Your search found 8 records
1 Alemayehu, Tadesse; McCartney, Matthew; Kebede, S. 2009. Modelling to evaluate the water resource implications of planned infrastructure development in the Lake Tana sub-basin, Ethiopia. Paper presented at the Conference on Applying Water Evaluation And Planning System (WEAP) as a Decision Support System (DSS) for IWRM, Damascus, Syria, 25-27 May 2009. 22p.
Lakes ; Water resources development ; Evaluation ; Environmental effects ; Simulation models ; Decision support tools ; Water power ; Irrigation programs ; Water demand / Ethiopia / Lake Tana sub-basin / Chara Chara weir
(Location: IWMI HQ Call no: e-copy only Record No: H042207)
(0.35 MB) (0.35 MB)
Lake Tana is important for domestic water supply, hydropower, fisheries, grazing and water for livestock, as well as reeds for boat construction. It is also important for water transport and as a tourist destination. Currently, the water resources of the catchment are largely untapped. However, water resource development is being encouraged to stimulate economic growth and reduce poverty. In this study, the Water Evaluation And Planning (WEAP) model was used to determine the water availability for different irrigation and hydropower schemes proposed. Three development scenarios were simulated and the likely impact of future water resource development on lake water levels was assessed. For each scenario, the model was used to simulate water demand in three sectors (i.e. irrigation, hydropower and downstream environmental flows) over a 36-year period of varying flow and rainfall. The simulation results revealed that if all the planned development occurs on average 2,198 GWhy-1 power could be generated and 677 Mm3y-1 of water supplied to irrigation schemes. However, the mean annual water level of the lake would be lowered by 0.44 meters with a consequent decrease in the average surface area of the lake of 30 km2. As well as adverse ecological impacts this would have significant implications for shipping and the livelihoods of many local people.
2 Awulachew, Seleshi Bekele; Erkossa, Teklu; Smakhtin, Vladimir; Fernando, Ashra. (Comps.) 2009. 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). 310p. [doi: https://doi.org/10.5337/2011.0014]
River basin management ; Watershed management ; Farming systems ; Water balance ; Reservoirs ; Water supply ; Irrigation requirements ; Irrigation programs ; Simulation models ; Sedimentation ; Rainfall-Runoff relationships ; Erosion ; Soil water ; Water balance ; Soil conservation ; Institutions ; Organizations ; Policy ; Water governance ; International waters / Africa / Ethiopia / Sudan / Nile River / Blue Nile River Basin / Abbay River Basin / Roseires Reservoir / Gumera Watershed / Lake Tana Sub Basin / Volta Basin / Koga Watershed / Gumera Watershed
(Location: IWMI HQ Call no: IWMI 333.9162 G100 AWU Record No: H042503)
(6.52 MB)
This proceeding provides the papers and discussion results of a two-day workshop that was organized at International Water Management Institute (IWMI) office in Addis Ababa during the period of February 6-8, 2009 in relation to CPWF Project 19 – Improved water and land management in the Ethiopian Highlands and its impact on downstream stakeholders dependent on the Blue Nile. Short title: Upstream Downstream (USDS) in the Nile. The project is being under implementation during the last one and half years in partnership with various institutions that include International Livestock Research Institute, Cornell University, Omdurman Islamic University-UNESCO Chair in Water Resources, Addis Ababa University, Bahir Dar University, Amhara Regional Agricultural Research Institute and Forum for Social Studies. The main aims of the workshop had been: Bring together key stakeholders relevant to the project; Present, debate and validate the intermediate results of the project; Disseminate key results to wider audiences through workshop participating stakeholders; Follow up on the progress of the project and plan remaining tasks of the project. The workshop focus themes were: General characterization of the Blue Nile Basin; Watershed modeling and analysis; Water demand and allocation modeling and simulation; Policy and institutions of the water management in the Blue Nile basin.
3 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%.
4 Mamo, S.; Birhanu, B.; Ayenew, T.; Taye, G. 2021. Three-dimensional groundwater flow modeling to assess the impacts of the increase in abstraction and recharge reduction on the groundwater, groundwater availability and groundwater-surface waters interaction: a case of the Rib Catchment in the Lake Tana sub-basin of the Upper Blue Nile River, Ethiopia. Journal of Hydrology: Regional Studies, 35:100831. [doi: https://doi.org/10.1016/j.ejrh.2021.100831]
Groundwater recharge ; Groundwater flow ; Models ; Water extraction ; Groundwater management ; Water availability ; Groundwater table ; Surface water ; Water levels ; Water budget ; Water demand ; Aquifers ; Boreholes ; Catchment areas ; Climate change ; Lakes ; Evapotranspiration ; Precipitation / Ethiopia / Upper Blue Nile River Basin / Lake Tana Sub-Basin / Rib Catchment
(Location: IWMI HQ Call no: e-copy only Record No: H050509)
https://www.sciencedirect.com/science/article/pii/S2214581821000604/pdfft?md5=7182aed98f4c645f21ee8875a2ef99c4&pid=1-s2.0-S2214581821000604-main.pdf
https://vlibrary.iwmi.org/pdf/H050509.pdf
https://vlibrary.iwmi.org/pdf/H050509.pdf
(7.52 MB) (7.52 MB)
Study region: Rib catchment in the Lake Tana sub-basin, Upper Blue Nile River, Ethiopia.
Study focus: This paper aimed to assess the impacts of future increase in abstraction and recharge reduction on the groundwater, groundwater availability, and groundwater-surface waters interaction based on a three-dimensional groundwater flow modeling. Calibration was made under the steady state condition. Scenario analysis performed for 1) increase in abstraction, 2) decrease in recharge, 3) the worst-case scenario that combined the aforementioned two scenarios and with additional extraction for irrigation, and 4) for the optimal-case scenario, which considers 5% recharge increase for the worst-case scenario model.
New hydrological insights for the region: It is found that the groundwater flows from uplands toward the Tana Lake. The total inflow to and outflow from the system in the calibrated model are 1733480 m3/d and 1840451 m3/d, respectively. Groundwater level drop, reduction in base flows to surface waters, and in evapotranspiration flux compared to the calibrated values encountered for all scenarios, which are significant (mean 38.4 m, 28.5–100 %, and 97.8 %, respectively) for the worst-case scenario. On the other hand, an increase in groundwater level (mean 9.8 m), base flows (0–14.4 %), and evapotranspiration flux (29.5 %) observed for the optimal scenario when compared to the worst-case scenario results. Results suggest that groundwater management measures should be implemented to mitigate the impacts.
Study focus: This paper aimed to assess the impacts of future increase in abstraction and recharge reduction on the groundwater, groundwater availability, and groundwater-surface waters interaction based on a three-dimensional groundwater flow modeling. Calibration was made under the steady state condition. Scenario analysis performed for 1) increase in abstraction, 2) decrease in recharge, 3) the worst-case scenario that combined the aforementioned two scenarios and with additional extraction for irrigation, and 4) for the optimal-case scenario, which considers 5% recharge increase for the worst-case scenario model.
New hydrological insights for the region: It is found that the groundwater flows from uplands toward the Tana Lake. The total inflow to and outflow from the system in the calibrated model are 1733480 m3/d and 1840451 m3/d, respectively. Groundwater level drop, reduction in base flows to surface waters, and in evapotranspiration flux compared to the calibrated values encountered for all scenarios, which are significant (mean 38.4 m, 28.5–100 %, and 97.8 %, respectively) for the worst-case scenario. On the other hand, an increase in groundwater level (mean 9.8 m), base flows (0–14.4 %), and evapotranspiration flux (29.5 %) observed for the optimal scenario when compared to the worst-case scenario results. Results suggest that groundwater management measures should be implemented to mitigate the impacts.
5 Taye, Meron Teferi; Haile, Alemseged Tamiru; Fekadu, A. G.; Nakawuka, P. 2021. Effect of irrigation water withdrawal on the hydrology of the Lake Tana sub-basin. Journal of Hydrology: Regional Studies, 38:100961. [doi: https://doi.org/10.1016/j.ejrh.2021.100961]
Irrigation water ; Water extraction ; Hydrology ; Irrigation schemes ; Small scale systems ; Water balance ; Dry season ; Water availability ; Water scarcity ; Irrigated land ; Hydroclimatology ; Crop production ; Water requirements ; Water use ; Rivers ; Smallholders ; Farmers / Ethiopia / Upper Blue Nile Basin / Lake Tana Sub-Basin
(Location: IWMI HQ Call no: e-copy only Record No: H050794)
https://www.sciencedirect.com/science/article/pii/S2214581821001907/pdfft?md5=7e540b0f0dc1c7747491b5c5fb401376&pid=1-s2.0-S2214581821001907-main.pdf
https://vlibrary.iwmi.org/pdf/H050794.pdf
https://vlibrary.iwmi.org/pdf/H050794.pdf
(7.37 MB) (7.37 MB)
Study region: The Lake Tana sub-basin, upper Blue Nile, Ethiopia.
Study focus: The Lake Tana sub-basin is one of the agricultural growth corridors for Ethiopia’s ambitious plan to expand irrigation. Despite the booming irrigation activities in the sub-basin, limited information exists on the rate of irrigation expansion and its impact on the water balance of the sub-basin. This study collected and organized smallholder irrigation data in the subbasin to identify the actual irrigated area, the abstracted irrigation water, and its implications on seasonal water availability. The area under small-scale irrigation was estimated through data obtained from ’woredas’ (districts) databases. Crop patterns were obtained through field surveys. Irrigation water abstracted at daily timescale was measured.
New hydrological insights for the Region: In the sub-basin, 38,694 ha was under small-scale irrigation in 2020/21. Surface water is the dominant water source, and it supplies about 80% of irrigation withdrawal. Water abstraction for small-scale irrigation is about 430 MCM per dry season (~50% of dry season flow). The eastern side of the sub-basin faces water shortages as the dry season flow is not sufficient for irrigation. With the prospects of more irrigation expansion, small-scale irrigation water withdrawals pose concerns of water scarcity at local level and to the water balance of the sub-basin. Hence, there is urgent need for adaptive management of the small-scale irrigation effect on the sub-basin’s hydrology.
Study focus: The Lake Tana sub-basin is one of the agricultural growth corridors for Ethiopia’s ambitious plan to expand irrigation. Despite the booming irrigation activities in the sub-basin, limited information exists on the rate of irrigation expansion and its impact on the water balance of the sub-basin. This study collected and organized smallholder irrigation data in the subbasin to identify the actual irrigated area, the abstracted irrigation water, and its implications on seasonal water availability. The area under small-scale irrigation was estimated through data obtained from ’woredas’ (districts) databases. Crop patterns were obtained through field surveys. Irrigation water abstracted at daily timescale was measured.
New hydrological insights for the Region: In the sub-basin, 38,694 ha was under small-scale irrigation in 2020/21. Surface water is the dominant water source, and it supplies about 80% of irrigation withdrawal. Water abstraction for small-scale irrigation is about 430 MCM per dry season (~50% of dry season flow). The eastern side of the sub-basin faces water shortages as the dry season flow is not sufficient for irrigation. With the prospects of more irrigation expansion, small-scale irrigation water withdrawals pose concerns of water scarcity at local level and to the water balance of the sub-basin. Hence, there is urgent need for adaptive management of the small-scale irrigation effect on the sub-basin’s hydrology.
6 Taye, Meron Teferi; Haile, Alemseged Tamiru; Genet, A.; Geremew, Y.; Wassie, S.; Abebe, B.; Alemayehu, B. 2022. Data quality deterioration in the Lake Tana Sub-basin, Ethiopia: scoping study to provide streamflow and water withdrawal data. Colombo, Sri Lanka: International Water Management Institute (IWMI). 32p. (IWMI Working Paper 204) [doi: https://doi.org/10.5337/2022.208]
Hydrological data ; Data quality ; Lakes ; Stream flow ; Water extraction ; Monitoring ; Flow measurement ; Water level measurement ; Data collection ; Surface water ; Water availability ; Water use ; Irrigation schemes ; Small scale systems ; Water supply ; Urban areas ; Rural settlement ; Drinking water ; Domestic water ; Industry ; Hydropower ; Livestock ; Rainfed agriculture ; Irrigated farming ; Farmer-led irrigation ; Water resources ; Water management ; Planning ; Stakeholders ; Partnerships ; River basin institutions ; Data management ; Alliances ; Climatic data ; Models / Ethiopia / Abbay Basin / Lake Tana Sub-Basin / Gilgel Abay River / Gumara River / Ribb River
(Location: IWMI HQ Call no: IWMI Record No: H051149)
(3.63 MB)
This working paper was prepared under a research project from the Future Leaders – African Independent Research (FLAIR) fellowship programme – focusing on understanding hydrological changes in the Lake Tana sub-basin, Ethiopia, due to water abstraction, land use and climate change. FLAIR is funded by the UK government’s Global Challenges Research Fund (GCRF) through The Royal Society, UK. The study was jointly conducted by the International Water Management Institute (IWMI) and staff of the Abbay Basin Development Office (ABDO). The paper provides information on the deterioration of streamflow data quality in the sub-basin. It demonstrates how to support the sub-basin by generating primary data and compiling current water abstraction data that are relevant for development planning. The project showed the possibility of conducting such activities with limited financial resources and time constraints but with strong collaboration. This work also demonstrated the need for a data alliance among stakeholders in the sub-basin.
7 Haile, Alemseged Tamiru; Geremew, Y.; Wassie, S.; Fekadu, A. G.; Taye, Meron Teferi. 2023. Filling streamflow data gaps through the construction of rating curves in the Lake Tana Sub-basin, Nile Basin. Journal of Water and Climate Change, 14(4):1162-1175. [doi: https://doi.org/10.2166/wcc.2023.372]
Stream flow ; Discharges ; Water levels ; Monitoring ; Tributaries ; Rivers ; Lakes ; Catchment areas ; Hydrology ; Collaboration / Ethiopia / Nile Basin / Lake Tana Sub-Basin / Gilgel Abay River / Gumara River / Ribb River
(Location: IWMI HQ Call no: e-copy only Record No: H051823)
https://iwaponline.com/jwcc/article-pdf/14/4/1162/1212045/jwc0141162.pdf
https://vlibrary.iwmi.org/pdf/H051823.pdf
https://vlibrary.iwmi.org/pdf/H051823.pdf
(0.90 MB) (924 KB)
In recent decades, streamflow data remain inaccessible for most river gauges in Ethiopia due to a lack of updated stage–discharge relationships, also called rating curves. In this study, researchers and hydrologic technicians collaborated to fill the recent streamflow data gaps at three gauging stations in the Lake Tana sub-basin of the Nile River. We conducted extensive field campaigns to improve the coverage of stage–discharge measurements for rating curve development. We evaluated the rating curve uncertainty during the time of its establishment and the sensitivity of the rating curves to sample size. The stage–discharge measurements conducted by the hydrological agency during the period 2016–2020 were found inadequate in number and coverage to establish reliable rating curves. Hence, converting recent water level measurements to discharge data was made possible using the rating curves developed in this study. The converted discharge data will be accessible to researchers to investigate the sub-basin’s hydrology. Our study emphasizes the need to improve the stage–discharge measurement frequency to keep up with the frequent change in the morphology of the rivers’ channels. The study demonstrated that collaboration between the data provider and data users can improve streamflow data availability and accessibility, which has become an increasing global challenge.
8 Fantaye, S. M.; Wolde, B. B.; Haile, Alemseged Tamiru; Taye, Meron Teferi. 2023. Estimation of shallow groundwater abstraction for irrigation and its impact on groundwater availability in the Lake Tana Sub-basin, Ethiopia. Journal of Hydrology: Regional Studies, 46:101365. [doi: https://doi.org/10.1016/j.ejrh.2023.101365]
Groundwater extraction ; Groundwater irrigation ; Shallow water ; Water availability ; Groundwater recharge ; Groundwater table ; Monitoring ; Water levels ; Small-scale irrigation ; Water use ; Surface water ; Water supply ; Irrigated land ; Aquifers ; Sediment ; Lakes ; Wells ; Dry season / Ethiopia / Lake Tana Sub-Basin / Upper Blue Nile River Basin
(Location: IWMI HQ Call no: e-copy only Record No: H051807)
https://www.sciencedirect.com/science/article/pii/S2214581823000526/pdfft?md5=1c7c23903dae2fe81a5cc06e7039b392&pid=1-s2.0-S2214581823000526-main.pdf
https://vlibrary.iwmi.org/pdf/H051807.pdf
https://vlibrary.iwmi.org/pdf/H051807.pdf
(9.32 MB) (9.32 MB)
Study region: Lake Tana sub-basin of the Upper Blue Nile River Basin, Ethiopia.
Study focus: Groundwater use for small-scale irrigation is increasing in the Lake Tana sub-basin. However, the abstraction amount and its impact are not well understood. In this study, a new methodological approach was utilized to estimate the irrigation water abstraction amount, which is based on groundwater level monitoring before, during, and at the end of the irrigation season (2021/2022). The monitoring was conducted on 361 hand-dug wells distributed throughout the sub-basin, which is subdivided into East, Southwest, and North zones.
New hydrological insights for the region: Groundwater abstraction for irrigation and associated groundwater level decline estimates are 10.6 × 106 m3 and 2.43 m in the East, 4.2 × 106 m3 and 3.23 m in the Southwest, and 0.6 × 106 m3 and 1.32 m in the North. These abstractions account for 103%, 97%, and 62% of the mean annual groundwater recharge in the East, Southwest, and North zones, respectively. Groundwater is overexploited in the East and Southwest zones although, at the sub-basin scale, the amount of groundwater used for irrigation is small compared to the renewable groundwater resource. However, if groundwater-based irrigation continues to expand especially in the East and Southwest zones, groundwater scarcity at the local scales will worsen. Adaptive management strategies are required to minimize the potential adverse effects on groundwater resources.
Study focus: Groundwater use for small-scale irrigation is increasing in the Lake Tana sub-basin. However, the abstraction amount and its impact are not well understood. In this study, a new methodological approach was utilized to estimate the irrigation water abstraction amount, which is based on groundwater level monitoring before, during, and at the end of the irrigation season (2021/2022). The monitoring was conducted on 361 hand-dug wells distributed throughout the sub-basin, which is subdivided into East, Southwest, and North zones.
New hydrological insights for the region: Groundwater abstraction for irrigation and associated groundwater level decline estimates are 10.6 × 106 m3 and 2.43 m in the East, 4.2 × 106 m3 and 3.23 m in the Southwest, and 0.6 × 106 m3 and 1.32 m in the North. These abstractions account for 103%, 97%, and 62% of the mean annual groundwater recharge in the East, Southwest, and North zones, respectively. Groundwater is overexploited in the East and Southwest zones although, at the sub-basin scale, the amount of groundwater used for irrigation is small compared to the renewable groundwater resource. However, if groundwater-based irrigation continues to expand especially in the East and Southwest zones, groundwater scarcity at the local scales will worsen. Adaptive management strategies are required to minimize the potential adverse effects on groundwater resources.
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