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| Titel |
Flow regime change in an endorheic basin in southern Ethiopia |
| VerfasserIn |
F. F. Worku, M. Werner, N. Wright, P. Zaag, S. S. Demissie |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 18, no. 9 ; Nr. 18, no. 9 (2014-09-30), S.3837-3853 |
| Datensatznummer |
250120483
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| Publikation (Nr.) |
 copernicus.org/hess-18-3837-2014.pdf |
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| Zusammenfassung |
Endorheic basins, often found in semi-arid and arid climates, are
particularly sensitive to variation in fluxes such as precipitation,
evaporation and runoff, resulting in variability of river flows as well as of
water levels in end-point lakes that are often present. In this paper we
apply the indicators of hydrological alteration (IHA) to characterise change
to the natural flow regime of the Omo–Ghibe Basin in southern Ethiopia.
Little water resource infrastructure has been developed in the basin to date,
and it is considered pristine. The basin is endorheic and is the main source
of flow to Lake Turkana in the East African Rift Valley. The water level in
Lake Turkana shows significant fluctuation, but increase of its level can be
observed over the past 20 years. The reasons are currently not well
understood.
Of the five groups of hydrological characteristics in the IHA (magnitude,
timing, duration, frequency and variability), only those related to magnitude
were found to show significant trends, with the main trend being the increase
of flow during the dry season. This trend was not reflected in climatological
drivers such as rainfall, evaporation and temperature (which shows a positive
trend), but rather is attributed to the substantial changes in land use and
land cover in the basin. The change in the basin hydrology is apparent mainly
in the more humid part of the basin. The significant shift from forest and
woodland to grassland and cropland results in a decrease of actual
evaporation and subsequent increase in (dry season) runoff. The long-term
trend of the increasing levels in Lake Turkana are related to these trends in
dry season flows, while shorter-term fluctuations of the lake levels are
attributed primarily to anomalies in consecutive wet and dry season rainfall. |
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