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| Titel |
Sediment yield in human-induced degraded catchments of the Northern Ethiopian Highlands: magnitude and dynamics |
| VerfasserIn |
M. Vanmaercke, A. Zenebe, J. Poesen, J. Nyssen, G. Verstraeten, J. Deckers, G. Govers |
| 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 |
250031652
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| Zusammenfassung |
| The Northern Ethiopian Highlands are a fragile environment, characterised by steep slopes,
intense rainfall and a sparse vegetation cover. The extreme poverty, stagnating technology
and high population and livestock densities induce serious soil erosion problems. This not
only leads to lower crop yields but also reduces the life expectancy of many dams and
reservoirs (used for power generation or water supply in the dry season) as a result of massive
sedimentation. Although these problems demand for a thorough solution, little is known
about the magnitude and dynamics of sediment transport in the Northern Ethiopian
Highlands. Therefore an intensive measuring campaign was conducted during the rainy
season of 2006 in 10 subcatchments of the Geba (drainage area: 5180 km2), a tributary of the
Tekeze (Atbara) river. These subcatchments range in size from 120 km2 to 4330 km2 and
represent contrasting environments typical for the Northern Ethiopian Highlands. In
this paper, the results of this measuring campaign are discussed. The sediment
yield for the 10 subcatchments range between 400 and 2500 t km-2 a-1, with an
average value of 1400 t km-2 a-1. The uncertainties on these sediment yields were
assessed by Monte Carlo simulations. Important spatial and temporal variations
in suspended sediment export were noted. A few flash floods were recorded in
detail for which clear positive hysteresis effects in sediment concentration were
found. The environmental factors, causing the large differences in sediment yield
between the studied catchments were assessed by means of a semi-quantitative model. |
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