Sediment transport by tidal currents and implications for slope stability: Fraser River delta, British Columbia

1995 ◽  
Vol 32 (7) ◽  
pp. 852-859 ◽  
Author(s):  
R. A. Kostaschuk ◽  
J. L. Luternauer ◽  
J. V. Barrie ◽  
P. H. Leblond ◽  
L. Werth Von Deichmann
Keyword(s):  
Sediment Transport ◽  
Slope Failure ◽  
Tidal Currents ◽  
River Delta ◽  
Fraser River ◽  
Dune Field ◽  
Fraser River Delta ◽  
Material Load ◽  
And Migration ◽  
Bed Material

Tidal currents on the sandy, southern slope of Fraser River delta have generated dunes with heights of 0.5–3.5 m and lengths of 11–108 m. Dune geometry and migration measurements indicate net sediment transport to the northwest in the direction of flood tidal currents. Two current meters moored in the dune field showed greater frequencies of occurrence and higher mean current speeds in the flood direction compared with the ebb. Predictions from two bed-material load models indicate sediment transport is overwhelmingly dominated by flood currents. There is no obvious source of sand to replace sediment transported in the dune field, suggesting net erosion of the surface. A previous analysis of bathymetric data also shows recent erosion of the lower slope and overall slope steepening. These patterns of erosion could lead to slope failure and damage to coastal structures.

Seismic site response in the greater Vancouver, British Columbia, area: spectral ratios from moderate earthquakes

1999 ◽  
Vol 36 (2) ◽  
pp. 195-209 ◽  
Author(s):  
John F Cassidy ◽  
Garry C Rogers
Keyword(s):  
Site Response ◽  
Strong Motion ◽  
River Delta ◽  
Data Sets ◽  
Fraser River ◽  
Spectral Ratios ◽  
Data Set ◽  
Seismic Site Response ◽  
Fraser River Delta ◽  
S Period

Three-component, digital recordings of two recent moderate earthquakes provide valuable new insight into the response to seismic shaking in the greater Vancouver area, particularly on the Fraser River delta. The 1996 M = 5.1 Duvall, Washington, earthquake (180 km southeast of Vancouver) triggered strong-motion seismographs at seven sites and the 1997 M = 4.3 Georgia Strait earthquake (37 km west of Vancouver) triggered instruments at 13 sites in the greater Vancouver area. The latter data set is especially important because it contains the first three-component recordings made on bedrock in greater Vancouver. Both data sets represent weak ground motion, with peak horizontal accelerations of 0.5-1.5% gravity (g) for the Duvall earthquake, and 0.2-2.4% g for the Georgia Strait earthquake. Using the method of spectral ratios, we estimate the site response for each of the strong-motion instrument soil sites. On the Fraser River delta amplification is observed over a relatively narrow frequency range of 1.5-4 Hz (0.25-0.67 s period), with peak amplification of 4-10 (relative to competent bedrock) for the thick soil delta centre sites, and about 7-11 for the delta edge sites. Relative to firm soil, the peak amplification ranges from 2 to 5 for the thick soil delta centre sites, and 2 to 6 for the delta edge sites. At higher frequencies, little or no amplification, and in many cases slight attenuation, is observed.Key words: seismic site response, Fraser delta, earthquakes.

Bedforms, bed material, and bedload transport in a salt-wedge estuary: Fraser River, British Columbia

1989 ◽  
Vol 26 (7) ◽  
pp. 1440-1452 ◽  
Author(s):  
R. A. Kostaschuk ◽  
M. A. Church ◽  
J. L. Luternauer
Keyword(s):  
British Columbia ◽  
River Discharge ◽  
Bedload Transport ◽  
Fraser River ◽  
Seasonal Fluctuations ◽  
Salt Wedge ◽  
Migration Rates ◽  
Material Load ◽  
Bed Material

The lower main channel of the Fraser River, British Columbia, is a sand-bed, salt-wedge estuary in which variations in velocity, discharge, and bedform characteristics are contolled by river discharge and the tides. Bed-material composition remains consistent over the discharge season and in the long term. Changes in bedform height and length follow but lag behind seasonal fluctuations in river discharge. Migration rates of bedforms respond more directly to river discharge and tidal fall than do height and length. Bedform characteristics were utilized to estimate bedload transport in the estuary, and a strong, direct, but very sensitive relationship was found between bed load and river discharge. Annual bedload transport in the estuary is estimated to be of the order of 0.35 Mt in 1986. Bedload transport in the estuary appears to be higher than in reaches upstream, possibly because of an increase in sediment movement along the bed to compensate for a reduction in suspended bed-material load produced by tidal slack water and the salt wedge.

scholarly journals Seabed slope instability on the Fraser River delta

1998 ◽  
Author(s):  
H A Christian ◽  
D C Mosher ◽  
J V Barrie ◽  
J A Hunter ◽  
J L Luternauer
Keyword(s):  
River Delta ◽  
Slope Instability ◽  
Fraser River ◽  
Fraser River Delta

Test of selected bed-material load transport models: Nottawasaga River, Ontario

1994 ◽  
Vol 21 (5) ◽  
pp. 770-777 ◽  
Author(s):  
T. J. Chandler ◽  
R. A. Kostaschuk
Keyword(s):  
Sediment Transport ◽  
Engineering Application ◽  
Model Performance ◽  
Material Transport ◽  
Flow Strength ◽  
Transport Models ◽  
Data Scatter ◽  
Load Transport ◽  
Material Load ◽  
Bed Material

Predictions from 13 bed-material load sediment transport models are compared with 19 measurements of bed-material transport in Nottawasaga River, Ontario, using summary plots and geometric statistics. Model selection is based on recent engineering application and suitability for the flow and sediment conditions of the river. The models of Laursen (1958) and Yang (1979) perform best, followed by those of Ackers and White (1973). The models of Van Rijn (1984), Maddock (1976), Karim and Kennedy (1983), Brownlie (1981), and Yang (1973) have considerable data scatter. The models of Engelund and Hansen (1967) and Shen and Hung (1972) are the poorest predictors. Poor model performance is primarily due to overestimation of flow strength needed for particle entrainment and an excessively steep slope in the relations between flow strength and sediment transport. Key words: bed-material load transport models, test, Nottawasaga River.

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