Stefan Wirtz Vom Fachbereich VI (Geographie/Geowissenschaften ...

Experimentelle Rinnenerosionsforschung vs. Modellkonzepte – Quantifizierung der hydraulischen und erosiven Wirksamkeit von Rinnen
s -1 . Tracer 1 shows a higher maximum value in the first run (0.52 m s -1 ) than in the second run
(0.38 m s -1 ), whereas the mean values are similar reaching 0.09 m s -1 in the first and 0.1 m s -1
in the second run. The maximum velocity value of tracer 2 is measured in the first run with
1.35 m s -1 compared to 1.09 m s -1 in the second run. The average is also higher in the first run
with 0.17 m s -1 against 0.13 m s -1 in the second run. The minimum velocities are 0.03 m s -1 in
the second run for the waterfront, tracer 1 and also tracer 2; in the first run, the minimum of
front and first tracer is 0.02 m s -1 , the lowest flow velocity of tracer 2 is 0.04 m s -1 .
In experiment 3 variations can be detected as well but they are not as high as in the first
experiment. The water does not reach the rill's end in the first run but the movement stops
after 11m. The waterfront shows again the lowest flow velocities and is cached by tracer 1 in
the first run after 6.5 m, in the second run after 13 m. The two tracers show again very similar
flow velocities, until tracer 1 outruns the waterfront and turns into the waterfront itself. The
maximum velocity of the waterfront is 0.04 m s -1 in the first run and 0.06 m s -1 in the second
run. The averages are 0.02 m s -1 and 0.03 m s -1 respectively. Tracer 1 reaches 0.25 m s -1 in the
first run and 0.27 m s -1 in the second run, the average is 0.06 m s -1 and 0.07 m s -1 . Also tracer 2
shows a higher maximum in the second run with 0.28 m s -1 against 0.11 m s -1 in the first run
and mean values of 0.05 m s -1 in the first and 0.08 m s -1 in the second run. The minimum
values are 0.01 m s -1 for the front, tracer 1 and tracer 2 in both runs.
Table 5: Overview over the sediment concentrations of the rill experiments
rill 1 rill 2 rill 3
Factor 1a 1b 2a 2b 3a 3b
MAX [g l -1 ] 2.06 2.31 2.37 6.31 2.31 1.59
MIN [g l -1 ] 0 0.05 0 0.3 0 0
MEAN [g l -1 ] 0.78 0.69 0.82 2.21 0.83 0.88
86