Field observations of river bed scour on the Peace River near Fort Vermilion, Alberta

Abstract

The results of field measurements of general and local scour on the Peace River at Fort Vermilion, Alberta are presented. The Peace River, the largest sand bed river in Alberta, has been regulated by the W. A. C. Bennett Dam since 1968, resulting in a general reduction in spring and summer discharges. Between 1971 and 1974 a 532 m twin box girder bridge structure, supported on steel H piles, was constructed at Fort Vermilion. A number of channel surveys have been carried out at the site at various discharges, providing considerable data with which to evaluate scour formulae used in practice. Comparison of measured results with predicted values of general scour indicates that most equations provide results in general agreement with the observed data, even though some of the regime equations may not be appropriate to sites with significant contractions. Computed local pier scour was generally greater than that measured at the site, although this is partly because of the nature of the pier footing configuration, which tended to arrest local scour. Key words: hydraulics, regime, rivers, sediment, scour.