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| Titel |
Changes in land cover, rainfall and stream flow in Upper Gilgel Abbay catchment, Blue Nile basin – Ethiopia |
| VerfasserIn |
T. H. M. Rientjes, A. T. Haile, E. Kebede, C. M. M. Mannaerts, E. Habib, T. S. Steenhuis |
| 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. 6 ; Nr. 15, no. 6 (2011-06-27), S.1979-1989 |
| Datensatznummer |
250012864
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| Publikation (Nr.) |
 copernicus.org/hess-15-1979-2011.pdf |
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| Zusammenfassung |
In this study we evaluated changes in land cover and rainfall in the Upper
Gilgel Abbay catchment in the Upper Blue Nile basin and how changes affected
stream flow in terms of annual flow, high flows and low flows. Land cover
change assessment was through classification analysis of remote sensing
based land cover data while assessments on rainfall and stream flow data are
by statistical analysis. Results of the supervised land cover classification
analysis indicated that 50.9 % and 16.7 % of the catchment area was
covered by forest in 1973 and 2001, respectively. This significant decrease
in forest cover is mainly due to expansion of agricultural land.
By use of a change detection procedure, three periods were identified for
which changes in rainfall and stream flow were analyzed. Rainfall was
analyzed at monthly base by use of the Mann-Kendall test statistic and
results indicated a statistically significant, decreasing trend for most
months of the year. However, for the wet season months of June, July and
August rainfall has increased. In the period 1973–2005, the annual flow
of the catchment decreased by 12.1 %. Low flow and high flow at daily
base were analyzed by a low flow and a high flow index that is based on a
95 % and 5 % exceedance probability. Results of the low flow index
indicated decreases of 18.1 % and 66.6 % for the periods 1982–2000 and
2001–2005 respectively. Results of high flows indicated an increase of
7.6 % and 46.6 % for the same periods. In this study it is concluded
that over the period 1973–2005 stream flow has changed in the Gilgel Abbay
catchment by changes in land cover and changes in rainfall. |
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