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Articles 121 - 124 of 124

Full-Text Articles in Geography

Bed Material Sampling Error In Sand Bed Rivers, Peter Ashmore, T R. Yuzyk, R Harrington Oct 1989

Bed Material Sampling Error In Sand Bed Rivers, Peter Ashmore, T R. Yuzyk, R Harrington

Geography & Environment Publications

A total of 468 bed material samples were collected at cross sections of the sand bed of the South Saskatchewan River at Saskatoon to assess the random and systematic errors in the results from four commonly used samplers. Statistically significant differences in particle size distribution occur between the results obtained from different samplers at the same location, in part due to variability in retention of the small particles. The differences are greatest in silty sand and least in well-sorted, medium sand. The precision of results from repetitive samples at the same location using the same sampler depends on both the …


Spatial And Temporal Patterns Of Suspended-Sediment Yield In The Saskatchewan River Basin, Peter Ashmore, T J. Day Sep 1988

Spatial And Temporal Patterns Of Suspended-Sediment Yield In The Saskatchewan River Basin, Peter Ashmore, T J. Day

Geography & Environment Publications

Long-term suspended-sediment concentration and load records are available for 23 Water Survey of Canada sediment-monitoring stations in the Saskatchewan River basin, where the drainage areas range from 10 to over 300 000 km2. Mean annual sediment yield is greatest in the western Alberta Plains along the Oldman and Red Deer rivers (over 100 t km−2 year−1) and tends to increase downstream along the North and South Saskatchewan rivers until major reservoirs in Saskatchewan intervene. Average sediment concentration shows a pattern of variation similar to that of yield. Temporal aspects of suspended-sediment transport vary along the …


Effective Discharge For Suspended Sediment Transport In Streams Of The Saskatchewan River Basin, Peter Ashmore, T J. Day Jun 1988

Effective Discharge For Suspended Sediment Transport In Streams Of The Saskatchewan River Basin, Peter Ashmore, T J. Day

Geography & Environment Publications

Effective discharge for suspended sediment load was determined for 21 sites in the Saskatchewan River basin at which sediment records range from 5 to 29 years in length. The drainage areas for these streams ranges from 10 to over 300,000 km2. The sediment discharge histograms have a variety of forms ranging from the classic unimodal form in which the peak occurs at discharges with a duration of 1–3% to those in which the effective discharge is the extreme event of record and cases in which a single effective discharge is difficult to define. The percentage duration of the …


Confluence Scour In Coarse Braided Streams, Peter Ashmore, Gary Parker Apr 1983

Confluence Scour In Coarse Braided Streams, Peter Ashmore, Gary Parker

Geography & Environment Publications

Laboratory models of a braided valley flat in coarse material were used in conjunction with field data to study confluence scour at braid anabranches. Correct prediction of the depth of scour is required for the design of buried pipeline crossings. Braid pattern and anabranches constantly shift and avulse so that scour holes have definable lifetimes. Although the scatter is large, the depth of water in the scour hole depends on confluence and relative anabranch discharge; this depth can be as high as six times the ambient depths in the anabranches.