Seiche Excitation in Port San Juan, British Columbia

1979 ◽  
Vol 36 (10) ◽  
pp. 1223-1227
Author(s):  
D. D. Lemon ◽  
P. H. LeBlond ◽  
T. R. Osborn
Keyword(s):  
British Columbia ◽  
Water Waves ◽  
Pressure Gauge ◽  
Low Frequency ◽  
San Juan ◽  
External Forcing ◽  
Edge Waves ◽  
Rectangular Basin ◽  
Juan De Fuca ◽  
Juan De Fuca Strait

Seiche motions observed in San Juan Harbour with a bottom-mounted pressure gauge have been Fourier-analyzed and interpreted in terms of a theoretical model of oscillations in a rectangular basin with an exponential depth profile. Two of the observed periods (at 14.6 and 38.5 min) are identified with resonances of the basin; two other significant low frequency peaks (at 21 and 55 min) do not coincide with resonant periods of the basin and must be due to strong external forcing. Higher frequency fluctuations (20–160 s) are attributed to swell and to its subharmonic interactions with edge waves. Key words: water waves, seiches, mathematical model, Juan de Fuca Strait, British Columbia

scholarly journals EXCITATION OF LOW FREQUENCY TRAPPED WAVES

1978 ◽  
Vol 1 (16) ◽  
pp. 25
Author(s):  
Robert King ◽  
Ronald Smith
Keyword(s):  
Incident Wave ◽  
Standing Waves ◽  
Low Frequency ◽  
Nonlinear Interactions ◽  
Edge Waves ◽  
Constant Depth ◽  
Side Band ◽  
Rectangular Basin ◽  
Trapped Wave ◽  
Narrow Wave

Weak nonlinear interactions in water of non-constant depth between an incident wave, a side-band incident wave and a relatively low frequency trapped wave are shown to lead to the generation of the trapped wave. Three situations are considered in detail: edge waves in a wide rectangular basin, progressive edge waves on a straight beach, and standing waves in a narrow wave tank.

Late Pleistocene history and geomorphology, southwestern Vancouver Island, British Columbia

1979 ◽  
Vol 16 (9) ◽  
pp. 1645-1657 ◽  
Author(s):  
Neville F. Alley ◽  
Steven C. Chatwin
Keyword(s):  
British Columbia ◽  
Continental Shelf ◽  
Late Pleistocene ◽  
Vancouver Island ◽  
Glacial Lakes ◽  
Small Lakes ◽  
Strait Of Georgia ◽  
Coast Mountains ◽  
Juan De Fuca ◽  
Juan De Fuca Strait

The major Pleistocene deposits and landforms on southwestern Vancouver Island are the result of the Late Wisconsin (Fraser) Glaciation. Cordilleran glaciers formed in the Vancouver Island Mountains and in the Coast Mountains had advanced down Strait of Georgia to southeastern Vancouver Island after 19 000 years BP. The ice split into the Puget and Juan de Fuca lobes, the latter damming small lakes along the southwestern coastal slope of the island. During the maximum of the glaciation (Vashon Stade), southern Vancouver Island lay completely under the cover of an ice-sheet which flowed in a south-southwesterly direction across Juan de Fuca Strait, eventually terminating on the edge of the continental shelf. Deglaciation was by downwasting during which ice thinned into major valleys and the strait. Most upland areas were free of ice down to an elevation of 400 m by before 13 000 years BP. A possible glacier standstill and (or) resurgence occurred along Juan de Fuca Strait and in some interior upland valleys before deglaciation was complete. Glacial lakes occupied major valleys during later stages of deglaciation.

Some Oceanographic Features of Juan de Fuca Strait

1961 ◽  
Vol 18 (6) ◽  
pp. 1027-1071 ◽  
Author(s):  
R. H. Herlinveaux ◽  
J. P. Tully
Keyword(s):  
Fresh Water ◽  
Brackish Water ◽  
San Juan ◽  
Ocean Water ◽  
Lower Zone ◽  
Strait Of Georgia ◽  
Deep Waters ◽  
Juan De Fuca ◽  
Juan De Fuca Strait ◽  
Flood Flow

The distribution and structure of dissolved oxygen, salinity, temperature and density, and their seasonal and tidal variations are summarized, and related to the tidal and estuarine mechanisms.Juan de Fuca Strait is a complex, deep, positive estuary. It is divided into inner and outer parts by a sill extending southward across the channel from Victoria, B.C. The Inner Strait is separated from the Strait of Georgia by the San Juan Archipelago. The water structure in the Strait of Georgia is highly stratified due to the shallow brackish upper zone maintained by the Fraser River discharge. This brackish water tends persistently seaward due to the estuarine mechanism. In the passages through the San Juan Archipelago the shallow and deep waters are mixed to near homogeneity by the turbulent tidal flows. In the Inner Strait the stratification is small. Part of this mixed water is fed back into the lower zone of the Strait of Georgia, and part escapes seaward in the upper zone of the outer part of Juan de Fuca Strait, where it overruns the intruding ocean water, creating a new stratification. The ebb flow is stronger than the flood in this upper zone, and the halocline is deepest on the northern side of the strait.The flood flow, augmented by the deep inflow required by the estuarine mechanism, is strongest in the lower zone. Here the ocean waters advance over the sill during the flood flow, but do not retreat during the ebb flow, which is relatively weak. These ocean waters are incorporated with the mixed waters in the Inner Strait. This mechanism is a tidal pump.The concentration of fresh water in the upper zone of Juan de Fuca Strait varies from 2 to 6% during the year. The amount (depth of fresh water when separated from the ocean water in the system) varies from 1 to 7 m. In this and all other properties there is a gradient from the Strait of Georgia into the Inner Strait. In the Outer Strait there are cross-channel gradients, but none longitudinally.Throughout the system the density structure is salinity dominated. During the summer the thermocline coincides with the halocline. In winter the waters are isothermal, or the upper waters become slightly colder than the deep waters. Then the stability depends on the salinity structure alone.The salinity is a linear function of temperature within 0.1 °C, except at the surface in summer. The slope of the relation varies with time (season) and location. The relation shows that the waters throughout the system are mixtures of ocean water and brackish water from the Strait of Georgia, and tributary inlets.

First Record of Whitebait Smelt (Allosmerus elongatus) from Juan de Fuca Strait, British Columbia

1971 ◽  
Vol 28 (10) ◽  
pp. 1681-1681
Author(s):  
W. E. Barraclough ◽  
R. M. Wilson
Keyword(s):  
British Columbia ◽  
First Record ◽  
Juan De Fuca ◽  
First Time ◽  
Juan De Fuca Strait

The whitebait smelt Allosmerus elongatus (Ayres) is recorded from British Columbia for the first time on the basis of three specimens from Juan de Fuca Strait caught November 2, 1969.

Concentrations of Nutrients and Chlorophyll on a Cross-Channel Transect in Juan de Fuca Strait, British Columbia

1978 ◽  
Vol 35 (3) ◽  
pp. 305-314 ◽  
Author(s):  
A. G. Lewis
Keyword(s):  
British Columbia ◽  
Key Words ◽  
Oceanic Water ◽  
Inshore Water ◽  
Geostrophic Flow ◽  
Juan De Fuca ◽  
Southern Side ◽  
Northern Side ◽  
The Cross ◽  
Juan De Fuca Strait

Nutrient and chlorophyll values were measured hourly at one of four stations on a cross-channel transect, over a 25-h period during each of 5 mo. Nitrate values increased with depth, chlorophyll decreased, and phosphate remained essentially unchanged during most months. Chlorophyll and phosphate values did not show consistent cross-channel trends, while nitrate levels were frequently higher on the southern side of the Strait. The cross-channel nitrate pattern can be at least partially explained in terms of geostrophic flow; greater amounts of nitrate-rich oceanic water enter at depth on the southern side of the Strait, while nitrate poor inshore water exists near the surface on the northern side. Key words: nutrients, chlorophyll, Juan de Fuca Strait

Sediment characteristics and sea-level history of Royal Roads Anchorage, Victoria, British Columbia

1988 ◽  
Vol 25 (11) ◽  
pp. 1800-1810 ◽  
Author(s):  
R. H. Linden ◽  
P. J. Schurer
Keyword(s):  
British Columbia ◽  
High Resolution ◽  
Sea Level ◽  
Seismic Reflection ◽  
Sediment Characteristics ◽  
Sea Floor ◽  
Juan De Fuca ◽  
History Of ◽  
Nearshore Sediments ◽  
Juan De Fuca Strait

High-resolution and airgun seismic-reflection mapping of the approaches to Esquimalt Harbour, Juan de Fuca Strait, reveal that offshore, sea-floor sediments consist of a widespread glaciomarine unit recognizable to the entrance of the strait. The upper part of the unit has been dated at approximately 10 000 radiocarbon years BP. An early postglacial sea-level low of at least −50 m appears to have formed a widespread unconformity. Nearshore sediments above the unconformity consist of sands, muddy fine sands, and minor gravel that were deposited in a prograding marine environment. Sediments have been accumulating off Esquimalt Harbour at a rate of approximately 1.9 cm per 100 years.

Stygobromus quatsinensis, a new amphipod crustacean (Crangonyctidae) from caves on Vancouver Island, British Columbia, with remarks on zoogeographic relationships

1987 ◽  
Vol 65 (9) ◽  
pp. 2202-2209 ◽  
Author(s):  
John R. Holsinger ◽  
D. Patrick Shaw
Keyword(s):  
British Columbia ◽  
Vancouver Island ◽  
Western United States ◽  
Pleistocene Glaciation ◽  
Juan De Fuca ◽  
Alternative Hypotheses ◽  
Amphipod Crustacean ◽  
Coarse Sediments ◽  
Juan De Fuca Strait ◽  
A New Species

Stygobromus quatsinensis, a new species of subterranean, freshwater amphipod crustacean, is described from caves on Vancouver Island, British Columbia, Canada. This is the 3rd stygobiont amphipod recorded from Canada and the 11th member of the genus Stygobromus to be found in localities north of the southern limits of Pleistocene glaciation. Stygobromus quatsinensis is a member of the hubbsi group, an assemblage of closely similar stygobiont species previously recorded from the central and western United States south of British Columbia. Two alternative hypotheses are proposed to explain the presence of S. quatsinensis on a glaciated island separated from the mainland by marine straits. One theory suggests that it evolved from putative ancestors that were present on the island before development of the Juan de Fuca Strait in the Eocene. The other suggests that it gained access to the island from the mainland through interstitial routes in coarse sediments of the Quadra Sand which infilled parts of the Georgia Strait in the late Pleistocene. Both theories assume that this species has survived glaciation in subglacial groundwater refugia.

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