Your search found 5 records
1 Awulachew, Seleshi Bekele; Tenaw, M.. 2008. Micro watershed to basin scale impacts of widespread adoption of watershed management interventions in Blue Nile Basin. Paper presented at the Challenge Program on Water and Food (CPWF) Workshop on Micro-Watershed to Basin Scale Adoption of SWC Technologies and Impacts, Tamale, Ghana, 22-25 September, 2008. 6p.
Watershed management ; Sedimentation ; Runoff ; Soil loss ; Water balance ; Rainfall runoff relationships ; Models / Africa / Sudan / Ethiopia / Abbay-Blue Nile River Basin / Gumera River Watershed / Ribb River / Addis Zemen
(Location: IWMI HQ Call no: e-copy only Record No: H041747)
High population pressure, inappropriate agricultural policies, improper land-use planning, over-dependency on agriculture as source of livelihood and extreme dependence on natural resources are inducing deforestation, overgrazing, expansion of agriculture to marginal lands and steep slopes, declining agricultural productivity and resource-use conflicts in many parts of Blue Nile. Increased land degradation from poor agricultural practices and erosion results in increased siltation and the reduced water quality in the river basin. The rainfall, runoff and sediment are highly variable both in time and space. Poor water and land management upstream severely affect runoff characteristics and the quality of water reaching downstream. The result is a downward spiral of poverty and food insecurity for millions of people both within the upper catchment and downstream across international borders. Quantification of the erosion, sedimentation processes and evaluation of impacts of interventions are difficult tasks. This paper schematizes the Blue Nile Basin (BNB) at various spatial levels as micro watershed, watershed, sub-basin to basin. It is revealed that sediment in the river systems are temporally varying phenomenon and strongly related to the early onset of rainfall. The hydrographs of the systems shows that the peak of sediment reaches first followed by peak of rainfall and then runoff. Furthermore, the sediment cumulative curve shows that most of the sediment volume passes in the river in the first three months of the rainy season. The paper also considers a particular watershed to model runoff, sediment and impact of watershed intervention. The result shows that runoff can be reasonably simulated with calibration of R2=0.87 and validation of result of 0.82, and comparable sediment modelling results. The study also demonstrates, by undertaking spatial analysis using topographic, soil and land use parameters it is possible to identify the high sediment risk sub-watersheds. Impact of typical watershed intervention using various widths of vegetative filter and application on high erosion risk watersheds shows reduction of sediment yield from 52% to 74%.
2 Awulachew, Seleshi Bekele; Tenaw, M.; Steenhuis, T.; Easton, Z.; Ahmed, A.; Bashar, K. E.; Hailesellassie, A. 2008. Impact of watershed interventions on runoff and sedimentation in Gumera Watershed. In Humphreys, E.; Bayot, R. S.; van Brakel, M.; Gichuki, F.; Svendsen, M.; Wester, P.; Huber-Lee, A.; Cook, S. Douthwaite, B.; Hoanh, Chu Thai; Johnson, N.; Nguyen-Khoa, Sophie; Vidal, A.; MacIntyre, I.; MacIntyre, R. (Eds.). Fighting poverty through sustainable water use: proceedings of the CGIAR Challenge Program on Water and Food, 2nd International Forum on Water and Food, Addis Ababa, Ethiopia, 10-14 November 2008. Vol.1. Keynotes; Cross-cutting topics. Colombo, Sri Lanka: CGIAR Challenge Program on Water and Food. pp.109-113.
River basins ; Flow ; Simulation models ; Watershed management ; Runoff ; Sedimentation ; Erosion ; Soil loss ; Soil degradation / Ethiopia / Sudan / Gumera Watershed / Abbay-Blue Nile River Basin
(Location: IWMI HQ Call no: IWMI 333.91 G000 HUM Record No: H041752)
http://cgspace.cgiar.org/bitstream/handle/10568/3706/IFWF2_proceedings_Volume%20I.pdf?sequence=1
https://vlibrary.iwmi.org/pdf/H041752.pdf
https://vlibrary.iwmi.org/pdf/H041752.pdf
(7.964MB)
3 Awulachew, Seleshi Bekele; Tenaw, M.. 2009. Micro watershed to basin scale impacts of widespread adoption of watershed management interventions in the Blue Nile Basin. In Humphreys, E.; Bayot, R. S. (Eds.). Increasing the productivity and sustainability of rainfed cropping systems of poor smallholder farmers: proceedings of the CGIAR Challenge Program on Water and Food, International Workshop on Rainfed Cropping Systems, Tamale, Ghana, 22-25 September 2008. Colombo, Sri Lanka: CGIAR Challenge Program on Water and Food. pp.223-231.
Watershed management ; Sedimentation ; Erosion ; Runoff ; Rainfall runoff relationships ; Models / Africa / Sudan / Ethiopia / Blue Nile River Basin / Gumera River Watershed / Ribb River / Addis Zemen
(Location: IWMI HQ Call no: 631 G000 HUM Record No: H042442)
http://www.dfid.gov.uk/r4d/PDF/Outputs/WaterfoodCP/CPWF_Proceedings_Rainfed_Workshop%5B1%5D.pdf
https://vlibrary.iwmi.org/pdf/H042442.pdf
https://vlibrary.iwmi.org/pdf/H042442.pdf
(0.63 MB) (8.92MB)
High population pressure, inappropriate agricultural policies, improper land-use planning, Over-dependency on agriculture as a source of livelihoods and extreme dependence on natural resources are inducing serious problems in many parts of the Blue Nile River Basin. These problems include deforestation, overgrazing, expansion of agriculture to marginal lands and steep slopes, declining agricultural productivity, and resource-use conflicts. Poor agricultural and other practices affect runoff characteristics and result in increased erosion and siltation and reduced water quality in the basin. The result is a downward spiral of poverty and food insecurity for millions of people both within the upper catchment and downstream across international borders. Quantification of erosion and sedimentation and evaluation of the impacts of interventions are difficult tasks. We studied rainfall-runoff and sediment-runoff relationships in the Gumera watershed, and calibrated the SWAT model for this watershed. The analysis shows that rainfall, runoff and sediment load are highly variable in both time and space. The amount of sediment in the river systems is strongly related to the onset of rainy season. The hydrographs show that the peak sediment concentration occurs first, followed by the peaks for rainfall and then runoff. Furthermore, the cumulative sediment load curve shows that most of the sediment enters the river in the first three months of the rainy season. The results show that both runoff and sedimentation can be reasonably simulated using the SWAT model (R2=0.82 and 0.79, respectively). The study demonstrated, that by undertaking spatial analysis using topographic, soil and land use parameters with the SWAT model, that it is possible to identify the high sediment risk sub-watersheds. The modelling studies showed that use of vegetative filters with widths of 5 and 10 m in high erosion risk watersheds reduced sediment yield by 52% and 74% respectively.
4 Tenaw, M.; Awulachew, Seleshi Bekele. 2009. Soil and Water Assessment Tool (SWAT)-based runoff and sediment yield modeling: a case of the Gumera Watershed in Lake Tana Sub Basin. In Awulachew, Seleshi Bekele; Erkossa, Teklu; Smakhtin, Vladimir; Fernando, Ashra (Comps.). Improved water and land management in the Ethiopian highlands: its impact on downstream stakeholders dependent on the Blue Nile. Intermediate Results Dissemination Workshop held at the International Livestock Research Institute (ILRI), Addis Ababa, Ethiopia, 5-6 February 2009. Colombo, Sri Lanka: International Water Management Institute (IWMI). pp.100-111.
Watersheds ; Assessment ; Erosion ; Runoff ; Sedimentation ; Models ; Case studies / Africa / Ethiopia / Gumera Watershed / Lake Tana Sub Basin
(Location: IWMI HQ Call no: IWMI 333.9162 G100 AWU Record No: H042511)
(0.99 MB)
Land degradation is a serious threat in the Gumera watershed which is reflected in the form of soil erosion. Erosion is a major watershed problem causing significant loss of soil fertility and productivity. Increased sediment loads that shorten the useful life of the reservoir, the lives of other water-related structures, and increase the cost of maintenance and sediment remediation are off-site impacts of erosion. To develop effective erosion control plans and to achieve reductions in sedimentation, it is important to quantify the sediment yield and identify areas that are vulnerable to erosion. In recent decades, several simulation models have been developed in order to estimate, quantify, enhance understanding of spatial and temporal variability of erosion, and identify areas which are high contributors of sediment at micro-watershed level and over large areas. We used SWAT (Soil and Water Assessment Tool) to predict sediment yield, runoff, identify spatial distribution of sediment, and to test the potential of watershed management interventions in reducing sediment load from ‘hot spot’ areas. The tool was calibrated and validated against measured flow and sediment data. Both, calibration and validation results, showed a good match between measured and simulated flow and suspended sediment. The model prediction results indicated that about 72% of the Gumera watershed is erosion potential area with an average annual sediment load ranging from 11 to /ha/yr 22 tons exceeding tolerable soil loss rates in the study area. The model was applied to evaluate the potential of filter strips with various widths to reduce sediment production from critical micro-watersheds. The investigation revealed that implementing vegetation filter strips can reduce sediment yield by 58 to 74%.
5 Awulachew, Seleshi Bekele; Tenaw, M.; Steenhuis, T.; Easton, Z.; Ahmed, A.; Bashar, K. E. 2008. Blue Nile flow, sediment and impact of watershed interventions: case of Gumera Watershed. Paper presented at the Second International Forum on Water and Food, Addis Ababa, Ethiopia, 10-13 November 2008. 8p.
Watershed management ; Erosion ; Sedimentation ; Runoff ; Models ; Flow ; River basins / Ethiopia / Gumera Watershed / Abbay-Blue Nile Basin
(Location: IWMI HQ Call no: e-copy only Record No: H043010)
(0.49 MB) (0.49 MB)
High population pressure, inappropriate agricultural policies, improper land-use planning, over-dependency on agriculture as source of livelihood and extreme dependence on natural resources are inducing deforestation, overgrazing, expansion of agriculture to marginal lands and steep slopes, declining agricultural productivity and resource-use conflicts in many parts of Blue Nile. Increased land degradation from poor agricultural practices and erosion results in increased siltation and the reduced water quality in the river basin. The rainfall, runoff and sediment are highly variable both in time and space. Poor water and land management upstream severely affect runoff characteristics and the quality of water reaching downstream. The result is a downward spiral of poverty and food insecurity for millions of people both within the upper catchment and downstream across international borders. Quantification of the erosion, sedimentation processes and evaluation of impacts of interventions are difficult tasks. This paper schematizes the Blue Nile Basin (BNB) at various spatial levels as micro watershed, watershed, sub-basin to basin. It considers a particular watershed to model runoff, sediment and impact of watershed intervention. The result shows that runoff can be reasonably simulated with calibration of R2=0.87 and validation of result of 0.82, and comparable sediment modelling results. The study also demonstrates, by undertaking spatial analysis using topographic, soil and land use parameters it is possible to identify the high sediment risk sub-watersheds. Impact of typical watershed intervention using various widths of vegetative filter and application on high erosion risk watersheds show reduction of sediment yield from 52% to 74%
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