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

Experimentelle Rinnenerosionsforschung vs. Modellkonzepte – Quantifizierung der hydraulischen und erosiven Wirksamkeit von Rinnen
The tertiary and quaternary sediments in the Bardenas Reales consist of open playa-lake
deposits, red, grey and green clayey marl and pockets of lacustrine, limestone-like, sandy and
gypsum-containing sediments as well as massive marly and lacustrine limestones that form
cuestas (Desir and Marín, 2007, Murelaga et al., 2002, Sancho et al., 2008). The climate in the
test area is semi-arid and characterised by irregular, heavy rainfall events with an average of
380 mm a -1 , the average annual temperature is 19.2°C, and the potential evapotranspiration
rate reaches 1084 mm. In summer and winter, only sporadic rainfall events reach the test
areas; the convective precipitation occurs in spring and autumn (Causapé et al., 2006,
Causapé et al., 2004, Desir and Marín, 2007, Sancho et al., 2008).
Fig. 1 Location of the Bardenas Reales
The position of our experimental site was 624817 E 4681907 N (UTM Zone 30). With highdefinition
aerial photography it was possible to estimate area and length values and to
describe soil surface characteristics such as vegetation cover or rills.
On a part of the 0.75 ha field with nearly bare soil, i.e. vegetation cover was only 1% and rock
fragments cover 2%, approximately 20 furrows have developed into rills in different stages of
development (Fig. 2). Average rill length was 10 m, thus we calculated a total rill length of
200 m. The relationship between rill length and area (rill density) was 267 m ha -1 . This is
lower than on the fields which were treated by the ‘ripping’ technique (a kind of deep
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