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| Titel |
Modelling water-harvesting systems in the arid south of Tunisia using SWAT |
| VerfasserIn |
M. Ouessar, A. Bruggeman, F. Abdelli, R. H. Mohtar, D. Gabriels, W. M. Cornelis |
| 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 ; 13, no. 10 ; Nr. 13, no. 10 (2009-10-29), S.2003-2021 |
| Datensatznummer |
250012034
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| Publikation (Nr.) |
 copernicus.org/hess-13-2003-2009.pdf |
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| Zusammenfassung |
| In many arid countries, runoff water-harvesting systems support the
livelihood of the rural population. Little is known, however, about the
effect of these systems on the water balance components of arid watersheds.
The objective of this study was to adapt and evaluate the GIS-based
watershed model SWAT (Soil Water Assessment Tool) for simulating the main
hydrologic processes in arid environments. The model was applied to the
270-km2 watershed of wadi Koutine in southeast Tunisia, which receives
about 200 mm annual rain. The main adjustment for adapting the model to this
dry Mediterranean environment was the inclusion of water-harvesting systems,
which capture and use surface runoff for crop production in upstream
subbasins, and a modification of the crop growth processes. The adjusted
version of the model was named SWAT-WH. Model evaluation was performed based
on 38 runoff events recorded at the Koutine station between 1973 and 1985.
The model predicted that the average annual watershed rainfall of the
12-year evaluation period (209 mm) was split into ET (72%), groundwater
recharge (22%) and outflow (6%). The evaluation coefficients for
calibration and validation were, respectively, R2 (coefficient of
determination) 0.77 and 0.44; E (Nash-Sutcliffe coefficient) 0.73 and 0.43;
and MAE (Mean Absolute Error) 2.6 mm and 3.0 mm, indicating that the model
could reproduce the observed events reasonably well. However, the runoff
record was dominated by two extreme events, which had a strong effect on the
evaluation criteria. Discrepancies remained mainly due to uncertainties in
the observed daily rainfall and runoff data. Recommendations for future
research include the installation of additional rainfall and runoff gauges
with continuous data logging and the collection of more field data to
represent the soils and land use. In addition, crop growth and yield
monitoring is needed for a proper evaluation of crop production, to allow an
economic assessment of the different water uses in the watershed. |
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