The analysis of a laboratory and field data set for sand-bed channels
defines the characteristics of upper-regime plane bed with sediment tr
ansport. The occurrence of upper-regime plane bed relates to the lamin
ar sublayer thickness delta and depends on shear velocity u, median g
rain size d(50) and grain shear Reynolds number R. Two different boun
dary conditions are recognized: (1) Transition to hydraulically smooth
when R < 11.6; and (2) transition to hydraulically rough when R* > 1
1.6. In the first case, upper-regime plane bed is obtained when u(2)
congruent to g delta, where g is the gravitational acceleration. In th
e second case, upper-regime plane bed is observed when d(50) congruent
to 2 delta. Temperature effects are possible when R approaches 11.6,
which explains the observations on the Missouri River. Resistance to
flow for plane bed with sediment transport increases with the Shields
parameter.