ERDC/CHL CHETN-IV-35
June 2001
Example 2: (gravel) QR = 50,000 m3/year, adR = 0.2, abR = 0.7, εrd = 0
This example simulates a shallow-draft channel in an inlet located on a gravel shore, so most of
the coarse-grained material is deposited on the updrift side of the channel, with little bypassing
by suspended transport ( asR = 1 - adR - abR = 0.1 ). Only the fine material is assumed to travel
over the channel by suspension. If the gravel gets into the channel, none is resuspended
sufficiently to leave it. The effective channel length is 1,000 m, so qR = 50,000/1,000 =
50 m3/m/year.
In this situation of a gravel shore, because most material remains at the updrift side of the
channel, little depth is lost (Figure 5). However, after 2 years, the updrift side of the channel has
intruded about 37 percent of the way across the channel (Figure 6), becoming a hazard to
navigation. The side of the channel grows approximately linearly, because little material is
deposited in the channel bottom through suspension. Therefore, the governing equation is only
weakly nonlinear, and the linearized (analytical) solution and numerical solution produce almost
the same results. Figure 7 shows that most of the material is deposited into the channel, with
little bypassing.
Fi