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

Experimentelle Rinnenerosionsforschung vs. Modellkonzepte – Quantifizierung der hydraulischen und erosiven Wirksamkeit von Rinnen
(FAO, 2006)), in which the particle density was measured to be 2.65 g cm -3 . Starting soil
moisture was 5.08 % w/w.
The rill at Freila (Fig 2, upper right) developed on a leveled field. The maximum depth of the
rill is about 0.2 m, the maximum width 0.25 m. Vegetation cover is not detectable, rock
fragment cover is about 5%. Using the cross sections of 0.0217 m² (5 m), 0.016 m² (12.5 m),
0.01 m² (15.5 m) and the flow length of 21 m, a volume of about 0.26 m³ was estimated for
the whole rill. The soil texture is classified as medium clay silt, with a particle density of 2.71
g cm -3 and a moderate bulk density of 1510 kg m -3 (BD3). Starting soil moisture was 2.4 %
w/w.
The rill at the Salada site (Fig 2 bottom left) formed on an unpaved road with an average
slope of 7.7°. The rill's headcut catchment covers an area of about 170 m². The maximum
width within the 15 m length tested is about 0.3 m, the maximum depth round 0.2 m. Only 5
% of the rill is covered by rock fragments, and there is no vegetation cover in the rill. The
cross section at the first measuring point at 4 m has an area of 0.0221 m², after 7 m, a cross
section of 0.0244 m² was measured and after 12 m, the cross section was 0.0144 m². For the
tested length of 15 m, there is a volume of 0.23 m³ calculated. The soil texture is classified as
silty clay loam, with a low bulk density (BD2) of 1320 kg m -3 . The particle density value
reaches 2.66 g cm -3 . Starting soil moisture was 4.48 % w/w.
The Belerda rill (Fig 2 bottom right) developed in a loam soil with a high content of sand (45
% of the fine soil) and coarse fragments (13 % of the total soil). It is located on a steep
agricultural road with an average slope of 17.1° and a catchment area of about 5400 m². We
tested 16 m of rill length, with a maximum width of 0.3 m and a maximum depth of 0.2 m.
Vegetation and rock fragments cover about 10%. The cross sections were measured at 4.5 m,
at 8 m and at 11 m, they reach areas of 0.014 m², 0.020 m² and 0.021 m² respectively leading
to an estimated rill volume of about 0,19 m³ . The bulk density is with 1450 kg m -3 moderate
(BD3), the grain density is only 2.61 g cm -3 . Starting soil moisture was 5.87 % w/w.
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