The concentration calculated from Brownlie's sediment transport equation applies only vertically

above the bed. The total sediment transport, computed in SAM, in weight per unit time is computed by

the following equation:

Qs ' ( C B D V

(5.19)

where: Qs

=

sediment transport in weight/time;

B

=

base width;

=

specific weight of water;

C

=

concentration;

D

=

hydraulic depth; and

V

=

average velocity.

An average concentration for the total discharge is then calculated by:

Qs

C'

(5.20)

0.0027 Q

where: C = concentration using the total discharge in ppm;

Qs = sediment transport in tons/day; and

Q = discharge in ft3/s.

Copeland's stable channel design method simultaneously solves Eqs. (5.11), (5.12), and (5.14)

to satisfy water and sediment continuity for a series of slopes and widths. The designer may then select any

point along a curve plotted with width on the x-axis and slope on the y-axis. The minimum slope can be

selected as an extremal hypothesis design according to Chang (1980):

If the minimum slope design is desired it can be evaluated graphically using a stable channel curve. A stable

channel curve is a plot of slope versus width, in which the minimum stream power design corresponds to

minimum slope. An example of a stable channel curve is given in Figure 5.43.

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