Author(s): S. M. Thompson

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Abstract: Detailed measurements of velocity, and of sediment transport inferred from delta build up, in a river scoured by flows up to 500 m3 to form a 1.4 hm3 delta, are used to calibrate a bed-load formula. According to this calibration, “jet zones” which occupy less than 6% of the channel area convey approximately half the load. The resulting ratings for bedload were: a. locally q s = 11 × 10-6 v 4.5 for v > 1.35, otherwise q s = 0; b. river Q s = 6.6 × lO-6 Q 1.5 where qs (m2 ) and Q s (m3 ) are sediment loads, v (m ) is the velocity and Q (m3 ) is the flow. The mean discharges of gravel and water over a period of approximately two years were 0.0165 and 218 nr respectively; a ”concentration“ of 204 g/m3. The median sediment diameter was 0.02 m and the channel slope 0.006. An attempt to reconcile field and laboratory data using the conventional scaling of transport with shear stress failed, but scaling with velocity was successful.

DOI: https://doi.org/10.1080/00221688509499356

Year: 1985