Abstract

The floating of sediment is a viable mechanism for moving relatively large amounts of sediment in low energy environments. The tidal flats of Boundary Bay, within the Fraser Delta complex, are an excellent example. The local consequences of flotation are the homogenization of grain size on the flats and high sedimentation rates in the flora zones. The necessary parameters (field and laboratory) for the calculation of the flotation load are discussed herein. The presence of floating sediment indicates that three factors are ideal: 1) proper atmospheric conditions (no fog or precipitation); 2) rising water with intact surface tension (no surface turbulence); and 3) appropriate floatable sediment for the incoming water velocity. The appropriateness of the floating sediment is a function of grain size, grain shape, grain surface texture and surface coating, and grain density. The presence of clays mixed in with the coarser sediment will adversely affect the floatibility of the coarser sediment.

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