Detecting Near-Field Tsunamis off the Coast of British Columbia

Major marine construction projects, resulting in the release of sediments, are subject to environmental assessment and other regulatory approval processes. An important tool used for this is the development of specialized numerical methods for these marine activities. An integrated set of numerical methods addresses four distinct topics: the near-field release and mixing of suspended sediments into the water column (i.e. the initial dilution zone); the transport of the suspended sediments under the influence of complex ocean currents in the far-field; the settling of the transported suspended sediments onto the seabed; and the potential for resuspension of the deposited sediments due to sporadic occurrences of unusually large near-bottom currents. A review of projects subjected to environmental assessment in the coastal waters of British Columbia from the year 2006 to 2017, is presented to illustrate the numerical models being used and their ongoing development. Improvements include higher resolution model grids to better represent the near-field, the depiction of particle size dependent vertical settling rates and the computation of resuspension of initially deposited sediments, especially in relation to temporary subsea piles of sediments arising from trenching for marine pipelines. The ongoing challenges for this numerical modeling application area are also identified.

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Bar evolution and development of stratification in the gravelly, braided, Kicking Horse River, British Columbia

Canadian Journal of Earth Sciences ◽

10.1139/e77-058 ◽

1977 ◽

Vol 14 (4) ◽

pp. 562-570 ◽

Cited By ~ 236

Author(s):

Frances J. Hein ◽

Roger G. Walker

Keyword(s):

British Columbia ◽

Current Velocity ◽

Near Field ◽

Spring Flood ◽

Velocity Increase ◽

Late Afternoon ◽

Discharge Fluctuations ◽

Evolution And Development ◽

Braided Stream ◽

Shielding Effects

The Kicking Horse River is a gravelly, braided stream characterized by very low winter discharge, a peak spring flood (70 m3s−1 in 1973), and summer diurnal discharge fluctuations (from 18 to 44 m3/s−1 in 1973) related to daily melting on the glaciers that supply the river. The reach studied, near Field, B.C., is characterized by abundant braid bars, and was subdivided into three parts.The upstream reach is characterized by only one major channel, with few unit bars within it. Clast movement takes place at peak flood stages, and the clasts move in 'diffuse gravel sheets' on the channel floor. These sheets are only one to two clast diameters in thickness, and when the clasts stop rolling, the sheet becomes a coarse lag. By contrast, in the midstream and downstream reaches, the channel is more anastomosing, and there are many in-channel bars, mostly transverse and diagonal unit bars. The diagonal bars mostly lack foreset slopes at their downstream margin, and it is suggested that massive to crudely horizontally stratified gravels would be deposited. Transverse bars normally have a foreset slope, giving rise to cross-stratified gravels.Several bars were monitored continuously at their active stages during the diurnal rise in discharge in the late afternoon – evening. Measurement of water slope, current velocity, depth, clast sizes, and rate of bar migration were made every 15 minutes at each of the stations on each bar. The bars tended to advance episodically during periods of velocity increase, as recorded at the upstream monitoring station. However, clast size at the bar front does not seem to increase as velocity increases, possibly due to shielding effects of the largest, stationary, clasts on the bed. This effect made existing initiation-of-bedload-movement equations difficult to apply, and of severely limited use with respect to the poorly sorted gravels.Stratification could not be directly observed in the bars, but we suggest that upstream, the diffuse gravel sheets would form crudely horizontally stratified gravels, probably with a long-axis-transverse imbrication. In the midstream and downstream reaches, in finer gravels, more cross-stratification would be present, related to migration of transverse bars.

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An Alluvial Fan, near Field, in British Columbia

Bulletin of the American Geographical Society ◽

10.2307/198026 ◽

1908 ◽

Vol 40 (6) ◽

pp. 340

Author(s):

Fred H. Lahee

Keyword(s):

British Columbia ◽

Near Field ◽

Alluvial Fan

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Modeling the Transport and Fate of Sediments Released from Marine Construction Projects in the Coastal Waters of British Columbia, Canada

Journal of Marine Science and Engineering ◽

10.3390/jmse6030103 ◽

2018 ◽

Vol 6 (3) ◽

pp. 103 ◽

Cited By ~ 1

Author(s):

David Fissel ◽

Yuehua Lin

Keyword(s):

British Columbia ◽

Numerical Methods ◽

Environmental Assessment ◽

Coastal Waters ◽

Construction Projects ◽

Numerical Models ◽

Near Field ◽

Suspended Sediments ◽

Initial Dilution ◽

Resolution Model

Major marine construction projects, resulting in the release of sediments, are subject to environmental assessment and other regulatory approval processes. An important tool used for this is the development of specialized numerical methods for these marine activities. An integrated set of numerical methods addresses four distinct topics: (1) The near-field release and mixing of suspended sediments into the water column (i.e., the initial dilution zone); (2) the transport of the suspended sediments under the influence of complex ocean currents in the far-field; (3) the settling of the transported suspended sediments onto the seabed; and (4) the potential for resuspension of the deposited sediments due to sporadic occurrences of unusually large near-bottom currents. A review of projects subjected to environmental assessment in the coastal waters of British Columbia, from the year 2006 to 2017, is presented to illustrate the numerical models being used and their ongoing development. Improvements include higher resolution model grids to better represent the near-field, the depiction of particle size dependent vertical settling rates and the computation of resuspension of initially deposited sediments, especially in relation to temporary subsea piles of sediments arising from trenching for marine pipelines. The ongoing challenges for this numerical modeling application area are also identified.

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A New Species of Aphid (Homoptera: Aphididae) from Sorbus

The Canadian Entomologist ◽

10.4039/ent97834-8 ◽

1965 ◽

Vol 97 (8) ◽

pp. 834-836 ◽

Cited By ~ 1

Author(s):

G. A. Bradley

Keyword(s):

British Columbia ◽

New Species ◽

Type Species ◽

Near Field ◽

A New Species ◽

Alate Female

AbstractThe species of aphid described here was collected from Sorbus scopulina Greene near Field, British Columbia. It belongs in the genus Nearctaphis Shaposhnikov, and the subgenus Nearctaphis, closely resembling the type species, Aphis bakeri Cowen, but with fused sclerotic plates on the dorsum of the abdomen in the apterous, as well as in the alate female.

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Near-field scanning optical microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100144644 ◽

1986 ◽

Vol 44 ◽

pp. 642-643

Author(s):

E. Betzig ◽

A. Harootunian ◽

M. Isaacson ◽

A. Lewis

Keyword(s):

Near Field ◽

Optical Microscope ◽

Visible Radiation ◽

Field Methods ◽

Optical Elements ◽

Optical Region ◽

Order Of Magnitude ◽

Nondestructive Imaging ◽

Scanning Optical Microscopy ◽

Near Field Scanning

In general, conventional methods of optical imaging are limited in spatial resolution by either the wavelength of the radiation used or by the aberrations of the optical elements. This is true whether one uses a scanning probe or a fixed beam method. The reason for the wavelength limit of resolution is due to the far field methods of producing or detecting the radiation. If one resorts to restricting our probes to the near field optical region, then the possibility exists of obtaining spatial resolutions more than an order of magnitude smaller than the optical wavelength of the radiation used. In this paper, we will describe the principles underlying such "near field" imaging and present some preliminary results from a near field scanning optical microscope (NS0M) that uses visible radiation and is capable of resolutions comparable to an SEM. The advantage of such a technique is the possibility of completely nondestructive imaging in air at spatial resolutions of about 50nm.

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