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| Titel |
Land use and climate change impacts on the hydrology of the upper Mara River Basin, Kenya: results of a modeling study to support better resource management |
| VerfasserIn |
L. M. Mango, A. M. Melesse, M. E. McClain, D. Gann, S. G. Setegn |
| 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 ; 15, no. 7 ; Nr. 15, no. 7 (2011-07-18), S.2245-2258 |
| Datensatznummer |
250012891
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| Publikation (Nr.) |
 copernicus.org/hess-15-2245-2011.pdf |
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| Zusammenfassung |
| Some of the most valued natural and cultural landscapes on Earth lie in
river basins that are poorly gauged and have incomplete historical climate
and runoff records. The Mara River Basin of East Africa is such a basin. It
hosts the internationally renowned Mara-Serengeti landscape as well as a
rich mixture of indigenous cultures. The Mara River is the sole source of
surface water to the landscape during the dry season and periods of drought.
During recent years, the flow of the Mara River has become increasingly
erratic, especially in the upper reaches, and resource managers are hampered
by a lack of understanding of the relative influence of different sources of
flow alteration. Uncertainties about the impacts of future climate change
compound the challenges. We applied the Soil Water Assessment Tool (SWAT) to
investigate the response of the headwater hydrology of the Mara River to
scenarios of continued land use change and projected climate change. Under
the data-scarce conditions of the basin, model performance was improved
using satellite-based estimated rainfall data, which may also improve the
usefulness of runoff models in other parts of East Africa. The results of
the analysis indicate that any further conversion of forests to agriculture
and grassland in the basin headwaters is likely to reduce dry season flows
and increase peak flows, leading to greater water scarcity at critical times
of the year and exacerbating erosion on hillslopes. Most climate change
projections for the region call for modest and seasonally variable increases
in precipitation (5–10 %) accompanied by increases in temperature
(2.5–3.5 °C). Simulated runoff responses to climate change scenarios were
non-linear and suggest the basin is highly vulnerable under low (−3 %) and
high (+25 %) extremes of projected precipitation changes, but under median
projections (+7 %) there is little impact on annual water yields or mean
discharge. Modest increases in precipitation are partitioned largely to
increased evapotranspiration. Overall, model results support the existing
efforts of Mara water resource managers to protect headwater forests and
indicate that additional emphasis should be placed on improving land
management practices that enhance infiltration and aquifer recharge as part
of a wider program of climate change adaptation. |
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