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| Titel |
A numerical tracing experiment of water erosion at the plot scale |
| VerfasserIn |
G. Nord, M. Esteves |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250022323
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| Zusammenfassung |
| A numerical experiment of water erosion was set up on a plot of 100m2 (20m long by 5m
wide) using PSEM_2D (Plot Soil Erosion Model). Various environmental factors were tested:
six topographies combining different slopes and microtopography, four extreme
rainfall events representative of the Temperate and the Mediterranean climates, four
different textured soils, and two conditions of upstream injected discharge. 192
simulations were run. The results enabled to study the processes that control erosion
and sediment yield at the plot scale. A notable contribution of this study was the
possibility to trace numerically eroded sediment. Sediment originated from five
successive zones of 20m2 (4m long by 5m wide) was labelled in a different way and
traced to assess re-deposition within the plot and exportation at the outlet of the
plot.
Over the 100m2 plot, the contribution of rainfall erosion processes was dominant for most
of the simulations without upstream injected discharge. However, in certain conditions of
runoff discharge, slope, and critical shear stress, flow erosion was activated in the downer part
of the plot, becoming the major source of sediment and producing substantial sediment yield.
For the simulations with upstream injected discharge, flow erosion processes were generally
the primary source of sediment over the whole plot and sediment yield was very
high.
Sediment that left the 100m2 plot originated mostly from the downer part of the slope. In
the case of low slope and break in slope, sediment came exclusively from the toeslope
pointing out the efficiency of the break in slope to reduce significantly sediment yield. In the
case of topographies with microrelief, an increase in slope caused an increase in both
sediment yield and maximum travel distance of sediment. In the case of fine sediment, plane
surfaces, and upstream injected discharge, the contribution of sediment from upper parts of
the plot and the maximum travel distance of sediment were enhanced. The microtopography
tested in this study emphasized the concentration of runoff in depressed zones and
accentuated rill erosion, especially at the toeslope where flow depth and velocity were the
more important. |
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