J. Warburton et T. Davies, VARIABILITY OF BEDLOAD TRANSPORT AND CHANNEL MORPHOLOGY IN A BRAIDED RIVER HYDRAULIC MODEL, Earth surface processes and landforms, 19(5), 1994, pp. 403-421
This paper investigates variability in bedload transport and channel m
orphology for 11 replicate experimental runs in an approximately 1:50
braided river model. The experiments, each of 90 h duration, were carr
ied out in a 20 x 3 m tilting flume. All the experiments started with
the same initial conditions. Bedload transport was measured at 5 min i
ntervals in a collection drum at the exit from the flume. The model sh
owed reasonable hydraulic similarity when compared to prototype rivers
. Results show that mean bedload transport rates for the 11 runs vary
in the range 0.98 to 1.49 g s-1 (mean = 1.21, coefficient of variation
11 per cent). Within-run transport rates commonly vary from close to
zero, to two and occasionally three or four times the mean rate. Withi
n the bedload series, several irregular phases of transport intensity
can be observed, but time series analysis of the data show little unde
rlying serial structure (an AR(2) auto-regressive model is appropriate
). Channel patterns are narrow/braided, are established quickly and re
main relatively stable throughout the runs, although channel widths in
crease between 20 and 103 per cent over the 11 runs. Channel behaviour
varies from aggradational to transitional between aggradation and deg
radation. Time-averaged bedload transport rate is weakly correlated wi
th braiding intensity. In general, these results demonstrate that for
a given set of controlling variables, bedload transport and channel mo
rphology can be approximately replicated.