsine and stibene were monitored to determine any possible danger from charging batteries. The health risks associated with aerosolized particles from cooking, smoking and exhaust gases were also measured. Results showed that all contaminants were within allowable limits. However, the study also confirmed that air purification measures on diesel submarines are minimal and poorly placed and that there is a lack of exhaust ventilation. Poor air exchange was worsened by compartmentalization and blackout curtains. Several recommendations were proposed to improve the management of air quality in Victoria class submarines. 18 refs., 2 tabs., 5 figs

An air quality assessment onboard an Oberon class submarine : HMCS Okanagan

Energy Technology Data Exchange (ETDEWEB)

Severs, Y.D.; Sabiston, B.H.

2000-09-01

The Defence and Civil Institute of Environmental Medicine (DCIEM) re-examined the air quality on an Oberon class submarine, the HMCS Okanagan, to determine if the atmosphere complied with Air Purification Standard BR 1326. The main objective of the assessment was to help in the development of future submarine air quality management. The information obtained from the Oberon class submarine could be readily applied to the Victoria class submarines. The assessment involved a trial aboard an Oberon under patrol conditions. The functional and detection capabilities of analytical air monitoring instruments were assessed for a 24-hour period to obtain data regarding the contaminants onboard the submarine. A profile of carbon dioxide accumulation and oxygen consumption was determined. This was followed by an assessment of the effectiveness of air purification such as carbon dioxide scrubbing, oxygen generation and snorting. Carbon monoxide was also monitored and carboxyhemoglobin was measured in both smokers and non-smokers. In order to determine if the sanitary or electrical systems, or engine exhaust posed any danger, ammonia, ozone and nitrous compounds were also measured. In addition, hydrogen, arsine and stibene were monitored to determine any possible danger from charging batteries. The health risks associated with aerosolized particles from cooking, smoking and exhaust gases were also measured. Results showed that all contaminants were within allowable limits. However, the study also confirmed that air purification measures on diesel submarines are minimal and poorly placed and that there is a lack of exhaust ventilation. Poor air exchange was worsened by compartmentalization and blackout curtains. Several recommendations were proposed to improve the management of air quality in Victoria class submarines. 18 refs., 2 tabs., 5 figs.

Exploration of submarine wake and powering performance using CFD method

International Nuclear Information System (INIS)

Huizhi, Y.; Hongcui, S.; Nan, Z.; Renyou, Y.; Liangmei, Y.

2005-01-01

In response to the needs of better design and less time, Computational Fluid Dynamic(CFD) methods have become an impartible part in the ship design, especially in the earlier design phases. In this paper FLUENT software was used to predict the wake character and powering performance of submarine at model scale. By an effective combination of the block topology, grid, turbulence model and validation, the simulation scheme was developed and applied to the predictions of multiple designs and optimizations of the earlier submarine design iterations. The incompressible RANS equations with different turbulence models were solved. To handle the block interface between the propeller and submarine stern, sliding girds in multiple blocks were employed, unstructural grids were used in the block around the propeller. Submarine with/without stator and/or propeller were studied. The flow feature, forces and powering performance at various conditions were calculated. The results were compared with experimental data, and a good agreement was obtained. (author)

2014/2015 Investigations of the Ontong Java and Kerguelen Plateaus

Science.gov (United States)

Coffin, M. F.; Whittaker, J. M.

2013-12-01

The two largest oceanic plateaus, Ontong Java in the western Pacific, and Kerguelen in the southern Indian Ocean, will be the focus of scheduled multidisciplinary/interdisciplinary shipboard expeditions in 2014 and 2015. In mid-2014, scientists aboard the Schmidt Ocean Institute's RV Falkor will investigate the origin and evolution of two large atolls, Ontong Java and Nukumanu, surmounting the ca 122 Ma Ontong Java Plateau, as well how Kroenke Canyon, which deeply incises the plateau, formed and evolved. First-ever multibeam bathymetry and sub-bottom profiling data from the atolls and canyon will reveal their submarine and shallow sub-seafloor morphology, and, if combined with geochemical and geochronological analyses of potential igneous basement samples, will yield important information on their origin and evolution. The primary goals of this atoll and canyon project are: to test potential genetic relationships between a) the atolls and the OJP, and b) the atolls and Kroenke Canyon; to understand and model how atolls and canyons form and evolve on oceanic plateaus, isolated from terrestrial influences and subject to sea level fluctuations; and to contribute to understanding tsunami risk on low-lying atolls. In late 2014 and early 2015, researchers aboard Australia's new Marine National Facility, RV Investigator, will investigate active submarine hotspot volcanism on the Kerguelen Plateau and its consequences. The project's overall aim is to test the hypothesis that hydrothermal activity driven by active submarine magmatism fertilizes surface waters with iron that enhances primary biological productivity. Surmounting the Cretaceous plateau, Heard and McDonald Islands are among the world's most active hotspot volcanoes, and new multibeam bathymetry and sub-bottom profiling data will enable identification of candidate active submarine volcanoes, which we will sample. In the overlying water column, we will collect samples to test for the presence or absence of

Canyon formation constraints on the discharge of catastrophic outburst floods of Earth and Mars

Science.gov (United States)

Lapotre, Mathieu G. A.; Lamb, Michael P.; Williams, Rebecca M. E.

2016-07-01

Catastrophic outburst floods carved amphitheater-headed canyons on Earth and Mars, and the steep headwalls of these canyons suggest that some formed by upstream headwall propagation through waterfall erosion processes. Because topography evolves in concert with water flow during canyon erosion, we suggest that bedrock canyon morphology preserves hydraulic information about canyon-forming floods. In particular, we propose that for a canyon to form with a roughly uniform width by upstream headwall retreat, erosion must occur around the canyon head, but not along the sidewalls, such that canyon width is related to flood discharge. We develop a new theory for bedrock canyon formation by megafloods based on flow convergence of large outburst floods toward a horseshoe-shaped waterfall. The model is developed for waterfall erosion by rock toppling, a candidate erosion mechanism in well fractured rock, like columnar basalt. We apply the model to 14 terrestrial (Channeled Scablands, Washington; Snake River Plain, Idaho; and Ásbyrgi canyon, Iceland) and nine Martian (near Ares Vallis and Echus Chasma) bedrock canyons and show that predicted flood discharges are nearly 3 orders of magnitude less than previously estimated, and predicted flood durations are longer than previously estimated, from less than a day to a few months. Results also show a positive correlation between flood discharge per unit width and canyon width, which supports our hypothesis that canyon width is set in part by flood discharge. Despite lower discharges than previously estimated, the flood volumes remain large enough for individual outburst floods to have perturbed the global hydrology of Mars.

Fuel-cell-propelled submarine-tanker-system study

International Nuclear Information System (INIS)

Court, K.E.; Kumm, W.H.; O'Callaghan, J.E.

1982-06-01

This report provides a systems analysis of a commercial Arctic Ocean submarine tanker system to carry fossil energy to markets. The submarine is to be propelled by a modular Phosphoric Acid Fuel Cell system. The power level is 20 Megawatts. The DOE developed electric utility type fuel cell will be fueled with methanol. Oxidant will be provided from a liquid oxygen tank carried onboard. The twin screw submarine tanker design is sized at 165,000 deadweight tons and the study includes costs and an economic analysis of the transport system of 6 ships. The route will be under the polar icecap from a loading terminal located off Prudhoe Bay, Alaska to a transshipment facility postulated to be in a Norwegian fjord. The system throughput of the gas-fed methanol cargo will be 450,000 barrels per day. The total delivered cost of the methanol including well head purchase price of natural gas, methanol production, and shipping would be $25/bbl from Alaska to the US East Coast. Of this, the shipping cost is $6.80/bbl. All costs in 1981 dollars

Formation of submarine gas hydrates

Energy Technology Data Exchange (ETDEWEB)

Soloviev, V.; Ginsburg, G.D. (Reserch Institute of Geology and Mineral Resources of the Ocean ' ' VNII Okeangeologia' ' , St. Petersburg (Russian Federation))

1994-03-01

Submarine gas hydrates have been discoverd in the course of deep-sea drilling (DSDP and ODP) and bottom sampling in many offshore regions. This paper reports on expeditions carried out in the Black, Caspian and Okhotsk Seas. Gas hydrate accumulations were discovered and investigated in all these areas. The data and an analysis of the results of the deep-sea drilling programme suggest that the infiltration of gas-bearing fluids is a necessary condition for gas hydrate accumulation. This is confirmed by geological observations at three scale levels. Firstly, hydrates in cores are usually associated with comparatively coarse-grained, permeable sediments as well as voids and fractures. Secondly, hydrate accumulations are controlled by permeable geological structures, i.e. faults, diapirs, mud volcanos as well as layered sequences. Thirdly, in the worldwide scale, hydrate accumulations are characteristic of continental slopes and rises and intra-continental seas where submarine seepages also are widespread. Both biogenic and catagenic gas may occur, and the gas sources may be located at various distances from the accumulation. Gas hydrates presumably originate from water-dissolved gas. The possibility of a transition from dissolved gas into hydrate is confirmed by experimental data. Shallow gas hydrate accumulations associated with gas-bearing fluid plumes are the most convenient features for the study of submarine hydrate formation in general. These accumulations are known from the Black, Caspian and Okhotsk Seas, the Gulf of Mexico and off northern California. (au) (24 refs.)

Red Rock Canyon National Conservation Area Transportation Feasibility Study

Science.gov (United States)

2012-07-31

Red Rock Canyon National Conservation Area is a popular Bureau of Land Management natural area located near Las Vegas, Nevada. Red Rock Canyon experiences heavy congestion on its Scenic Drive and associated parking areas, due to high volumes of visit...

Environmental analysis of Lower Pueblo/Lower Los Alamos Canyon, Los Alamos, New Mexico

International Nuclear Information System (INIS)

Ferenbaugh, R.W.; Buhl, T.E.; Stoker, A.K.; Becker, N.M.; Rodgers, J.C.; Hansen, W.R.

1994-12-01

The radiological survey of the former radioactive waste treatment plant site (TA-45), Acid Canyon, Pueblo Canyon, and Los Alamos Canyon found residual contamination at the site itself and in the channel and banks of Acid, Pueblo, and lower Los Alamos Canyons all the way to the Rio Grande. The largest reservoir of residual radioactivity is in lower Pueblo Canyon, which is on DOE property. However, residual radioactivity does not exceed proposed cleanup criteria in either lower Pueblo or lower Los Alamos Canyons. The three alternatives proposed are (1) to take no action, (2) to construct a sediment trap in lower Pueblo Canyon to prevent further transport of residual radioactivity onto San Ildefonso Indian Pueblo land, and (3) to clean the residual radioactivity from the canyon system. Alternative 2, to cleanup the canyon system, is rejected as a viable alternative. Thousands of truckloads of sediment would have to be removed and disposed of, and this effort is unwarranted by the low levels of contamination present. Residual radioactivity levels, under either present conditions or projected future conditions, will not result in significant radiation doses to persons exposed. Modeling efforts show that future transport activity will not result in any residual radioactivity concentrations higher than those already existing. Thus, although construction of a sediment trap in lower Pueblo Canyon is a viable alternative, this effort also is unwarranted, and the no-action alternative is the preferred alternative

Environmental analysis of Lower Pueblo/Lower Los Alamos Canyon, Los Alamos, New Mexico

Energy Technology Data Exchange (ETDEWEB)

Ferenbaugh, R.W.; Buhl, T.E.; Stoker, A.K.; Becker, N.M.; Rodgers, J.C.; Hansen, W.R.

1994-12-01

The radiological survey of the former radioactive waste treatment plant site (TA-45), Acid Canyon, Pueblo Canyon, and Los Alamos Canyon found residual contamination at the site itself and in the channel and banks of Acid, Pueblo, and lower Los Alamos Canyons all the way to the Rio Grande. The largest reservoir of residual radioactivity is in lower Pueblo Canyon, which is on DOE property. However, residual radioactivity does not exceed proposed cleanup criteria in either lower Pueblo or lower Los Alamos Canyons. The three alternatives proposed are (1) to take no action, (2) to construct a sediment trap in lower Pueblo Canyon to prevent further transport of residual radioactivity onto San Ildefonso Indian Pueblo land, and (3) to clean the residual radioactivity from the canyon system. Alternative 2, to cleanup the canyon system, is rejected as a viable alternative. Thousands of truckloads of sediment would have to be removed and disposed of, and this effort is unwarranted by the low levels of contamination present. Residual radioactivity levels, under either present conditions or projected future conditions, will not result in significant radiation doses to persons exposed. Modeling efforts show that future transport activity will not result in any residual radioactivity concentrations higher than those already existing. Thus, although construction of a sediment trap in lower Pueblo Canyon is a viable alternative, this effort also is unwarranted, and the no-action alternative is the preferred alternative.

Submarine landslides: advances and challenges

Science.gov (United States)

Locat, Jacques; Lee, Homa J.

2002-01-01

Due to the recent development of well-integrated surveying techniques of the sea floor, significant improvements were achieved in mapping and describing the morphology and architecture of submarine mass movements. Except for the occurrence of turbidity currents, the aquatic environment (marine and fresh water) experiences the same type of mass failure as that found on land. Submarine mass movements, however, can have run-out distances in excess of 100 km, so their impact on any offshore activity needs to be integrated over a wide area. This great mobility of submarinemass movements is still not very well understood, particularly for cases like the far-reaching debris flows mapped on the Mississippi Fan and the large submarine rock avalanches found around many volcanic islands. A major challenge ahead is the integration of mass movement mechanics in an appropriate evaluation of the hazard so that proper risk assessment methodologies can be developed and implemented for various human activities offshore, including the development of natural resources and the establishment of reliable communication corridors. Key words : submarine slides, hazards, risk assessment, morphology, mobility, tsunami. Le dveloppement rcent de techniques de levs hydrograhiques pour les fonds marins nous a permis d'atteindre une qualit ingale dans la cartographie et la description des glissements sous marins. l'exception des courants de turbidit, on retrouve dans le domaine aquatique les mmes types de mouvements de terrain que sur terre. Par contre, les glissements sous-marins peuvent atteindre des distances excdant 100 km de telle sorte que leur impact sur les activits offshore doit tre pris en compte sur degrandes tendues. La grande mobilit des glissements sous-marins n'est pas encore bien comprise, comme pour le cas des coules dedbris cartographies sur le cne du Mississippi ainsi que pour les grandes avalanches rocheuses sous-marines retrouves au pourtour des les volcaniques. Un dfi majeur

Airborne Radar Search for Diesel Submarines

National Research Council Canada - National Science Library

Pilnick, Steven E; Landa, Jose

2005-01-01

.... In this research, a detection rate model is developed to analyze the effectiveness of airborne radar search for a diesel submarine assumed to be intermittently operating with periscopes or masts...

On the escape of pollutants from urban street canyons

Energy Technology Data Exchange (ETDEWEB)

Baik, J.J.; Kim, J.J. [Kwangju Inst. of Science and Technology (Korea). Dept. of Environmental Science and Engineering

2002-07-01

Pollutant transport from urban street canyons is numerically investigated using a two-dimensional flow and dispersion model. The ambient wind blows perpendicular to the street and passive pollutants are released at the street level. Results from the control experiment with a street aspect ratio of 1 show that at the roof level of the street canyon, the vertical turbulent flux of pollutants is upward everywhere and the vertical flux of pollutants by mean flow is upward or downward. The horizontally integrated vertical flux of pollutants by mean flow at the roof level of the street canyon is downward and its magnitude is much smaller than that by turbulent process. These results indicate that pollutants escape from the street canyon mainly by turbulent process and that the net effect of mean flow is to make some escaped pollutants reenter the street canyon. Further experiments with different inflow turbulence intensities, inflow wind speeds, and street aspect ratio confirm the findings from the control experiment. In the case of two isolated buildings, the horizontally integrated vertical flux of pollutants by mean flow is upward due to flow separation but the other main results are the same as those from the control experiment. (author)

Study on the locational criteria for submarine rock repositories of low and medium level radioactive wastes

Energy Technology Data Exchange (ETDEWEB)

Kim, G H; Kang, W J; Kim, T J. and others [Chungnam National Univ., Taejon (Korea, Republic of)

1992-01-15

Submarine repositories have significant advantages over their land counterparts locating close to the areas of daily human activities. Consequently, the construction of submarine repositories on the vast continental shelves around Korean seas is considered to be highly positive. In this context, the development of locational criteria primarily targeting the safety of submarine rock repositories is very important.The contents of the present study are: analyzing characteristics of marine environment: Search of potential hazards to, and environmental impact by, the submarine repositories; Investigation of the oceanographic, geochemical, ecological and sedimentological characteristics of estuaries and coastal seas. Locating potential hazards to submarine repositories by: Bibliographical search of accidents leading to the destruction of submarine structures by turbidity currents and other potentials; Review of turbidity currents. Consideration of environmental impact caused by submarine repositories: Logistics to minimize the environmental impacts in site selection; Removal and dispersion processes of radionuclides in sea water. Analyses of oceanographical characteristics of, and hazard potentials in, the Korean seas. Evaluation of the MOST 91-7 criteria for applicability to submarine repositories and the subsequent proposition of additional criteria.

Study on the locational criteria for submarine rock repositories of low and medium level radioactive wastes

International Nuclear Information System (INIS)

Kim, G. H.; Kang, W. J.; Kim, T. J. and others

1992-01-01

Submarine repositories have significant advantages over their land counterparts locating close to the areas of daily human activities. Consequently, the construction of submarine repositories on the vast continental shelves around Korean seas is considered to be highly positive. In this context, the development of locational criteria primarily targeting the safety of submarine rock repositories is very important.The contents of the present study are: analyzing characteristics of marine environment: Search of potential hazards to, and environmental impact by, the submarine repositories; Investigation of the oceanographic, geochemical, ecological and sedimentological characteristics of estuaries and coastal seas. Locating potential hazards to submarine repositories by: Bibliographical search of accidents leading to the destruction of submarine structures by turbidity currents and other potentials; Review of turbidity currents. Consideration of environmental impact caused by submarine repositories: Logistics to minimize the environmental impacts in site selection; Removal and dispersion processes of radionuclides in sea water. Analyses of oceanographical characteristics of, and hazard potentials in, the Korean seas. Evaluation of the MOST 91-7 criteria for applicability to submarine repositories and the subsequent proposition of additional criteria

Observations of nearshore groundwater discharge: Kahekili Beach Park submarine springs, Maui, Hawaii

Science.gov (United States)

Swarzenski, Peter W.; Dulai, H.; Kroeger, K.D.; Smith, C.G.; Dimova, N.; Storlazzi, C. D.; Prouty, N.G.; Gingerich, S.B.; Glenn, C. R.

2016-01-01

Study regionThe study region encompasses the nearshore, coastal waters off west Maui, Hawaii. Here abundant groundwater—that carries with it a strong land-based fingerprint—discharges into the coastal waters and over a coral reef.Study focusCoastal groundwater discharge is a ubiquitous hydrologic feature that has been shown to impact nearshore ecosystems and material budgets. A unique combined geochemical tracer and oceanographic time-series study addressed rates and oceanic forcings of submarine groundwater discharge at a submarine spring site off west Maui, Hawaii.New hydrological insights for the regionEstimates of submarine groundwater discharge were derived for a primary vent site and surrounding coastal waters off west Maui, Hawaii using an excess 222Rn (t1/2 = 3.8 d) mass balance model. Such estimates were complemented with a novel thoron (220Rn,t1/2 = 56 s) groundwater discharge tracer application, as well as oceanographic time series and thermal infrared imagery analyses. In combination, this suite of techniques provides new insight into the connectivity of the coastal aquifer with the near-shore ocean and examines the physical drivers of submarine groundwater discharge. Lastly, submarine groundwater discharge derived constituent concentrations were tabulated and compared to surrounding seawater concentrations. Such work has implications for the management of coastal aquifers and downstream nearshore ecosystems that respond to sustained constituent loadings via this submarine route.

Indian, Japanese, And U.S. Responses To Chinese Submarine Modernization

Science.gov (United States)

2016-03-01

NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public release; distribution is unlimited INDIAN, JAPANESE ...DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE INDIAN, JAPANESE , AND U.S. RESPONSES TO CHINESE SUBMARINE MODERNIZATION 5. FUNDING NUMBERS 6...is unlimited INDIAN, JAPANESE , AND U.S. RESPONSES TO CHINESE SUBMARINE MODERNIZATION David E. Kiser Lieutenant Commander, United States

Exploring the submarine Graham Bank in the Sicily Channel

Directory of Open Access Journals (Sweden)

Mauro Coltelli

2016-05-01

Full Text Available In the Sicily Channel, volcanic activity has been concentrated mainly on the Pantelleria and Linosa islands, while minor submarine volcanism took place in the Adventure, Graham and Nameless banks. The volcanic activity spanned mostly during Plio-Pleistocene, however, historical submarine eruptions occurred in 1831 on the Graham Bank and in 1891 offshore Pantelleria Island. On the Graham Bank, 25 miles SW of Sciacca, the 1831 eruption formed the short-lived Ferdinandea Island that represents the only Italian volcano active in historical times currently almost completely unknown and not yet monitored. Moreover, most of the Sicily Channel seismicity is concentrated along a broad NS belt extending from the Graham Bank to Lampedusa Island. In 2012, the Istituto Nazionale di Geofisica e Vulcanologia (INGV carried out a multidisciplinary oceanographic cruise, named “Ferdinandea 2012”, the preliminary results of which represent the aim of this paper. The cruise goal was the mapping of the morpho-structural features of some submarine volcanic centres located in the northwestern side of the Sicily Channel and the temporary recording of their seismic and degassing activity. During the cruise, three OBS/Hs (ocean bottom seismometer with hydrophone were deployed near the Graham, Nerita and Terribile submarine banks. During the following 9 months they have recorded several seismo-acoustic signals produced by both tectonic and volcanic sources. A high-resolution bathymetric survey was achieved on the Graham Bank and on the surrounding submarine volcanic centres. A widespread and voluminous gas bubbles emission was observed by both multibeam sonar echoes and a ROV (remotely operated vehicle along the NW side of the Graham Bank, where gas and seafloor samples were also collected.

Hydraulics of outburst floods spilling over a steep-walled canyon: Implications for paleo-discharges on Mars

Science.gov (United States)

Lapotre, Mathieu; Lamb, Michael

2013-04-01

Canyons carved by outburst floods are common landforms on Earth and Mars. These canyons are generally found in fractured basalts and jointed sedimentary rocks. Flood-carved canyons commonly have steep headwalls and a roughly constant width, and are often thought to have formed from upstream headwall propagation due to waterfall erosion. Because morphology is readily available from satellite imagery, these canyons offer a unique opportunity to quantify the discharge of rare, catastrophic paleo-floods on Earth and Mars. However, mechanistic relationships that relate canyon size to flood discharge have yet to be developed. We propose that the width of a canyon headwall in fractured rock is set by the spatial distribution of erosion around the rim of the canyon, which is controlled by the distribution of shear stresses induced by the overflowing water as it is focused into the canyon head. We test this hypothesis by performing a series of numerical simulations of flood-water focusing using ANUGA Hydro, a 2D-depth averaged, fully turbulent, hydraulic numerical modeling suite allowing for Froude-number transitions. The numerical simulations were designed to explore five dimensionless variables: the aspect ratio of the canyon (length normalized by width), the canyon width to flood-water width ratio, the canyon width to normal-flow depth ratio, the Froude number, and the topographic gradient upstream of the canyon. Preliminary results show that flow focusing leads to increased shear stresses at the canyon head compared to the sides of the canyon for subcritical floods and higher canyon aspect ratios. This suggests that proto-canyons start growing from a topographic defect in all directions until they reach a critical length for the side walls to dry. Once this critical length is attained, canyons focus most of the flood waters into their heads, and propagate upstream only, maintaining roughly constant widths. Preliminary results suggest that canyon width may be used to

Regional economic impacts of Grand Canyon river runners.

Science.gov (United States)

Hjerpe, Evan E; Kim, Yeon-Su

2007-10-01

Economic impact analysis (EIA) of outdoor recreation can provide critical social information concerning the utilization of natural resources. Outdoor recreation and other non-consumptive uses of resources are viewed as environmentally friendly alternatives to extractive-type industries. While outdoor recreation can be an appropriate use of resources, it generates both beneficial and adverse socioeconomic impacts on rural communities. The authors used EIA to assess the regional economic impacts of rafting in Grand Canyon National Park. The Grand Canyon region of northern Arizona represents a rural US economy that is highly dependent upon tourism and recreational expenditures. The purpose of this research is twofold. The first is to ascertain the previously unknown regional economic impacts of Grand Canyon river runners. The second purpose is to examine attributes of these economic impacts in terms of regional multipliers, leakage, and types of employment created. Most of the literature on economic impacts of outdoor recreation has focused strictly on the positive economic impacts, failing to illuminate the coinciding adverse and constraining economic impacts. Examining the attributes of economic impacts can highlight deficiencies and constraints that limit the economic benefits of recreation and tourism. Regional expenditure information was obtained by surveying non-commercial boaters and commercial outfitters. The authors used IMPLAN input-output modeling to assess direct, indirect, and induced effects of Grand Canyon river runners. Multipliers were calculated for output, employment, and income. Over 22,000 people rafted on the Colorado River through Grand Canyon National Park in 2001, resulting in an estimated $21,100,000 of regional expenditures to the greater Grand Canyon economy. However, over 50% of all rafting-related expenditures were not captured by the regional economy and many of the jobs created by the rafting industry are lower-wage and seasonal. Policy

The Jurassic section along McElmo Canyon in southwestern Colorado

Science.gov (United States)

O'Sullivan, Robert B.

1997-01-01

In McElmo Canyon, Jurassic rocks are 1500-1600 ft thick. Lower Jurassic rocks of the Glen Canyon Group include (in ascending order) Wingate Sandstone, Kayenta Formation and Navajo Sandstone. Middle Jurassic rocks are represented by the San Rafael Group, which includes the Entrada Sandstone and overlying Wanakah Formation. Upper Jurassic rocks comprise the Junction Creek Sandstone overlain by the Morrison Formation. The Burro Canyon Formation, generally considered to be Lower Cretaceous, may be Late Jurassic in the McElmo Canyon area and is discussed with the Jurassic. The Upper Triassic Chinle Formation in the subsurface underlies, and the Upper Cretaceous Dakota Sandstone overlies, the Jurassic section. An unconformity is present at the base of the Glen Canyon Group (J-0), at the base of the San Rafael Group (J-2), and at the base of the Junction Creek Sandstone (J-5). Another unconformity of Cretaceous age is at the base of the Dakota Sandstone. Most of the Jurassic rocks consist of fluviatile, lacustrine and eolian deposits. The basal part of the Entrada Sandstone and the Wanakah Formation may be of marginal marine origin.

Big Canyon Creek Ecological Restoration Strategy.

Energy Technology Data Exchange (ETDEWEB)

Rasmussen, Lynn; Richardson, Shannon

2007-10-01

He-yey, Nez Perce for steelhead or rainbow trout (Oncorhynchus mykiss), are a culturally and ecologically significant resource within the Big Canyon Creek watershed; they are also part of the federally listed Snake River Basin Steelhead DPS. The majority of the Big Canyon Creek drainage is considered critical habitat for that DPS as well as for the federally listed Snake River fall chinook (Oncorhynchus tshawytscha) ESU. The Nez Perce Soil and Water Conservation District (District) and the Nez Perce Tribe Department of Fisheries Resources Management-Watershed (Tribe), in an effort to support the continued existence of these and other aquatic species, have developed this document to direct funding toward priority restoration projects in priority areas for the Big Canyon Creek watershed. In order to achieve this, the District and the Tribe: (1) Developed a working group and technical team composed of managers from a variety of stakeholders within the basin; (2) Established geographically distinct sub-watershed areas called Assessment Units (AUs); (3) Created a prioritization framework for the AUs and prioritized them; and (4) Developed treatment strategies to utilize within the prioritized AUs. Assessment Units were delineated by significant shifts in sampled juvenile O. mykiss (steelhead/rainbow trout) densities, which were found to fall at fish passage barriers. The prioritization framework considered four aspects critical to determining the relative importance of performing restoration in a certain area: density of critical fish species, physical condition of the AU, water quantity, and water quality. It was established, through vigorous data analysis within these four areas, that the geographic priority areas for restoration within the Big Canyon Creek watershed are Big Canyon Creek from stream km 45.5 to the headwaters, Little Canyon from km 15 to 30, the mainstem corridors of Big Canyon (mouth to 7km) and Little Canyon (mouth to 7km). The District and the Tribe

Detecting frontal ablation processes from direct observations of submarine terminus morphology

Science.gov (United States)

Fried, M.; Carroll, D.; Catania, G. A.; Sutherland, D. A.; Stearns, L. A.; Bartholomaus, T. C.; Shroyer, E.; Nash, J. D.

2017-12-01

Tidewater glacier termini couple glacier and ocean systems. Subglacial discharge emerging from the terminus produces buoyant plumes that modulate submarine melting, calving, fjord circulation and, in turn, changes in ice dynamics from back-stress perturbations. However, the absence of critical observational data at the ice-ocean interface limits plume and, by extension, melt models from incorporating realistic submarine terminus face morphologies and assessing their impact on terminus behavior at tidewater glaciers. Here we present a comprehensive inventory and characterization of submarine terminus face shapes from a side-looking, multibeam echo sounding campaign across Kangerdlugssuaq Sermerssua glacier, central-west Greenland. We combine these observations with in-situ measurements of ocean stratification and remotely sensed subglacial discharge, terminus positions, ice velocity, and ice surface datasets to infer the spectrum of processes sculpting the submarine terminus face. Subglacial discharge outlet locations are confirmed through observations of sediment plumes, localized melt-driven undercutting of the terminus face, and bathymetry of the adjacent seafloor. From our analysis, we differentiate terminus morphologies resulting from submarine melt and calving and assess the contribution of each process to the net frontal ablation budget. Finally, we constrain a plume model using direct observations of the submarine terminus face and conduit geometry. Plume model simulations demonstrate that the majority of discharge outlets are fed by small discharge fluxes, suggestive of a distributed subglacial hydrologic system. Outlets with the largest, concentrated discharge fluxes are morphologically unique and strongly control seasonal terminus position. At these locations, we show that the spatiotemporal pattern of terminus retreat is well correlated with time periods when local melt rate exceeds ice velocity.

Intrinsic controls on the range of volumes, morphologies, and dimensions of submarine lobes

Science.gov (United States)

Prélat, A.; Covault, J. A.; Hodgson, D. M.; Fildani, A.; Flint, S. S.

2010-12-01

Submarine lobe dimensions from six different systems are compared: 1) the exhumed Permian Fan 3 lobe complex of the Tanqua Karoo, South Africa; 2) the modern Amazon fan channel-mouth lobe complex, offshore Brazil; 3) a portion of the modern distal Zaïre fan, offshore Angola/Congo; 4) a Pleistocene fan of the Kutai basin, subsurface offshore Indonesia; 5) the modern Golo system, offshore east Corsica, France; and 6) a shallow subsurface lobe complex , offshore Nigeria. These six systems have significantly different source-to-sink configurations (shelf dimension and slope topography), sediment supply characteristics (available grain size range and supply rate), tectonic settings, (palaeo) latitude, and delivery systems. Despite these differences, lobe deposits share similar geometric and dimensional characteristics. Lobes are grouped into two distinct populations of geometries that can be related to basin floor topography. The first population corresponds to areally extensive but thin lobes (average width 14 km × length 35 km × thickness 12 m) that were deposited onto low relief basin floor areas. Examples of such systems include the Tanqua Karoo, the Amazon, and the Zaïre systems. The second population corresponds to areally smaller but thicker lobes (average width 5 km × length 8 km × thickness 30 m) that were deposited into settings with higher amplitude of relief, like in the Corsican trough, the Kutai basin, and offshore Nigeria. The two populations of lobe types, however, share similar volumes (a narrow range around 1 or 2 km 3), which suggests that there is a control to the total volume of sediment that individual lobes can reach before they shift to a new locus of deposition. This indicates that the extrinsic processes control the number of lobes deposited per unit time rather than their dimensions. Two alternative hypotheses are presented to explain the similarities in lobe volumes calculated from the six very different systems. The first states that

Marble Canyon spring sampling investigation

International Nuclear Information System (INIS)

McCulley, B.

1985-10-01

The Mississippian Leadville Limestone is the most permeable formation in the lower hydrostratigraphic unit underlying the salt beds of the Paradox Formation in Gibson Dome, Paradox Basin, Utah, which is being considered as a potential nuclear waste repository site. The closest downgradient outcrop of the Mississippian limestone is along the Colorado River in Marble Canyon, Arizona. This report describes the sampling and interpretation of springs in that area to assess the relative contribution of Gibson Dome-type Leadville Limestone ground water to that spring discharge. The high-volume (hundreds of liters per second or thousands of gallons per minute) springs discharging from fault zones in Marble Canyon are mixtures of water recharged west of the Colorado River on the Kaibab Plateau and east of the river in the Kaiparowits basin. No component of Gibson Dome-type Leadville Limestone ground water is evident in major and trace element chemistry or isotopic composition of the Marble Canyon Springs. A low-volume (0.3 liters per second or 5 gallons per minute) spring with some chemical and isotopic characteristics of Gibson Dome-type Leadville Limestone water diluted by Kaiparowits basin-type water issues from a travertine mound in the Bright Angel Shale on the Little Colorado River. However, the stable isotopic composition and bromide levels of that spring discharge, in addition to probable ground-water flow paths, contradict the dilution hypothesis

A local area network and information management system for a submarine overhaul facility

OpenAIRE

Bushmire, Jeffrey D

1990-01-01

A preliminary design of a local area network for a submarine overhaul facility is developed using System Engineering concepts. SOFLAN, the Submarine Overhaul Facility Local Area Network, is necessary to provide more timely and accurate information to submarine overhaul managers in order to decrease the overhaul time period and become more competitive. The network is a microcomputer based system following the Ethernet and IEEE 802.3 standards with a server .. client architecture. SOFLAN serves...

A submarine volcanic eruption leads to a novel microbial habitat.

Science.gov (United States)

Danovaro, Roberto; Canals, Miquel; Tangherlini, Michael; Dell'Anno, Antonio; Gambi, Cristina; Lastras, Galderic; Amblas, David; Sanchez-Vidal, Anna; Frigola, Jaime; Calafat, Antoni M; Pedrosa-Pàmies, Rut; Rivera, Jesus; Rayo, Xavier; Corinaldesi, Cinzia

2017-04-24

Submarine volcanic eruptions are major catastrophic events that allow investigation of the colonization mechanisms of newly formed seabed. We explored the seafloor after the eruption of the Tagoro submarine volcano off El Hierro Island, Canary Archipelago. Near the summit of the volcanic cone, at about 130 m depth, we found massive mats of long, white filaments that we named Venus's hair. Microscopic and molecular analyses revealed that these filaments are made of bacterial trichomes enveloped within a sheath and colonized by epibiotic bacteria. Metagenomic analyses of the filaments identified a new genus and species of the order Thiotrichales, Thiolava veneris. Venus's hair shows an unprecedented array of metabolic pathways, spanning from the exploitation of organic and inorganic carbon released by volcanic degassing to the uptake of sulfur and nitrogen compounds. This unique metabolic plasticity provides key competitive advantages for the colonization of the new habitat created by the submarine eruption. A specialized and highly diverse food web thrives on the complex three-dimensional habitat formed by these microorganisms, providing evidence that Venus's hair can drive the restart of biological systems after submarine volcanic eruptions.

B-Plant Canyon Ventilation Control System Description; FINAL

International Nuclear Information System (INIS)

MCDANIEL, K.S.

1999-01-01

Project W-059 installed a new B Plant Canyon Ventilation System. Monitoring and control of the system is implemented by the Canyon Ventilation Control System (CVCS). This document describes the CVCS system components which include a Programmable Logic Controller (PLC) coupled with an Operator Interface Unit (OIU) and application software. This document also includes an Alarm Index specifying the setpoints and technical basis for system analog and digital alarms

Rapid formation of a modern bedrock canyon by a single flood event

Science.gov (United States)

Lamb, Michael P.; Fonstad, Mark A.

2010-07-01

Deep river canyons are thought to form slowly over geological time (see, for example, ref. 1), cut by moderate flows that reoccur every few years. In contrast, some of the most spectacular canyons on Earth and Mars were probably carved rapidly during ancient megaflood events. Quantification of the flood discharge, duration and erosion mechanics that operated during such events is hampered because we lack modern analogues. Canyon Lake Gorge, Texas, was carved in 2002 during a single catastrophic flood. The event offers a rare opportunity to analyse canyon formation and test palaeo-hydraulic-reconstruction techniques under known topographic and hydraulic conditions. Here we use digital topographic models and visible/near-infrared aerial images from before and after the flood, discharge measured during the event, field measurements and sediment-transport modelling to show that the flood moved metre-sized boulders, excavated ~7m of limestone and transformed a soil-mantled valley into a bedrock canyon in just ~3days. We find that canyon morphology is strongly dependent on rock type: plucking of limestone blocks produced waterfalls, inner channels and bedrock strath terraces, whereas abrasion of cemented alluvium sculpted walls, plunge pools and streamlined islands. Canyon formation was so rapid that erosion might have been limited by the ability of the flow to transport sediment. We suggest that our results might improve hydraulic reconstructions of similar megafloods on Earth and Mars.

Implications of tree planting on pollutant dispersion in street canyons

NARCIS (Netherlands)

Gromke, C.B.; Ruck, B.

2009-01-01

Traffic pollutant dispersion processes inside urban street canyons with avenue-like tree planting have been studied in wind tunnel experiments. Tree planting of different crown porosities and their effects on the pollutant concentrations at the canyon walls have been investigated for wind

78 FR 21415 - Glen Canyon Dam Adaptive Management Work Group

Science.gov (United States)

2013-04-10

... DEPARTMENT OF THE INTERIOR Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group... Adaptive Management Work Group (AMWG) makes recommendations to the Secretary of the Interior concerning... Federal advisory committee, the AMWG, a technical work group, a Grand Canyon Monitoring and Research...

SUBMARINE LANDSLIDE AND LOCALIZED TSUNAMI POTENTIALITY OF MENTAWAI BASIN, SUMATRA, INDONESIA

Directory of Open Access Journals (Sweden)

Haryadi Permana

2017-07-01

Full Text Available The new bathymetry and seismic data were acquired during the PreTI-Gap marine survey (February 15 to March 6, 2008. The survey was carried out along the NE margin of Mentawai Island using multi-beam swath bathymetry equipment, and 28-channels seismic streamer and four-airgun source. The first target was the Mega Island region near the epicenter of the 2007 great earthquake. The shallow bathymetry is characterized as a flat coral platform suggesting that 200 km elongated plateau is slowly subsiding without any active faults. Further north, from South Pagai to North of Siberut Islands, the seafloor morphology changes significantly. The deep and wide canyons or valleys produce very rough seafloor morphology between 50 and 1100 m water. In general, the submarine topography shows two break slopes at different depths. Between slope breaks, the undulating, hilly and circular features dominate, possibly caused by landslides. A push-up ridge is observed that dams the sediments eroded within a steep slope northeastward side. The seismic reflection data acquired along 14 dip seismic lines at the NE flank of Mentawai Islands, from Siberut to the South of Pagai Islands. We observed a set of southwestward dipping back thrust bounding the NE margin of the Mentawai Island. Keywords: submarine landslide, tsunami, Mentawai basin, Sumatra. Data batimetri dan seismik baru telah dihasilkan selama survey kelautan PreTi-Gap (15 Februari hingga 6 Maret 2008. Survei dilaksanakan sepanjang tepian timurlaut P. Mentawai menggunakan peralatan multibeam, seismic saluran ganda 28 kanal dengan sumber energi airgun. Sasaran pertama adalah memetakan kawasan pulau dekat pusat gempa tahun 2007. Kenampakan batimetri dangkal dicirikan dengan adanya dataran terumbu karang yang secara perlahan mengalami penurunan tanpa aktifitas sesar. Lebih jauh ke Utar, dari Pagai Selatan ke utara P. Siberut, morfologi dasar laut memperlihatkan perubahan secara signifikan, dimana lembah dasar laut

Numerical Study of Traffic Pollutant Dispersion within Different Street Canyon Configurations

Directory of Open Access Journals (Sweden)

Yucong Miao

2014-01-01

Full Text Available The objective of this study is to numerically study flow and traffic exhaust dispersion in urban street canyons with different configurations to find out the urban-planning strategies to ease the air pollution. The Computational Fluid Dynamics (CFD model used in this study—Open Source Field Operation and Manipulation (OpenFOAM software package—was firstly validated against the wind-tunnel experiment data by using three different k-ε turbulence models. And then the patterns of flow and dispersion within three different kinds of street canyon configuration under the perpendicular approaching flow were numerically studied. The result showed that the width and height of building can dramatically affect the pollution level inside the street canyon. As the width or height of building increases, the pollution at the pedestrian level increases. And the asymmetric configuration (step-up or step-down street canyon could provide better ventilation. It is recommended to design a street canyon with nonuniform configurations. And the OpenFOAM software package can be used as a reliable tool to study flows and dispersions around buildings.

Hybrid Intelligent Control for Submarine Stabilization

Directory of Open Access Journals (Sweden)

Minghui Wang

2013-05-01

Full Text Available Abstract While sailing near the sea surface, submarines will often undergo rolling motion caused by wave disturbance. Fierce rolling motion seriously affects their normal operation and even threatens their security. We propose a new control method for roll stabilization. This paper studies hybrid intelligent control combining a fuzzy control, a neural network and extension control technology. Every control strategy can achieve the ideal control effect within the scope of its effective control. The neuro-fuzzy control strategy is used to improve the robustness of the controller. The speed control strategy and the course control strategy are conducted to extend the control range. The paper also proposes the design of the controller and carries out the simulation experiment in different sea conditions. The simulation results show that the control method proposed can indeed effectively improve the control performance of submarine stabilization.

The use of nuclear powered submarines for oceanographic research in ICE covered regions

International Nuclear Information System (INIS)

Sambrotto, Raymond; Chayes, Dale

2000-01-01

Nuclear powered submarines offer a variety of advantages as platforms for oceanographic research. Their speed and ability to remain submerged for extended periods greatly extends their spatial coverage and isolates them from surface ocean conditions as compared to conventional ships. These advantages are particularly obvious in ice covered oceans that remain among the least explored regions on the globe. Scientific research in these regions has been limited to selected seasons and places where ice conditions are favorable for available observational platforms. However, much broader scientific observations are needed to assess such impacts as pollutants and possible climate variations on polar regions. To overcome some of the observational limitations of surface ships in the Arctic, the U.S. Navy made available nuclear powered submarines for civilian oceanographic research during the Scientific Ice Expedition (Scicex) program from 1993 to 1999. Together, these cruises sampled along more than 85,000 km of track throughout the international waters of the Arctic Ocean during selected periods from March to October. This sampling forms the basis of the present analysis of the limitations and capabilities of nuclear submarines as observational platforms for scientific research. Scientific observations were made in four general disciplines: ocean physics; biology and chemistry; sea ice; and marine geology and geophysics. Sampling of ocean biology and chemistry was most constrained because the water samples typically required in such studies were limited to the operating depths of the submarine. However, the surface 250 m contains all of the biological production, as well as informative chemical tracers for the flow of Atlantic and Pacific water masses. Measurements of ocean physics were less constrained because in addition to the on-board measurements, expendable probes are available to sample water depths inaccessible to the submarine. The submarine proved to be an

Impact of aspect ratio and solar heating on street canyon air temperature

International Nuclear Information System (INIS)

Memon, R.A.; Lal, K.

2011-01-01

The results obtained from RNG (Re-Normalization Group) version of k-and turbulence model are reported in this study. The model is adopted to elucidate the impact of different building aspect ratios (i.e., ratio of building-height-to-street-canyon-width) and solar heating on temperatures in street canyon. The validation of Navier-Stokes and energy an sport equations showed that the model prediction for air-temperature and ambient wind provides reasonable accuracy. The model was applied on AR (Aspect Ratios) one to eight and surface temperature difference (delta and theta/sub s-a/)) of 2 -8. Notably, air-temperatures were higher in high AR street canyons in particular on the leeward side of the street canyon. Further investigation showed that the difference between the air-temperature 'high and low AR street canyons (AR) was positive and high with higher delta and theta/sub s-a/) conversely, the AR become negative and low gradually with lower values of delta and theta(/sub s-a/). These results could be very beneficial for the city and regional planners, civil engineers Id HVAC experts who design street canyons and strive for human thermal comfort with minimum possible energy requirements. (author)

78 FR 7810 - Glen Canyon Dam Adaptive Management Work Group

Science.gov (United States)

2013-02-04

... DEPARTMENT OF THE INTERIOR Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group... Adaptive Management Work Group (AMWG) makes recommendations to the Secretary of the Interior concerning..., the AMWG, a technical work group (TWG), a Grand Canyon Monitoring and Research Center, and independent...

76 FR 24516 - Glen Canyon Dam Adaptive Management Work Group

Science.gov (United States)

2011-05-02

... DEPARTMENT OF THE INTERIOR Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group... Adaptive Management Work Group (AMWG) makes recommendations to the Secretary of the Interior concerning..., the AMWG, a technical work group (TWG), a Grand Canyon Monitoring and Research Center, and independent...

Observations of nearshore groundwater discharge: Kahekili Beach Park submarine springs, Maui, Hawaii

Directory of Open Access Journals (Sweden)

P.W. Swarzenski

2017-06-01

New hydrological insights for the region: Estimates of submarine groundwater discharge were derived for a primary vent site and surrounding coastal waters off west Maui, Hawaii using an excess 222Rn (t1/2 = 3.8 d mass balance model. Such estimates were complemented with a novel thoron (220Rn, t1/2 = 56 s groundwater discharge tracer application, as well as oceanographic time series and thermal infrared imagery analyses. In combination, this suite of techniques provides new insight into the connectivity of the coastal aquifer with the near-shore ocean and examines the physical drivers of submarine groundwater discharge. Lastly, submarine groundwater discharge derived constituent concentrations were tabulated and compared to surrounding seawater concentrations. Such work has implications for the management of coastal aquifers and downstream nearshore ecosystems that respond to sustained constituent loadings via this submarine route.

Stability of submarine slopes in the northern South China Sea: a numerical approach

Science.gov (United States)

Zhang, Liang; Luan, Xiwu

2013-01-01

Submarine landslides occur frequently on most continental margins. They are effective mechanisms of sediment transfer but also a geological hazard to seafloor installations. In this paper, submarine slope stability is evaluated using a 2D limit equilibrium method. Considerations of slope, sediment, and triggering force on the factor of safety (FOS) were calculated in drained and undrained ( Φ=0) cases. Results show that submarine slopes are stable when the slope is 13° with earthquake peak ground acceleration (PGA) of 0.5 g; whereas with a weak layer, a PGA of 0.2 g could trigger instability at slopes >10°, and >3° for PGA of 0.5 g. The northern slope of the South China Sea is geomorphologically stable under static conditions. However, because of the possibility of high PGA at the eastern margin of the South China Sea, submarine slides are likely on the Taiwan Bank slope and eastern part of the Dongsha slope. Therefore, submarine slides recognized in seismic profiles on the Taiwan Bank slope would be triggered by an earthquake, the most important factor for triggering submarine slides on the northern slope of the South China Sea. Considering the distribution of PGA, we consider the northern slope of the South China Sea to be stable, excluding the Taiwan Bank slope, which is tectonically active.

H-Canyon Recovery Crawler

Energy Technology Data Exchange (ETDEWEB)

Kriikku, E. M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hera, K. R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Marzolf, A. D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Phillips, M. H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2015-08-01

The Nuclear Material Disposition Project group asked the Savannah River National Lab (SRNL) Research and Development Engineering (R&DE) department to help procure, test, and deploy a remote crawler to recover the 2014 Inspection Crawler (IC) that tipped over in the H-Canyon Air Exhaust Tunnel. R&DE wrote a Procurement Specification for a Recovery Crawler (RC) and SRNS Procurement Department awarded the contract to Power Equipment Manufacturing Inc. (PEM). The PEM RC was based on their standard sewer inspection crawler with custom arms and forks added to the front. The arms and forks would be used to upright the 2014 Inspection Crawler. PEM delivered the RC and associated cable reel, 2014 Inspection Crawler mockup, and manuals in late April 2015. R&DE and the team tested the crawler in May of 2015 and made modifications based on test results and Savannah River Site (SRS) requirements. R&DE delivered the RC to H-Area at the end of May. The team deployed the RC on June 9, 10, and 11, 2015 in the H-Canyon Air Exhaust Tunnel. The RC struggled with some obstacles in the tunnel, but eventually made it to the IC. The team spent approximately five hours working to upright the IC and eventually got it on its wheels. The IC travelled approximately 20 feet and struggled to drive over debris on the air tunnel floor. Unfortunately the IC tripped over trying to pass this obstacle. The team decided to leave the IC in this location and inspect the tunnel with the RC. The RC passed the IC and inspected the tunnel as it travelled toward H-Canyon. The team turned the RC around when it was about 20 feet from the H-Canyon crossover tunnel. From that point, the team drove the RC past the manway towards the new sand filter and stopped approximately 20 feet from the new sand filter. The team removed the RC from the tunnel, decontaminated the RC, and stored it the manway building, 294-2H. The RC deployment confirmed the IC was not in a condition to perform useful tunnel inspections and

33 CFR 165.1171 - Copper Canyon, Lake Havasu, Colorado River-Regulated Navigation Area.

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Copper Canyon, Lake Havasu... Guard District § 165.1171 Copper Canyon, Lake Havasu, Colorado River—Regulated Navigation Area. (a) Location. The following is a regulated navigation area: (1) In the water area of Copper Canyon, Lake Havasu...

A Numerical Simulation of Traffic-Related Air Pollution Exposures in Urban Street Canyons

Science.gov (United States)

Liu, J.; Fu, X.; Tao, S.

2016-12-01

Urban street canyons are usually associated with intensive vehicle emissions. However, the high buildings successively along both sides of a street block the dispersion of traffic-generated air pollutants, which enhances human exposure and adversely affects human health. In this study, an urban scale traffic pollution dispersion model is developed with the consideration of street distribution, canyon geometry, background meteorology, traffic assignment, traffic emissions and air pollutant dispersion. Vehicle exhausts generated from traffic flows will first disperse inside a street canyon along the micro-scale wind field (generated by computational fluid dynamics (CFD) model) and then leave the street canyon and further disperse over the urban area. On the basis of this model, the effects of canyon geometry on the distribution of NOx and CO from traffic emissions were studied over the center of Beijing, China. We found that an increase of building height along the streets leads to higher pollution levels inside streets and lower pollution levels outside, resulting in higher domain-averaged concentrations over the area. In addition, street canyons with equal (or highly uneven) building heights on two sides of a street tend to lower the urban-scale air pollution concentrations at pedestrian level. Our results indicate that canyon geometry strongly influences human exposure to traffic pollutants in the populated urban area. Carefully planning street layout and canyon geometry in consideration of traffic demand as well as local weather pattern may significantly reduce the chances of unhealthy air being inhaled by urban residents.

Draft environmental assessment: Lavender Canyon site, Utah. Nuclear Waste Policy Act (Section 112)

International Nuclear Information System (INIS)

1984-12-01

In February 1983, the US Department of Energy (DOE) identified the Lavender Canyon site in Utah, as one of nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Lavender Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for Nuclear Waste Repositories. These evaluations are reported in this draft environmental assessment (EA), which is being issued for public review and comment. The DOE findings and determinations that are based on these evaluations are preliminary and subject to public review and comment. A final EA will be prepared after considering the comments received. On the basis of the evaluations contained in this draft EA, the DOE has found that the Lavender Canyon site is not disqualified under the guidelines. The site is contained in the Paradox Basin, which is one of five distinct geohydrologic settings considered for the first repository. This setting contains one other potentially acceptable site - the Davis Canyon site. Although the Lavender Canyon site appears to be suitable for site characterization, the DOE has concluded that the Davis Canyon site is the preferred site in the Paradox Basin. On the basis of these findings, the DOE is proposing to nominate the Davis Canyon site rather than the Lavender Canyon site as one of the five sites suitable for characterization

Passive air exchanges between building and urban canyon via openings in a single facade

International Nuclear Information System (INIS)

Syrios, K.; Hunt, G.R.

2008-01-01

The results of an experimental study examining the steady exchange of air and heat between a building and an urban canyon are presented. The focus is on the effect of the canyon aspect ratio on the airflow through openings made exclusively in one side of the building. The interaction of the external wind flow and the internal thermally-driven flow was shown to depend upon the ratio of the building height H b to the canyon width W (distance between buildings forming the canyons). The trends observed as this aspect ratio (H b /W) was varied allow for identification of canyon geometries that yield reduced or enhanced building ventilation airflow rates

Cold-water coral ecosystems in Cassidaigne Canyon: An assessment of their environmental living conditions

OpenAIRE

Fabri, Marie-claire; Bargain, Annaelle; Pairaud, Ivane; Pedel, Laura; Taupier-letage, I.

2017-01-01

The Cassidaigne canyon is one of the two canyons (together with Lacaze-Duthiers) of the French Mediterranean coast in which cold-water corals have settled and formed large colonies, providing a structural habitat for other species. Nevertheless, the communities settled in the Cassidaigne canyon are physically impacted by discharges of bauxite residues. New information on the distribution of the species Madrepora oculata and the associated species diversity in Cassidaigne canyon was provid...

Standardized methods for Grand Canyon fisheries research 2015

Science.gov (United States)

Persons, William R.; Ward, David L.; Avery, Luke A.

2013-01-01

This document presents protocols and guidelines to persons sampling fishes in the Grand Canyon, to help ensure consistency in fish handling, fish tagging, and data collection among different projects and organizations. Most such research and monitoring projects are conducted under the general umbrella of the Glen Canyon Dam Adaptive Management Program and include studies by the U.S. Geological Survey (USGS), U.S. Fish and Wildlife Service (FWS), National Park Service (NPS), the Arizona Game and Fish Department (AGFD), various universities, and private contractors. This document is intended to provide guidance to fieldworkers regarding protocols that may vary from year to year depending on specific projects and objectives. We also provide herein documentation of standard methods used in the Grand Canyon that can be cited in scientific publications, as well as a summary of changes in protocols since the document was first created in 2002.

75 FR 34476 - Glen Canyon Dam Adaptive Management Work Group

Science.gov (United States)

2010-06-17

... DEPARTMENT OF THE INTERIOR Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group... Management Work Group. The purpose of the Adaptive Management Work Group is to advise and to provide... of the Glen Canyon Dam Adaptive Management Work Group is in the public interest in connection with...

Draft environmental assessment: Davis Canyon site, Utah. Nuclear Waste Policy Act (Section 112)

International Nuclear Information System (INIS)

1984-12-01

In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah, as one of nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for Nuclear Waste Repositories. These evaluations are reported in this draft environmental assessment (EA), which is being issued for public review and comment. The DOE findings and determinations that are based on these evaluations are preliminary and subject to public review and comment. A final EA will be prepared after considering the comments received. On the basis of the evaluations reported in this draft EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. The site is in the Paradox Basin, which is one of five distinct geohydrologic settings considered for the first repository. This setting contains one other potentially acceptable site - the Lavender Canyon site. Although the Lavender Canyon site appears to be suitable for site characterization, the DOE has concluded that the Davis Canyon site is the preferred site in the Paradox Basin. Furthermore, the DOE finds that the site is suitable for site characterization because the evidence does not support a conclusion that the site will not be able to meet each of the qualifying conditions specified in the guidelines. On the basis of these findings, the DOE is proposing to nominate the Davis Canyon site as one of five sites suitable for characterization. Having compared the Davis Canyon site with the other four sites proposed for nomination, the DOE has determined that the Davis Canyon site is not one of the three preferred sites for recommendation to the President as candidates for characterization

Airborne Radar Search for Diesel Submarines (ARSDS)

National Research Council Canada - National Science Library

Pilnick, Steven E; Landa, Jose

2005-01-01

.... In this research, a detection rate model is developed to analyze the effectiveness of an airborne radar search for a diesel submarine assumed to be intermittently operating with periscopes or masts...

Design of a small nuclear reactor for extending the operational envelope of the Victoria Class Submarine

International Nuclear Information System (INIS)

Cole, C.J.P.

2003-01-01

The purpose of this research is to conceptually design a small, inherently safe, quasi-homogeneous nuclear reactor that will provide enough power to maintain the hotel load of the Victoria Class Submarine and extend her operational envelope. This research is in its early stages. The purpose of this paper is to outline the background of the research, present results found to date, and indicate the direction of the research over the next two years. The Canadian Forces has recently acquired four U.K. built Upholder Class submarines to replace the ageing Oberon Class submarines purchased in the early 1960's. The Upholders, like the Oberons, are diesel-electric powered. The Upholders were renamed the Victoria Class upon commissioning in Canada. Submarines are strategic military weapons that have several roles including: intelligence gathering, inflicting surprise attacks, controlling shipping lanes and covert operations. For each of these roles the submarine must remain undetected. To remain undetected, it is imperative that the submarine remains submerged. To remain submerged and continue to function, a submarine requires an air-independent power generation system, such as a nuclear reactor. (author)

PAUT-based defect detection method for submarine pressure hulls

Directory of Open Access Journals (Sweden)

Min-jae Jung

2018-03-01

Full Text Available A submarine has a pressure hull that can withstand high hydraulic pressure and therefore, requires the use of highly advanced shipbuilding technology. When producing a pressure hull, periodic inspection, repair, and maintenance are conducted to maintain its soundness. Of the maintenance methods, Non-Destructive Testing (NDT is the most effective, because it does not damage the target but sustains its original form and function while inspecting internal and external defects. The NDT process to detect defects in the welded parts of the submarine is applied through Magnetic particle Testing (MT to detect surface defects and Ultrasonic Testing (UT and Radiography Testing (RT to detect internal defects. In comparison with RT, UT encounters difficulties in distinguishing the types of defects, can yield different results depending on the skills of the inspector, and stores no inspection record. At the same time, the use of RT gives rise to issues related to worker safety due to radiation exposure. RT is also difficult to apply from the perspectives of the manufacturing of the submarine and economic feasibility. Therefore, in this study, the Phased Array Ultrasonic Testing (PAUT method was applied to propose an inspection method that can address the above disadvantages by designing a probe to enhance the precision of detection of hull defects and the reliability of calculations of defect size. Keywords: Submarine pressure hull, Non-destructive testing, Phased array ultrasonic testing

Cold-water coral banks and submarine landslides: a review

Science.gov (United States)

de Mol, Ben; Huvenne, Veerle; Canals, Miquel

2009-06-01

This paper aims to review the relation between cold-water coral bank development and submarine landslides. Both are common features on continental margins, but so far it has not been reviewed which effect—if at all—they may have upon each other. Indirect and direct relations between coral banks and landslides are evaluated here, based on four case studies: the Magellan Mound Province in the Porcupine Seabight, where fossil coral banks appear partly on top of a buried slide deposit; the Sula Ridge Reef Complex and the Storegga landslide both off mid-Norway; and the Mauritania coral bank province, associated with the Mauritanian Slide Complex. For each of these locations, positive and negative relationships between both features are discussed, based on available datasets. Locally submarine landslides might directly favour coral bank development by creating substratum where corals can settle on, enhancing turbulence due to abrupt seabed morphological variations and, in some cases, causing fluid seepage. In turn, some of these processes may contribute to increased food availability and lower sedimentation rates. Landslides can also affect coral bank development by direct erosion of the coral banks, and by the instantaneous increase of turbidity, which may smother the corals. On the other hand, coral banks might have a stabilising function and delay or stop the headwall retrogradation of submarine landslides. Although local relationships can be deduced from these case studies, no general and direct relationship exists between submarine landslides and cold-water coral banks.

Submarine paleoseismology based on turbidite records.

Science.gov (United States)

Goldfinger, Chris

2011-01-01

Many of the largest earthquakes are generated at subduction zones or other plate boundary fault systems near enough to the coast that marine environments may record evidence of them. During and shortly after large earthquakes in the coastal and marine environments, a spectrum of evidence may be left behind, mirroring onshore paleoseismic evidence. Shaking or displacement of the seafloor can trigger processes such as turbidity currents, submarine landslides, tsunami (which may be recorded both onshore and offshore), and soft-sediment deformation. Marine sites may also share evidence of fault scarps, colluvial wedges, offset features, and liquefaction or fluid expulsion with their onshore counterparts. This article reviews the use of submarine turbidite deposits for paleoseismology, focuses on the dating and correlation techniques used to establish stratigraphic continuity of marine deposits, and outlines criteria for distinguishing earthquake deposits and the strategies used to acquire suitable samples and data for marine paleoseismology.

Benthic Foraminifers identify the source of displaced sediment from a sediment density flow at 1840 m near the Seafloor Instrument Node of the Monterey Coordinated Canyon Experiment

Science.gov (United States)

McGann, M.; Maier, K. L.; Gales, J. A.; Paull, C. K.; Gwiazda, R.; Barry, J.; Carvajal, C.; Clare, M. A.; Cartigny, M.; Chaffey, M. R.; Parsons, D. R.; O'Reilly, T. C.; Rosenberger, K. J.; Wolfson-Schwehr, M.; Simmons, S.; Sumner, E.; Talling, P.; Xu, J.

2017-12-01

Submarine canyons are found along the slopes of most continental margins and turbidity currents are thought to be the primary mechanism responsible for transporting sediment through them to deep-sea fans. The initiation sites of these flows are difficult to locate with any degree of precision from lithology alone. Fortunately, the presence of allochthonous microscopic remains, such as benthic foraminifers, can aid in the identification of the source of the displaced sediments. In Monterey Canyon, offshore California, a Seafloor Instrument Node (SIN) and adjacent mooring in the Coordinated Canyon Experiment indicate that a February 2017 turbidity current reached 1840 m water depth. In April 2017, one push core was obtained on each of four sides of the SIN just outside its frame and six others from 30-100 m away. Each was cut into 1 cm slices, stained with rose Bengal, washed, and analyzed for their microscopic constituents. Material recovered included terrestrial debris (wood, leaves, seeds, highway safety spheres, and volcanic glass) as well as foraminiferal tests. Dead benthic foraminifers from the estuarine (0-10 m), inner shelf (0-50 m), outer shelf (50-150 m), slope break (150 m), upper bathyal (150-500 m), and middle bathyal (500-2000 m) biofacies were present, suggesting a staged progression of sediment downslope from the continental shelf and slope. Living (rose Bengal stained) foraminifers recovered represent estuarine (Ammonia tepida, Elphidium excavatum), inner shelf (Buccella frigida, B. tenerrima, Buliminella elegantissima, Cibicides fletcheri, Nonionella spp., Rotorbinella turbinata), and upper bathyal (Bolivina pacifica, B. spissa, Epistominella exigua, Uvigerina peregrina) species as well as an in-situ middle bathyal biofacies (Bolivina argentea, B. spissa, Buliminella tenuata, Epistominella pacifica, Globobulimina spp., Uvigerina peregrina, U. hispida). The presence of living allochthonous benthic foraminifers from these shallower biofacies suggests

Seismic reflection results of the GYRE 1997 Cruise at the Bryant Canyon of the Louisiana Gulf Coast

Science.gov (United States)

Nealon, Jeffrey W.; Dillon, William P.; Twichell, David

2000-01-01

The TexasLouisiana continental slope is one of the few remaining frontiers for hydrocarbon exploration within the US Exclusive Economic Zone.  This area has a complex seafloor morphology and highly discontinuous shallow stratigraphy that are the result of deformation by the highly mobile Louann salt that underlies much of this margin shoreward of the Sigsbee Escarpment.Gas hydrates exist both on the sea floor and at depth throughout the gas hydrate stability zone which extends to several hundred meters beneath the sea floor at greater water depths.  Multibeam bathymetry, GLORIA sidescan sonar imagery, and site-specific studies have identified the presence of faults, mass-wasting deposits, variable sediment types, and gas hydrates exposed on the seafloor.  The expression of these features on the seafloor suggests a tectonically active area.  The distribution of these different processes and their relation to the subsurface stratigraphy and tectonic setting are not well understood, yet an understanding of these issues is essential as exploration extends into this deep-water area.To address the questions of surficial processes and their connection with deeper structures underlying this continental margin, a three-week cruise was conducted by the USGS in April, 1997 aboard the RV GYRE. The study area focussed on Bryant Canyon, a former submarine canyon, through which turbidity currents transported sands from a shelf-edge delta upslope of the study area to the Bryant Fan on the rise seaward of the base of the slope.  The cruise was divided into two parts.  The first part was devoted to collecting seismic-reflection profiles across parts of the canyon system to define the shallow stratigraphy and to determine the presence and distribution of gas hydrates in this area.  Approximately 555 km of single-channel seismic-reflection data were collected during this first part of the cruise.  A track map showing the locations of the profiles, low-resolution images of the

Are amphitheater headed canyons indicative of a particular formative process?

Science.gov (United States)

Ryan, A. J.; Whipple, K. X.; Johnson, J. P.

2012-12-01

Tributary canyons with amphitheater-shaped heads have previously been interpreted as evidence for groundwater seepage erosion, particularly in environments where fluvial processes are assumed to be negligible. However, some have questioned whether this canyon morphology is truly diagnostic of a particular formative process. We seek to determine the relative roles of fluvial and groundwater-related processes and the strength of stratigraphic control on the Colorado Plateau through a combination of fieldwork and GIS analysis. Amphitheater valleys may have overhanging or steep-sided headwalls with a semicircular plan-view pattern. It is reasonable to assume that this form is a result of focused erosion at the base of the headwall (i.e. sapping). Two frequently cited agents may lead to undermining: plunge-pool scour at the base of waterfalls and seepage induced weathering and erosion where the groundwater table intersects the land surface. Both processes are enhanced where weaker, less permeable layers underlie stronger cap rock. We conducted preliminary fieldwork in two locations on the Colorado Plateau, where there are many classic examples of amphitheater headed canyons. The Escalante River landscape is highly variable with a range of canyon and valley-head forms, many of which cut through the thick Navajo Sandstone into the underlying shale and sand of the Kayenta Formation. Northeast of Escalante National Monument, at the base of the Henry Mountains, is Tarantula Mesa. The canyons there are also considerably variable, with nearly all containing at least one abrupt amphitheater knickpoint at the valley head or farther downstream. Our observations are presented here with an analysis of the canyon profiles, surrounding topography, and potential structural controls. We have found that nearly all amphitheaters in both locales show signs of groundwater seepage weathering and plausibly seepage erosion. However, many also contain plunge pools and evidence of substantial

Effects of building roof greening on air quality in street canyons

Science.gov (United States)

Baik, Jong-Jin; Kwak, Kyung-Hwan; Park, Seung-Bu; Ryu, Young-Hee

2012-12-01

Building roof greening is a successful strategy for improving urban thermal environment. It is of theoretical interest and practical importance to study the effects of building roof greening on urban air quality in a systematic and quantitative way. In this study, we examine the effects of building roof greening on air quality in street canyons using a computational fluid dynamics (CFD) model that includes the thermodynamic energy equation and the transport equation of passive, non-reactive pollutants. For simplicity, building roof greening is represented by specified cooling. Results for a simple building configuration with a street canyon aspect ratio of one show that the cool air produced due to building roof greening flows into the street canyon, giving rise to strengthened street canyon flow. The strengthened street canyon flow enhances pollutant dispersion near the road, which decreases pollutant concentration there. Thus, building roof greening improves air quality near the road. The degree of air quality improvement near the road increases as the cooling intensity increases. In the middle region of the street canyon, the air quality can worsen when the cooling intensity is not too strong. Results for a real urban morphology also show that building roof greening improves air quality near roads. The degree of air quality improvement near roads due to building roof greening depends on the ambient wind direction. These findings provide a theoretical foundation for constructing green roofs for the purpose of improving air quality near roads or at a pedestrian level as well as urban thermal environment. Further studies using a CFD model coupled with a photochemistry model and a surface energy balance model are required to evaluate the effects of building roof greening on air quality in street canyons in a more realistic framework.

Near-inertial motions in the DeSoto Canyon during Hurricane Georges

Science.gov (United States)

Jordi, Antoni; Wang, Dong-Ping; Hamilton, Peter

2016-09-01

Hurricane Georges passed directly over an array of 13 moorings deployed in the DeSoto Canyon in the northern Gulf of Mexico on 27-28 September 1998. Current velocity data from the mooring array were analyzed together with a primitive-equation model simulation with realistic hurricane forcing, to characterize the generation and propagation of the hurricane-generated near-inertial waves. The model successfully reproduces the observed mean (sub-inertial) and near-inertial motions. The upper ocean response is strongly impacted by the canyon 'wall': a strong jet is formed along the slope, and the near-inertial motions on the shelf are rapidly suppressed. The model results moreover suggest that strong near-inertial waves in the mixed layer are mostly trapped in an energy flux recirculating gyre around the canyon. This gyre retains the near-inertial energy in the canyon region and enhances the transfer of near-inertial energy below the mixed layer. Additional simulations with idealized topographies show that the presence of a steep slope rather than the canyon is fundamental for the generation of this recirculating gyre. The near-inertial wave energy budget shows that during the study period the wind generated an input of 6.79 × 10-2 Wm-2 of which about 1/3, or 2.43 × 10-2 Wm-2, was transferred below the mixed layer. The horizontal energy flux into and out of the canyon region, in contrast, was relatively weak.

Bedrock Canyons Carved by the Largest Known Floods on Earth and Mars

Science.gov (United States)

Lamb, M. P.; Lapôtre, M. G. A.; Larsen, I. J.; Williams, R. M. E.

2017-12-01

The surface of Earth is a dynamic and permeable interface where the rocky crust is sculpted by ice, wind and water resulting in spectacular mountain ranges, vast depositional basins and environments that support life. These landforms and deposits contain a rich, yet incomplete, record of Earth history that we are just beginning to understand. Some of the most dramatic landforms are the huge bedrock canyons carved by catastrophic floods. On Mars, similar bedrock canyons, known as Outflow Channels, are the most important indicators of large volumes of surface water in the past. Despite their importance and now decades of observations of canyon morphology, we lack a basic understanding of how the canyons formed, which limits our ability to reconstruct flood discharge, duration and water volume. In this presentation I will summarize recent work - using mechanistic numerical models and field observations - that suggests that bedrock canyons carved by megafloods rapidly evolve to a size and shape such that boundary shear stresses just exceed that required to entrain fractured blocks of rock. The threshold shear stress constraint allows for quantitative reconstruction of the largest known floods on Earth and Mars, and implies far smaller discharges than previous methods that assume flood waters fully filled the canyons to high water marks.

Acute Exposure to Low-to-Moderate Carbon Dioxide Levels and Submariner Decision Making.

Science.gov (United States)

Rodeheffer, Christopher D; Chabal, Sarah; Clarke, John M; Fothergill, David M

2018-06-01

Submarines routinely operate with higher levels of ambient carbon dioxide (CO2) (i.e., 2000 - 5000 ppm) than what is typically considered normal (i.e., 400 - 600 ppm). Although significant cognitive impairments are rarely reported at these elevated CO2 levels, recent studies using the Strategic Management Simulation (SMS) test have found impairments in decision-making performance during acute CO2 exposure at levels as low as 1000 ppm. This is a potential concern for submarine operations, as personnel regularly make mission-critical decisions that affect the safety and efficiency of the vessel and its crew while exposed to similar levels of CO2. The objective of this study was to determine if submariner decision-making performance is impacted by acute exposure to levels of CO2 routinely present in the submarine atmosphere during sea patrols. Using a subject-blinded balanced design, 36 submarine-qualified sailors were randomly assigned to receive 1 of 3 CO2 exposure conditions (600, 2500, or 15,000 ppm). After a 45-min atmospheric acclimation period, participants completed an 80-min computer-administered SMS test as a measure of decision making. There were no significant differences for any of the nine SMS measures of decision making between the CO2 exposure conditions. In contrast to recent research demonstrating cognitive deficits on the SMS test in students and professional-grade office workers, we were unable to replicate this effect in a submariner population-even with acute CO2 exposures more than an order of magnitude greater than those used in previous studies that demonstrated such effects.Rodeheffer CD, Chabal S, Clarke JM, Fothergill DM. Acute exposure to low-to-moderate carbon dioxide levels and submariner decision making. Aerosp Med Hum Perform. 2018; 89(6):520-525.

3D View of Grand Canyon, Arizona

Science.gov (United States)

2000-01-01

The Grand Canyon is one of North America's most spectacular geologic features. Carved primarily by the Colorado River over the past six million years, the canyon sports vertical drops of 5,000 feet and spans a 445-kilometer-long stretch of Arizona desert. The strata along the steep walls of the canyon form a record of geologic time from the Paleozoic Era (250 million years ago) to the Precambrian (1.7 billion years ago).The above view was acquired by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument aboard the Terra spacecraft. Visible and near infrared data were combined to form an image that simulates the natural colors of water and vegetation. Rock colors, however, are not accurate. The image data were combined with elevation data to produce this perspective view, with no vertical exaggeration, looking from above the South Rim up Bright Angel Canyon towards the North Rim. The light lines on the plateau at lower right are the roads around the Canyon View Information Plaza. The Bright Angel Trail, which reaches the Colorado in 11.3 kilometers, can be seen dropping into the canyon over Plateau Point at bottom center. The blue and black areas on the North Rim indicate a forest fire that was smoldering as the data were acquired on May 12, 2000.Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, Calif., is the U.S. Science team leader; Moshe Pniel of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The primary goal of the ASTER mission is to obtain high-resolution image data in 14 channels over the entire land surface, as

THE INFLUENCE OF BUOYANCY ON FLOW AND POLLUTANT DISPERSION IN STREET CANYONS

OpenAIRE

Buccolieri, Riccardo; Pulvirenti, Beatrice; Di Sabatino, Silvana; Britter, Rex

2008-01-01

Abstract: In this paper, the effect of buoyancy on flow and pollutant dispersion within street canyons is studied by means of computational fluid dynamics simulations. We consider a neutral boundary layer approaching a 3D street canyon assuming a wind direction perpendicular to the street canyon. The Boussinesq hypothesis for incompressible fluids is chosen for modelling buoyancy. We distinguish three cases: leeward, ground and windward wall heating. Thermal effects on both the flow ...

Pollutant Concentrations in Street Canyons of Different Aspect Ratio with Avenues of Trees for Various Wind Directions

Science.gov (United States)

Gromke, Christof; Ruck, Bodo

2012-07-01

This study summarizes the effects of avenues of trees in urban street canyons on traffic pollutant dispersion. We describe various wind-tunnel experiments with different tree-avenue models in combination with variations in street-canyon aspect ratio W/ H (with W the street-canyon width and H the building height) and approaching wind direction. Compared to tree-free street canyons, in general, higher pollutant concentrations are found. Avenues of trees do not suppress canyon vortices, although the air ventilation in canyons is hindered significantly. For a perpendicular wind direction, increases in wall-average and wall-maximum concentrations at the leeward canyon wall and decreases in wall-average concentrations at the windward wall are found. For oblique and perpendicular wind directions, increases at both canyon walls are obtained. The strongest effects of avenues of trees on traffic pollutant dispersion are observed for oblique wind directions for which also the largest concentrations at the canyon walls are found. Thus, the prevailing assumption that attributes the most harmful dispersion conditions to a perpendicular wind direction does not hold for street canyons with avenues of trees. Furthermore, following dimensional analysis, an estimate of the normalized wall-maximum traffic pollutant concentration in street canyons with avenues of trees is derived.

Impact of roof height non-uniformity on pollutant transport between a street canyon and intersections

International Nuclear Information System (INIS)

Nosek, Štěpán; Kukačka, Libor; Jurčáková, Klára; Kellnerová, Radka; Jaňour, Zbyněk

2017-01-01

This paper presents an extension of our previous wind-tunnel study (Nosek et al., 2016) in which we highlighted the need for investigation of the removal mechanisms of traffic pollution from all openings of a 3D street canyon. The extension represents the pollution flux (turbulent and advective) measurements at the lateral openings of three different 3D street canyons for the winds perpendicular and oblique to the along-canyon axis. The pollution was simulated by emitting a passive gas (ethane) from a homogeneous ground-level line source positioned along the centreline of the investigated street canyons. The street canyons were formed by courtyard-type buildings of two different regular urban-array models. The first model has a uniform building roof height, while the second model has a non-uniform roof height along each building's wall. The mean flow and concentration fields at the canyons' lateral openings confirm the findings of other studies that the buildings' roof-height variability at the intersections plays an important role in the dispersion of the traffic pollutants within the canyons. For the perpendicular wind, the non-uniform roof-height canyon appreciably removes or entrains the pollutant through its lateral openings, contrary to the uniform canyon, where the pollutant was removed primarily through the top. The analysis of the turbulent mass transport revealed that the coherent flow structures of the lateral momentum transport correlate with the ventilation processes at the lateral openings of all studied canyons. These flow structures coincide at the same areas and hence simultaneously transport the pollutant in opposite directions. - Highlights: • The pollutant transport strongly depends on the roof-height arrangement. • The non-uniform canyons also remove the pollutants through their lateral openings. • The higher the upstream wall, the more pollutant is removed through the top. • The lateral coherent structures correlate

Effect of stable stratification on dispersion within urban street canyons: A large-eddy simulation

Science.gov (United States)

Li, Xian-Xiang; Britter, Rex; Norford, Leslie K.

2016-11-01

This study employs a validated large-eddy simulation (LES) code with high tempo-spatial resolution to investigate the effect of a stably stratified roughness sublayer (RSL) on scalar transport within an urban street canyon. The major effect of stable stratification on the flow and turbulence inside the street canyon is that the flow slows down in both streamwise and vertical directions, a stagnant area near the street level emerges, and the vertical transport of momentum is weakened. Consequently, the transfer of heat between the street canyon and overlying atmosphere also gets weaker. The pollutant emitted from the street level 'pools' within the lower street canyon, and more pollutant accumulates within the street canyon with increasing stability. Under stable stratification, the dominant mechanism for pollutant transport within the street canyon has changed from ejections (flow carries high-concentration pollutant upward) to unorganized motions (flow carries high-concentration pollutant downward), which is responsible for the much lower dispersion efficiency under stable stratifications.

Submarine mass wasting on the Ionian Calabrian margin

Science.gov (United States)

Ceramicola, S.; Forlin, E.; Coste, M.; Cova, A.; Praeg, D.; Fanucci, F.; Critelli, S.

2010-12-01

Mass wasting processes on continental margins have strong relevance both for geohazards of coastal areas and for the emplacement and monitoring of offshore infrastructures. The seabed dynamics of the Ionian Calabrian Margin (ICM) are currently being examined in the context of the project MAGIC (Marine Geohazard along the Italian Coasts). The objective of this project is the definition of elements that may constitute geological risk for coastal areas. The ICM is a tectonically-active margin, the structures of which reflect two main processes: frontal compression and fore-arc extension during the SE advance of the Calabrian accretionary prism since the late Miocene; and a rapid uplift (up to 1mm/yr) of onshore and shallow shelf areas since the mid-Pleistocene. These processes are reflected in different tectonic settings at seabed, which is characterized by a narrow continental shelf above a slope of irregular morphology in water depths of 150-2000 m. In the north, a broad slope is dominated by ridges and intervening basins that are the morphological expression of the southern Apennine fold-and-thrust belt; in the south, the continental slope descends steeply towards the deep-water Crotone and Spartivento fore-arc basins. The overall objective of this study is to map major features of mass wasting on the slopes of the ICM, investigate possible triggering mechanisms and consider the geohazards these features may represent for coastal areas. The study is based on an integrated analysis of multibeam morpho-bathymetric data and subbottom profiles, which together allow the recognition of four main types of mass wasting phenomena along the slopes of the ICM: 1) mass transport complexes (MTCs) within intra-slope basins - these are identified in the northern area, within the piggy-back basins: seabed imagery show the slopes of all the seabed ridges to be marked by headwall scarps recording widespread failure, while Chirp profiles show the adjacent basins to contain

Aquatic macroinvertebrates and water quality in Sandia Canyon

International Nuclear Information System (INIS)

Bennett, K.

1994-05-01

In 1990, field studies of water quality and stream macroinvertebrate communities were initiated in Sandia Canyon at Los Alamos National Laboratory. The studies were designed to establish baseline data and to determine the effects of routine discharges of industrial and sanitary waste. Water quality measurements were taken and aquatic macroinvertebrates sampled at three permanent stations within the canyon. Two of the three sample stations are located where the stream regularly receives industrial and sanitary waste effluents. These stations exhibited a low diversity of macroinvertebrates and slightly degraded water quality. The last sample station, located approximately 0.4 km (0.25 mi) downstream from the nearest wastewater outfall, appears to be in a zone of recovery where water quality parameters more closely resemble those found in natural streams in the Los Alamos area. A large increase in macroinvertebrate diversity was also observed at the third station. These results indicate that effluents discharged into Sandia Canyon have a marked effect on water quality and aquatic macroinvertebrate communities

Topology Model of the Flow around a Submarine Hull Form

Science.gov (United States)

2015-12-01

UNCLASSIFIED Topology Model of the Flow around a Submarine Hull Form S.-K. Lee Maritime Division Defence Science and Technology Group DST-Group–TR...3177 ABSTRACT A topology model constructed from surface-streamer visualisation describes the flow around a generic conventional submarine hull form at...pure yaw angles of 0 ◦, 10 ◦ and 18 ◦. The model is used to develop equations for sway-force and yaw-moment coefficients which relate to the hull - form

Fourmile Canyon Fire Findings

Science.gov (United States)

Russell Graham; Mark Finney; Chuck McHugh; Jack Cohen; Dave Calkin; Rick Stratton; Larry Bradshaw; Ned Nikolov

2012-01-01

The Fourmile Canyon Fire burned in the fall of 2010 in the Rocky Mountain Front Range adjacent to Boulder, Colorado. The fire occurred in steep, rugged terrain, primarily on privately owned mixed ponderosa pine and Douglas-fir forests. The fire started on September 6 when the humidity of the air was very dry (¡Ö

Hazard assessment for a submarine landslide generated local-source tsunami from Kaikoura Canyon

Science.gov (United States)

DuBois, J.

2012-04-01

The Kaikoura Canyon, sediment sink for the Canterbury rivers north of Christchurch, comes to within 500 meters of shore at Goose Bay and accumulates approximately 1.5x106 m3 of sediment each year (Lewis and Barnes, 1999). This sediment, which has accumulated to about seventy meters in thickness (Walters et al., 2006), exhibits tensional fractures, is located in a tectonically active area and could result in catastrophic failure and potentially a local-source tsunami (Lewis and Banes, 1999; Lewis, 1998; Walters et al, 2006). Evidence suggests that this may have happened in the last two hundred years (Lewis, 1998; Lewis and Barnes 1999) and with a return period on the nearby Alpine and Hope faults also in the range of a one to two hundred years (Walters et al, 2006) could happen again relatively soon. A review of the historical record and oral traditions for Kaikoura shows that historically Kaikoura has been affected by 11 events of which 10 are from distant sources and one, though debatable, is possibly from a local source. There are some preserved traditions for the Kaikoura area. These taniwha stories from near Oaro and from the Lyell Creek have been repeated and changed though time though the general essence remains the same. These taniwha legends, though not conclusive, indicate a dangerous shoreline where people have been killed in the past, possibly by flooding or tsunami. Archaeological investigations at Kaikoura found evidence of a Maori occupational layers interrupted by water-worn stones, a "lens of clean gravel between occupation layers" and in other areas of the excavation, the gravels separate discontinuous periods of occupation (Fomison 1963; Foster, 2006). Additionally "pea-gravel" sized greywacke pebbles were found dispersed throughout sections of the South Bay shore platforms, though they were attributesd to slopewash (Duckmanton, 1974) this is less likely since the nearby hills are limestone. A geological investigation along the Kaikoura Coast, at

Broaching the Ship: Rethinking Submarines as a Signaling Tool in Naval Diplomacy

Science.gov (United States)

2015-03-01

Bateman , “Perils of the Deep: the Dangers of Submarine Proliferation in the Seas of East Asia,” Asian Security 7, no. 1 (Spring 2011), 64. 89 Brent...Science. London: Routledge, 2012. Bateman , Sam. “Perils of the Deep: The Dangers of Submarine Proliferation in the Seas of East Asia.” Asian Security

Information Assurance as a System of Systems in the Submarine Force

Science.gov (United States)

2013-09-01

Shell SSL Secure Socket Layer SSN Submerged Ship Nuclear STDA Submarine Tactical Display Auxiliary SUBLAN Submarine Local Area Network...Internet Protocol TLS T Transport Layer Security TS-SCI Top Secret-Special Compartment Information TYCOM Type Commander USB Universal...administrators or users. Layer 4 and 5: This is the layer that deals with providing a protected connection via a Secure Socket Layer ( SSL ) and Transport Layer

Numerical Simulation of Recent Turbidity Currents in the Monterey Canyon System, Offshore California

Science.gov (United States)

Heimsund, S.; Xu, J.; Nemec, W.

2007-12-01

The method of computational fluid dynamics (CFD) has been used, in the form of a 3D numerical model (Flow- 3D®), to perform a full-scale simulation of turbidity currents measured in December 2002 by three moorings in the Soquel and Monterey canyons. The model was verified by simulation of laboratory flows, and was upscaled to the Monterey Canyon system on the basis of high-resolution bathymetric data and flow measurements. The measured velocity profiles were sufficient to assess the flow thickness, initial velocity and duration in the canyon head zone. A computational grid with a highest feasible resolution was used, and both bathymetry and hydrostatic pressure were accounted for. The volumetric sediment concentration and exact grain- size composition of the flows were unknown, and thus a range of values for the initial concentration and bed roughness were assumed and assessed on a trial-and-error basis. The simulations reveal the behavior of a turbidity current along its descent path, including its local hydraulic characteristics (the 3D field of velocity, sediment concentration, shear stress, strain rate, and dynamic viscosity, as well as the magnitude of velocity and turbulent shear). The results confirm that the velocity structure of turbidity current is highly sensitive to variation in seafloor topography. The December 17th flow in the Soquel Canyon appears to have lost capacity by dilution over a relatively short distance and shown significant velocity fluctuations, which is attributed to the rugged topography of the canyon floor. A major loss of momentum occurred when the flow plunged at high angle into the Monterey Canyon, crashing against its bend's southern wall. The December 20th flow in the Monterey Canyon, in contrast, developed a considerably longer body and strongly accelerated towards the canyon's sharp second bend before crashing against its western wall. The mooring data show a down-canyon decline of velocity and suggest gradual waning, but the

Differentiation of Palaeogene sand by glauconitic and geochemical fingerprinting, Siri Canyon, Danish North Sea

Energy Technology Data Exchange (ETDEWEB)

Olivarius, M.; Knudsen, Christian; Svendsen, Johan B.

2011-07-01

The submarine Siri Canyon is NE-SW-oriented and located in the Danish North Sea. It contains a number of oil reservoirs with glauconite-rich sand. The reservoirs of interest in the Nini oil field are the Late Paleocene Tyr Member of the Lista Formation and the Kolga Member of the Sele Formation, presumably of Early Eocene age. These members have previously been known as the Ty and Hermod members. The sand shows signs of injection, both in cores and in seismic data. The aim of this work is to chemically characterise and fingerprint the sand in order to reveal the origin of the sand found in three horizontal wells, which could have been injected from one or both of the Tyr and Kolga members. Core samples were collected from two vertical wells of known stratigraphy to make a basis of comparison, whereas samples of the cuttings were collected from the three horizontal wells with ages primarily corresponding to the Kolga Member. The purpose was moreover to evaluate whether cuttings samples can be used for fingerprinting as an alternative to core samples. The interest in discriminating between the ages of the injected sand is the fact that the reservoir properties (porosity and permeability) are largely controlled by the original composition of the sand. Consequently, results from this study could affect the property modelling of the field. (LN)

Research on the hydrogeological and geochemical conditions at the coastal area and submarine formations

International Nuclear Information System (INIS)

Tokunaga, Tomochika; Taniguchi, Makoto; Goto, Junji

2003-05-01

One of the major concerns for the high-level radioactive waste disposal is the possibility of the radionuclides to reach biosphere by groundwater flow. Recent research results have shown that the fresh groundwater discharge from subsea formations are widespread phenomena, thus, it is necessary to evaluate the submarine groundwater discharge as possible pathways of contaminant discharge towards the biosphere. It is also important to unravel the groundwater flow and associated material transport at the coastal area and subsea formations. To better understand the groundwater flow processes and the submarine groundwater discharge, we have conducted the hydrological, hydrogeological, geochemical, and numerical modeling studies at the Kurobe alluvial fan and its offshore, Toyama Prefecture, Japan. In this report, the results of the following research activities are presented: 1) Development and application of a method to detect the locations of the submarine groundwater discharge. 2) Development and application of a method to collect uncontaminated groundwater samples from subsea formations. 3) Measurements of submarine groundwater discharge fluxes by automated seepage meter. 4) Hydrological and geochemical studies for groundwater flow at the coastal area. 5) Geochemical studies to understand sources of fresh submarine groundwater discharge. 6) Examination of groundwater flow and submarine groundwater discharge using methane concentration and carbon isotope ratio. 7) Numerical modeling studies for coastal groundwater flow system. (author)

A Nuclear Submarine in the South Atlantic: The Framing of Threats and Deterrence

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Mônica Herz

Full Text Available Abstract In this article, we analyse one aspect of Brazilian nuclear policy during the tenure of the Workers Party (2003–2016: the development of a nuclear-propelled submarine. We propose that the project of building a nuclear-propelled submarine has become possible partly because of the mobilisation of a set of arguments for the construction of the South Atlantic as a strategic area, framed in terms of security and development. On the other hand, we contend that the need for a nuclear-propelled submarine is framed through the mobilisation of a specific notion of deterrence. In other words, we claim that the notions of ‘strategic area’, ‘general deterrence’, ‘conventional deterrence’, and ‘deterrence by denial’ can help us analyse the fundamental aspects involved in the framing of the South Atlantic as a security concern, justifying the nuclear-propelled submarine project.

Coastal submarine hydrothermal activity off northern Baja California

International Nuclear Information System (INIS)

Vidal, V.M.V.; Vidal, F.V.; Isaacs, J.D.; Young, D.R.

1978-01-01

In situ observations of submarine hydrothermal activity have been conducted in Punta Banda. Baja Califronia, Mexico, approximately 400 m from the coast and at a seawater depth of 30 m. The hydrothermal activity occurs within the Agua Blanca Fault, a major transverse structure of Northern Baja California. Hot springwater samples have been collected and analyzed. Marked differences exist between the submarine hot springwater, local land hot springwaters, groundwater, and local seawater. SiO 2 , HCO 3 , Ca, K, Li, B, Ba, Rb, Fe, Mn, As, and Zn are enriched in the submarine hot springwater, while Cl, Na, So 4 2 , Mg, Cu, Ni, Cd, Cr, and perhaps Pb are depleted in relation to average and local seawater values. Very high temperatures, at the hydrothermal vents, have been recorded (102 0 C at 4-atm pressure). Visible gaseous emanations rich in CH 4 and N 2 coexist with the hydrothermal solutions. Metalliferous deposits, pyrite, have been encountered with high concentrations of Fe, S, Si, Al, Mn, Ca, and the volatile elements As, Hg, Sb, and Tl, X ray dispersive spectrometry (1500-ppm detection limit). X ray diffraction, and scanning electron microscopy of the isolated metalliferous precipitates indicate that the principal products of precipitation are pyrite and gypsum accompanied by minor amounts of amorphous material containing Si and Al. Chemical analyses and XRD of the reference control rocks of the locality (volcanics) versus the hydrothermally altered rocks indicate that high-temperature and high-pressure water-rock interactions can in part explain the water chemistry characteristics of the submarine hydrothermal waters. Their long residence time, the occurrence of an extensive marine sedimentary formation, their association with CH 4 and their similarities with connate waters of oil and gas fields suggest that another component of their genesis could be in cation exchange reactions within deeply buried sediments of marine origin

Influence of cetane improvers on the air quality in an urban street canyon

International Nuclear Information System (INIS)

Huang, H.; Akutsu, Y.; Arai, M.; Tamura, M.

2000-01-01

The concentration distributions of NO x , PM, HC and CO in an urban street canyon have been estimated using a two-dimensional air quality numerical model based on the k-e turbulent model and the atmospheric convection diffusion equation when various cetane improvers were used in diesel fuels. A wind vortex can be found within the street canyon, and the pollutants emitted from the bottom of the street canyon tend to follow the course of the wind field, moving circularly. The addition of cetane improvers can improve the air quality in a street canyon, all of the pollutants were found to decrease with increasing cetane number. (Author)

Impact of roof height non-uniformity on pollutant transport between a street canyon and intersections.

Science.gov (United States)

Nosek, Štěpán; Kukačka, Libor; Jurčáková, Klára; Kellnerová, Radka; Jaňour, Zbyněk

2017-08-01

This paper presents an extension of our previous wind-tunnel study (Nosek et al., 2016) in which we highlighted the need for investigation of the removal mechanisms of traffic pollution from all openings of a 3D street canyon. The extension represents the pollution flux (turbulent and advective) measurements at the lateral openings of three different 3D street canyons for the winds perpendicular and oblique to the along-canyon axis. The pollution was simulated by emitting a passive gas (ethane) from a homogeneous ground-level line source positioned along the centreline of the investigated street canyons. The street canyons were formed by courtyard-type buildings of two different regular urban-array models. The first model has a uniform building roof height, while the second model has a non-uniform roof height along each building's wall. The mean flow and concentration fields at the canyons' lateral openings confirm the findings of other studies that the buildings' roof-height variability at the intersections plays an important role in the dispersion of the traffic pollutants within the canyons. For the perpendicular wind, the non-uniform roof-height canyon appreciably removes or entrains the pollutant through its lateral openings, contrary to the uniform canyon, where the pollutant was removed primarily through the top. The analysis of the turbulent mass transport revealed that the coherent flow structures of the lateral momentum transport correlate with the ventilation processes at the lateral openings of all studied canyons. These flow structures coincide at the same areas and hence simultaneously transport the pollutant in opposite directions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Trees in urban street canyons and their impact on the dispersion of automobile exhausts

NARCIS (Netherlands)

Gromke, C.B.; Ruck, B.

2007-01-01

The aim of the present study is to clarify the influence of trees on the dispersion of automobile exhausts in urban street canyons. For this purpose, measurements have been performed with a small scale wind tunnel model of an idealized, isolated street canyon with model trees placed along the canyon

Small Mammal Sampling in Mortandad and Los Alamos Canyons, 2005

International Nuclear Information System (INIS)

Kathy Bennett; Sherri Sherwood; Rhonda Robinson

2006-01-01

As part of an ongoing ecological field investigation at Los Alamos National Laboratory, a study was conducted that compared measured contaminant concentrations in sediment to population parameters for small mammals in the Mortandad Canyon watershed. Mortandad Canyon and its tributary canyons have received contaminants from multiple solid waste management units and areas of concern since establishment of the Laboratory in the 1940s. The study included three reaches within Effluent and Mortandad canyons (E-1W, M-2W, and M-3) that had a spread in the concentrations of metals and radionuclides and included locations where polychlorinated biphenyls and perchlorate had been detected. A reference location, reach LA-BKG in upper Los Alamos Canyon, was also included in the study for comparison purposes. A small mammal study was initiated to assess whether potential adverse effects were evident in Mortandad Canyon due to the presence of contaminants, designated as contaminants of potential ecological concern, in the terrestrial media. Study sites, including the reference site, were sampled in late July/early August. Species diversity and the mean daily capture rate were the highest for E-1W reach and the lowest for the reference site. Species composition among the three reaches in Mortandad was similar with very little overlap with the reference canyon. Differences in species composition and diversity were most likely due to differences in habitat. Sex ratios, body weights, and reproductive status of small mammals were also evaluated. However, small sample sizes of some species within some sites affected the analysis. Ratios of males to females by species of each site (n = 5) were tested using a Chi-square analysis. No differences were detected. Where there was sufficient sample size, body weights of adult small mammals were compared between sites. No differences in body weights were found. Reproductive status of species appears to be similar across sites. However, sample

Small Mammal Sampling in Mortandad and Los Alamos Canyons, 2005

Energy Technology Data Exchange (ETDEWEB)

Bennett, Kathy; Sherwood, Sherri; Robinson, Rhonda

2006-08-15

As part of an ongoing ecological field investigation at Los Alamos National Laboratory, a study was conducted that compared measured contaminant concentrations in sediment to population parameters for small mammals in the Mortandad Canyon watershed. Mortandad Canyon and its tributary canyons have received contaminants from multiple solid waste management units and areas of concern since establishment of the Laboratory in the 1940s. The study included three reaches within Effluent and Mortandad canyons (E-1W, M-2W, and M-3) that had a spread in the concentrations of metals and radionuclides and included locations where polychlorinated biphenyls and perchlorate had been detected. A reference location, reach LA-BKG in upper Los Alamos Canyon, was also included in the study for comparison purposes. A small mammal study was initiated to assess whether potential adverse effects were evident in Mortandad Canyon due to the presence of contaminants, designated as contaminants of potential ecological concern, in the terrestrial media. Study sites, including the reference site, were sampled in late July/early August. Species diversity and the mean daily capture rate were the highest for E-1W reach and the lowest for the reference site. Species composition among the three reaches in Mortandad was similar with very little overlap with the reference canyon. Differences in species composition and diversity were most likely due to differences in habitat. Sex ratios, body weights, and reproductive status of small mammals were also evaluated. However, small sample sizes of some species within some sites affected the analysis. Ratios of males to females by species of each site (n = 5) were tested using a Chi-square analysis. No differences were detected. Where there was sufficient sample size, body weights of adult small mammals were compared between sites. No differences in body weights were found. Reproductive status of species appears to be similar across sites. However, sample

Savannah River Site: Canyons and associated facilities utilization study

International Nuclear Information System (INIS)

Ellison, D.; Dickenson, J.

1995-01-01

The Westinghouse Savannah River Company was asked by the U.S. Department of Energy (DOE) to study options for utilization of Savannah River Site (SRS) Canyons and Associated Facilities to support existing and potential future material stabilization and/or disposition missions. This report is WSRC's response to that request. It includes: (1) A compilation of pending DOE material stabilization and/or disposition decisions involving utilization of SRS canyons and associated facilities, including discussion of quantities and expected availability of materials for which SRS handling and/or processing capability is a reasonable alternative under consideration. (2) A description of SRS canyons and associated facilities affected by pending DOE material stabilization and/or disposition decisions, including discussion of material handling and/or processing capabilities and capacities. (3) A comparative evaluation of three proposed scenarios for SRS canyon utilization with respect to startup and operating schedules; annual and life cycle costs; impacts on completion of commitments in the DOE Implementation Plan (IP) for Defense Nuclear Facilities Safety Board (DNFSB) Recommendation 94-1; SRS ability to support alternatives under consideration in pending DOE materials stabilization and/or disposition decisions; and timing for potential transition to deactivation. (4) The sensitivity of the comparative evaluation of the three canyon utilization scenarios to the effect of the selection of other alternatives for individual stabilization missions or individual new missions. Briefings on the scope of this study have been presented to key representatives of several SRS public stakeholder groups. Briefings on the major conclusions from this study have been presented to WSRC Management, DOE-SR, EM-60, EM-1, and the DNFSB

Thermal effects on vehicle emission dispersion in an urban street canyon

Energy Technology Data Exchange (ETDEWEB)

Xiaomin Xie; Zhen Huang; Jiasong Wang; Zheng Xie [Shanghai Jiao Tong Univ., School of Mechanical Engineering, Shanghai (China)

2005-05-15

The impact of the thermal effects on vehicle emission dispersion within street canyons is examined. The results show that heating from building wall surfaces and horizontal surfaces lead to strong buoyancy forces close to surfaces receiving direct solar radiation. This thermally induced flow is combined with mechanically induced flows formed in the canyon where there is no solar heating, and affects the transport of pollutants from the canyon to the layer aloft. The relative influence of each of these effects can be estimates by Gr/Re{sup 2}. When the windward wall is warmer than the air, an upward buoyancy flux opposes the downward advection flux along the wall; if Gr/Re{sup 2} > 2, the flow structure is divided into two counter-rotating cells, and pollutants are accumulated on the windward side of the canyon. When the horizontal surface is heated, and Gr/Re{sup 2} > 4, the flow structure is divided into two counter-rotating cells by upward buoyancy flux. Pollutants are accumulated at the windward side of the canyon. When the leeward side is heated, the buoyancy flux adds to the upward advection flux along the wall strengthening the original vortex and pollutant effects of transport compared to the isothermal case. (Author)

Fault tree analysis of Project S-4404, Upgrade Canyon Exhaust System

International Nuclear Information System (INIS)

Browne, E.V.; Low, J.M.; Lux, C.R.

1992-01-01

Project S-4404, Upgrade Canyon Exhaust Systems, is a $177 million project with the purpose of upgrading the Exhaust Systems for both F and H Canyon Facilities. This upgrade will replace major portions of the F and H-Canyon exhaust systems, downstream of their respective sand filters with higher capacity and more reliable systems. Because of the high cost, DOE requested Program Control ampersand Integration (PC ampersand I) to examine specific deletions to the project. PC ampersand I requested Nuclear Processes Safety Research (NPSR) to perform an analysis to compare failure rates for the existing F ampersand H Canyon exhaust systems with the proposed exhaust system and specific proposed exhaust system alternatives. The objective of this work was to perform an analysis and compare failure rates for the existing F ampersand H Canyon exhaust systems with the proposed project exhaust system and proposed project alternatives. Based on fault tree analysis, two conclusions are made. First, D ampersand D activities can be eliminated from the project with no significant decrease to exhaust system safety. Deletion of D ampersand D activities would result in a cost savings of $29 million. Second, deletion of DOE Order 6430.1A requirements regarding DBAs would decrease exhaust system safety by a factor of 12

In-service inspection of the vessels of nuclear submarine reactors

International Nuclear Information System (INIS)

Saglio, R.; Mercier L'Abbe, G.

1977-02-01

Description is given of a machine of automatic inspection of the reactor vessels of nuclear submarines, that was developed by the French Atomic Energy Commission (CEA). A focused ultrasound testing method is used. The equipment such described meets the safety requirements prescribed for the primary circuits of nuclear submarine boiler plants. The sensitivity and resolution power of the apparatus allow such high precision to be obtained as rupture mechanics gains a credibility that could not have been obtained with using conventional apparatus [fr

Environmental and human impact on the sedimentary dynamic in the Rhone Delta subaquatic canyons (France-Switzerland)

Science.gov (United States)

Arantegui, A.; Corella, J. P.; Loizeau, J. L.; Anselmetti, F. S.; Girardclos, S.

2012-04-01

Deltas are very sensitive environments and highly vulnerable to variations in water discharge and the amount of suspended sediment load provided by the delta-forming currents. Human activities in the watershed, such as building of dams and irrigation ditches, or river bed deviations, may affect the discharge regime and sediment input, thus affecting delta growth. Underwater currents create deeply incised canyons cutting into the delta lobes. Understanding the sedimentary processes in these subaquatic canyons is crucial to reconstruct the fluvial evolution and human impact on deltaic environments and to carry out a geological risk assessment related to mass movements, which may affect underwater structures and civil infractructure. Recently acquired high-resolution multibeam bathymetry on the Rhone Delta in Lake Geneva (Sastre et al. 2010) revealed the complexity of the underwater morphology formed by active and inactive canyons first described by Forel (1892). In order to unravel the sedimentary processes and sedimentary evolution in these canyons, 27 sediment cores were retrieved in the distal part of each canyon and in the canyon floor/levee complex of the active canyon. Geophysical, sedimentological, geochemical and radiometric dating techniques were applied to analyse these cores. Preliminary data show that only the canyon originating at the current river mouth is active nowadays, while the others remain inactive since engineering works in the watershed occurred, confirming Sastre et al. (2010). However, alternating hemipelagic and turbiditic deposits on the easternmost canyons, evidence underflow processes during the last decades as well. Two canyons, which are located close to the Rhone river mouth, correspond to particularly interesting deeply incised crevasse channels formed when the underwater current broke through the outer bend of a meander in the proximal northern levee. In these canyons, turbidites occur in the sediment record indicating ongoing

Evaluation of turbulence from traffic using experimental data obtained in a street canyon

Energy Technology Data Exchange (ETDEWEB)

Mazzeo, N.A.; Venegas, L.E. [Univ. of Buenos Aires, Buenos Aires (Argentina). Dept. of Atmospheric and Oceanic Sciences, National Scientific and Technological Research Council

2004-07-01

High air pollution levels have been observed in street canyons. Within these streets, pedestrians, cyclists, drivers and residents are likely to be exposed to pollutant concentrations exceeding current air quality standards. Airflow and dispersion in street canyons are very complicated. Depending on the synoptic wind three main dispersion conditions can be identified: a) low wind conditions, b) perpendicular or near perpendicular flow for winds over 1.5-2.0 m/s blowing at an angle of more than 30 to the canyon axes, c) parallel or near parallel flow for winds over 1.5-2.0 m/s blowing from all other directions. Under condition b), airflow in canyons with H/W{approx}1 (H is the height and W is the width of the canyon) is characterised by the formation of a single vortex within the canyon. The dispersion of gaseous pollutants in a street canyon depends generally on the rate at which the street exchanges air vertically with the above roof-level atmosphere and laterally with connecting streets. There is evidence that when the synoptic wind speed is low, the mechanical traffic-produced turbulence (TPT) might place a significant role in dispersion of traffic-generated pollutants. In this paper, we analyse interactions between wind and traffic induced dispersive air motions. Data from full-scale measurements in Goettinger Strasse (Hannover, Germany) are used for application of parameterisation proposed by Di Sabatino, S. et al. (2003) and Kastner-Klein, P. et al. (2003). (orig.)

Exercise Aboard Attack Submarines: Rationale and New Options

National Research Council Canada - National Science Library

Watenpaugh, Donald

2004-01-01

.... However, most submariners do not exercise during deployment for a variety of reasons, including lack of space, time limitations, equipment limitations, lack of entertainment or recreational value...

Operating Below Crush Depth: The Formation, Evolution, and Collapse of the Imperial Japanese Navy Submarine Force in World War II

Science.gov (United States)

2011-06-10

Subamrine, Medium) LCDR Lieutenant Commander LT Lieutenant NM Nautical Mile RADM Rear Admiral ST Sen- Taka (Submarine, High Speed) STo Sen-Toku...Special Submarine) STS Sen- Taka -Sho (Submarine, High Speed(Victory)) USS United States Ship VADM Vice Admiral 1 CHAPTER 1 INTRODUCTION On...Kirai-Sen meaning Mine-Layer, KT for Kai-Toku-Chu meaning Medium, Special Submarine, ST for Sen- Taka meaning Submarine, High speed, STo for Sen Toku

Submarine Volcanic Eruptions and Potential Analogs for Venus

Science.gov (United States)

Wilson, L.; Mouginismark, P. J.; Fryer, P.; Gaddis, L. R.

1985-01-01

As part of an analysis program to better understand the diversity of volcanic processes on the terrestrial planets, an investigation of the volcanic landforms which exist on the Earth's ocean floor was initiated. In part, this analysis is focused toward gaining a better understanding of submarine volcanic landforms in their own right, but also it is hoped that these features may show similarities to volcanic landforms on Venus, due to the high ambient water (Earth) and atmospheric (Venus) pressures. A series of numerical modelling experiments was performed to investigate the relative importance of such attributes as water pressure and temperature on the eruption process, and to determine the rate of cooling and emplacement of lava flows in the submarine environment. Investigations to date show that the confining water pressure and the buoyancy effects of the surrounding water significantly affect the styles of volcanism on the ocean floor. In the case of Venusian volcanism, confining pressures will not be as great as that found at the ocean's abyssal plains, but nevertheless the general trend toward reducing magma vesiculation will hold true for Venus as well as the ocean floor. Furthermore, other analogs may also be found between submarine volcanism and Venusian activity.

The sinking of the Soviet Mike class nuclear powered submarine

International Nuclear Information System (INIS)

1989-01-01

The purpose of this preliminary study is to assess the quantities of the longer-lived or persistent radioactive materials, or source terms, that have been lost at sea with the sinking of the Soviet MIKE class submarine off Bear Island on 7 April 1989. The report arrives at an assessment of the amount of radioactivity and compares this to the quantities of radioactive materials dumped by the UK from 1953 to 1982 at which time sea dumping of radioactive wastes was suspended by international resolve. This comparison can be used to assess the relative significance of the sinking of this submarine. The study does not extrapolate the estimated radioactive source terms to an environmental or radiological significance of the sinking, although it is concluded that unless the submarine is recovered intact from the ocean floor, the by far greater part of the radioactive materials on board will disperse to the marine environment at some future time, if they are not doing so already. (author)

BLANCO MOUNTAIN AND BLACK CANYON ROADLESS AREAS, CALIFORNIA.

Science.gov (United States)

Diggles, Michael F.; Rains, Richard L.

1984-01-01

The mineral survey of the Blanco Mountain and Black Canyon Roadless Areas, California indicated that areas of probable and substantiated mineral-resource potential exist only in the Black Canyon Roadless Area. Gold with moderate amounts of lead, silver, zinc, and tungsten, occurs in vein deposits and in tactite. The nature of the geological terrain indicates little likelihood for the occurrence of energy resources in the roadless areas. Detailed geologic mapping might better define the extent of gold mineralization. Detailed stream-sediment sampling and analysis of heavy-mineral concentrations could better define tungsten resource potential.

Lightning protection for the process canyons at the Savannah River site

International Nuclear Information System (INIS)

McAfee, D.E.

1995-01-01

Westinghouse Savannah River Company (WSRC) has performed Lightning Studies for the existing Process Canyons at the Savannah River Site (SRS). These studies were initiated to verify the lightning protection systems for the facilities and to compare the installations to the National Fire Protection (NFPA) Standard 780, Lighting Protection Code, 1992. The original study of the F-Canyon was initiated to develop answers to concerns raised by the Defense Nuclear Facility Safety Board (DNFSB). Once this study was completed it was determined that a similar study for H-Canyon would be prudent; followed by an evaluation of the Defense Waste Processing Facility (DWPF) Vitrification Building (S-Canyon). This paper will provide an overview of the nature of lightning and the principals of lightning protection. This will provide the reader with a basic understanding of the phenomena of lighting and its potential for damaging structures, components, and injuring personnel in or near the structure

Coastal submarine springs in Lebanon and Syria: Geological, geochemical, and radio-isotopic study

International Nuclear Information System (INIS)

Al-Charideh, A.

2004-10-01

The coastal karst aquifer system (upper Cretaceous) and the submarine springs in the Syrian coast have been studies using chemical and isotopic methods in order to determine the hydraulic connections between the groundwater and the submarine springs. Results show that the groundwater and submarine springs are having the same slope on the σ 18 O/σ 2 H plot indicate the same hydrological origin for both. In addition this relation is very close to the local meteoric water line (LMWL) reflecting a rapid infiltration of rainfall to recharge coastal aquifer. The calculated percentage of freshwater in the two locations (Bassieh and Tartous) range from 20 to 96%. The estimation rate of the permanent submarine springs (BS1, BS2 and TS2, TS3) is 11m 3 /s or 350 million m 3 /y. The maximum residence time of the groundwater in the Cenomanian/Turonian aquifer was estimated at around 8 years, using the piston-flow model.(author)

Losses in armoured three-phase submarine cables

DEFF Research Database (Denmark)

Ebdrup, Thomas; Silva, Filipe Miguel Faria da; Bak, Claus Leth

2014-01-01

The number of offshore wind farms will keep increasing in the future as a part of the shift towards a CO2 free energy production. The energy harvested from the wind farm must be brought to shore, which is often done by using a three-phase armoured submarine power cable. The use of an armour...... increases the losses in armoured cables compared to unarmoured cables. In this paper a thorough state of the art analysis is conducted on armour losses in three-phase armoured submarine power cables. The analysis shows that the IEC 60287-1-1 standard overestimates the armour losses which lead...... to the installation of cables with excessive phase conductor cross section. This paper also presents an example of the potential economic benefits of having a better knowledge of the losses introduced by the armour....

Submarine Groundwater Discharge in the Coastal Zone

Science.gov (United States)

Bakti, Hendra

2018-02-01

Indonesia is one of the archipelagic countries that has the longest coastline in the world. Because it is located in the tropics, in general it has a very high rainfall. Each island has a different morphology which is composed of a variety of rocks with different hydrogeological properties. This natural condition allows for the presence of groundwater in different amount in each island. The difference in groundwater hydraulics gradients in aquifer continuous to the sea has triggered the discharge of groundwater to offshore known as submarine groundwater discharge (SGD). Its presence can be as seepage or submarine springs with components derived from land and sea and a mixture between them. The understanding of SGD phenomenon is very important because it can be useful as a source of clean water in coastal areas, affecting marine health, and improving marine environment.

Geology and geomorphology of the Lower Deschutes River Canyon, Oregon.

Science.gov (United States)

Robin A. Beebee; Jim E. O' Connor; Gordon E. Grant

2002-01-01

This field guide is designed for geologists floating the approximately 80 kilometers (50 miles) of the Deschutes River from the Pelton-Round Butte Dam Complex west of Madras to Maupin, Oregon. The first section of the guide is a geologic timeline tracing the formation of the units that compose the canyon walls and the incision of the present canyon. The second section...

Origin of Theater-Headed Tributaries to Escalante and Glen Canyons, Utah: Analogs to Martian Valley Networks

Science.gov (United States)

Irwin, R. P.; Fortezzo, C. M.; Tooth, S. E.; Howard, A. D.; Zimbelman, J. R.; Barnhart, C. J.; Benthem, A. J.; Brown, C. C.; Parsons, R. A.

2008-12-01

Some tributaries to Glen and Escalante Canyons in southern Utah share similar characteristics to typical Martian fluvial valleys, motivating their frequent use as process analogs. In the spring of 2008, we investigated six tributary canyons formed in Navajo sandstone (two branches of Bowns, Explorer, Fence, and two branches of a tributary between the latter two) to test the hypothesis that seepage weathering and erosion are the dominant geomorphic processes. Measurements included spring discharge, pH, and hardness; compressive strength by Schmidt hammer of Navajo and underlying Kayenta beds; Selby bulk strength of Navajo sandstone; discharge estimates for flash floods; size of transported rocks; and vertical profiles of valley headwalls and alcoves. Plateau slickrock surfaces are commonly rounded on 10-100-m length scales and yield abundant runoff, as during rainfall observed on May 21-22. Incision into the Navajo surface by overland flow yields narrow, high-gradient valleys with V-shaped cross-sections; abrasion by sediment and weathering by standing water in closely spaced potholes facilitate downcutting. These small contributing valleys funnel waterfalls over the broad headscarps, forming small plunge pools. Headwalls are largely swept clear of debris relative to sidewalls. Canyon dimensions increase significantly below seeps, and wide alcoves are found only at these locations. We found no significant difference in rock strength at the top and bottom of the Navajo headwalls, suggesting that headscarp retreat requires basal weathering. Diverse weathering processes affect different sections of the headscarp relief. An intermittent waterfall may directly attack the base of an alcove, processes related to vegetation usually affect its lower slope (wetted by seepage from a discrete layer exposed in the deepest zone), and salt weathering often occurs on the roof. Scarps above an alcove are relatively unweathered and retreat primarily by sheet fracturing. The parabolic

The characters of emergency rescue and the measures to prevent accidents for nuclear-powered submarine

International Nuclear Information System (INIS)

Wang Yuexing

1999-01-01

The characteristics of emergency rescue and the measures for preventing and decreasing accidents in nuclear-powered submarine have been presented. The breakdown of equipment and human factors are the main reasons which lead to accidents. Four preventive measures are suggested: enhancing capabilities to take precautions against fire, seriously controlling the environmental factors which affect the health of the submariners, reinforcing the constitutions of the submariners, and working out emergency planning against serious accidents in advance

Environmental analysis of Acid/middle Pueblo Canyon, Los Alamos, New Mexico

International Nuclear Information System (INIS)

Ferenbaugh, R.W.; Buhl, T.E.; Stoker, A.K.; Hansen, W.R.

1982-08-01

The radiological survey of the former radioactive waste treatment plant site (TA-45), Acid Canyon, and Pueblo Canyon found residual radioactivity at the site itself and in the channel and banks of Acid, Pueblo, and lower Los Alamos Canyons, all the way to the Rio Grande. The largest reservoir of radioactive material is in lower Pueblo Canyon, which is on DOE property. The only areas where residual radioactivity exceeds the proposed cleanup criteria are at the former vehicle decontamination facility, located between the former treatment plant site and Acid Canyon, around the former untreated waste outfall and for a short distance below, and in two small areas farther down in Acid Canyon. The three alternatives proposed are (1) to take no action, (2) to fence the areas where the residual radioactivity exceeds the proposed criteria (minimal action), and (3) to clean up the former vehicle decontamination facility and around the former untreated waste outfall. Calculations based on actual measurements indicate that the annual dose at the location having the greatest residual radioactivity would be about 12% of the applicable guideline. Most doses are much smaller than that. No environmental impacts are associated with either the no-action or minimal action alternatives. The impact associated with the cleanup alternative is very small. The preferred alternative is to clean up the areas around the former vehicle decontamination facility and the untreated waste outfall. This course of action is recommended not because of any real danger associated with the residual radioactivity, but rather because the cleanup operation is a minor effort and would conform with the ALARA (as low as reasonably achievable) philosophy

Environmental analysis of Acid/middle Pueblo Canyon, Los Alamos, New Mexico

Energy Technology Data Exchange (ETDEWEB)

Ferenbaugh, R.W.; Buhl, T.E.; Stoker, A.K.; Hansen, W.R.

1982-08-01

The radiological survey of the former radioactive waste treatment plant site (TA-45), Acid Canyon, and Pueblo Canyon found residual radioactivity at the site itself and in the channel and banks of Acid, Pueblo, and lower Los Alamos Canyons, all the way to the Rio Grande. The largest reservoir of radioactive material is in lower Pueblo Canyon, which is on DOE property. The only areas where residual radioactivity exceeds the proposed cleanup criteria are at the former vehicle decontamination facility, located between the former treatment plant site and Acid Canyon, around the former untreated waste outfall and for a short distance below, and in two small areas farther down in Acid Canyon. The three alternatives proposed are (1) to take no action, (2) to fence the areas where the residual radioactivity exceeds the proposed criteria (minimal action), and (3) to clean up the former vehicle decontamination facility and around the former untreated waste outfall. Calculations based on actual measurements indicate that the annual dose at the location having the greatest residual radioactivity would be about 12% of the applicable guideline. Most doses are much smaller than that. No environmental impacts are associated with either the no-action or minimal action alternatives. The impact associated with the cleanup alternative is very small. The preferred alternative is to clean up the areas around the former vehicle decontamination facility and the untreated waste outfall. This course of action is recommended not because of any real danger associated with the residual radioactivity, but rather because the cleanup operation is a minor effort and would conform with the ALARA (as low as reasonably achievable) philosophy.

Morphology and sediment dynamics of the Capbreton canyon (Bay of Biscay, SW France)

Science.gov (United States)

Gaudin, M.; Umr 5805; Ifremer Team

2003-04-01

The Canyon of Capbreton extending in the Bay of Biscay (SW France) is the deepest canyon in the world. Its structure and morphology was studied using new multibeam bathymetry, acoustic imagery and high-resolution seismic data. The canyon head appears only 250 m away from the coast line and runs westward parallel to the north coast of Spain for 160 km due to structural control, then turns northward, widens and abruptly disappears in the continental rise by 3500 m water depth. Its northern margin is flat and progrades clearly westward. Conversely the southern margin is steep and progrades towards the north (i.e. towards the canyon). Down to 800 m water depth, the canyon deeply incises the continental shelf and the axial channel is meandering (sinuosity of 1.9). The canyon shows both major and minor stream beds, perched tributary valleys, nested terraces and abandoned meanders. The terraces have three morphologies: (1) flat, (2) with a raised side or (3) with a horseshoe structure. These morphologies have been interpreted as overbank deposits or nested levees (1 and 2) or as the result of meander abandon (3). Terraces of types (1) and (2) contain mainly fine deposits resulting from decantation of the top of turbulent surges that flow in the canyon. Westward (800 to 2000 m water depth) the main talweg remains sinuous (1.7). On the southern margin, several straight or slightly sinuous S-N tributary valleys are followed by alignments of pockmarks that also indicate a structural control. On the northern margin, a single large tributary valley with a sinuous central talweg, flowing from the upper Aquitaine continental slope, is interpreted as a giant slump scar due to sediment instability. This valley is bordered to the west by a topographic high with sediment waves on the external flank that might be interpreted as a sedimentary levee. The canyon recorded a recent turbidite activity. An 18 cm-thick turbidite was deposited at 650 m water depth by a turbidity current

A sand budget for Marble Canyon, Arizona: implications for long-term monitoring of sand storage change

Science.gov (United States)

Grams, Paul E.

2013-01-01

Recent U.S. Geological Survey research is providing important insights into how best to monitor changes in the amount of tributary-derived sand stored on the bed of the Colorado River and in eddies in Marble Canyon, Arizona. Before the construction of Glen Canyon Dam and other dams upstream, sandbars in Glen, Marble, and Grand Canyons were replenished each year by sediment-rich floods. Sand input into the Colorado River is crucial to protecting endangered native fish, animals, and plants and cultural and recreational resources along the river in Glen Canyon National Recreation Area and Grand Canyon National Park.

Safety Evaluation for Packaging (onsite) T Plant Canyon Items

International Nuclear Information System (INIS)

OBRIEN, J.H.

2000-01-01

This safety evaluation for packaging (SEP) evaluates and documents the ability to safely ship mostly unique inventories of miscellaneous T Plant canyon waste items (T-P Items) encountered during the canyon deck clean off campaign. In addition, this SEP addresses contaminated items and material that may be shipped in a strong tight package (STP). The shipments meet the criteria for onsite shipments as specified by Fluor Hanford in HNF-PRO-154, Responsibilities and Procedures for all Hazardous Material Shipments

Safety Evaluation for Packaging (onsite) T Plant Canyon Items

Energy Technology Data Exchange (ETDEWEB)

OBRIEN, J.H.

2000-07-14

This safety evaluation for packaging (SEP) evaluates and documents the ability to safely ship mostly unique inventories of miscellaneous T Plant canyon waste items (T-P Items) encountered during the canyon deck clean off campaign. In addition, this SEP addresses contaminated items and material that may be shipped in a strong tight package (STP). The shipments meet the criteria for onsite shipments as specified by Fluor Hanford in HNF-PRO-154, Responsibilities and Procedures for all Hazardous Material Shipments.

Data Quality Objectives Summary Report for the 221-U Canyon Disposition Alternatives

International Nuclear Information System (INIS)

Miller, M.S.; Oaces, L.E.; Baxter, J.; Brown, T.M.; Enoke, D.E.; Carlson, D.; Rugg, J.E.

1997-08-01

The 221-U Canyon Disposition Alternatives Data Quality Objective (DQO) Process identifies the sampling and analytical requirements necessary to support future detailed evaluation of alternatives via the CERCLA process, for final disposition of the 221-U Canyon Facility. Viable alternatives for the disposition of the 221-U Facility have been identified in a CERCLA Phase I Feasibility Study (FS) (DOE-RL 1997) for the Canyon Disposition Initiative (CDI). The scope of this DQO Process is limited to the 221-U Process Canyon Building and equipment contained within the facility. Associated stacks, filters, solvent handling, vaults, and storage facilities external to the 221-U Building are not addressed in this DQO. This DQO focuses on the 221-U Building because it provides the greatest potential source of contaminant volumes and concentrations and the physical structure poses the greatest challenge for disposition decisions

Bell Canyon test summary report

International Nuclear Information System (INIS)

Christensen, C.L.; Peterson, E.W.

1981-04-01

The Bell Canyon Test was an in situ evaluation of the ability of a cement grout plug to seal boreholes. It consisted of a 2-m-long, 20-cm-diameter grout plug in an anhydrite formation at a depth of 1370 m, directly above an aquifer that provided a 12.4 MPa (1800 psi) differential pressure. The aquifer had a production capability of 38,000 l/day (240 bbl/day, 10 4 gal/day). The observed leakage after plug installation was 0.6 l/day, which is equivalent to a 50 microdarcy flow path assuming all flow occurred through the plug cross-sectional area. Laboratory results and analysis of field data indicate that the bulk of the flow occurred through a microstructure at the interface between the plug and the host rock. The Bell Canyon Test demonstrated that a plug could be formulated, emplaced, and tested under actual conditions and provide acceptable performance. When these results are related to the WIPP performance assessment models, they provide additional confidence that borehole plugging can be accomplished satisfactorily. The Bell Canyon results can also be used as basis for future activities in the generic repository sealing program for similar emplacements and performance assessment evaluations. If the observed leakage rates are not acceptable at other sites, the BCT results would indicate that the first step in improving such emplacements should deal with improved bonding of the plug to the rock at these sites. The results obtained from the BCT, when coupled with results from long-term durability assessments, form a plug performance data basis for repository designers at other proposed waste repository sites

NDT in submarines construction-HY 80

International Nuclear Information System (INIS)

Russo, C.A.; Talmadge, J.

1988-01-01

In submarines construction, provided that metallurgic characteristics have been established, the NDT methods and equipments as well as the application ways should be taken into account. It is then fundamental purpose of this work to emphasize all that coming from conventional context in the field of use of already known nondestructive techniques

They Have Not Yet Begun to Fight: Women in the United States Navy Submarine Fleet

Science.gov (United States)

2016-03-11

submarine duty could lead to sexual problems aboard ship and marital problems at home .”22 Some argue that wives do not trust women at sea with...enforces the argument that women are here to stay in submarines. While political and military experts continue to debate the roles of women in submarines...ACSC/Meyer, J/FY16 AIR COMMAND AND STAFF COLLEGE AIR UNIVERSITY They Have Not Yet Begun to Fight: Women in the United States

Thermal bioclimate in idealized urban street canyons in Campinas, Brazil

Science.gov (United States)

Abreu-Harbich, Loyde V.; Labaki, Lucila C.; Matzarakis, Andreas

2014-01-01

Among several urban design parameters, the height-to-width ratio (H/W) and orientation are important parameters strongly affecting thermal conditions in cities. This paper quantifies changes in thermal comfort due to typical urban canyon configurations in Campinas, Brazil, and presents urban guidelines concerning H/W ratios and green spaces to adapt urban climate change. The study focuses on thermal comfort issues of humans in urban areas and performs evaluation in terms of physiologically equivalent temperature (PET), based on long-term data. Meteorological data of air temperature, relative humidity, wind speed and solar radiation over a 7-year period (2003-2010) were used. A 3D street canyon model was designed with RayMan Pro software to simulate the influence of urban configuration on urban thermal climate. The following configurations and setups were used. The model canyon was 500 m in length, with widths 9, 21, and 44 m. Its height varied in steps of 2.5 m, from 5 to 40 m. The canyon could be rotated in steps of 15°. The results show that urban design parameters such as width, height, and orientation modify thermal conditions within street canyons. A northeast-southwest orientation can reduce PET during daytime more than other scenarios. Forestry management and green areas are recommended to promote shade on pedestrian areas and on façades, and to improve bioclimate thermal stress, in particular for H/W ratio less than 0.5. The method and results can be applied by architects and urban planners interested in developing responsive guidelines for urban climate issues.

75 FR 27550 - Electrical Interconnection of the Juniper Canyon I Wind Project

Science.gov (United States)

2010-05-17

... DEPARTMENT OF ENERGY Bonneville Power Administration Electrical Interconnection of the Juniper Canyon I Wind Project AGENCY: Bonneville Power Administration (BPA), Department of Energy (DOE). ACTION... would be generated from their proposed Juniper Canyon I Wind Energy Project (Wind Project) in Klickitat...

Numerical modeling of the late Cenozoic geomorphic evolution of Grand Canyon, Arizona

Science.gov (United States)

Pelletier, J. D.

2008-12-01

The late Cenozoic geomorphic evolution of Grand Canyon has been influenced by three primary tectonic and drainage adjustment events. First, incision into the Paleozoic strata of the southwestern margin of the Colorado Plateau began at 16 Ma in response to relief production along the Grand Wash Fault. Second, the ancestral Upper Colorado River reversed drainage and became integrated with the Lower Colorado River basin through Grand Canyon between 5.5 and 6 Ma. Third, the Colorado River was influenced by Plio- Quaternary normal faulting along the Hurricane and Toroweap Faults. Despite the relatively firm constraints available on the timing of these events, the geomorphic evolution of Grand Canyon is still not well constrained and many questions remain. For example, was there a deeply-incised gorge in western Grand Canyon before Colorado River integration? How and where was the Colorado River integrated? How have incision rates varied in space and time? In this paper, I describe the results of a numerical modeling study designed to address these questions. The model integrates the stream power model for bedrock channel erosion with cliff retreat and the flexural-isostatic response to erosion. The model honors the structural geology of the Grand Canyon region, including the variable erodibility of rocks in the Colorado Plateau and the occurrence of Plio-Quaternary normal faulting along the Hurricane-Toroweap Fault system. We present the results of two models designed to bracket the possible drainage architectures of the southwestern margin of the Colorado Plateau in Miocene time. In the first model, we assume a 13,000 km2 drainage basin primarily sourced from the Hualapai and Coconino Plateaux. The results of this model indicate that relief production along the Grand Wash fault initiated the formation of a large (700 m) knickpoint that migrated headward at a rate of 15 km/Myr prior to drainage integration at 6 Ma to form a deep gorge in western Grand Canyon. This model

Diablo Canyon plant information management system and integrated communication system

International Nuclear Information System (INIS)

Stanley, J.W.; Groff, C.

1990-01-01

The implementation of a comprehensive maintenance system called the plant information management system (PIMS) at the Diablo Canyon plant, together with its associated integrated communication system (ICS), is widely regarded as the most comprehensive undertaking of its kind in the nuclear industry. This paper provides an overview of the program at Diablo Canyon, an evaluation of system benefits, and highlights the future course of PIMS

Diablo Canyon plant information management system and integrated communication system

Energy Technology Data Exchange (ETDEWEB)

Stanley, J.W.; Groff, C.

1990-06-01

The implementation of a comprehensive maintenance system called the plant information management system (PIMS) at the Diablo Canyon plant, together with its associated integrated communication system (ICS), is widely regarded as the most comprehensive undertaking of its kind in the nuclear industry. This paper provides an overview of the program at Diablo Canyon, an evaluation of system benefits, and highlights the future course of PIMS.

Nuclear submarine utilization. Financial deadlock and search for its output

International Nuclear Information System (INIS)

Dovgusha, V.V.; Tikhonov, M.N.

1995-01-01

Program of nuclear submarine utilization in the Russian Federation is described. The program provides for complete solution of all problems, connected with nuclear submarine utilization, including reconstruction of ship-repair and ship-cutting plants, metal fabrication plants, construction of points of temporary radioactive waste storages, new burials, as well as required social support of personnel, working under unhealthy conditions. The program is based on guaranteed and sufficient financing from extra-budgetary sources, as well as on new technologies, enabling to utilize all written off ships during 10-15 years

Subjective Symptomology and Postural Control During Simulation of a Survival Environmemt Aboard a Disabled Submarine

National Research Council Canada - National Science Library

Cymerman, Allen

2000-01-01

Subjective symptoms and postural control were assessed in 7 submariners during 5 days exposure to a simulated disabled submarine environment (DISSUB) (4C, 2.5% carbon dioxide, 16.75% oxygen, 85% humidity...

Collection of Arctic Ocean Data from US Navy Submarines on the New SCICEX Program

Science.gov (United States)

Smethie, W. M.; Sambrotto, R.; Boyd, T.; Richter-Menge, J.; Corbett, J.

2011-12-01

The SCICEX submarine Arctic science program originated in the 1990s when six dedicated science cruises were conducted in the Arctic Ocean aboard US Navy Sturgeon class submarines. After the cold war era Sturgeon class submarines were retired, several Science Accommodation cruises, for which a few days for scientific measurements were added to planned submarine transits through the Arctic Ocean, were carried out when opportunities arose. Renewed interest in conducting further Science Accommodation cruises on a regular basis to better document and understand how the Arctic Ocean responds to climate change resulted in publication of a scientific plan in 2010 (http://www.arctic.gov/publications/scicex_plan.pdf). In the spring of 2011 testing of data collection and water sampling methods aboard newer Virginia and Seawolf class submarines on transit from a Navy ice camp in the Beaufort Sea, was conducted in order to develop protocols and evaluate techniques. Ice draft measurements were also taken in the vicinity of the ice camp and near the North Pole to evaluate new data collection systems. This evaluation will include a comparison of the ice draft data with a comprehensive set of in situ ice thickness measurements taken near the ice camp. Under-ice submarine-launched eXpendable Condutivity Temperature Depth (XCTD) probes were deployed from the USS Connecticut (SSN-22), a Seawolf class submarine, and the resulting profiles compared to CTD casts from the APLIS ice station and historical profiles. Water samples were collected through the hull for measurements of tritium, helium isotopes, oxygen isotopes, chlorofluorocarbons, sulfur hexafluoride, nutrients, dissolved organic carbon, bacterioplankton, phytoplankton and particulates levels. These samples were returned to Lamont-Doherty Earth Observatory and were in the process of being measured at the time this abstract was written. Measurements completed at this time indicate good samples can be collected for CFC-12

Study of line source characteristics for 2-D physical modelling of pollutant dispersion in street canyons

Energy Technology Data Exchange (ETDEWEB)

Meroney, Robert N. [Fluid Mechanics and Wind Engineering Program, Civil Engineering Department, Colorado State University Fort Collins, CO (United States); Pavageau, Michel; Rafailidis, Stilianos; Schatzmann, Michael [Meteorologisches Institut, Universitaet Hamburg, Hamburg (Germany)

1996-08-01

The University of Hamburg initiated a wind tunnel study of car exhaust dispersion from street canyons in an urban environment to investigate how pollution dispersion is affected by street geometry. Particular emphasis at the beginning of this work was put on the design of a line source to represent traffic exhaust. Pollution dispersion was studied in two dimensions (i.e., infinite-length streets were assumed). The case of an isolated street canyon in open country was examined first. The same street canyon geometry was subsequently studied in an urban environment, i.e., with additional canyons of similar geometry upstream and downstream of the test street. The dynamic and dispersion characteristics of the flow in the two cases were quite different. In the canyon amidst open country we observed better canyon ventilation than in the urban roughness case

German Submarine Offensives and South African Countermeasures

African Journals Online (AJOL)

Evert

Scientia Militaria vol 44, no 1, 2016, pp 168-189. doi: 10.5787/44-1-1166 ..... report the presence of a body of German submarines moving south towards Cape Town. Despite ...... London: Arms and Armour Press, 1989, 100–101; Keegan op.

Review of the Diablo Canyon probabilistic risk assessment

International Nuclear Information System (INIS)

Bozoki, G.E.; Fitzpatrick, R.G.; Bohn, M.P.; Sabek, M.G.; Ravindra, M.K.; Johnson, J.J.

1994-08-01

This report details the review of the Diablo Canyon Probabilistic Risk Assessment (DCPRA). The study was performed under contract from the Probabilistic Risk Analysis Branch, Office of Nuclear Reactor Research, USNRC by Brookhaven National Laboratory. The DCPRA is a full scope Level I effort and although the review touched on all aspects of the PRA, the internal events and seismic events received the vast majority of the review effort. The report includes a number of independent systems analyses sensitivity studies, importance analyses as well as conclusions on the adequacy of the DCPRA for use in the Diablo Canyon Long Term Seismic Program

Feral Cattle in the White Rock Canyon Reserve at Los Alamos National Laboratory

Energy Technology Data Exchange (ETDEWEB)

Hathcock, Charles D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hansen, Leslie A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2014-03-27

At the request of the Los Alamos Field Office (the Field Office), Los Alamos National Security (LANS) biologists placed remote-triggered wildlife cameras in and around the mouth of Ancho Canyon in the White Rock Canyon Reserve (the Reserve) to monitor use by feral cattle. The cameras were placed in October 2012 and retrieved in January 2013. Two cameras were placed upstream in Ancho Canyon away from the Rio Grande along the perennial flows from Ancho Springs, two cameras were placed at the north side of the mouth to Ancho Canyon along the Rio Grande, and two cameras were placed at the south side of the mouth to Ancho Canyon along the Rio Grande. The cameras recorded three different individual feral cows using this area as well as a variety of local native wildlife. This report details our results and issues associated with feral cattle in the Reserve. Feral cattle pose significant risks to human safety, impact cultural and biological resources, and affect the environmental integrity of the Reserve. Regional stakeholders have communicated to the Field Office that they support feral cattle removal.

Sediment transport along the Cap de Creus Canyon flank during a mild, wet winter

Directory of Open Access Journals (Sweden)

J. Martín

2013-05-01

Full Text Available Cap de Creus Canyon (CCC is known as a preferential conduit for particulate matter leaving the Gulf of Lion continental shelf towards the slope and the basin, particularly in winter when storms and dense shelf water cascading coalesce to enhance the seaward export of shelf waters. During the CASCADE (CAscading, Storm, Convection, Advection and Downwelling Events cruise in March 2011, deployments of recording instruments within the canyon and vertical profiling of the water column properties were conducted to study with high spatial-temporal resolution the impact of such processes on particulate matter fluxes. In the context of the mild and wet 2010–2011 winter, no remarkable dense shelf water formation was observed. On the other hand, the experimental setup allowed for the study of the impact of E-SE storms on the hydrographical structure and the particulate matter fluxes in the CCC. The most remarkable feature in terms of sediment transport was a period of dominant E-SE winds from 12 to 16 March, including two moderate storms (maximum significant wave heights = 4.1–4.6 m. During this period, a plume of freshened, relatively cold and turbid water flowed at high speeds along the southern flank of the CCC in an approximate depth range of 150–350 m. The density of this water mass was lighter than the ambient water in the canyon, indicating that it did not cascade off-shelf and that it merely downwelled into the canyon forced by the strong cyclonic circulation induced over the shelf during the storms and by the subsequent accumulation of seawater along the coast. Suspended sediment load in this turbid intrusion recorded along the southern canyon flank oscillated between 10 and 50 mg L−1, and maximum currents speeds reached values up to 90 cm s−1. A rough estimation of 105 tons of sediment was transported through the canyon along its southern wall during a 3-day-long period of storm-induced downwelling. Following the veering of the wind

A Helicopter submarine Search Game

Science.gov (United States)

1988-09-01

Figure 3. Graphical representation of Baston and Bostock ................. 10 Figure 4. Dips and Speed Circle...dimen.ional helicopter submarine gaines studied by Meinardi [Ref. 7] and more recently by Baston and Bostock [Ref. 8]. Meinardi solves a discr,-te form of...the game while Baston and Bostock solve the continuous case. Bes.ides Danskin’s game, not much work has been done on the two dimensional case except

Health Risks Among Submarine Personnel in the U.S. Navy, 1974-1979

Science.gov (United States)

1986-12-11

observed dif- ferences in hospitalization rates ( Lilienfeld , 1980). T- tests were used to assess statistical significance of the descriptive variables...the direct method of adjustment ( Lilienfeld , 1980). The standard population was the sum of the two groups. Age-adjusted rates for submariners and...must undergo stringent psychological and medical screening prior to assignment aboard a nuclear submarine because of the relatively long periods of

Relativistic Archimedes law for fast moving bodies and the general-relativistic resolution of the 'submarine paradox'

International Nuclear Information System (INIS)

Matsas, George E. A.

2003-01-01

We investigate and solve in the context of general relativity the apparent paradox which appears when bodies floating in a background fluid are set in relativistic motion. Suppose some macroscopic body, say, a submarine designed to lie just in equilibrium when it rests (totally) immersed in a certain background fluid. The puzzle arises when different observers are asked to describe what is expected to happen when the submarine is given some high velocity parallel to the direction of the fluid surface. On the one hand, according to observers at rest with the fluid, the submarine would contract and, thus, sink as a consequence of the density increase. On the other hand, mariners at rest with the submarine using an analogous reasoning for the fluid elements would reach the opposite conclusion. The general relativistic extension of the Archimedes law for moving bodies shows that the submarine sinks. As an extra bonus, this problem suggests a new gedankenexperiment for the generalized second law of thermodynamics

The impact of traffic-flow patterns on air quality in urban street canyons

International Nuclear Information System (INIS)

Thaker, Prashant; Gokhale, Sharad

2016-01-01

We investigated the effect of different urban traffic-flow patterns on pollutant dispersion in different winds in a real asymmetric street canyon. Free-flow traffic causes more turbulence in the canyon facilitating more dispersion and a reduction in pedestrian level concentration. The comparison of with and without a vehicle-induced-turbulence revealed that when winds were perpendicular, the free-flow traffic reduced the concentration by 73% on the windward side with a minor increase of 17% on the leeward side, whereas for parallel winds, it reduced the concentration by 51% and 29%. The congested-flow traffic increased the concentrations on the leeward side by 47% when winds were perpendicular posing a higher risk to health, whereas reduced it by 17–42% for parallel winds. The urban air quality and public health can, therefore, be improved by improving the traffic-flow patterns in street canyons as vehicle-induced turbulence has been shown to contribute significantly to dispersion. - Highlights: • CFD is used to study impact of traffic-flow patterns on urban air quality. • Facilitating free-flow patterns induce more turbulence in street canyons. • Traffic-generated turbulence alters pollutant levels in urban street canyons. - This study investigates the effect of vehicle-induced-turbulence generated during free-flow traffic pattern in reduction of air pollutant concentrations in urban street canyons.

Validation of a two-dimensional pollutant dispersion model in an isolated street canyon

Energy Technology Data Exchange (ETDEWEB)

Chan, T.L.; Dong, G.; Leung, C.W.; Cheung, C.S. [The Hong Kong Polytechnic University, Kowloon (Hong Kong). Research Centre for Combustion and Pollution Control, Department of Mechanical Engineering; Hung, W.T. [The Hong Kong Polytechnic University, Kowloon (Hong Kong). Department of Civil and Structural Engineering

2002-07-01

A two-dimensional numerical model based on Reynolds-averaged Navier-Stokes equations coupled with a series of standard, Renormalization Group (RNG) and realizable k-{epsilon} turbulence models was developed to simulate the fluid-flow development and pollutant dispersion within an isolated street canyon using the FLUENT code. In the present study, the validation of the numerical model was evaluated using an extensive experimental database obtained from the atmospheric boundary layer wind tunnel at the Meteorological Institute of Hamburg University, Germany (J. Wind Eng. Ind. Aerodyn. 62 (1996) 37). Among the studied turbulence models, the RNG k-{epsilon} turbulence model was found to be the most optimum turbulence model coupled with the two-dimensional street canyon model developed in the present study. Both the calculated and measured dimensionless pollutant concentrations have been shown to be less dependent on the variation of wind speed and source strength conditions for the studied street canyon aspect ratio of the B/H=1 case. However, the street canyon configuration has significant influence on the pollutant dispersion. The wider street and lower height of the buildings are favorable to pollutant dilution within the street canyon. The fluid-flow development has demonstrated that the rotative vortex or vortices generated within the urban street canyon can transport the pollutants from a line source to the wall surfaces of the buildings. (author)

A Numerical Study on the Effects of Street‒canyon Aspect‒ratio on Reactive Pollutant Dispersion

Science.gov (United States)

Park, S. J.; Kim, J.

2014-12-01

In this study, the effects of street‒canyon aspect‒ratio on reactive pollutant dispersion were investigated using the coupled CFD‒chemistry model. For this, flow characteristics were analyzed first in street canyons with different aspect ratios and flow regimes were classified according to the building height. For each flow regime, dispersion characteristics were investigated in views of reactive pollutant concentration and VOCs‒NOX ratio. Finally, the relations between pollutant concentration and aspect ratio in urban street canyons were investigated. In the case of H/S = 1.0 (H is building height and S is street width), one clockwise‒rotating vortex appeared vertically and the reverse and outward flows were dominant near the street bottom. In the case of H/S = 2.0, two counter‒rotating vortices appeared vertically in the street canyon. The primary (secondary) vortex rotating clockwise (counterclockwise) was formed in upper (lower) layer. The flow patterns affected the reactive pollutant concentration in street canyons. As building height increased, mean concentration of NO decreased when one vortex was generated in street canyons and increased when two vortexes appeared in street canyons. O3 concentration showed almost contrasted tendency with those of NO because O3 was depleted by the NO titration.

Vegetative communities, Davis and Lavender Canyons, Paradox Basin, Utah: ecosystem studies

International Nuclear Information System (INIS)

1983-04-01

The major vegetative communities of Davis and Lavender canyons located in southeastern Utah are characterized. The report identifies potential secondary impacts and appropriate mitigation options. The Davis Canyon and Lavender Canyon Study Area contains nine major vegetative communities: galleta-shadscale, juniper-blackbrush, juniper-shadscale-ephedra, shadscale-ephedra, grayia-shadscale, juniper, drywash, greasewood, and riparian. The natural recovery times of these communities are exceedingly long. Natural reinvasion of various species would take from 15 to 100 years. No threatened or endangered plant species were identified in the study area. Davis and Lavender canyons have been subject to off-road vehicle activity and extensive grazing. The plant communities may be subject to additional impacts as a result of increased human activity and off-highway activities such as camping, hiking, and hunting could result in changes in cover, composition, and frequency of plant species. Mitigation options for potential impacts include shuttle-busing workers to the site from the highway and fencing site access roads to prevent vehicles from leaving the roads

Fluctuating helical asymmetry and morphology of snails (Gastropoda in divergent microhabitats at 'Evolution Canyons I and II,' Israel.

Directory of Open Access Journals (Sweden)

Shmuel Raz

Full Text Available Developmental instability of shelled gastropods is measured as deviations from a perfect equiangular (logarithmic spiral. We studied six species of gastropods at 'Evolution Canyons I and II' in Carmel and the Galilee Mountains, Israel, respectively. The xeric, south-facing, 'African' slopes and the mesic, north-facing, 'European' slopes have dramatically different microclimates and plant communities. Moreover, 'Evolution Canyon II' receives more rainfall than 'Evolution Canyon I.'We examined fluctuating asymmetry, rate of whorl expansion, shell height, and number of rotations of the body suture in six species of terrestrial snails from the two 'Evolution Canyons.' The xeric 'African' slope should be more stressful to land snails than the 'European' slope, and 'Evolution Canyon I' should be more stressful than 'Evolution Canyon II.' Only Eopolita protensa jebusitica showed marginally significant differences in fluctuating helical asymmetry between the two slopes. Contrary to expectations, asymmetry was marginally greater on the 'European' slope. Shells of Levantina spiriplana caesareana at 'Evolution Canyon I,' were smaller and more asymmetric than those at 'Evolution Canyon II.' Moreover, shell height and number of rotations of the suture were greater on the north-facing slopes of both canyons.Our data is consistent with a trade-off between drought resistance and thermoregulation in snails; Levantina was significantly smaller on the 'African' slope, for increasing surface area and thermoregulation, while Eopolita was larger on the 'African' slope, for reducing water evaporation. In addition, 'Evolution Canyon I' was more stressful than Evolution Canyon II' for Levantina.

Safety analysis -- 200 Area Savannah River Plant, F-Canyon Operations. Supplement 4

Energy Technology Data Exchange (ETDEWEB)

Beary, M.M.; Collier, C.D.; Fairobent, L.A.; Graham, R.F.; Mason, C.L.; McDuffee, W.T.; Owen, T.L.; Walker, D.H.

1986-02-01

The F-Canyon facility is located in the 200 Separations Area and uses the Purex process to recover plutonium from reactor-irradiated uranium. The irradiated uranium is normally in the form of solid or hollow cylinders called slugs. These slugs are encased in aluminum cladding and are sent to the F-Canyon from the Savannah River Plant (SRP) reactor areas or from the Receiving Basin for Offsite Fuels (RBOF). This Safety Analysis Report (SAR) documents an analysis of the F-Canyon operations and is an update to a section of a previous SAR. The previous SAR documented an analysis of the entire 200 Separations Area operations. This SAR documents an analysis of the F-Canyon and is one of a series of documents for the Separations Area as specified in the Savannah River Implementation Plans. A substantial amount of the information supporting the conclusions of this SAR is found in the Systems Analysis. Some F-Canyon equipment has been updated during the time between the Systems Analysis and this SAR and a complete description of this equipment is included in this report. The primary purpose of the analysis was to demonstrate that the F-Canyon can be operated without undue risk to onsite or offsite populations and to the environment. In this report, risk is defined as the expected frequency of an accident, multiplied by the resulting radiological consequence in person-rem. The units of risk for radiological dose are person-rem/year. Maximum individual exposure values have also been calculated and reported.

Decompression illness in goats following simulated submarine escape: 1993-2006.

Science.gov (United States)

Seddon, F M; Thacker, J C; Fisher, A S; Jurd, K M; White, M G; Loveman, G A M

2014-01-01

The United Kingdom Ministry of Defence commissioned work to define the relationship between the internal pressure of a distressed submarine (DISSUB), the depth from which escape is made and the risk of decompression illness (DCI). The program of work used an animal model (goat) to define these risks and this paper reports the incidence and type of DCI observed. A total of 748 pressure exposures comprising saturation only, escape only or saturation followed by escape were conducted in the submarine escape simulator between 1993 and 2006. The DCI following saturation exposures was predominantly limb pain, whereas following escape exposures the DCI predominantly involved the central nervous system and was fast in onset. There was no strong relationship between the risk of DCI and the range of escape depths investigated. The risk of DCI incurred from escape following saturation was greater than that obtained by combining the risks for the independent saturation only, and escape only, exposures. The output from this program of work has led to improved advice on the safety of submarine escape.

Large-Eddy Simulation of Flow and Pollutant Transport in Urban Street Canyons with Ground Heating

Science.gov (United States)

Li, Xian-Xiang; Britter, Rex E.; Koh, Tieh Yong; Norford, Leslie K.; Liu, Chun-Ho; Entekhabi, Dara; Leung, Dennis Y. C.

2010-11-01

Our study employed large-eddy simulation (LES) based on a one-equation subgrid-scale model to investigate the flow field and pollutant dispersion characteristics inside urban street canyons. Unstable thermal stratification was produced by heating the ground of the street canyon. Using the Boussinesq approximation, thermal buoyancy forces were taken into account in both the Navier-Stokes equations and the transport equation for subgrid-scale turbulent kinetic energy (TKE). The LESs were validated against experimental data obtained in wind-tunnel studies before the model was applied to study the detailed turbulence, temperature, and pollutant dispersion characteristics in the street canyon of aspect ratio 1. The effects of different Richardson numbers ( Ri) were investigated. The ground heating significantly enhanced mean flow, turbulence, and pollutant flux inside the street canyon, but weakened the shear at the roof level. The mean flow was observed to be no longer isolated from the free stream and fresh air could be entrained into the street canyon at the roof-level leeward corner. Weighed against higher temperature, the ground heating facilitated pollutant removal from the street canyon.

77 FR 8895 - Jimbilnan, Pinto Valley, Black Canyon, Eldorado, Ireteba Peaks, Nellis Wash, Spirit Mountain, and...

Science.gov (United States)

2012-02-15

..., Pinto Valley, Black Canyon, Eldorado, Ireteba Peaks, Nellis Wash, Spirit Mountain, and Bridge Canyon..., Eldorado, Ireteba Peaks, Nellis Wash, Spirit Mountain, and Bridge Canyon Wilderness Areas, Lake Mead... wilderness character; providing for reasonable use of Spirit Mountain and adjacent areas in a manner meeting...

Parametric study of the dispersion aspects in a street-canyon area

Energy Technology Data Exchange (ETDEWEB)

Koutsourakis, N.; Neofytou, P.; Venetsanos, A.G.; Bartzis, J.G. [NCSR Demokritos (Greece). Environmental Research Lab.

2004-07-01

Continuously increasing vehicles' fleet is still considered to be the main emission factor in urban environments, despite the enormous progress of modern catalytic technology. Under that perspective, calculation of transportation induced pollutant dispersion is of augmented importance, especially within street canyons, where poor ventilation can result in awkward concentration levels. Computational Fluid Dynamics (CFD) studies have been conducted in the past by Neofytou, P. et al, so as to define appropriate locations for measuring-instrument placement by numerically simulating the flow and pollution dispersion fields in the vicinity of the measuring site taking into account the wind rose of the area and selecting locations of high pollution concentrations so that non-zero indications are assured. Vardoulakis, S. et al, provides a general overview of the street-canyon studies concerning both modelling and experimental investigations and offers plenty of references on air quality within street canyons. Besides air-quality, street canyon CFD studies have also been performed to evaluate accident consequences and hydrogen safety, Venetsanos A. et al. The current study examines a real street canyon in Thessaloniki, Greece. It was performed in order to examine dispersion patterns for different parameters' scenarios and help deciding where to place actual pollutant measurement instruments to better capture traffic pollution data. Various wind directions and speeds are examined and height influence on concentration levels is investigated. Complex area geometry is a key factor of the whole study. (orig.)

Carbonaceous aerosol particles from common vegetation in the Grand Canyon

International Nuclear Information System (INIS)

Hallock, K.A.; Mazurek, M.A.; Cass, G.R.

1992-05-01

The problem of visibility reduction in the Grand Canyon due to fine organic aerosol particles in the atmosphere has become an area of increased environmental concern. Aerosol particles can be derived from many emission sources. In this report, we focus on identifying organic aerosols derived from common vegetation in the Grand Canyon. These aerosols are expected to be significant contributors to the total atmospheric organic aerosol content. Aerosol samples from living vegetation were collected by resuspension of surface wax and resin components liberated from the leaves of vegetation common to areas of the Grand Canyon. The samples were analyzed using high-resolution gas chromatography/mass spectrometry (GC/MS). Probable identification of compounds was made by comparison of sample spectra with National Institute of Standards and Technology (NIST) mass spectral references and positive identification of compounds was made when possible by comparison with authentic standards as well as NIST references. Using these references, we have been able to positively identify the presence of n-alkane and n-alkanoic acid homolog series in the surface waxes of the vegetation sampled. Several monoterpenes, sesquiterpenes, and diterpenes were identified also as possible biogenic aerosols which may contribute to the total organic aerosol abundance leading to visibility reduction in the Grand Canyon

The urban canyon and building energy use: Urban density versus daylight and passive solar gains

DEFF Research Database (Denmark)

Strømann-Andersen, Jakob Bjørn; Sattrup, Peter Andreas

2011-01-01

.It was found that the geometry of urban canyons has an impact on total energy consumption in the range of up to +30% for offices and +19% for housing, which shows that the geometry of urban canyons is a key factor in energy use in buildings. It was demonstrated how the reflectivity of urban canyons plays...

Environmental isotopic and hydrochemical study of the coastal submarine springs in Lebanon and Syria

International Nuclear Information System (INIS)

Al-Charideh, A. R.

2007-08-01

The groundwater of major karst system and the submarine springs in the Syrian coastal limestone aquifer have been studied using chemical and isotopic techniques. Stable isotopes show that the groundwater and submarine springs originates from the direct infiltration of atmospheric water. The elevation of recharge zones feeding the Banyas area (400-600 m a.s.l). The δ 18 O e xtracted for the major submarine spring at Bassieh suggests a mean recharge area elevation of 600-700 m a.s.l. Based on the measured velocity and percentage of fresh water at the submarine springs outlet (Bassieh and Tartous), the estimated discharge rate is 350 million m 3 /y. Adopting a model with exponential time distribution, the mean turnover time of groundwater in the Al-sen spring was evaluated to be 60 years. A value of about 3.7 billion m 3 was obtained for the maximum groundwater reservoir size.(Author)

Alteration of submarine volcanic rocks in oxygenated Archean oceans

Science.gov (United States)

Ohmoto, H.; Bevacqua, D.; Watanabe, Y.

2009-12-01

Most submarine volcanic rocks, including basalts in diverging plate boundaries and andesites/dacites in converging plate boundaries, have been altered by low-temperature seawater and/or hydrothermal fluids (up to ~400°C) under deep oceans; the hydrothermal fluids evolved from shallow/deep circulations of seawater through the underlying hot igneous rocks. Volcanogenic massive sulfide deposits (VMSDs) and banded iron formations (BIFs) were formed by mixing of submarine hydrothermal fluids with local seawater. Therefore, the behaviors of various elements, especially of redox-sensitive elements, in altered submarine volcanic rocks, VMSDs and BIFs can be used to decipher the chemical evolution of the oceans and atmosphere. We have investigated the mineralogy and geochemistry of >500 samples of basalts from a 260m-long drill core section of Hole #1 of the Archean Biosphere Drilling Project (ABDP #1) in the Pilbara Craton, Western Australia. The core section is comprised of ~160 m thick Marble Bar Chert/Jasper Unit (3.46 Ga) and underlying, inter-bedded, and overlying submarine basalts. Losses/gains of 65 elements were quantitatively evaluated on the basis of their concentration ratios against the least mobile elements (Ti, Zr and Nb). We have recognized that mineralogical and geochemical characteristics of many of these samples are essentially the same as those of hydrothermally-altered modern submarine basalts and also those of altered volcanic rocks that underlie Phanerozoic VMSDs. The similarities include, but are not restricted to: (1) the alteration mineralogy (chlorite ± sericite ± pyrophyllite ± carbonates ± hematite ± pyrite ± rutile); (2) the characteristics of whole-rock δ18O and δ34S values; (3) the ranges of depletion and enrichment of Si, Al, Mg, Ca, K, Na, Fe, Mn, and P; (4) the enrichment of Ba (as sulfate); (5) the increases in Fe3+/Fe2+ ratios; (6) the enrichment of U; (7) the depletion of Cr; and (8) the negative Ce anomalies. Literature data

The Italian Submarine Force in the Battle of the Atlantic: Left in the Dark

Science.gov (United States)

2014-12-12

ADM Admiral ASW Anti-submarine warfare BDA Battle damage assessment C2 Command and Control CDR Commander HF/DF High frequency direction finder...damage assessment ( BDA ) if you will, the submarine captain decided if further action might be warranted, and made a decision as to how to engage

Captured in Stone: Women in the Rock Art of Canyon de Chelly.

Science.gov (United States)

Travis, Tara

1997-01-01

Describes the pictographs (painted images on stone) and petroglyphs (pecked images on stone) found in the Canyon de Chelly National Monument in Arizona. Canyon de Chelly includes one of the largest concentrations of American Indian rock art in the southwest. Discusses the depiction of women in these images. (MJP)

Trees as environmental modifier to improve street canyon for pedestrian activities in Muscat

Science.gov (United States)

Khudhayer, Wael A.; Shaaban, Awni K.; Sukor, Nur Sabahiah Abdul

2017-10-01

Street shading efficiency is a function of orientation and profile proportion of its height to width. Under high sun altitude conditions, minimization of solar irradiance within the urban environment may often be a significant criterion in urban design. This reduction in solar irradiance achieved when the obstruction angle is large (high H/W ratio, H=height, W=width). High H/W values often lessen the solar access to streets. The horizontal sprawl of Muscat region is an example of low H/W ratio represented the remarkable challenge that causes the lack of shading rates in the urban street. This characteristic proliferates the negative impact on the pedestrian activities in the urban street. This research aims to improve the morphology of the street to promote the pedestrian behavior. The amendment based on suggesting different configurations of trees to increase effective shading of the urban street in Muscat. The street canyon abstracted into a virtual elongated channel formed of floor and walls of equal heights on both sides. Four street orientations (E/W, N/S, NE/SW, NW/SE) and three H/W ratio (0.5,1 and 2) are considered sufficient representative of street typologies. A mathematical model developed for calculation of shading efficiency of each street canyon. The trees assumed in this study as canyon's modifier to adjust the low H/W ratio of a street canyon to a higher one. Local trees and other plants in Muscat were studied concerning their morphology. The analysis selected two case study in Muscat to investigate the shading performance of their street canyons subsequently propose the modifications to improve it. The research concluded that the suggested changes of the street canyon by using a particular type of trees could increase the H/W ratio of street canyon significantly.

Wind tunnel simulation of air pollution dispersion in a street canyon.

Science.gov (United States)

Civis, Svatopluk; Strizík, Michal; Janour, Zbynek; Holpuch, Jan; Zelinger, Zdenek

2002-01-01

Physical simulation was used to study pollution dispersion in a street canyon. The street canyon model was designed to study the effect of measuring flow and concentration fields. A method of C02-laser photoacoustic spectrometry was applied for detection of trace concentration of gas pollution. The advantage of this method is its high sensitivity and broad dynamic range, permitting monitoring of concentrations from trace to saturation values. Application of this method enabled us to propose a simple model based on line permeation pollutant source, developed on the principle of concentration standards, to ensure high precision and homogeneity of the concentration flow. Spatial measurement of the concentration distribution inside the street canyon was performed on the model with reference velocity of 1.5 m/s.

Origin of Abiotic Methane in Submarine Hydrothermal Systems

Science.gov (United States)

Seewald, J. S.; German, C. R.; Grozeva, N. G.; Klein, F.; McDermott, J. M.; Ono, S.; Reeves, E. P.; Wang, D. T.

2018-05-01

Results of recent investigations into the chemical and isotopic composition of actively venting submarine hydrothermal fluids and volatile species trapped in fluid inclusions will be discussed in the context of processes responsible for abiotic CH4 formation.

Environmental assessment of submarine power cables

Energy Technology Data Exchange (ETDEWEB)

Isus, Daniel; Martinez, Juan D. [Grupo General Cable Sistemas, S.A., 08560-Manlleu, Barcelona (Spain); Arteche, Amaya; Del Rio, Carmen; Madina, Virginia [Tecnalia Research and Innovation, 20009 San Sebastian (Spain)

2011-03-15

Extensive analyses conducted by the European Community revealed that offshore wind energy have relatively benign effects on the marine environment by comparison to other forms of electric power generation [1]. However, the materials employed in offshore wind power farms suffer major changes to be confined to the marine environment at extreme conditions: saline medium, hydrostatic pressure... which can produce an important corrosion effect. This phenomenon can affect on the one hand, to the material from the structural viewpoint and on the other hand, to the marine environment. In this sense, to better understand the environmental impacts of generating electricity from offshore wind energy, this study evaluated the life cycle assessment for some new designs of submarine power cables developed by General Cable. To achieve this goal, three approaches have been carried out: leaching tests, eco-toxicity tests and Life Cycle Assessment (LCA) methodologies. All of them are aimed to obtaining quantitative data for environmental assessment of selected submarine cables. LCA is a method used to assess environmental aspects and potential impacts of a product or activity. LCA does not include financial and social factors, which means that the results of an LCA cannot exclusively form the basis for assessment of a product's sustainability. Leaching tests results allowed to conclude that pH of seawater did not significantly changed by the presence of submarine three-core cables. Although, it was slightly higher in case of broken cable, pH values were nearly equals. Concerning to the heavy metals which could migrate to the aquatic medium, there were significant differences in both scenarios. The leaching of zinc is the major environmental concern during undersea operation of undamaged cables whereas the fully sectioned three-core cable produced the migration of significant quantities of copper and iron apart from the zinc migrated from the galvanized steel. Thus, the tar

Environmental assessment of submarine power cables

International Nuclear Information System (INIS)

Isus, Daniel; Martinez, Juan D.; Arteche, Amaya; Del Rio, Carmen; Madina, Virginia

2011-03-01

Extensive analyses conducted by the European Community revealed that offshore wind energy have relatively benign effects on the marine environment by comparison to other forms of electric power generation [1]. However, the materials employed in offshore wind power farms suffer major changes to be confined to the marine environment at extreme conditions: saline medium, hydrostatic pressure... which can produce an important corrosion effect. This phenomenon can affect on the one hand, to the material from the structural viewpoint and on the other hand, to the marine environment. In this sense, to better understand the environmental impacts of generating electricity from offshore wind energy, this study evaluated the life cycle assessment for some new designs of submarine power cables developed by General Cable. To achieve this goal, three approaches have been carried out: leaching tests, eco-toxicity tests and Life Cycle Assessment (LCA) methodologies. All of them are aimed to obtaining quantitative data for environmental assessment of selected submarine cables. LCA is a method used to assess environmental aspects and potential impacts of a product or activity. LCA does not include financial and social factors, which means that the results of an LCA cannot exclusively form the basis for assessment of a product's sustainability. Leaching tests results allowed to conclude that pH of seawater did not significantly changed by the presence of submarine three-core cables. Although, it was slightly higher in case of broken cable, pH values were nearly equals. Concerning to the heavy metals which could migrate to the aquatic medium, there were significant differences in both scenarios. The leaching of zinc is the major environmental concern during undersea operation of undamaged cables whereas the fully sectioned three-core cable produced the migration of significant quantities of copper and iron apart from the zinc migrated from the galvanized steel. Thus, the tar

The sedimentary record of submarine channel morphodynamics

NARCIS (Netherlands)

de Leeuw, J.

2017-01-01

Submarine channels are ubiquitous on the ocean floor and are considered to be the equivalent of rivers on land. These channels are created by turbidity currents, which originate from the continental margins and which can transport sediment for thousands of kilometres into the oceans. The aim of this

77 FR 59607 - Black Canyon Hydro, LLC; Notice of Environmental Site Review

Science.gov (United States)

2012-09-28

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 14110-001] Black Canyon Hydro, LLC; Notice of Environmental Site Review On Wednesday, October 3, 2012, at 3 p.m., Commission staff will be participating in an environmental site review for the proposed Black Canyon Hydroelectric Project. All interested participants should mee...

Submarine flow discharge changes as a way to explain incission-overspilling and other cycles in submarine channel sequences

Science.gov (United States)

Milana, J. P.; Kneller, B.; Dykstra, M.

2009-04-01

-stratification. The second bedform recognized is related to described macrodunes, and is comparable to large-scale antidunes, and produce tabular bodies with very subtle undulating structure. The third and perhaps more important is described as "gravel sheets" although they could be also low-relief gravel dunes developed during low-flow events, on top of the large-scale bedforms or directly over a flat gravelly bed. It is well known that bedforms produce the effect of delay averaged sediment velocity with respect to flow velocity, and thus we propose that this delay has an important geological effect as it creates a lag time between the onset of discharge increase and the time the channel bed reaches an equilibrium with the dominant flows. The effect of changes in the transport efficiency of submarine slope systems in the resulting depositional architecture is already known. However, we introduce here the concept of lagging the coarsest-grained fractions, delayed by the fact they involve in bedform building which move at lower velocities of the flows and hence allow the system to pass along a stage in which flows are big and fast, but the bed is not in equilibrium with them and as a result, canyoning may occur. These changes in external conditions (flow discharge) is likely to occur as a result of changes of turbid water near the slope by fluvial action and hence it would be t result of the interplay of river discharge and eustacy.

Estimating the empirical probability of submarine landslide occurrence

Science.gov (United States)

Geist, Eric L.; Parsons, Thomas E.; Mosher, David C.; Shipp, Craig; Moscardelli, Lorena; Chaytor, Jason D.; Baxter, Christopher D. P.; Lee, Homa J.; Urgeles, Roger

2010-01-01

The empirical probability for the occurrence of submarine landslides at a given location can be estimated from age dates of past landslides. In this study, tools developed to estimate earthquake probability from paleoseismic horizons are adapted to estimate submarine landslide probability. In both types of estimates, one has to account for the uncertainty associated with age-dating individual events as well as the open time intervals before and after the observed sequence of landslides. For observed sequences of submarine landslides, we typically only have the age date of the youngest event and possibly of a seismic horizon that lies below the oldest event in a landslide sequence. We use an empirical Bayes analysis based on the Poisson-Gamma conjugate prior model specifically applied to the landslide probability problem. This model assumes that landslide events as imaged in geophysical data are independent and occur in time according to a Poisson distribution characterized by a rate parameter λ. With this method, we are able to estimate the most likely value of λ and, importantly, the range of uncertainty in this estimate. Examples considered include landslide sequences observed in the Santa Barbara Channel, California, and in Port Valdez, Alaska. We confirm that given the uncertainties of age dating that landslide complexes can be treated as single events by performing statistical test of age dates representing the main failure episode of the Holocene Storegga landslide complex.

Trees in urban street canyons and their impact on the dispersion of automobile exhausts

OpenAIRE

Gromke, Christof; Ruck, Bodo

2007-01-01

The aim of the present study is to clarify the influence of trees on the dispersion of automobile exhausts in urban street canyons. For this purpose, measurements have been performed with a small scale wind tunnel model of an idealized, isolated street canyon with model trees placed along the canyon center axis. Sulfur hexafluoride (SF6) was released from a line source embedded in the street surface, simulating vehicle exhaust emissions. The influence of various tree planting arrangements on ...

Radon as an indicator of submarine groundwater discharge in coastal regions

International Nuclear Information System (INIS)

Jacob, Noble; Shivanna, K.; Suresh Babu, D.S.

2009-01-01

This article reviews the various available methodologies to estimate submarine groundwater discharge (SGD) and demonstrates the utility of radon with a case study. An attempt has been made to identify the existence of submarine groundwater discharge (SGD) and semi-quantitatively estimate its rate in the coastal area of Vizhinjam, Thiruvananthapuram, Kerala. Natural 222 Rn (half-life = 3.8 days) was used as a tracer of SGD because of its conservative nature, short half-life, easiness in measurement and high abundance in groundwater. As in situ radon ( 222 Rn) monitoring study conducted in this region indicated comparatively higher 222 Rn activities (average 14.1±1.7 Bq/m 3 ) in the coastal waters revealing significant submarine groundwater discharge. The SGD may be a combination of fresh groundwater and recirculated seawater that is controlled by the hydraulic gradient in the adjacent aquifer and varying tidal conditions in the coastal waters. Using a transient 222 Rn mass balance model for the coastal waters, SGD rates were computed and the average value was found to be 10.9±6.1 cm/day. These estimates are comparable with those reported in the literature. In general, identification and estimation of submarine groundwater discharge is important in the Indian context because of the possibility of large amounts of groundwater loss through its long coastline, that can be judiciously exploited to cater to the present water requirements for drinking and irrigation purposes. (author)

Migration of Sr-20, Cs-137, and Pu-239/240 in Canyon below Los Alamos outfall

International Nuclear Information System (INIS)

Murphy, J.M.; Mason, C.F.V.; Boak, J.M.; Longmire, P.A.

1996-01-01

Technical Area-21 (TA-21) of Los Alamos National Laboratory (LANL) is on a mesa bordered by two canyons DP Canyon and Los Alamos (LA) Canyon. DP Canyon is a small semiarid watershed with a well defined channel system where the stream flow is ephemeral. TA-21 has had a complex history of waste disposal as research to determine the chemical and metallurgical properties of nuclear materials occurred here from 1945-1978. Due to these operations, the TA-21 mesa top and bordering canyons have been monitored and characterized by the LANL Environmental Restoration Program. Results identify radionuclide values at outfall. 21-011 (k) which exceed Screening Action Levels, and points along DP Canyon which exceed regional background levels. The radiocontaminants considered in this study are strontium-90, cesium-137, and plutonium-239. This research examines sediment transport and speciation of radionuclide contaminant migration from a source term named SWMU 21-011 (k) down DP Canyon. Three dimensional surface plots of data from 1977-1994 are used to portray the transport and redistribution of radioactive contaminants in an alluvial stream channel. An overall decrease in contamination concentration since 1983 has been observed which could be due to more stringent laboratory controls and also to the removal of main plutonium processing laboratories to another site

Migration of Sr-20, Cs-137, and Pu-239/240 in Canyon below Los Alamos outfall

Energy Technology Data Exchange (ETDEWEB)

Murphy, J.M.; Mason, C.F.V.; Boak, J.M.; Longmire, P.A.

1996-04-01

Technical Area-21 (TA-21) of Los Alamos National Laboratory (LANL) is on a mesa bordered by two canyons DP Canyon and Los Alamos (LA) Canyon. DP Canyon is a small semiarid watershed with a well defined channel system where the stream flow is ephemeral. TA-21 has had a complex history of waste disposal as research to determine the chemical and metallurgical properties of nuclear materials occurred here from 1945-1978. Due to these operations, the TA-21 mesa top and bordering canyons have been monitored and characterized by the LANL Environmental Restoration Program. Results identify radionuclide values at outfall. 21-011 (k) which exceed Screening Action Levels, and points along DP Canyon which exceed regional background levels. The radiocontaminants considered in this study are strontium-90, cesium-137, and plutonium-239. This research examines sediment transport and speciation of radionuclide contaminant migration from a source term named SWMU 21-011 (k) down DP Canyon. Three dimensional surface plots of data from 1977-1994 are used to portray the transport and redistribution of radioactive contaminants in an alluvial stream channel. An overall decrease in contamination concentration since 1983 has been observed which could be due to more stringent laboratory controls and also to the removal of main plutonium processing laboratories to another site.

Lava delta deformation as a proxy for submarine slope instability

Science.gov (United States)

Di Traglia, Federico; Nolesini, Teresa; Solari, Lorenzo; Ciampalini, Andrea; Frodella, William; Steri, Damiano; Allotta, Benedetto; Rindi, Andrea; Marini, Lorenzo; Monni, Niccolò; Galardi, Emanuele; Casagli, Nicola

2018-04-01

The instability of lava deltas is a recurrent phenomenon affecting volcanic islands, which can potentially cause secondary events such as littoral explosions (due to interactions between hot lava and seawater) and tsunamis. It has been shown that Interferometric Synthetic Aperture Radar (InSAR) is a powerful technique to forecast the collapse of newly emplaced lava deltas. This work goes further, demonstrating that the monitoring of lava deltas is a successful strategy by which to observe the long-term deformation of subaerial-submarine landslide systems on unstable volcanic flanks. In this paper, displacement measurements derived from Synthetic Aperture Radar (SAR) imagery were used to detect lava delta instability at Stromboli volcano (Italy). Recent flank eruptions (2002-2003, 2007 and 2014) affected the Sciara del Fuoco (SdF) depression, created a "stacked" lava delta, which overlies a pre-existing scar produced by a submarine-subaerial tsunamigenic landslide that occurred on 30 December 2002. Space-borne X-band COSMO-SkyMED (CSK) and C-band SENTINEL-1A (SNT) SAR data collected between February 2010 and October 2016 were processed using the SqueeSAR algorithm. The obtained ground displacement maps revealed the differential ground motion of the lava delta in both CSK and SNT datasets, identifying a stable area (characterized by less than 2 mm/y in both datasets) within the northern sector of the SdF and an unstable area (characterized by velocity fields on the order of 30 mm/y and 160 mm/y in the CSK and SNT datasets, respectively) in the central sector of the SdF. The slope stability of the offshore part of the SdF, as reconstructed based on a recently performed multibeam bathymetric survey, was evaluated using a 3D Limit Equilibrium Method (LEM). In all the simulations, Factor of Safety (F) values between 0.9 and 1.1 always characterized the submarine slope between the coastline and -250 m a.s.l. The critical surfaces for all the search volumes corresponded to

Human rhinovirus capsid dynamics is controlled by canyon flexibility

International Nuclear Information System (INIS)

Reisdorph, Nichole; Thomas, John J.; Katpally, Umesh; Chase, Elaine; Harris, Ken; Siuzdak, Gary; Smith, Thomas J.

2003-01-01

Quantitative enzyme accessibility experiments using nano liquid chromatography electrospray mass spectrometry combined with limited proteolysis and isotope-labeling was used to examine the dynamic nature of the human rhinovirus (HRV) capsid in the presence of three antiviral compounds, a neutralizing Fab, and drug binding cavity mutations. Using these methods, it was found that the antivirals WIN 52084 and picovir (pleconaril) stabilized the capsid, while dansylaziridine caused destabilization. Site-directed mutations in the drug-binding cavity were found to stabilize the HRV14 capsid against proteolytic digestion in a manner similar to WIN 52084 and pleconaril. Antibodies that bind to the NIm-IA antigenic site and penetrate the canyon were also observed to protect the virion against proteolytic cleavage. These results demonstrate that quantifying the effects of antiviral ligands on protein 'breathing' can be used to compare their mode of action and efficacy. In this case, it is apparent that hydrophobic antiviral agents, antibodies, or mutations in the canyon region block viral breathing. Therefore, these studies demonstrate that mobility in the canyon region is a major determinant in capsid breathing

Scientific Ocean Drilling to Assess Submarine Geohazards along European Margins

Science.gov (United States)

Ask, M. V.; Camerlenghi, A.; Kopf, A.; Morgan, J. K.; Ocean DrillingSeismic Hazard, P. E.

2008-12-01

Submarine geohazards are some of the most devastating natural events in terms of lives lost and economic impact. Earthquakes pose a big threat to society and infrastructure, but the understanding of their episodic generation is incomplete. Tsunamis are known for their potential of striking coastlines world-wide. Other geohazards originating below the sea surface are equally dangerous for undersea structures and the coastal population: submarine landslides and volcanic islands collapse with little warning and devastating consequences. The European scientific community has a strong focus on geohazards along European and nearby continental margins, especially given their high population densities, and long historic and prehistoric record of hazardous events. For example, the Mediterranean is surrounded by very densely-populated coastline and is the World's leading holiday destination, receiving up 30% of global tourism. In addition, its seafloor is criss-crossed by hydrocarbon pipelines and telecommunication cables. However, the governing processes and recurrence intervals of geohazards are still poorly understood. Examples include, but are not limited to, earthquakes and volcanic eruptions along the active tectonic margins of the Mediterranean and Sea of Marmara, landslides on both active and passive margins, and tsunamites and seismites in the sedimentary record that suggest a long history of similar events. The development of geophysical networks, drilling, sampling and long-term monitoring are crucial to the understanding of earthquake, landslide, and tsunami processes, and to mitigate the associated risks in densely populated and industrialized regions such as Europe. Scientific drilling, particularly in the submarine setting, offers a unique tool to obtain drill core samples, borehole measurements and long-term observations. Hence, it is a critical technology to investigate past, present, and possible future influences of hazardous processes in this area. The

Size distributions and failure initiation of submarine and subaerial landslides

Science.gov (United States)

ten Brink, Uri S.; Barkan, R.; Andrews, B.D.; Chaytor, J.D.

2009-01-01

Landslides are often viewed together with other natural hazards, such as earthquakes and fires, as phenomena whose size distribution obeys an inverse power law. Inverse power law distributions are the result of additive avalanche processes, in which the final size cannot be predicted at the onset of the disturbance. Volume and area distributions of submarine landslides along the U.S. Atlantic continental slope follow a lognormal distribution and not an inverse power law. Using Monte Carlo simulations, we generated area distributions of submarine landslides that show a characteristic size and with few smaller and larger areas, which can be described well by a lognormal distribution. To generate these distributions we assumed that the area of slope failure depends on earthquake magnitude, i.e., that failure occurs simultaneously over the area affected by horizontal ground shaking, and does not cascade from nucleating points. Furthermore, the downslope movement of displaced sediments does not entrain significant amounts of additional material. Our simulations fit well the area distribution of landslide sources along the Atlantic continental margin, if we assume that the slope has been subjected to earthquakes of magnitude ??? 6.3. Regions of submarine landslides, whose area distributions obey inverse power laws, may be controlled by different generation mechanisms, such as the gradual development of fractures in the headwalls of cliffs. The observation of a large number of small subaerial landslides being triggered by a single earthquake is also compatible with the hypothesis that failure occurs simultaneously in many locations within the area affected by ground shaking. Unlike submarine landslides, which are found on large uniformly-dipping slopes, a single large landslide scarp cannot form on land because of the heterogeneous morphology and short slope distances of tectonically-active subaerial regions. However, for a given earthquake magnitude, the total area

Turbulent ventilation of a street canyon

DEFF Research Database (Denmark)

Nielsen, Morten

2000-01-01

A selection of turbulence data corresponding to 185 days of field measurements has een analysed. The non-ideal building geometry influenced the circulation patterns in the street canyon and the largest average vertical velocities were observed in the wake of an unbroken line of buildings. The sta...

Compilation of PRF Canyon Floor Pan Sample Analysis Results

Energy Technology Data Exchange (ETDEWEB)

Pool, Karl N. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Minette, Michael J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wahl, Jon H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Greenwood, Lawrence R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Coffey, Deborah S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); McNamara, Bruce K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bryan, Samuel A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Scheele, Randall D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Delegard, Calvin H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Sinkov, Sergey I. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Soderquist, Chuck Z. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Fiskum, Sandra K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Brown, Garrett N. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Clark, Richard A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2016-06-30

On September 28, 2015, debris collected from the PRF (236-Z) canyon floor, Pan J, was observed to exhibit chemical reaction. The material had been transferred from the floor pan to a collection tray inside the canyon the previous Friday. Work in the canyon was stopped to allow Industrial Hygiene to perform monitoring of the material reaction. Canyon floor debris that had been sealed out was sequestered at the facility, a recovery plan was developed, and drum inspections were initiated to verify no additional reactions had occurred. On October 13, in-process drums containing other Pan J material were inspected and showed some indication of chemical reaction, limited to discoloration and degradation of inner plastic bags. All Pan J material was sealed back into the canyon and returned to collection trays. Based on the high airborne levels in the canyon during physical debris removal, ETGS (Encapsulation Technology Glycerin Solution) was used as a fogging/lock-down agent. On October 15, subject matter experts confirmed a reaction had occurred between nitrates (both Plutonium Nitrate and Aluminum Nitrate Nonahydrate (ANN) are present) in the Pan J material and the ETGS fixative used to lower airborne radioactivity levels during debris removal. Management stopped the use of fogging/lock-down agents containing glycerin on bulk materials, declared a Management Concern, and initiated the Potential Inadequacy in the Safety Analysis determination process. Additional drum inspections and laboratory analysis of both reacted and unreacted material are planned. This report compiles the results of many different sample analyses conducted by the Pacific Northwest National Laboratory on samples collected from the Plutonium Reclamation Facility (PRF) floor pans by the CH2MHill’s Plateau Remediation Company (CHPRC). Revision 1 added Appendix G that reports the results of the Gas Generation Rate and methodology. The scope of analyses requested by CHPRC includes the determination of

A kuroko-type polymetallic sulfide deposit in a submarine silicic caldera

Science.gov (United States)

Iizasa; Fiske; Ishizuka; Yuasa; Hashimoto; Ishibashi; Naka; Horii; Fujiwara; Imai; Koyama

1999-02-12

Manned submersible studies have delineated a large and actively growing Kuroko-type volcanogenic massive sulfide deposit 400 kilometers south of Tokyo in Myojin Knoll submarine caldera. The sulfide body is located on the caldera floor at a depth of 1210 to 1360 meters, has an area of 400 by 400 by 30 meters, and is notably rich in gold and silver. The discovery of a large Kuroko-type polymetallic sulfide deposit in this arc-front caldera raises the possibility that the numerous unexplored submarine silicic calderas elsewhere might have similar deposits.

Submarine geologic disposal of nuclear waste

International Nuclear Information System (INIS)

Hollister, C.D.; Corliss, B.H.; Anderson, D.R.

1980-01-01

Site suitability characteristics of submarine geological formations for the disposal of radioactive wastes include the distribution coefficient of the host medium, permeability, viscoelastic nature of the sediments, influence of organic material on remobilization, and effects of thermal stress. The submarine geological formation that appears to best satisfy these criteria is abyssal ''red'' clay. Regions in the ocean that have coarse-grained deposits, high or variable thermal conductivity, high organic carbon content, and sediment thickness of less than 50 m are not being considered at this time. The optimum geological environment should be tranquil and have environmental predictability over a minimum of 10 5 years. Site selection activities for the North Atlantic and North Pacific are reviewed and future activities which include international cooperation are discussed. A paleoenvironmental model for Cenozoic sedimentation in the central North Pacific is presented based on studies of a long core from the Mid-Plate Gyre MPG-1 area, and is an example of the type of study that will be carried out in other seabed study areas. The data show that the MPG-1 region has been an area of slow, continuous accumulation during the past 65 million years. (author)

Virtual Reality Training System for a Submarine Command Center

National Research Council Canada - National Science Library

Maxwell, Douglas B

2008-01-01

The invention as disclosed is a system that uses a combined real and virtual display interaction methodology to generate the visual appearance of submarine combat control rooms and allow interaction...

Gender integration on U.S. Navy submarines: views of the first wave

OpenAIRE

Ellis, Krysten J.; Munson, Garold I.

2015-01-01

Approved for public release; distribution is unlimited This project is an ethnographic case study documenting the experiences of the first group of women integrated into the United States Submarine Force. The study seeks to: 1) document the process through which each of the women was selected and became a submariner; 2) identify hindering and supporting issues and concerns (e.g., life-work balance, job-role expectations, and career development); 3) describe the organizational culture and c...

Submarine geology and geomorphology of active Sub-Antarctic volcanoes: Heard and McDonald Islands

Science.gov (United States)

Watson, S. J.; Coffin, M. F.; Whittaker, J. M.; Lucieer, V.; Fox, J. M.; Carey, R.; Arculus, R. J.; Bowie, A. R.; Chase, Z.; Robertson, R.; Martin, T.; Cooke, F.

2016-12-01

Heard and McDonald Islands (HIMI) are World Heritage listed sub-Antarctic active volcanic islands in the Southern Indian Ocean. Built atop the Kerguelen Plateau by Neogene-Quaternary volcanism, HIMI represent subaerial exposures of the second largest submarine Large Igneous Province globally. Onshore, processes influencing island evolution include glaciers, weathering, volcanism, vertical tectonics and mass-wasting (Duncan et al. 2016). Waters surrounding HIMI are largely uncharted, due to their remote location. Hence, the extent to which these same processes shape the submarine environment around HIMI has not been investigated. In early 2016, we conducted marine geophysical and geologic surveys around HIMI aboard RV Investigator (IN2016_V01). Results show that volcanic and sedimentary features prominently trend east-west, likely a result of erosion by the eastward flowing Antarctic Circumpolar Current and tidal currents. However, spatial patterns of submarine volcanism and sediment distribution differ substantially between the islands. >70 sea knolls surround McDonald Island suggesting substantial submarine volcanism. Geophysical data reveals hard volcanic seafloor around McDonald Island, whereas Heard Island is characterised by sedimentary sequences tens of meters or more thick and iceberg scours - indicative of glacial processes. Differences in submarine geomorphology are likely due to the active glaciation of Heard Island and differing rock types (Heard: alkali basalt, McDonald: phonolite), and dominant products (clastics vs. lava). Variations may also reflect different magmatic plumbing systems beneath the two active volcanoes (Heard produces larger volumes of more focused lava, whilst McDonald extrudes smaller volumes of more evolved lavas from multiple vents across the edifice). Using geophysical data, corroborated with new and existing geologic data, we present the first geomorphic map revealing the processes that shape the submarine environment around HIMI.

Assesment of longwave radiation effects on air quality modelling in street canyons

Science.gov (United States)

Soucasse, L.; Buchan, A.; Pain, C.

2016-12-01

Computational Fluid Dynamics is widely used as a predictive tool to evaluate people's exposure to pollutants in urban street canyons. However, in low-wind conditions, flow and pollutant dispersion in the canyons are driven by thermal effects and may be affected by longwave (infrared) radiation due to the absorption and emission of water vapor contained in the air. These effects are mostly ignored in the literature dedicated to air quality modelling at this scale. This study aims at quantifying the uncertainties due to neglecting thermal radiation in air quality models. The Large-Eddy-Simulation of air flow in a single 2D canyon with a heat source on the ground is considered for Rayleigh and Reynolds numbers in the range of [10e8-10e10] and [5.10e3-5.10e4] respectively. The dispersion of a tracer is monitored once the statistically steady regime is reached. Incoming radiation is computed for a mid-latitude summer atmosphere and canyon surfaces are assumed to be black. Water vapour is the only radiating molecule considered and a global model is used to treat the spectral dependancy of its absorption coefficient. Flow and radiation fields are solved in a coupled way using the finite element solvers Fluidity and Fetch which have the capability of adapting their space and angular resolution according to an estimate of the solution error. Results show significant effects of thermal radiation on flow patterns and tracer dispersion. When radiation is taken into account, the air is heated far from the heat source leading to a stronger natural convection flow. The tracer is then dispersed faster out of the canyon potentially decreasing people's exposure to pollution within the street canyon.

Multicore fibers for high-capacity submarine transmission systems

DEFF Research Database (Denmark)

Nooruzzaman, Md.; Morioka, Toshio

2018-01-01

Applications of multicore fibers (MCFs) in undersea transmission systems are investigated, and various potential architectures of branching units for MCF-based undersea transmission systems are presented. Some MCF-based submarine network architectures based on the amount of data traffic are also...

Crustal volumes of the continents and of oceanic and continental submarine plateaus

Science.gov (United States)

Schubert, G.; Sandwell, D.

1989-01-01

Using global topographic data and the assumption of Airy isostasy, it is estimated that the crustal volume of the continents is 7182 X 10 to the 6th cu km. The crustal volumes of the oceanic and continental submarine plateaus are calculated at 369 X 10 to the 6th cu km and 242 X 10 to the 6th cu km, respectively. The total continental crustal volume is found to be 7581 X 10 to the 6th cu km, 3.2 percent of which is comprised of continental submarine plateaus on the seafloor. An upper bound on the contintental crust addition rate by the accretion of oceanic plateaus is set at 3.7 cu km/yr. Subduction of continental submarine plateaus with the oceanic lithosphere on a 100 Myr time scale yields an upper bound to the continental crustal subtraction rate of 2.4 cu km/yr.

A submarine landslide source for the devastating 1964 Chenega tsunami, southern Alaska

Science.gov (United States)

Brothers, Daniel; Haeussler, Peter J.; Lee Liberty,; David Finlayson,; Geist, Eric L.; Labay, Keith A.; Michael Byerly,

2016-01-01

During the 1964 Great Alaska earthquake (Mw 9.2), several fjords, straits, and bays throughout southern Alaska experienced significant tsunami runup of localized, but unexplained origin. Dangerous Passage is a glacimarine fjord in western Prince William Sound, which experienced a tsunami that devastated the village of Chenega where 23 of 75 inhabitants were lost – the highest relative loss of any community during the earthquake. Previous studies suggested the source of the devastating tsunami was either from a local submarine landslide of unknown origin or from coseismic tectonic displacement. Here we present new observations from high-resolution multibeam bathymetry and seismic reflection surveys conducted in the waters adjacent to the village of Chenega. The seabed morphology and substrate architecture reveal a large submarine landslide complex in water depths of 120–360 m. Analysis of bathymetric change between 1957 and 2014 indicates the upper 20–50 m (∼0.7 km3) of glacimarine sediment was destabilized and evacuated from the steep face of a submerged moraine and an adjacent ∼21 km2 perched sedimentary basin. Once mobilized, landslide debris poured over the steep, 130 m-high face of a deeper moraine and then blanketed the terminal basin (∼465 m water depth) in 11 ± 5 m of sediment. These results, combined with inverse tsunami travel-time modeling, suggest that earthquake- triggered submarine landslides generated the tsunami that struck the village of Chenega roughly 4 min after shaking began. Unlike other tsunamigenic landslides observed in and around Prince William Sound in 1964, the failures in Dangerous Passage are not linked to an active submarine delta. The requisite environmental conditions needed to generate large submarine landslides in glacimarine fjords around the world may be more common than previously thought. 

Experimental Investigation of Effect of the Sail with Leading Edge Fillet on Flow around a Submarine

OpenAIRE

Mohsen Rahmany; Amir Hamzeh Farajollahi; Mojtaba Dehghan Manshadi

2016-01-01

Because of connecting the various appendages of submarine to the main body the vortices have been created that disrupt the flow uniformity and make the undesirable features such as vortex formation to flow. Vortices that have been created due to the connectivity of sail to the body of submarines have a significant impact on non-uniformity of submarine wake at location of the propeller disc. In present research the use of hot wire anemometer has created vertical flow field in back of the two s...

Long-term surveillance plan for the Burro Canyon disposal cell, Slick Rock, Colorado

International Nuclear Information System (INIS)

1996-11-01

This long-term surveillance plant (LTSP) describes the US Department of energy's (DOE) long-term care program for the Uranium Mill Tailings Remediation Action (UMTRA) Project's burro Canyon disposal cell in San Miguel County, Colorado. This LTSP describes the long-term surveillance program the DOE will implement to ensure that the Burro Canyon disposal cell performs as designed. The program is based on site inspections to identify threats to disposal cell integrity. No ground water monitoring will be required at the Burro Canyon disposal cell because the ground water protection strategy is supplemental standards based on low-yield from the upper-most aquifer

Turbidity Current Bedforms

NARCIS (Netherlands)

Cartigny, Matthieu; Postma, G.

2017-01-01

Turbidity currents in the submarine seascape are what river flows are in terrestrial landscapes. While rivers transport sediment from the mountains through valleys towards the sea, turbidity currents transport sediment from the shallow marine realms through canyons towards the deeper abyssal plains.

Effectiveness of green infrastructure for improvement of air quality in urban street canyons.

Science.gov (United States)

Pugh, Thomas A M; Mackenzie, A Robert; Whyatt, J Duncan; Hewitt, C Nicholas

2012-07-17

Street-level concentrations of nitrogen dioxide (NO(2)) and particulate matter (PM) exceed public health standards in many cities, causing increased mortality and morbidity. Concentrations can be reduced by controlling emissions, increasing dispersion, or increasing deposition rates, but little attention has been paid to the latter as a pollution control method. Both NO(2) and PM are deposited onto surfaces at rates that vary according to the nature of the surface; deposition rates to vegetation are much higher than those to hard, built surfaces. Previously, city-scale studies have suggested that deposition to vegetation can make a very modest improvement (street canyons. This study shows that increasing deposition by the planting of vegetation in street canyons can reduce street-level concentrations in those canyons by as much as 40% for NO(2) and 60% for PM. Substantial street-level air quality improvements can be gained through action at the scale of a single street canyon or across city-sized areas of canyons. Moreover, vegetation will continue to offer benefits in the reduction of pollution even if the traffic source is removed from city centers. Thus, judicious use of vegetation can create an efficient urban pollutant filter, yielding rapid and sustained improvements in street-level air quality in dense urban areas.

German Submarine Offensives and South African Countermeasures

African Journals Online (AJOL)

Evert

World War, with a number of opportunistic attacks also made by submarines travelling to the Far ..... This time round, however, the strategic importance of the Indian Ocean ... offensive operations in the Indian Ocean between the Gulf of Aden and the ... American seaboards, which ensured that an attack around the coast off ...

The Influence of Roof Material on Diurnal Urban Canyon Breathing

Science.gov (United States)

Abuhegazy, Mohamed; Yaghoobian, Neda

2017-11-01

Improvements in building energy use, air quality in urban canyons and in general urban microclimates require understanding the complex interaction between urban morphology, materials, climate, and inflow conditions. Review of the literature indicates that despite a long history of valuable urban microclimate studies, more comprehensive approaches are needed to address energy, and heat and flow transport in urban areas. In this study, a more comprehensive simulation of the diurnally varying street canyon flow and associated heat transport is numerically investigated, using Large-eddy Simulation (LES). We use computational modeling to examine the impact of diurnal variation of the heat fluxes from urban surfaces on the air flow and temperature distribution in street canyons with a focus on the role of roof materials and their temperature footprints. A detailed building energy model with a three-dimensional raster-type geometry provides urban surface heat fluxes as thermal boundary conditions for the LES to determine the key aero-thermodynamic factors that affect urban street ventilation.

Prehistoric deforestation at Chaco Canyon?

Science.gov (United States)

Wills, W H; Drake, Brandon L; Dorshow, Wetherbee B

2014-08-12

Ancient societies are often used to illustrate the potential problems stemming from unsustainable land-use practices because the past seems rife with examples of sociopolitical "collapse" associated with the exhaustion of finite resources. Just as frequently, and typically in response to such presentations, archaeologists and other specialists caution against seeking simple cause-and effect-relationships in the complex data that comprise the archaeological record. In this study we examine the famous case of Chaco Canyon, New Mexico, during the Bonito Phase (ca. AD 860-1140), which has become a prominent popular illustration of ecological and social catastrophe attributed to deforestation. We conclude that there is no substantive evidence for deforestation at Chaco and no obvious indications that the depopulation of the canyon in the 13th century was caused by any specific cultural practices or natural events. Clearly there was a reason why these farming people eventually moved elsewhere, but the archaeological record has not yet produced compelling empirical evidence for what that reason might have been. Until such evidence appears, the legacy of Ancestral Pueblo society in Chaco should not be used as a cautionary story about socioeconomic failures in the modern world.

Experimental simulation of air quality in street canyon under changes of building orientation and aspect ratio.

Science.gov (United States)

Yassin, Mohamed F; Ohba, Masaake

2012-09-01

To assist validation of numerical simulations of urban pollution, air quality in a street canyon was investigated using a wind tunnel as a research tool under neutral atmospheric conditions. We used tracer gas techniques from a line source without buoyancy. Ethylene (C(2)H(4)) was used as the tracer gas. The street canyon model was formed of six parallel building rows of the same length. The flow and dispersion field was analyzed and measured using a hot-wire anemometer with split fiber probe and fast flame ionization detector. The diffusion flow field in the boundary layer within the street canyon was examined at different locations, with varying building orientations (θ=90°, 112.5°, 135° and 157.5°) and street canyon aspect ratios (W/H=1/2, 3/4 and 1) downwind of the leeward side of the street canyon model. Results show that velocity increases with aspect ratio, and with θ>90°. Pollutant concentration increases as aspect ratio decreases. This concentration decreases exponentially in the vertical direction, and decreases as θ increases from 90°. Measured pollutant concentration distributions indicate that variability of building orientation and aspect ratio in the street canyon are important for estimating air quality in the canyon. The data presented here can be used as a comprehensive database for validation of numerical models.

Numerical Modeling of Large-Scale Rocky Coastline Evolution

Science.gov (United States)

Limber, P.; Murray, A. B.; Littlewood, R.; Valvo, L.

2008-12-01

Seventy-five percent of the world's ocean coastline is rocky. On large scales (i.e. greater than a kilometer), many intertwined processes drive rocky coastline evolution, including coastal erosion and sediment transport, tectonics, antecedent topography, and variations in sea cliff lithology. In areas such as California, an additional aspect of rocky coastline evolution involves submarine canyons that cut across the continental shelf and extend into the nearshore zone. These types of canyons intercept alongshore sediment transport and flush sand to abyssal depths during periodic turbidity currents, thereby delineating coastal sediment transport pathways and affecting shoreline evolution over large spatial and time scales. How tectonic, sediment transport, and canyon processes interact with inherited topographic and lithologic settings to shape rocky coastlines remains an unanswered, and largely unexplored, question. We will present numerical model results of rocky coastline evolution that starts with an immature fractal coastline. The initial shape is modified by headland erosion, wave-driven alongshore sediment transport, and submarine canyon placement. Our previous model results have shown that, as expected, an initial sediment-free irregularly shaped rocky coastline with homogeneous lithology will undergo smoothing in response to wave attack; headlands erode and mobile sediment is swept into bays, forming isolated pocket beaches. As this diffusive process continues, pocket beaches coalesce, and a continuous sediment transport pathway results. However, when a randomly placed submarine canyon is introduced to the system as a sediment sink, the end results are wholly different: sediment cover is reduced, which in turn increases weathering and erosion rates and causes the entire shoreline to move landward more rapidly. The canyon's alongshore position also affects coastline morphology. When placed offshore of a headland, the submarine canyon captures local sediment

MVAC Submarine cable, magnetic fields measurements and analysis

DEFF Research Database (Denmark)

Arentsen, Martin Trolle; Expethit, Adrian; Pedersen, Morten Virklund

2017-01-01

Standard 60287. Researchers believe that the wire armour of three phased submarine cables is the reason for the inaccurate calculations by the standard. Studies show that the magnetic behaviour of these cables are changed due to the wire armour. In order to investigate this hypothesis, this paper intends...... to supply the theoretical research with data from magnetic field measurements on a wire armoured 3-phase submarine cable, together with an investigation of the induced currents in the different cable components. The influence of the physical arrangement of the armour wires on the electric behaviour is also...... investigated, since several researchers believe that the twisting of the armour wires result in zero net induced voltage over one helix length. This is shown to be valid for the tested cable. Finally a replica of the armour has been built with just a single conductor in the centre. This setup was used...

Understanding losses in three core armoured submarine cables

DEFF Research Database (Denmark)

Silva, Filipe Miguel Faria da; Ebdrup, Thomas; Bak, Claus Leth

2016-01-01

. For practical an economical reasons the preferred choice of cable for both the array and the transmission cables are three-core armoured submarine cables. Therefore, it has becoming increasingly important to be able to calculate the ampacity of such cables accurately. At present time, the ampacity of three......-core armoured submarine cables is calculated according to IEC 60287-1-1 [1]. Various measurements conducted both by cable manufacturers and transmission system operators (TSO) have shown that using the cable rating method stated in IEC 60287-1-1 underestimates the cable ampacity [2]-[6]. Furthermore......, measurements conducted within the cable industry have shown that an armoured three core cable has higher losses than equal unarmoured three core cables. It is also suggested that the inaccuracy in the IEC armour’s loss factor (λ2) is the main responsible for the conservatism in the IEC cable rating method...

Submarine Biofouling Control- Chlorination DATS Study at Pearl Harbor

National Research Council Canada - National Science Library

Wegand, John

2001-01-01

The intent of this document is to sumarize the chlorination studies performed at Naval Station, Pearl Harbor in support of biofouling control initiatives for the submarine community, as requested by NAVSEA 92T...

Flow and Pollutant Transport in Urban Street Canyons of Different Aspect Ratios with Ground Heating: Large-Eddy Simulation

Science.gov (United States)

Li, Xian-Xiang; Britter, Rex E.; Norford, Leslie K.; Koh, Tieh-Yong; Entekhabi, Dara

2012-02-01

A validated large-eddy simulation model was employed to study the effect of the aspect ratio and ground heating on the flow and pollutant dispersion in urban street canyons. Three ground-heating intensities (neutral, weak and strong) were imposed in street canyons of aspect ratio 1, 2, and 0.5. The detailed patterns of flow, turbulence, temperature and pollutant transport were analyzed and compared. Significant changes of flow and scalar patterns were caused by ground heating in the street canyon of aspect ratio 2 and 0.5, while only the street canyon of aspect ratio 0.5 showed a change in flow regime (from wake interference flow to skimming flow). The street canyon of aspect ratio 1 does not show any significant change in the flow field. Ground heating generated strong mixing of heat and pollutant; the normalized temperature inside street canyons was approximately spatially uniform and somewhat insensitive to the aspect ratio and heating intensity. This study helps elucidate the combined effects of urban geometry and thermal stratification on the urban canyon flow and pollutant dispersion.

How can we identify and communicate the ecological value of deep-sea ecosystem services?

Science.gov (United States)

Jobstvogt, Niels; Townsend, Michael; Witte, Ursula; Hanley, Nick

2014-01-01

Submarine canyons are considered biodiversity hotspots which have been identified for their important roles in connecting the deep sea with shallower waters. To date, a huge gap exists between the high importance that scientists associate with deep-sea ecosystem services and the communication of this knowledge to decision makers and to the wider public, who remain largely ignorant of the importance of these services. The connectivity and complexity of marine ecosystems makes knowledge transfer very challenging, and new communication tools are necessary to increase understanding of ecological values beyond the science community. We show how the Ecosystem Principles Approach, a method that explains the importance of ocean processes via easily understandable ecological principles, might overcome this challenge for deep-sea ecosystem services. Scientists were asked to help develop a list of clear and concise ecosystem principles for the functioning of submarine canyons through a Delphi process to facilitate future transfers of ecological knowledge. These ecosystem principles describe ecosystem processes, link such processes to ecosystem services, and provide spatial and temporal information on the connectivity between deep and shallow waters. They also elucidate unique characteristics of submarine canyons. Our Ecosystem Principles Approach was successful in integrating ecological information into the ecosystem services assessment process. It therefore has a high potential to be the next step towards a wider implementation of ecological values in marine planning. We believe that successful communication of ecological knowledge is the key to a wider public support for ocean conservation, and that this endeavour has to be driven by scientists in their own interest as major deep-sea stakeholders.

Transformation of PBDE mixtures during sediment transport and resuspension in marine environments (Gulf of Lion, NW Mediterranean Sea)

International Nuclear Information System (INIS)

Salvadó, Joan A.; Grimalt, Joan O.; López, Jordi F.; Durrieu de Madron, Xavier; Heussner, Serge; Canals, Miquel

2012-01-01

Polybromodiphenyl ethers (PBDEs) in superficial sediments from the Gulf of Lion were studied. They were largely predominated by BDE 209 (98.7% of all PBDEs) indicating that the main source of these pollutants was the commercial mixture deca-BDE. This compound and the less brominated BDE exhibited a southwestward decreasing concentration gradient following the dominant marine currents and bottom relief, e.g. the Mud Belt, the submarine canyons and the Open Continental Slope. All PBDEs exhibited statistically significant correlations confirming the common origin. However, a progressive transformation of the dumped BDE 209 was identified showing a depletion paralleled by increases of the less brominated BDEs (from 8.6% to 22%). These less brominated compounds were accumulated at about 100–140 km away from the Rhone prodelta, e.g. at the end of the submarine canyons, evidencing that these transformation compounds can be accumulated at long distances from the dumping sites in the marine system. Highlights: ► Polybromodiphenyl ethers are associated to organic carbon in marine sediments. ► PBDEs in marine sediments can accumulate further away than 140 km from the spill site. ► BDE-209 in marine sediments generate congeners found in banned commercial mixtures. ► BDE-209 in marine sediments generates new congeners not found in commercial mixtures. ► Submarine canyons channel PBDEs from the continental platform to the deep shelf. - Decomposition of decabromodiphenyl ether in marine sediments generates congeners found in banned mixtures in areas located far away from the discharge sites.

Towards an impact assessment of bauxite red mud waste on the knowledge of the structure and functions of bathyal ecosystems: The example of the Cassidaigne canyon (north-western Mediterranean Sea)

International Nuclear Information System (INIS)

Dauvin, Jean-Claude

2010-01-01

Since 1967, the alumina plants in the Marseilles area (Barasse and Gardanne) have been discharging the mineral residue (i.e., red mud) resulting from the alkaline processing of bauxite into the submarine Cassidaigne canyon (north-western Mediterranean Sea) through pipes situated at 320-330 m in depth. The Barasse pipe stopped being used in 1988. From 1987 to 1996, many decrees and regulations were promulgated by the French State to rule the conditions under which the Gardanne alumina refinery was authorized to dispose of the bauxite residue in the sea. The refinery was required: (i) to study the hydrodynamic circulation in the Cassidaigne canyon to evaluate the potential dispersion and transport of fine elements discharged into the water mass and their impact on the pelagic ecosystem; (ii) to survey the marine environment every five years to control the expansion and thickness of the red mud deposit and compare the evolution of the benthic macrofauna at representative sampling sites in the environment affected by the red mud discharge with that of reference sites outside of the red mud plume; (iii) to study the effect of the discharge on fishing activities; and (iv) to investigate the toxicity of the red mud, particularly its persistence, accumulation, interaction and effect on the marine ecosystem, paying special attention to the bio-accumulation of chromium and vanadium. A Scientific Committee was created to insure an independent evaluation of the studies promised by the manufacturer in response to the State's regulations. Since the beginning of the 1960s, data have been accumulating on the structure and long-term functioning of the Cassidaigne bathyal ecosystem. This paper presents the collaborative efforts of the State-Manufacturer-Committee triplet and summarizes the main results obtained during the last period's sea campaigns (1991-2007). This paper also illustrates how national regulations concerning manufacturers, such as Gardanne alumina refinery, have

Environmental assessment of remedial action, acid/middle Pueblo Canyon, Los Alamos, New Mexico

International Nuclear Information System (INIS)

1982-08-01

The radiological survey of the former radioactive waste treatment plant site (TA-45), Acid Canyon, and Pueblo Canyon found residual radioactivity at the site itself and in the channel and banks of Acid, Pueblo, and lower Los Alamos Canyons, all the way to the Rio Grande. The largest reservoir of radioactive material is in lower Pueblo Canyon, which is on DOE property. The only areas where residual radioactivity exceeds the proposed cleanup criteria are at the former vehicle decontamination facility, located between the former treatment plant site and Acid Canyon, around the former untreated waste outfall and for a short distance below, and in two small areas farther down in Acid Canyon. The three alternatives proposed are (1) to take no action, (2) to fence the areas where the residual radioactivity exceeds the proposed criteria (minimal action), and (3) to clean up the former vehicle decontamination facility and around the former untreated waste outfall. Calculations based on actual measurements indicate that the annual dose at the location having the greatest residual radioactivity would be about 12% of the applicable guideline. Most doses are much smaller than that. No environmental impacts are associated with either the no-action or minimal action alternatives. The impact associated with the cleanup alternative is very small. The preferred alternative is to clean up the areas around the former vehicle decontamination facility and the untreated waste outfall. This course of action is recommended not because of any real danger associated with the residual radioactivity, but rather because the cleanup operation is a minor effort and would conform with the ALARA (as low as reasonably achievable) philosophy

ESR dating of submarine hydrothermal activities using barite in sulfide deposition

Science.gov (United States)

Toyoda, S.; Fujiwara, T.; Ishibashi, J.; Isono, Y.; Uchida, A.; Takamasa, A.; Nakai, S.

2012-12-01

The temporal change of submarine hydrothermal activities has been an important issue in the aspect of the evolution of hydrothermal systems which is related with ore formation (Urabe, 1995) and biological systems sustained by the chemical species arising from hydrothermal activities (Macdonald et al., 1980). Determining the ages of the hydrothermal deposit will provide essential information on such studies. Dating methods using disequilibrium between radioisotopes such as U-Th method (e.g. You and Bickle, 1998), 226}Ra-{210Pb and 228}Ra-{228Th method (e.g. Noguchi et al., 2011) have been applied to date submarine hydrothermal deposits. ESR (electron spin resonance) dating method is commonly applied to fossil teeth, shells, and quartz of Quaternay period where the natural accumulated dose is obtained from the intensities of the ESR signals which are created by natural radiation. The natural dose is divided by the dose rate to the mineral/sample to deduce the age. Okumura et al., (2010) made the first practical application of ESR (electron spin resonance) dating technique to a sample of submarine hydrothermal barite (BaSO4) to obtain preliminary ages, where Kasuya et al. (1991) first pointed out that barite can be used for ESR dating. Knowing that ESR dating of barite is promising, in this paper, we will present how we have investigated each factor that contributes ESR dating of barite in submarine hydrothermal sulfide deposition. (1) The best ESR condition for measuring the SO3- signal in barite is with the microwave power of 1mW and modulation amplitude of 0.1mT. (2) As results of heating experiments, the signal was found to be stable for the dating age range of several thousands. (3) 226Ra replacing Ba in barite is the source of the radiation. The amount of radioactive elements in sulfide mineral surrounding barite is negligible. (4) The external radiation from the sea water is negligible even in the submarine hydrothermal area where the radiation level is much

Relationship between rooftop and on-road concentrations of traffic-related pollutants in a busy street canyon: Ambient wind effects

International Nuclear Information System (INIS)

Kwak, Kyung-Hwan; Lee, Sang-Hyun; Seo, Jaemyeong Mango; Park, Seung-Bu; Baik, Jong-Jin

2016-01-01

Rooftop and on-road measurements of O_3, NO_2, NO_x, and CO concentrations were conducted to investigate the relationship between rooftop and on-road concentrations in a busy and shallow street canyon with an aspect ratio of ∼0.3 in Seoul, Republic of Korea, from 15 April to 1 May 2014. The median road-to-roof concentration ratios, correlation coefficients between rooftop and on-road concentrations, and temporal variations of rooftop and on-road concentrations are analyzed according to the rooftop wind directions which are two cross-canyon and two along-canyon directions. The analysis results indicate that the relationship is strong when the rooftop is situated on the downwind side rather than on the upwind side. Relative to the cross-canyon wind directions, one of the along-canyon wind directions can more enhance the relationship. A conceptual framework is proposed to explain the effect of ambient wind direction on the relationship between rooftop and on-road concentrations in a street canyon. - One of the along-canyon wind directions can enhance the relationship between rooftop and on-road concentrations of traffic-related pollutants in a busy and shallow street canyon.

[Dynamics of functional status of submarine personnel during the pre-deployment period].

Science.gov (United States)

Khankevich, Iu R; Bloshchinskiĭ, I A; Val'skiĭ, A V; Nabokov, N L

2014-09-01

Authors came to conclusions that during the pre-deployment period submarine personnel are stressed out. During this period submarine personnel .usually resupply, conduct maintenance and other monitoring-and-checkout measures, which leads to functional stress. Authors came to conclusion that it is necessary to use simple and easy, but at the same time informative methods for early diagnosis of worsen functional health status. One of these methods is evaluation of indicators of cardiovascular system. This method is a base for functional health status prophylaxis.

Influence of roadside hedgerows on air quality in urban street canyons

Science.gov (United States)

Gromke, Christof; Jamarkattel, Nabaraj; Ruck, Bodo

2016-08-01

Understanding pollutant dispersion in the urban environment is an important aspect of providing solutions to reduce personal exposure to vehicle emissions. To this end, the dispersion of gaseous traffic pollutants in urban street canyons with roadside hedges was investigated. The study was performed in an atmospheric boundary layer wind tunnel using a reduced-scale (M = 1:150) canyon model with a street-width-to-building-height ratio of W/H = 2 and a street-length-to-building-height ratio of L/H = 10. Various hedge configurations of differing height, permeability and longitudinal segmentation (continuous over street length L or discontinuous with clearings) were investigated. Two arrangements were examined: (i) two eccentric hedgerows sidewise of the main traffic lanes and (ii) one central hedgerow between the main traffic lanes. In addition, selected configurations of low boundary walls, i.e. solid barriers, were examined. For a perpendicular approach wind and in the presence of continuous hedgerows, improvements in air quality in the center area of the street canyon were found in comparison to the hedge-free reference scenario. The pollutant reductions were greater for the central hedge arrangements than for the sidewise arrangements. Area-averaged reductions between 46 and 61% were observed at pedestrian head height level on the leeward side in front of the building for the centrally arranged hedges and between 18 and 39% for the two hedges arranged sidewise. Corresponding area-averaged reductions ranging from 39 to 55% and from 1 to 20% were found at the bottom of the building facades on the leeward side. Improvements were also found in the areas at the lateral canyon ends next to the crossings for the central hedge arrangements. For the sidewise arrangements, increases in traffic pollutants were generally observed. However, since the concentrations in the end areas were considerably lower compared to those in the center area, an overall improvement remained

An Investigation of Amphitheater-Headed Canyon Distribution, Morphology Variation, and Longitudinal Profile Controls in Escalante and Tarantula Mesa, Utah.

Science.gov (United States)

Ryan, A. J.; Whipple, K. X.

2014-12-01

Amphitheater-headed canyons are primarily distinguished from typical fluvial channels by their abrupt headwall terminations. A key goal in the study of river canyons is to establish a reliable link between form and formation processes. This is of particular significance for Mars, where, if such links can be established, amphitheater-headed canyons could be used to determine ancient erosion mechanisms and, by inference, climate conditions. Type examples in arid regions on Earth, such as in Escalante River, Utah, previously have been interpreted as products of groundwater seepage erosion. We investigate amphitheater-headed canyons in Escalante and Tarantula Mesa where variations in canyon head morphology may hold clues for the relative roles of rock properties and fluvial and groundwater processes. In lower Escalante, amphitheaters are only present where canyons have breached the Navajo Sandstone - Kayenta Formation contact. In some canyons, amphitheater development appears to have been inhibited by an abundance of coarse bedload. In Tarantula Mesa, canyons have a variety of headwalls, from amphitheaters to stepped knickzones. Headwall morphology distribution is directly related to the spatially variable presence of knickpoint-forming, fine-grained interbeds within cliff-forming sandstones. Amphitheaters only form where the sandstone unit is undisrupted by these interbeds. Finally, most canyons in Escalante and Tarantula Mesa, regardless of substrate lithology, amphitheater presence, or groundwater spring intensity, are well described by a slope-area power law relationship with regionally constant concavity and normalized steepness indices. This suggests that all channels here are subject to the same erosion rates, independent of groundwater weathering intensity. Thus: 1) variations in canyon headwall form do not necessary relate to differences in fluvial history, 2) stratigraphic variations are clearly of importance in sedimentary canyon systems, and 3) although

Effects of street canyon design on pedestrian thermal comfort in the hot-humid area of China.

Science.gov (United States)

Zhang, Yufeng; Du, Xiaohan; Shi, Yurong

2017-08-01

The design characteristics of street canyons were investigated in Guangzhou in the hot-humid area of China, and the effects of the design factors and their interactions on pedestrian thermal comfort were studied by numerical simulations. The ENVI-met V4.0 (BASIC) model was validated by field observations and used to simulate the micrometeorological conditions and the standard effective temperature (SET) at pedestrian level of the street canyons for a typical summer day of Guangzhou. The results show that the micrometeorological parameters of mean radiant temperature (MRT) and wind speed play key roles in pedestrian thermal comfort. Street orientation has the largest contribution on SET at pedestrian level, followed by aspect ratio and greenery, while surface albedo and interactions between factors have small contributions. The street canyons oriented southeast-northwest or with a higher aspect ratio provide more shade, higher wind speed, and better thermal comfort conditions for pedestrians. Compared with the east-west-oriented street canyons, the north-south-oriented street canyons have higher MRTs and worse pedestrian thermal comfort due to their wider building spacing along the street. The effects of greenery change with the road width and the time of the day. Street canyon design is recommended to improve pedestrian thermal comfort. This study provides a better understanding of the effects of street canyon design on pedestrian thermal comfort and is a useful guide on urban design for the hot-humid area of China.

Transport and deposition of plutonium-contaminated sediments by fluvial processes, Los Alamos Canyon, New Mexico

International Nuclear Information System (INIS)

Graf, W.L.

1996-01-01

Between 1945 and 1952 the development of nuclear weapons at Los Alamos National Laboratory, New Mexico, resulted in the disposal of plutonium into the alluvium of nearby Acid and (to a lesser degree) DP Canyons. The purpose of this paper is to explore the connection between the disposal sites and the main river, a 20 km link formed by the fluvial system of Acid, Pueblo, DP, and Los Alamos Canyons. Empirical data from 15 yr of annual sediment sampling throughout the canyon system has produced 458 observations of plutonium concentration in fluvial sediments. These data show that, overall, mean plutonium concentrations in fluvial sediment decline from 10,000 fCi/g near the disposal area to 100 fCi/g at the confluence of the canyon system and the Rio Grande. Simulations using a computer model for water, sediment, and plutonium routing in the canyon system show that discharges as large as the 25 yr event would fail to develop enough transport capacity to completely remove the contaminated sediments from Pueblo Canyon. Lesser flows would move some materials to the Rio Grande by remobilization of stored sediments. The simulations also show that the deposits and their contaminants have a predictable geography because they occur where stream power is low, hydraulic resistance is high, and the geologic and/or geomorphic conditions provide enough space for storage. 38 refs., 13 figs., 1 tab

Annotated bibliography: Marine geologic hazards of the Hawaiian Islands with special focus on submarine slides and turbidity currents

Energy Technology Data Exchange (ETDEWEB)

Normark, W.R.; Herring, H.H.

1993-10-01

This annotated bibliography was compiled to highlight the submarine geology of the Hawaiian Islands and identify known and potential marine geologic hazards with special emphasis on turbidity currents, submarine slides and tsunamis. Some references are included that are not specific to Hawaii but are needed to understand the geologic processes that can affect the integrity of submarine cables and other man-made structures. Entries specific to the Hawaiian Island area are shown in bold type.

The human factor in the operation of nuclear powered submarines

International Nuclear Information System (INIS)

Dambier, M.

1982-05-01

The conditions characterizing the operation of nuclear powered submarines are described and the precautionary measures suitable to reduce the incidence of human errors and their consequences are explained

Estimation of health damage due to emission of air pollutants by cars: the canyon effect

Energy Technology Data Exchange (ETDEWEB)

Spadaro, J.V. [Ecole des Mines, Centre d' Energetique, Paris, 75 (France); Rabl, A.

1999-07-01

Since current epidemiological evidence suggests that air pollution has harmful effects even at typical ambient concentrations and the dispersion is significant over hundreds to thousands of km, the estimation of total health damage involves consideration of local and regional effects. In recent years, several estimates have been published of health damage due to air pollution from cars, in particular by Delucchi et al of UC Davis and by the ExternE Project of the European Commission. To capture the geographic extent of pollutant dispersion, local and regional models have been used in combination. The present paper addresses a potentially significant contribution of the total damage, not yet taken into account in these studies: the increased concentration of pollutants inside urban street canyons. This canyon effect is appreciable only for primary pollutants, the time constants for the formation of secondary pollutants being long compared to the residence time in the canyon. We assumed linearity of incremental health impact with incremental concentration, in view of the lack of epidemiological evidence for no-effect thresholds or significant deviations from linearity at typical ambient concentrations; therefore, only long term average concentrations matter. We use the FLUENT software to model the dispersion inside a street canyon for a wide range of rectangular geometries and wind velocities. Our results suggest that the canyon effect is of marginal significance for total damages, the contribution of the canyon effect being roughly 10 to 20% of the total. The relative importance of the canyon effect is, of course, highly variable with local conditions; it could be much smaller but it is unlikely to add more than 100% to the flat terrain estimate. (Author)

Submarine slope failures due to pipe structure formation.

Science.gov (United States)

Elger, Judith; Berndt, Christian; Rüpke, Lars; Krastel, Sebastian; Gross, Felix; Geissler, Wolfram H

2018-02-19

There is a strong spatial correlation between submarine slope failures and the occurrence of gas hydrates. This has been attributed to the dynamic nature of gas hydrate systems and the potential reduction of slope stability due to bottom water warming or sea level drop. However, 30 years of research into this process found no solid supporting evidence. Here we present new reflection seismic data from the Arctic Ocean and numerical modelling results supporting a different link between hydrates and slope stability. Hydrates reduce sediment permeability and cause build-up of overpressure at the base of the gas hydrate stability zone. Resulting hydro-fracturing forms pipe structures as pathways for overpressured fluids to migrate upward. Where these pipe structures reach shallow permeable beds, this overpressure transfers laterally and destabilises the slope. This process reconciles the spatial correlation of submarine landslides and gas hydrate, and it is independent of environmental change and water depth.

Colorado Canyons National Conservation Area 2003 visitor use survey: Completion report

Science.gov (United States)

Ponds, Phadrea; Gillette, Shana C.; Koontz, Lynne

2004-01-01

This report represents the analysis of research conducted by the U.S. Geological Survey (USGS) for the Bureau of Land Management (BLM). The purpose is to provide socio-economic and recreational use information that can be used in the development of a Resource Management Plan (RMP) for the Colorado Canyons National Conservation Area (CCNCA). The results reported here deal primarily with recreation-based activities in four areas: Kokopelli Loops, Rabbit Valley, Loma Boat Launch, and Devil’s Canyon.

A concentration correction scheme for Lagrangian particle model and its application in street canyon air dispersion modelling

Energy Technology Data Exchange (ETDEWEB)

Jiyang Xia [Shanghai Jiao Tong University, Shanghai (China). Department of Engineering Mechanics; Leung, D.Y.C. [The University of Hong Kong (Hong Kong). Department of Mechanical Engineering

2001-07-01

Pollutant dispersion in street canyons with various configurations was simulated by discharging a large number of particles into the computation domain after developing a time-dependent wind field. Trajectory of the released particles was predicted using a Lagrangian particle model developed in an earlier study. A concentration correction scheme, based on the concept of 'visibility', was adopted for the Lagrangian particle model to correct the calculated pollutant concentration field in street canyons. The corrected concentrations compared favourably with those from wind tunnel experiments and a linear relationship between the computed concentrations and wind tunnel data were found. The developed model was then applied to four simulations to test for the suitability of the correction scheme and to study pollutant distribution in street canyons with different configurations. For those cases with obstacles presence in the computation domain, the correction scheme gives more reasonable results compared with the one without using it. Different flow regimes are observed in the street canyons, which depend on building configurations. A counter-clockwise rotating vortex may appear in a two-building case with wind flow from left to right, causing lower pollutant concentration at the leeward side of upstream building and higher concentration at the windward side of downstream building. On the other hand, a stable clockwise rotating vortex is formed in the street canyon with multiple identical buildings, resulting in poor natural ventilation in the street canyon. Moreover, particles emitted in the downstream canyon formed by buildings with large height-to-width ratios will be transported to upstream canyons. (author)

The Glen Canyon Dam adaptive management program: progress and immediate challenges

Science.gov (United States)

Hamill, John F.; Melis, Theodore S.; Boon, Philip J.; Raven, Paul J.

2012-01-01

Adaptive management emerged as an important resource management strategy for major river systems in the United States (US) in the early 1990s. The Glen Canyon Dam Adaptive Management Program (‘the Program’) was formally established in 1997 to fulfill a statutory requirement in the 1992 Grand Canyon Protection Act (GCPA). The GCPA aimed to improve natural resource conditions in the Colorado River corridor in the Glen Canyon National Recreation Area and Grand Canyon National Park, Arizona that were affected by the Glen Canyon dam. The Program achieves this by using science and a variety of stakeholder perspectives to inform decisions about dam operations. Since the Program started the ecosystem is now much better understood and several biological and physical improvements have been achieved. These improvements include: (i) an estimated 50% increase in the adult population of endangered humpback chub (Gila cypha) between 2001 and 2008, following previous decline; (ii) a 90% decrease in non-native rainbow trout (Oncorhynchus mykiss), which are known to compete with and prey on native fish, as a result of removal experiments; and (iii) the widespread reappearance of sandbars in response to an experimental high-flow release of dam water in March 2008.Although substantial progress has been made, the Program faces several immediate challenges. These include: (i) defining specific, measurable objectives and desired future conditions for important natural, cultural and recreational attributes to inform science and management decisions; (ii) implementing structural and operational changes to improve collaboration among stakeholders; (iii) establishing a long-term experimental programme and management plan; and (iv) securing long-term funding for monitoring programmes to assess ecosystem and other responses to management actions. Addressing these challenges and building on recent progress will require strong and consistent leadership from the US Department of the Interior

Three Years of Experience of Wet Gas Allocation on Canyon Express

Energy Technology Data Exchange (ETDEWEB)

Singh, Aditya; Hall, James; Letton, Winsor

2005-07-01

In September 2002, production was begun from the three fields that together form the Canyon Express System- King's Peak, Aconcagua, and Camden Hills. The 9 wells from these fields are connected to a pair of 12-inch flow lines carrying the commingled wet gas a distance of approximately 92 kilometers back to the Canyon Station platform for processing. At the 21st NSFMW in October 2003, an initial report was given on the status of Wet Gas Allocation for the Canyon Express project. As discussed in that paper, dual-differential, subsea wet gas meters were chosen for the task of allocating gas and liquids back to individual wells. However, since the gas from all three fields was very dry (Lockhart-Martinelli parameter less than 0.01) and because the operating pressures were quite high (250 bar), application of the dual-differential function of the meters yielded errors in both liquid and gas flow rates. Furthermore, as these problems were being uncovered, scale was beginning to collect inside some of the meters. Taken together, these problems produced system imbalances as great as 20%. To address the problems, one of the individual flow metering elements within each wet gas meter was chosen as the allocation meter, operating as a single-phase gas meter. After three years of operation of the Canyon Express Project, considerable experience has been accumulated. Since at the time it held the record for deep water hydrocarbon production, application of the technologies discussed here were challenging and required considerable flexibility. It is believed that the Canyon Express experiences will benefit future deep water flow metering projects. The knowledge acquired thus far is surveyed and summarized. The emphasis is on the technical aspects. (tk)

Yuntaishan Global Geopark VS Grand Canyon World Heritage Site A Contrast of Yuntai/Grand Canyon Physiognomy

Science.gov (United States)

Ting, Zhao; Xun, Zhao

2017-04-01

1). Sights of Yuntai/Grand Canyon: Immaculate. Physiognomy of Yuntai/Grand Canyon: Typical representatives of stratiform ravine physiognomy The physiognomy is distributed widely on the second geological ladder zone (Xing'an Peak-Mt. Yan-Mt. Taihang-West Henan Province; Mountainous areas in west Hubei Province-West Hunan Province; East Guizhou Province-West Guangxi Province) and in the valleys of the Yellow River; similar physiognomy is also to be found in the Grand Canyon of U.S and the Great Rift Valley in east Africa, etc. The physiognomy has the following features: broken mounds sprinkle the ancient plateau, insignificant streams and brooks carve dongas on the plateau, grits, fine or coarse in terms of sizes, that are near to sources jam water channels, and riverbanks and slopes are covered by slope sediments, remains and flood residues; on the edge of the plateau, there are towering ragged cliffs and long walls when ruptures and joints don't develop; when they do develop, facets of the plateau will be incised by the intercrossing development to form high or low peak walls that resemble plates or peak pillars that reaches into the sky; Under the river valleys and gulches where water gather on the face of the plateau, suspending waterfalls wash away the soft layers of rock and soil, which collapse into urn-shaped valleys, and gigantic stones fall up-side-down to form stone awls that has no distinctive layers and single components; more often than not, they would pile up into complicated caves and holes, wherein sands and mud are flushed away by floods; Inside the valley, erosion by means of wind and water are even stronger, and narrow valleys, shield-like valleys, gorges, suspending valleys, and valley-in-valleys are clearly cut, and ruts formed by water flush and urn-shaped valleys can often be found together. In the lower reaches of rivers, wide valleys, winding streams and yoke lakes grow into major sights, and the flush and collapse on the valley slopes formed

Simple models for the simulation of submarine melt for a Greenland glacial system model

Science.gov (United States)

Beckmann, Johanna; Perrette, Mahé; Ganopolski, Andrey

2018-01-01

Two hundred marine-terminating Greenland outlet glaciers deliver more than half of the annually accumulated ice into the ocean and have played an important role in the Greenland ice sheet mass loss observed since the mid-1990s. Submarine melt may play a crucial role in the mass balance and position of the grounding line of these outlet glaciers. As the ocean warms, it is expected that submarine melt will increase, potentially driving outlet glaciers retreat and contributing to sea level rise. Projections of the future contribution of outlet glaciers to sea level rise are hampered by the necessity to use models with extremely high resolution of the order of a few hundred meters. That requirement in not only demanded when modeling outlet glaciers as a stand alone model but also when coupling them with high-resolution 3-D ocean models. In addition, fjord bathymetry data are mostly missing or inaccurate (errors of several hundreds of meters), which questions the benefit of using computationally expensive 3-D models for future predictions. Here we propose an alternative approach built on the use of a computationally efficient simple model of submarine melt based on turbulent plume theory. We show that such a simple model is in reasonable agreement with several available modeling studies. We performed a suite of experiments to analyze sensitivity of these simple models to model parameters and climate characteristics. We found that the computationally cheap plume model demonstrates qualitatively similar behavior as 3-D general circulation models. To match results of the 3-D models in a quantitative manner, a scaling factor of the order of 1 is needed for the plume models. We applied this approach to model submarine melt for six representative Greenland glaciers and found that the application of a line plume can produce submarine melt compatible with observational data. Our results show that the line plume model is more appropriate than the cone plume model for simulating

Influence of local parameters on the dispersion of traffic-related pollutants within street canyons

Science.gov (United States)

Karra, Styliani; Malki-Epshtein, Liora; Martin Hyde Collaboration

2011-11-01

Ventilation within urban cities and street canyons and the associated air quality is a problem of increasing interest in the last decades. It is important for to minimise exposure of the population to traffic-related pollutants at street level. The residence time of pollutants within the street canyons depends on the meteorological conditions such as wind speed and direction, geometry layout and local parameters (position of traffic lane within the street). An experimental study was carried out to investigate the influence of traffic lane position on the dispersion of traffic-related pollutants within different street canyons geometries: symmetrical (equal building heights on both sides of the street), non-symmetrical (uniform building heights but lower on one side of the street) and heterogeneous (non-uniform building heights on both sides of the street) under constant meteorological conditions. Laboratory experiments were carried out within a water channel and simultaneous measurements of velocity field and concentration scalar levels within and above the street canyons using PIV and PLIF techniques. Traffic -related emissions were simulated using a line emission source. Two positions were examined for all street geometries: line emission source was placed in the centre of the street canyon; line emission source was placed off the centre of the street. TSI Incorporated.

SUBMARINE MASS MOVEMENT AND LOCALIZED TSUNAMI POTENTIALITY OF MENTAWAI BASIN, SUMATERA, INDONESIA

Directory of Open Access Journals (Sweden)

Haryadi Permana

2017-07-01

Full Text Available The new bathymetry and seismic data were acquired during the PreTI-Gap marine survey (February 15 to March 6, 2008. The survey was carried out along the NE margin of Mentawai Island using multi-beam swath bathymetry equipment, and 28-channels seismic streamer and four-airgun source. The first target was the Mega Island region near the epicenter of the 2007 great earthquake. The shallow bathymetry is characterized as a flat coral platform suggesting that 200 km elongated plateau is slowly subsiding without any active faults. Further north, from South Pagai to North of Siberut Islands, the seafloor morphology changes significantly. The deep and wide canyons or valleys produce very rough seafloor morphology between 50 and 1100 m water depth. In general, the submarine topography shows two break slopes at different depths. Between slope breaks, the undulating, hilly and circular features dominate, possibly caused by mass movement. A push-up ridge is observed that dams the sediments eroded within a steep slope northeastward side. The seismic reflection data acquired along 14 dip seismic lines at the NE flank of Mentawai Islands, from Siberut to the South of Pagai Islands. We observed a set of southwestward dipping back thrust bounding the NE margin of the Mentawai Island and the push-up ridge observed on bathymetric image, which suggest that Mentawai fault is not pure a strike slip fault, but consists of a set of back thrusts. Such kind of back thrust movement at the flank of Mentawai basin can trigger mass movement or landslide that can produce localized tsunami causing damages to Sumatera mainland such as Padang, Painan or northern Bengkulu provinces and Mentawai Islands. Therefore, it is important to re-design the tsunami warning system, especially in this region, in order to mitigate tsunami risk to coastal region of western Sumatera.

ACUMEN 2012: Atlantic Canyons Undersea Mapping Expeditions

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Between February and August 2012, a team of NOAA and external partners will conduct a mapping ‘blitz’ focused on deepwater canyons off the northeastern...

Variability in eddy sandbar dynamics during two decades of controlled flooding of the Colorado River in the Grand Canyon

Science.gov (United States)

Mueller, Erich R.; Grams, Paul E.; Hazel, Joseph E.; Schmidt, John C.

2018-01-01

Sandbars are iconic features of the Colorado River in the Grand Canyon, Arizona, U.S.A. Following completion of Glen Canyon Dam in 1963, sediment deficit conditions caused erosion of eddy sandbars throughout much of the 360 km study reach downstream from the dam. Controlled floods in 1996, 2004, and 2008 demonstrated that sand on the channel bed could be redistributed to higher elevations, and that floods timed to follow tributary sediment inputs would increase suspended sand concentrations during floods. Since 2012, a new management protocol has resulted in four controlled floods timed to follow large inputs of sand from a major tributary. Monitoring of 44 downstream eddy sandbars, initiated in 1990, shows that each controlled flood deposited significant amounts of sand and increased the size of subaerial sandbars. However, the magnitude of sandbar deposition varied from eddy to eddy, even over relatively short distances where main-stem suspended sediment concentrations were similar. Here, we characterize spatial and temporal trends in sandbar volume and site-scale (i.e., individual eddy) sediment storage as a function of flow, channel, and vegetation characteristics that reflect the reach-scale (i.e., kilometer-scale) hydraulic environment. We grouped the long-term monitoring sites based on geomorphic setting and used a principal component analysis (PCA) to correlate differences in sandbar behavior to changes in reach-scale geomorphic metrics. Sites in narrow reaches are less-vegetated, stage changes markedly with discharge, sandbars tend to remain dynamic, and sand storage change dominantly occurs in the eddy compared to the main channel. In wider reaches, where stage-change during floods may be half that of narrow sites, sandbars are more likely to be stabilized by vegetation, and floods tend to aggrade the vegetated sandbar surfaces. In these locations, deposition during controlled floods is more akin to floodplain sedimentation, and the elevation of sandbar

A comparative study of sediment waves and cyclic steps based on geometries, internal structures and numerical modeling

NARCIS (Netherlands)

Cartigny, M.; Postma, G.; Berg, J.H. van den; Mastbergen, D.R.

2011-01-01

Although sediment waves cover many levees and canyon floors of submarine fan systems, their relation to the turbidity currents that formed them is still poorly understood. Over the recent years some large erosional sediment waves have been interpreted as cyclic steps. Cyclic steps are a series of

2013 Pacific Gas and Electric Diablo Canyon Power Plant (DCPP): San Simeon, CA Central Coast

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Diablo Canyon Power Plant (DCPP) LiDAR and Imagery datasets are comprised of three separate LiDAR surveys: Diablo Canyon (2010), Los Osos (2011), and San Simeon...

2011 Pacific Gas and Electric Diablo Canyon Power Plant (DCPP): Los Osos, CA Central Coast

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Diablo Canyon Power Plant (DCPP) LiDAR and Imagery datasets are comprised of three separate LiDAR surveys: Diablo Canyon (2010), Los Osos (2011), and San Simeon...

Biomonitoring of physiological status and cognitive performance of underway submariners undergoing a novel watch-standing schedule

Science.gov (United States)

Duplessis, C. A.; Cullum, M. E.; Crepeau, L. J.

2005-05-01

Submarine watch-standers adhere to a 6 hour-on, 12 hour-off (6/12) watch-standing schedule, yoking them to an 18-hr day, engendering circadian desynchronization and chronic sleep deprivation. Moreover, the chronic social crowding, shift work, and confinement of submarine life provide additional stressors known to correlate with elevated secretory immunoglobulin A (sIgA) and cortisol levels, reduced performance, immunologic dysfunction, malignancies, infections, gastrointestinal illness, coronary disease, anxiety, and depression. We evaluated an alternative, compressed, fixed work schedule designed to enhance circadian rhythm entrainment, sleep hygiene, performance, and health on 10 underway submariners, who followed the alternative and 6/12 schedules for approximately 2 weeks each. We measured subjects" sleep, cognitive performance, and salivary biomarker levels. Pilot analysis of the salivary data on one subject utilizing ELISA suggests elevated biomarker levels of stress. Average PM cortisol levels were 0.2 μg/L (normal range: nondetectable - 0.15 μg/L), and mean sIgA levels were 562 μg/ml (normal range: 100-500 μg/ml). Future research exploiting real-time salivary bioassays, via fluorescent polarimetry technology, identified by the Office of Naval Research (ONR) as a future Naval requirement, allows researchers to address correlations between stress-induced elaboration of salivary biomarkers with physiological and performance decrements, thereby fostering insight into the underway submariner"s psychoimmunological status. This may help identify strategies that enhance resilience to stressors. Specifically, empirically-based modeling can identify optimal watch-standing schedules and stress-mitigating procedures -- within the operational constraints of the submarine milieu and the mission --that foster improved circadian entrainment and reduced stress reactivity, enhancing physiological health, operational performance, safety, and job satisfaction.

Navy Ohio Replacement (SSBN[X]) Ballistic Missile Submarine Program: Background and Issues for Congress

Science.gov (United States)

2016-04-05

Navy Ohio Replacement (SSBN[X]) Ballistic Missile Submarine Program: Background and Issues for Congress Ronald O’Rourke Specialist in Naval...Affairs April 5, 2016 Congressional Research Service 7-5700 www.crs.gov R41129 Navy Ohio Replacement (SSBN[X]) Ballistic Missile Submarine...1,091.1 million in research and development funding for the Ohio replacement program (ORP), a program to design and build a new class of 12 ballistic

Rose Canyon Sustainable Aquaculture Project, San Diego, CA

Science.gov (United States)

Documents related to EPA's preparation of an Environmental Assessment (EA) to analyze the potential impacts related to the issuance of a National Pollutant Discharge Elimination System (NPDES) permit for the Rose Canyon Sustainable Aquaculture Project.

Long-term surveillance plan for the Burro Canyon disposal cell, Slick Rock, Colorado

International Nuclear Information System (INIS)

1998-05-01

This long-term surveillance plan (LTSP) describes the US Department of Energy (DOE) long-term care program for the Uranium Mill Tailings Remedial Action (UMTRA) Project Burro Canyon disposal cell in San Miguel County, Colorado. The US Nuclear Regulatory Commission (NRC) developed regulations for the issuance of a general license for the custody and long-term care of UMTRA Project disposal sites in 10 CFR Part 40. The purpose of this general license is to ensure that the UMTRA Project disposal sites are cared for in a manner that protects the public health and safety and the environment. Before each disposal site is licensed, the NRC requires the DOE to submit a site-specific LTSP. The DOE prepared this LTSP to meet this requirement for the Burro Canyon disposal cell. The general license becomes effective when the NRC concurs with the DOE's determination that remedial action is complete at the Burro Canyon disposal cell and the NRC formally accepts this LTSP. Attachment 1 contains the concurrence letters from NRC. This LTSP describes the long-term surveillance program the DOE will implement to ensure that the Burro Canyon disposal cell performs as designed. The program is based on site inspections to identify threats to disposal cell integrity. Ground water monitoring will not be required at the Burro Canyon disposal cell because the ground water protection strategy is supplemental standards based on low yield from the uppermost aquifer

At Periscope Depth: Exploring Submarine Proliferation In Southeast Asia

Science.gov (United States)

2015-09-01

papers and op-eds; and relevant books . This thesis will not include human subjects because the scope of the research will not permit gathering...Soviet-built submarines required.36 Furthermore, the hulls were purchased secondhand and thus had a shortened

Street canyon ventilation control by proper planning and development

Directory of Open Access Journals (Sweden)

Balakin Vladimir Vasil'evich

2014-05-01

separate buildings of reasonable length and sufficient intervals between them, and with street width over 9 H… 10 H , the buildings’ influence on wind speed lessens, and the vortices do not form between buildings. Thus the danger of excess air pollution within street canyon is eliminated. On the other hand, the air flow over the trafficway slows down more at the intervals between the buildings than at their mid-lengths, and this effect is more prominent when the buildings are narrow in the direction along the street (like 10…25 meters. This could be explained by forming, and gradual increasing in number, of small chaotic vortices with conflicting directions, even counter-directional, at the corners of buildings as the intervals between buildings increase in number. In real life, in order to protect the streets from strong winds, it is advisable to use certain planning methods, like alternate side-shifting or rotating the buildings in the row, additional space between them and the trafficway, alternating buildings of different height, and other non-linear plan and height configurations. At the same time, they should ensure lesser concentrations of toxic air pollutants within the streets, and the intervals between the buildings should be at least corresponding to the sunlight norms and fire regulations.

Health and environmental risk assessment associated with a potential recovery of the Russian submarine K-27

Energy Technology Data Exchange (ETDEWEB)

Hosseini, A.; Amundsen, I.; Brown, J.E.; Dowdall, M.; Standring, W. [Norwegian Radiation Protection Authority/CERAD CoE (Norway); Bartnicki, J. [Norwegian Meteorological Institute/CERAD CoE (Norway); Karcher, M. [O.A.Sys - Ocean Atmosphere Systems GmbH (Germany); Lind, O.C.; Salbu, B. [Norwegian University of Life Sciences/CERAD CoE (Norway)

2014-07-01

The nuclear submarine K-27 is one of several objects with spent nuclear fuel (SNF) which has been dumped in the Arctic. It contained two liquid metal reactors (LMRs) of 70 MW maximum thermal power each and used Pb-Bi as the coolant. The reactors were loaded with 180 kg of U-235 at an enrichment of 90 %. In September 1981, the submarine was sunk in the shallow waters of Stepovoy Fjord at an estimated depth of 30 m. Concerns have been expressed by various parties regarding the issue of dumped nuclear waste in the Kara Sea and in particular the submarine K-27. To address these concerns and to provide a better basis for evaluating possible radiological impact (especially as a consequence of a potential recovery of the submarine), an environmental impact assessment has been undertaken. The study is based on construction of different hypothetical accident scenarios and evaluating possible associated consequences for human and the environment. In general, three main scenarios seem probable and thus appropriate for consideration. One is the 'zero- alternative', i.e. investigate the current and future impact assuming no interventions. The second considers an accidental scenario involving the raising of the submarine and the third an accidental scenario related to the transportation of the submarine to shore for defueling. With regards to the accidental scenarios related to raising and transportation of the submarine, two alternatives can be considered depending on where and how a hypothetical accident will take place and whether the subsequent releases occur under water or at the water surface. The issue of an uncontrolled chain reaction occurring as a result of a potential recovery of the submarine will be included in the assessment. The work includes application of state of the art 3D hydrodynamic and atmospheric dispersion models to investigate the transport, distribution and fate of relevant radionuclides following a hypothetical accident in aquatic and

Assessment of changes at Glen Canyon Dam

International Nuclear Information System (INIS)

Cherry, D.; McCoy, J.; Crandall, S.

1991-01-01

This paper describes the complexity associated with the assessment of financial impacts of proposed and actual short-term restrictions at Glen Canyon Dam. The reasons for these restrictions are discussed as well as the methods used to measure their financial impact to Western Area Power Administration

Formation of Box Canyon, Idaho, by megaflood: implications for seepage erosion on Earth and Mars.

Science.gov (United States)

Lamb, Michael P; Dietrich, William E; Aciego, Sarah M; Depaolo, Donald J; Manga, Michael

2008-05-23

Amphitheater-headed canyons have been used as diagnostic indicators of erosion by groundwater seepage, which has important implications for landscape evolution on Earth and astrobiology on Mars. Of perhaps any canyon studied, Box Canyon, Idaho, most strongly meets the proposed morphologic criteria for groundwater sapping because it is incised into a basaltic plain with no drainage network upstream, and approximately 10 cubic meters per second of seepage emanates from its vertical headwall. However, sediment transport constraints, 4He and 14C dates, plunge pools, and scoured rock indicate that a megaflood (greater than 220 cubic meters per second) carved the canyon about 45,000 years ago. These results add to a growing recognition of Quaternary catastrophic flooding in the American northwest, and may imply that similar features on Mars also formed by floods rather than seepage erosion.

33 CFR 165.1155 - Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach, California.

Science.gov (United States)

2010-07-01

... Nuclear Power Plant, Avila Beach, California. 165.1155 Section 165.1155 Navigation and Navigable Waters... Coast Guard District § 165.1155 Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach... surface to bottom, within a 2,000 yard radius of Diablo Canyon Nuclear Power Plant centered at position 35...

Fluid mechanical dispersion of airborne pollutants inside urban street canyons subjecting to multi-component ventilation and unstable thermal stratifications.

Science.gov (United States)

Mei, Shuo-Jun; Liu, Cheng-Wei; Liu, Di; Zhao, Fu-Yun; Wang, Han-Qing; Li, Xiao-Hong

2016-09-15

The pedestrian level pollutant transport in street canyons with multiple aspect ratios (H/W) is numerically investigated in the present work, regarding of various unstable thermal stratification scenarios and plain surrounding. Non-isothermal turbulent wind flow, temperature field and pollutant spread within and above the street canyons are solved by the realizable k-ε turbulence model along with the enhanced wall treatment. One-vortex flow regime is observed for shallow canyons with H/W=0.5, whereas multi-vortex flow regime is observed for deep canyons with H/W=2.0. Both one-vortex and multi-vortex regimes could be observed for the street canyons with H/W=1.0, where the secondary vortex could be initiated by the flow separation and intensified by unstable thermal stratification. Air exchange rate (AER) and pollutant retention time are adopted to respectively evaluate the street canyon ventilation and pollutant removal performance. A second-order polynomial functional relationship is established between AER and Richardson number (Ri). Similar functional relationship could be established between retention time and Ri, and it is only valid for canyons with one-vortex flow regime. In addition, retention time could be prolonged abruptly for canyons with multi-vortex flow regime. Very weak secondary vortex is presented at the ground level of deep canyons with mild stratification, where pollutants are highly accumulated. However, with the decrease of Ri, pollutant concentration adjacent to the ground reduces accordingly. Present research could be applied to guide the urban design and city planning for enhancing pedestrian environment. Copyright © 2016 Elsevier B.V. All rights reserved.

Enhancement of submarine pressure hull steel ultrasonic inspection using imaging and artificial intelligence

Science.gov (United States)

Hay, D. Robert; Brassard, Michel; Matthews, James R.; Garneau, Stephane; Morchat, Richard

1995-06-01

The convergence of a number of contemporary technologies with increasing demands for improvements in inspection capabilities in maritime applications has created new opportunities for ultrasonic inspection. An automated ultrasonic inspection and data collection system APHIUS (automated pressure hull intelligent ultrasonic system), incorporates hardware and software developments to meet specific requirements for the maritime vessels, in particular, submarines in the Canadian Navy. Housed within a hardened portable computer chassis, instrumentation for digital ultrasonic data acquisition and transducer position measurement provide new capabilities that meet more demanding requirements for inspection of the aging submarine fleet. Digital data acquisition enables a number of new important capabilites including archiving of the complete inspection session, interpretation assistance through imaging, and automated interpretation using artificial intelligence methods. With this new reliable inspection system, in conjunction with a complementary study of the significance of real defect type and location, comprehensive new criteria can be generated which will eliminate unnecessary defect removal. As a consequence, cost savings will be realized through shortened submarine refit schedules.

North Atlantic octocorals: Distribution, Ecology and Phylogenetics

OpenAIRE

Morris, Kirsty Janet

2011-01-01

Most studies of deep-sea benthic fauna have concentrated on soft sediments with little sampling in rocky areas and even less on non-vent mid-ocean ridges and within submarine canyons, mainly as a result of difficulty accessing them. To assess the distribution and abundance of cold-water corals along an Axial Volcanic Ridges along the Mid-Atlantic ridge at 45oN 27oW, and within the Whittard Canyon along the Irish Margin video footage from the ROV Isis taken during a three scientific cruises wa...

Simulations of the impacts of building height layout on air quality in natural-ventilated rooms around street canyons.

Science.gov (United States)

Yang, Fang; Zhong, Ke; Chen, Yonghang; Kang, Yanming

2017-10-01

Numerical simulations were conducted to investigate the effects of building height ratio (i.e., HR, the height ratio of the upstream building to the downstream building) on the air quality in buildings beside street canyons, and both regular and staggered canyons were considered for the simulations. The results show that the building height ratio affects not only the ventilation fluxes of the rooms in the downstream building but also the pollutant concentrations around the building. The parameter, outdoor effective source intensity of a room, is then proposed to calculate the amount of vehicular pollutants that enters into building rooms. Smaller value of this parameter indicates less pollutant enters the room. The numerical results reveal that HRs from 2/7 to 7/2 are the favorable height ratios for the regular canyons, as they obtain smaller values than the other cases. While HR values of 5/7, 7/7, and 7/5 are appropriate for staggered canyons. In addition, in terms of improving indoor air quality by natural ventilation, the staggered canyons with favorable HR are better than those of the regular canyons.