b. 31 hours; note slumped sidewalls, especially in mid-rill.
a. 30 minutes; note slush from panels on soil surface.
c. 31 hours; note soil masses that have flowed and slid.
Figure 24. Rill after T1 began.
rill. The rill R before F1 at the four profile loca-
These changes in the hydraulic geometry of
tions averaged about 5.5 cm (Fig. 25, Table 5).
the rill are the main aspect of the experiment be-
After T1, it changed insignificantly at profiles 1
cause they affect the hydraulic radius, R, of the
and 7 and decreased by about 33% at profiles 3
rill, which would partially determine the velocity
and 5. Such a reduction in R would cause the vel-
and, thus, the erosivity of subsequent flows in the
6.0
5.0
4.0
3.0
2.0
1.0
0.0
7
7
5
5
3
3
1
1
7
5
3
1
(T1) (T2)
(T1) (T2)
(T1) (T2)
(T1) (T2)
Profiles
Figure 25. Hydraulic radius, R, after T1 and T2.
25
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