| 1. |
- Mekonnen, Muluneh Admass, et al.
(författare)
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Hydrological modelling of Ethiopian catchments using limited data
- 2009
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Ingår i: Hydrological Processes. - : Wiley. - 0885-6087 .- 1099-1085. ; 23:23, s. 3401-3408
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The hydrological component of Soil and Water Assessment Tool (SWAT) model is adapted for Ethiopian catchments based on primary knowledge of the coherence spectrum between dis-charge and runoff. The implication is that only periods longer than about 50 days can be reliably represented in the model based on the available data. An improved method reflecting soil water retention in terms of cumulative evapotranspiration, so that its value is less dependent on soil storage and more dependent on antecedent climate, is used. The improved method is attractive for Ethiopian conditions due to limited soil data availability and the fact that the time-scale of cumulative evaporation can be evaluated over periods longer than 50 days. The spectrum analysis was done on the available nearby climatic data in three watersheds in Ethiopia to analyze the effects of data limitation on the temporal and spatial scales suitable to account for in comparta-mentalized runoff models. The time scales of SWAT for the surface runoff and groundwater flow response were constrained so as to be consistent with the results of the spectrum analysis. The performance of the SWAT model to predict daily stream flow response was compared to the Seasonal Model (SM) and the Original Linear Purturbation Model (OLPM) both of which need previous seasonal behavior of the stream flow.
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| 2. |
- Setegn, Shimelis Gebriye, et al.
(författare)
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Spatial delineation of soil erosion vulnerability in the Lake Tana Basin, Ethiopia
- 2009
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Ingår i: Hydrological Processes. - : Wiley. - 0885-6087 .- 1099-1085. ; 23:26, s. 3738-3750
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Tidskriftsartikel (refereegranskat)abstract
- The main objective of this study was to identify the most vulnerable areas to soil erosion in the Lake Tana Basin, Blue Nile, Ethiopia using the Soil and Water Assessment Tool (SWAT), a physically based distributed hydrological model, and a Geographic Information System based decision support system that uses multi-criteria evaluation (NICE). The SWAT model was used to estimate the sediment yield within each sub-basin and identify the most sediment contributing areas in the basin. Using the NICE analysis, an attempt was made to combine a set of factors (land use, soil, slope and river layers) to make a decision according to the stated objective. On the basis of simulated SWAT, sediment yields greater than 30 tons/ha for each of the sub-basin area, 18.4% of the watershed was determined to be high erosion potential area. The NICE results indicated that 12-30.5% of the watershed is high erosion potential area. Both approaches show comparable watershed area with high soil erosion susceptibility. The output of this research can aid policy and decision makers in determining the soil erosion 'hot spots' and the relevant soil and water conservation measures. (C) Copyright 2009 John Wiley & Sons, Ltd.
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| 3. |
- Setegn, Shimelis Gebriye, et al.
(författare)
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SWAT model application and prediction uncertainty analysis in the Lake Tana Basin, Ethiopia
- 2010
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Ingår i: Hydrological Processes. - : Wiley. - 0885-6087 .- 1099-1085. ; 24:3, s. 357-367
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Tidskriftsartikel (refereegranskat)abstract
- Lake Tana Basin is of significant importance to Ethiopia concerning water resources aspects and the ecological balance of the area. Many years of mismanagement, wetland losses due to urban encroachment and population growth, and droughts are causing its rapid deterioration. The main objective of this study was to assess the performance and applicability of the soil water assessment tool (SWAT) model for prediction of streamflow in the Lake Tana Basin, so that the influence of topography, land use, soil and climatic condition on the hydrology of Lake Tana Basin can be well examined. The physically based SWAT model was calibrated and validated for four tributaries of Lake Tana. Sequential uncertainty fitting (SUFI-2), parameter solution (ParaSol) and generalized likelihood uncertainty estimation (GLUE) calibration and uncertainty analysis methods were compared and used for the set-up of the SWAT model. The model evaluation statistics for streamflows prediction shows that there is a good agreement between the measured and simulated flows that was verified by coefficients of determination and Nash Sutcliffe efficiency greater than 0.5. The hydrological water balance analysis of the basin indicated that baseflow is an important component of the total discharge within the study area that contributes more than the surface runoff. More than 60% of losses in the watershed are through evapotranspiration. Copyright (C) 2009 John Wiley & Sons, Ltd.
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