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| Titel |
Critical review of SWAT applications in the upper Nile basin countries |
| VerfasserIn |
A. Griensven, P. Ndomba, S. Yalew, F. Kilonzo |
| 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 ; 16, no. 9 ; Nr. 16, no. 9 (2012-09-20), S.3371-3381 |
| Datensatznummer |
250013476
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| Publikation (Nr.) |
 copernicus.org/hess-16-3371-2012.pdf |
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| Zusammenfassung |
| The Soil and Water Assessment Tool (SWAT) is an integrated river basin model
that is widely applied within the Nile basin. Up to date, more than 20 peer-reviewed
papers describe the use of SWAT for a variety of problems in the
upper Nile basin countries, such as erosion modelling, land use and climate
change impact modelling and water resources management. The majority of the
studies are focused on locations in the tropical highlands in Ethiopia and around Lake
Victoria. The popularity of SWAT is attributed to the fact that the tool is
freely available and that it is readily applicable through the development
of geographic information system (GIS) based interfaces and its easy linkage
to sensitivity, calibration and uncertainty analysis tools. The online and
free availability of basic GIS data that are required for SWAT made its
applicability more straightforward even in data-scarce areas. However, the
easy use of SWAT may not always lead to appropriate models which is also a
consequence of the quality of the available free databases in these regions.
In this paper, we aim at critically reviewing the use of SWAT in the context
of the modelling purpose and problem descriptions in the tropical highlands
of the Nile basin countries. To evaluate the models that are described in
journal papers, a number of criteria are used to evaluate the model set-up,
model performances, physical representation of the model parameters, and the
correctness of the hydrological model balance. On the basis of performance
indicators, the majority of the SWAT models were classified as giving
satisfactory to very good results. Nevertheless, the hydrological mass
balances as reported in several papers contained losses that might not be
justified. Several papers also reported the use of unrealistic parameter
values. More worrying is that many papers lack this information. For this
reason, most of the reported SWAT models have to be evaluated critically. An
important gap is the lack of attention that is given to the vegetation and
crop processes. None of the papers reported any adaptation to the crop
parameters, or any crop-related output such as leaf area index, biomass or
crop yields. A proper simulation of the land cover is important for
obtaining correct runoff generation, evapotranspiration and erosion
computations. It is also found that a comparison of SWAT applications on the
same or similar case study but by different research teams and/or model
versions resulted in very different results. It is therefore recommended to
find better methods to evaluate the representativeness of the distributed
processes and parameters (especially when land use studies are envisaged) or
predictions of the future through environmental changes. The main
recommendation is that more details on the model set-up, the parameters and
outputs should be provided in the journal papers or supplementary materials
in order to allow for a more stringent evaluation of these models. |
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