Your search found 20 records
1 McCartney, Matthew; Alemayehu, T.; Shiferaw, A.; Awulachew, Seleshi Bekele. 2010. Evaluation of current and future water resources development in the Lake Tana Basin, Ethiopia. Colombo, Sri Lanka: International Water Management Institute (IWMI). 31p. (IWMI Research Report 134) [doi: https://doi.org/10.3910/2010.204]
Lakes ; Weirs ; Environmental flows ; Water resources development ; Models / Ethiopia / Lake Tana Basin / Chara Chara Weir
(Location: IWMI HQ Call no: IWMI 333.91 G136 MAC Record No: H042875)
(925.49KB)
Lake Tana, located in the headwaters of the Blue Nile, is valuable for many people including the communities who live around the lakeshore and those who live immediately downstream. The area has been identified as a region for hydropower and irrigation development, vital for economic growth in Ethiopia. A multidisciplinary study was conducted to assess the possible impacts of this development. This study found that current development has benefited some local people but adversely affected others. Future development will exacerbate pressure on the lake. Hard choices must be made about how the water is best utilized. It is important that all stakeholders, including local people, are involved in the decision-making process.
2 Abtew, W.; Melesse, A. M. (Eds.) 2008. Proceedings of the workshop on Hydrology and Ecology of the Nile River Basin under Extreme Conditions, Addis Ababa, Ethiopia, 16-19 June 2008. Sandy, UT, USA: Aardvark Global Publishing. 368p. + 1CD.
Water resources ; Water management ; Hydrology ; Ecology ; River basin management ; Lakes ; Climate change ; International waters ; Water security ; Land use ; Environmental flows ; Downstream ; Weirs ; Simulation models ; Water balance ; Water use ; Water availability ; Watersheds ; Water productivity ; Water policy ; Erosion ; Sedimentation ; Rain ; GIS ; Remote sensing ; Evaporation ; Water power ; Investment ; Irrigation schemes ; Flooding ; Risks / Africa / Ethiopia / Kenya / Tanzania / Nile River Basin / Mara River / Lake Victoria Catchment / Gilgel Abbay Catchment / Lake Tana Basin / Chara Chara Weir / Rift Valley Lakes / Fogera Woreda / Geray Irrigation scheme / West Gojjam Zone / Amhara Region
(Location: IWMI HQ Call no: 551.48 G136 ABT Record No: H044302)
(0.46 MB)
3 Abdo, K. S.; Rientjes, T. H. M.; Gieske, A. S. M. 2008. Assessment of climate change impacts on the hydrology of Gilgel Abbay Catchment in Lake Tana Basin, Ethiopia. In Abtew, W.; Melesse, A. M. (Eds.). Proceedings of the Workshop on Hydrology and Ecology of the Nile River Basin under Extreme Conditions, Addis Ababa, Ethiopia, 16-19 June 2008. Sandy, UT, USA: Aardvark Global Publishing. pp.39-56.
Climate change ; Hydrology ; Catchment areas ; Lakes ; Models ; Calibration ; Sensitivity analysis / Ethiopia / Gilgel Abbay Catchment / Lake Tana Basin
(Location: IWMI HQ Call no: 551.48 G136 ABT Record No: H044316)
(1.14 MB)
4 Abtew, W.; Melesse, A. M. (Eds.) 2008. Proceedings of the workshop on Hydrology and Ecology of the Nile River Basin under Extreme Conditions, Addis Ababa, Ethiopia, 16-19 June 2008. Sandy, UT, USA: Aardvark Global Publishing. 368p. + 1CD.
Water resources ; Water management ; Hydrology ; Ecology ; River basin management ; Lakes ; Climate change ; International waters ; Water security ; Land use ; Environmental flows ; Downstream ; Weirs ; Simulation models ; Water balance ; Water use ; Water availability ; Watersheds ; Water productivity ; Water policy ; Erosion ; Sedimentation ; Rain ; GIS ; Remote sensing ; Evaporation ; Water power ; Investment ; Irrigation schemes ; Flooding ; Risks / Africa / Ethiopia / Kenya / Tanzania / Nile River Basin / Mara River / Lake Victoria Catchment / Gilgel Abbay Catchment / Lake Tana Basin / Chara Chara Weir / Rift Valley Lakes / Fogera Woreda / Geray Irrigation scheme / West Gojjam Zone / Amhara Region
(Location: IWMI HQ Call no: 551.48 G136 ABT c2 Record No: H044337)
5 Berhanu, Beza; Haile, Alemseged Tamiru. 2014. Evaluating climate change impact on water demand of irrigation schemes in the Lake Tana basin using newly developed climate change scenario [Abstract only] In Arba Minch University. A base for building climate resilient green economy: proceedings of the 14th Symposium on Sustainable Water Resources Development, Arba Minch, Ethiopia, 27-28 June 2014. Arba Minch, Ethiopia: Arba Minch University. pp.29-30.
Climate change ; Water demand ; Irrigation schemes ; Irrigation requirements ; Irrigation water ; River basins / Ethiopia / Lake Tana Basin
(Location: IWMI HQ Call no: e-copy only Record No: H046870)
6 Haile, Alemseged Tamiru; Yan, F.; Habib, E. 2015. Accuracy of the CMORPH satellite-rainfall product over Lake Tana Basin in eastern Africa. Atmospheric Research, 163:177-187. [doi: https://doi.org/10.1016/j.atmosres.2014.11.011]
Rain ; Satellites ; River basins ; Lakes ; Remote sensing ; Spatial distribution ; Wet season ; Dry season / Eastern Africa / Lake Tana Basin
(Location: IWMI HQ Call no: e-copy only Record No: H046880)
In this study, we assessed the accuracy of rainfall occurrence, amount and distribution over the Lake Tana basin in Ethiopia, Eastern Africa, as represented in the NOAA satellite-based Climate Prediction Center Morphing technique (CMORPH) rainfall product. This analysis is carried out at high spatial and temporal resolutions (8 × 8 km2 and daily) using observations from rain gauges as a reference for the period covering January 2003 to December 2006. Graphical comparisons and several statistical metrics such as bias, correlation coefficient, and standard deviation of rainfall differences are used to perform the evaluation analysis. Spatial maps of these statistical metrics were developed to assess the spatial dependency in the CMORPH accuracy. The bias is decomposed into different components, hit, missed, and false, in order to gain additional insight into the possible sources of systematic deviations in CMORPH. Overall, CMORPH was able to capture the seasonal and spatial patterns of rainfall over the basin, but with varying degrees of accuracy that depend on topography, latitude and lake-versus-land conditions within the basin. The results show that CMORPH captured rain occurrence relatively well in both wet and dry seasons over the southern part of the basin but it significantly overestimated those over the lake and its southern shore. The bias of CMORPH in the study area is characterized by seasonal and spatial variations (-25 to 30% in wet season and -40 to 60% in dry season). False as well as missed rains contribute significantly to the total rainfall amounts over the basin. Significant levels of the differences are observed at the daily resolution of CMORPH. The relation between CMORPH and gauge rainfall amounts is stronger (correlationmostly N0.4) in thewet season than in the dry (mostly b0.4).
7 Yiak, D. L.; Tilahun, S. A.; Schmitter, Petra; Nakawuka, Prossie; Steenhuis, T. S. 2015. Groundwater recharge of Robit - Bata Experimental Watershed, Lake Tana Basin, Ethiopia [Abstract only] Paper presented at the 3rd International Conference on the Advancements of Science and Technology [ICAST], Bahir Dar, Ethiopia, 8-9 May 2015. 1p.
Groundwater recharge ; Groundwater irrigation ; Watersheds ; Water use ; Water table ; River basins ; Rain / Ethiopia / Lake Tana Basin / Robit - Bata Experimental Watershed
(Location: IWMI HQ Call no: e-copy only Record No: H047313)
(0.04 MB)
Irrigation development is a policy priority for the Laka Tana basin. However available baseflow can irrigate less than 3% of area. The irrigated area can be increased from water stored in constructed reservoirs, pumping water from Lake Tana and by using groundwater. While groundwater has the greatest potential for increasing irrigation in the near future, the main drawback is a lack of information on sustainable groundwater use and specifically the ground water recharge. Therefore the objective of this research is to calculate the annual recharge to the ground water. The study is conducted in Robit-Bata, an experimental watershed of 911 ha, located at the south-eastern edge of Lake Tana. Farmers have excavated more than 300 hand dug wells for irrigation and we used 50 shallow groundwater wells and observed water table fluctuation and precipitation for the past one year. The annual recharge was estimated using water – level fluctuation method. Specific yield was taken to be the difference of porosity and field capacity of the subsurface formation. The annual average areal groundwater recharge of the watershed was 200 mm/year, which is 12% of the rainfall and ranged from 80mm to 500mm for the various locations in the watershed. The greatest recharge amounts were found at the foot of the hillside in river course plane areas consisting mostly weathered basalt rock. Here the groundwater was up to 15 m deep and rose steadily during the rainy monsoon phase. Smaller amount of recharge occurred both near the top of the hills with tough rock formation and in the, flat areas near to stream sandy and clay deposits and groundwater at, shallow well depth. Our study indicates that the current use of the groundwater is sustainable, but will become unsustainable if many more wells are constructed. Sufficiency and sustainable use of the shallow groundwater needs further research.
8 Tadesse, A.; Dagnew, D. C.; Belete, M. A.; Tilahun, S. A.; Mekuria, Wolde; Steenhuis, T. 2015. Impact of soil and water conservation practices on sediment losses and discharge in the headwaters of the Lake Tana Basin in the Ethiopian highlands [Abstract only] Paper presented at the 10th Alexander von Humboldt Conference 2015 on Water-Food-Energy River and Society in the Tropics. EGU Topical Conference Series, Addis Ababa, Ethiopia, 18-20 November 2015. 1p.
Soil conservation ; Water conservation ; Sediment ; Water erosion ; Watersheds ; Discharges ; River basins ; Highlands ; Runoff / Ethiopia / Blue Nile Basin / Lake Tana Basin / Tikur-Wuha Watershed / Guali Watershed
(Location: IWMI HQ Call no: e-copy only Record No: H047342)
http://meetingorganizer.copernicus.org/AvH10/AvH10-42-1.pdf
https://vlibrary.iwmi.org/pdf/H047342.pdf
https://vlibrary.iwmi.org/pdf/H047342.pdf
(0.04 MB) (37.63 KB)
Donor and governmental sponsored soil and water conservation measures has been carried out in the last half century in the Lake Tana basin, Ethiopia. However, sediment loads in to the lake has never been reduced suggesting that the effectiveness of integrated soil and water conservation measures reducing soil loss needs to be investigated. The present study was conducted in two watersheds (Tikur-Wuha covers 500 ha and Guali covers190 ha) located in the headwaters of Lake Tana to investigate the impacts of soil and water conservation practices on discharge and sediment loads. In both watersheds different soil and water conservation technologies have been implemented since 2010 by the Tana Belese integrated watershed management project: gully treatment, stone buds, soil bunds, stone faced soil bunds, water ways, cut- off drains, hill side terracing, micro basins and area closures. Daily rainfall, runoff and sediment concentration were collected from 2010 – 2012. The results showed that average runoff volume was reduced by 13% in Tikur-wuha and by 7% in Guali from 2010-2012. The sediment load in Tikur-wuha watershed was reduced by 48% in 2011 and 30% in 2012, while sediment load in Guali watershed was reduced by 1% and 35% in 2011 and 2012 respectively. The results support that the implemented integrated SWC measures through government sponsored with full participation of the community and through incorporating different SWC technology options were effective in reducing runoff and sediment load. We recommend fortifying the government led SWC campaign with full participation of the local community to reduce soil erosion and siltation of Lake Tana.
9 Sugden, Fraser; Punch, S. 2016. Changing aspirations, education, and migration: young people’s declining agroecological knowledge in rural Asia. In Nicola, A.; Natascha, K.; Tracey, S. (Eds.). Geographies of global issues: change and threat. Dordrecht, Netherlands: Springer. pp.483-499. (Geographies of Children and Young People 8)
Ecosystem services ; Water harvesting ; Water requirements ; Water quality ; Watersheds ; Water use ; Water yield ; Water productivity ; Intensification ; Upstream ; Downstream ; Stream flow ; Climate change ; Crop yield ; Irrigation water ; Ponds ; Sediment ; Agricultural production ; Dry season ; Onions ; Sustainable agriculture ; Ecological factors ; Decision support systems ; Soils ; Assessment ; Supplemental irrigation ; Nutrients ; Food security ; Food production ; Calibration ; River basins ; Case studies / Ethiopia / Africa South of Sahara / Lake Tana Basin
(Location: IWMI HQ Call no: e-copy only Record No: H047886)
This chapter explores the interrelationships between economic change and environmental issues, by showing how aspiration, education, and migration are variously connected to a loss of agroecological knowledges for rural young people. It reviews a series of case studies from Vietnam, India, and China on the implications for rural youth of changed aspirations and ecological and economic stress. The economic and cultural pressures of globalization mean young people increasingly aspire for a life outside of agrarian- and natural resource-based livelihoods. A consequence of this change has been the migration of young people to urban centers and a drive for families to invest in education. Thishasfar reaching consequences for communities.Those who stay behind face an increased labor burden, and economic pressures can be aggravated when the promise of improved livelihoods outside is notrealized. The chapter also points to the negative implications of these changed aspirations on the intergenerational transfer of agroecological knowledge. Thus, in relation to issues of environment and development, the chapter considers why this complex set of relationships between aspiration, education, and migration is important in the context of children and young people’s lives.
10 Dile, Y. T.; Karlberg, L.; Daggupati, P.; Srinivasan, R.; Wiberg, D.; Rockstrom, J. 2016. Assessing the implications of water harvesting intensification on upstream–downstream ecosystem services: a case study in the Lake Tana basin. Science of The Total Environment, 542:22-35. [doi: https://doi.org/10.1016/j.scitotenv.2015.10.065]
Water harvesting ; Water requirements ; Water quality ; Water use ; Intensification ; Stream flow ; Upstream ; Downstream ; Ecosystem services ; Crop yield ; Supplemental irrigation ; Irrigation water ; Sediment ; Sustainable agriculture ; Intensification ; Ecology ; Decision support systems ; Ponds ; Watersheds ; Soils ; Assessment ; Nutrient availability ; Onions ; Food security ; Food production ; Economic aspects ; Case studies / Ethiopia / Africa South of Sahara / Lake Tana Basin
(Location: IWMI HQ Call no: e-copy only Record No: H047928)
Water harvesting systems have improved productivity in various regions in sub-Saharan Africa. Similarly, they can help retain water in landscapes, build resilience against droughts and dry spells, and thereby contribute to sustainable agricultural intensification. However, there is no strong empirical evidence that shows the effects of intensification of water harvesting on upstream–downstream social–ecological systems at a landscape scale. In this paper we develop a decision support system (DSS) for locating and sizing water harvesting ponds in a hydrological model, which enables assessments of water harvesting intensification on upstream–downstream ecosystem services in meso-scale watersheds. The DSS was used with the Soil and Water Assessment Tool (SWAT) for a case-study area located in the Lake Tana basin, Ethiopia. We found that supplementary irrigation in combination with nutrient application increased simulated teff (Eragrostis tef, staple crop in Ethiopia) production up to three times, compared to the current practice. Moreover, after supplemental irrigation of teff, the excess water was used for dry season onion production of 7.66 t/ha (median). Water harvesting, therefore, can play an important role in increasing local- to regional-scale food security through increased and more stable food production and generation of extra income from the sale of cash crops. The annual total irrigation water consumption was ~ 4%–30% of the annual water yield from the entire watershed. In general, water harvesting resulted in a reduction in peak flows and an increase in low flows. Water harvesting substantially reduced sediment yield leaving the watershed. The beneficiaries of water harvesting ponds may benefit from increases in agricultural production. The downstream social–ecological systems may benefit from reduced food prices, reduced flooding damages, and reduced sediment influxes, as well as enhancements in low flows and water quality. The benefits of water harvesting warrant economic feasibility studies and detailed analyses of its ecological impacts.
11 Moges, M. A.; Schmitter, Petra; Tilahun, S. A.; Steenhuis, T. S. 2018. Watershed modeling for reducing future non-point source sediment and phosphorus load in the Lake Tana Basin, Ethiopia. Journal of Soils and Sediments, 18(1):309-322. [doi: https://doi.org/10.1007/s11368-017-1824-z]
Watershed management ; Models ; Sediment ; Phosphorus ; River basins ; Saturation ; Intensification ; Water quality ; Water balance ; Humid climate ; Runoff ; Hydrometeorology ; Calibration / Ethiopia / Lake Tana Basin
(Location: IWMI HQ Call no: e-copy only Record No: H048307)
Purpose - Agricultural intensification to meet the food needs of the rapidly growing population in developing countries affects water quality. In regions such as the Lake Tana basin, knowledge is lacking on measures to reduce non-point source pollutants in humid tropical monsoon climates. The aim of this paper was, therefore, to develop a non-point model that can predict the placement of practices to reduce the transport of sediment and phosphorus (P) in a (sub) humid watershed. Materials and methods - In order to achieve the objective, hydrometeorological, sediment, and P data were collected in the watershed since 2014. The parameter efficient semi-distributed watershed model (PED-WM) was calibrated and validated in the Ethiopian highlands to simulate runoff and associated sediments generated through saturation excess. The P module added to PED-WM was used to predict dissolved (DP) and particulate P (PP) loads aside from discharge and sediment loads of the 700 ha of the Awramba watershed of Lake Tana basin. The PED-WM modules were evaluated using the statistical model performance measuring techniques. The model parameter based prediction of source areas for the non-point source sediment and P was also evaluated spatially and compared with the Topographic Wetness Index (TWI) of the watershed. Results and discussion - The water balance component of the non-point source model performed well in predicting discharge, sediment, DP, and PP with NSE of 0.7, 0.65, 0.65, and 0.63, respectively. In addition, the predicted discharge followed the hydrograph with insignificant deviation from its pattern due to seasonality. The model predicted a sediment yield of 28.2 t ha-1 year-1 and P yield of 9.2 kg ha-1 year-1 from Awrmaba. Furthermore, non-point source areas contributed to 2.7 kg ha-1 year-1 (29%) of DP at the outlet. The main runoff and sediment source areas identified using PED-WM were the periodically saturated runoff areas. These saturated areas were also the main source for DP and PP transport in the catchment. Conclusions - Using the PED-WM with the P module enables the identification of the source areas as well as the prediction of P and sediment loading which yields valuable information for watershed management and placement of best management practices.
12 Tegegne, G.; Park, D. K.; Kim, Y.-O. 2017. Comparison of hydrological models for the assessment of water resources in a data-scarce region, the Upper Blue Nile River Basin. Journal of Hydrology: Regional Studies, 14:49-66. [doi: https://doi.org/10.1016/j.ejrh.2017.10.002]
Water resources ; Assessment ; Hydrology ; Rainfall-runoff relationships ; Models ; Performance indexes ; Calibration ; River basins ; Watersheds ; Stream flow ; Discharges ; Sensitivity analysis ; Uncertainty / Ethiopia / Upper Blue Nile River Basin / Lake Tana Basin / Gilgelabay Watershed / Gummera Watershed / Megech Watershed / Ribb Watershed
(Location: IWMI HQ Call no: e-copy only Record No: H048437)
http://www.sciencedirect.com/science/article/pii/S2214581816301409/pdfft?md5=91c08d466b85e555a7a7bc4b056c6245&pid=1-s2.0-S2214581816301409-main.pdf
https://vlibrary.iwmi.org/pdf/H048437.pdf
https://vlibrary.iwmi.org/pdf/H048437.pdf
(1.53 MB) (1.53 MB)
Study region: The Lake Tana Basin (15,114 km2) in Ethiopia, which is a source of the Blue Nile River Basin.
Study focus: We assessed daily streamflow predictions by applying two simple conceptual models and one complex model for four major gauged watersheds of the study area and compared these model’s capabilities in reproducing observed streamflow in the time and quantile domains.
New hydrological insights for the region: The multi-criteria based model comparison shows that the simple conceptual models performed best in smaller watersheds for reproducing observed streamflow in the time domain, whereas the complex model performed best for the largest watershed. For reproducing observed streamflow in the quantile domain, the simple conceptual models performed best for simulation of high, moist, mid-range, and dry-flows in the Gilgelabay watershed; of dry and low-flows in the Gummera and Megech watersheds; and of high flows in the Ribb watershed. For the remaining flow ranges of each watershed, the complex model performed better. This study also addressed the sensitivity of the complex model for the number of partitioned subbasins. In the largest watershed, the performance of the complex model improved when the number of partitioned subbasins was increased. This finding indicates that the distributed models are especially applicable for the complex watershed because of its physical heterogeneity. In general, integrating these three models may be suitable for water resources assessment.
Study focus: We assessed daily streamflow predictions by applying two simple conceptual models and one complex model for four major gauged watersheds of the study area and compared these model’s capabilities in reproducing observed streamflow in the time and quantile domains.
New hydrological insights for the region: The multi-criteria based model comparison shows that the simple conceptual models performed best in smaller watersheds for reproducing observed streamflow in the time domain, whereas the complex model performed best for the largest watershed. For reproducing observed streamflow in the quantile domain, the simple conceptual models performed best for simulation of high, moist, mid-range, and dry-flows in the Gilgelabay watershed; of dry and low-flows in the Gummera and Megech watersheds; and of high flows in the Ribb watershed. For the remaining flow ranges of each watershed, the complex model performed better. This study also addressed the sensitivity of the complex model for the number of partitioned subbasins. In the largest watershed, the performance of the complex model improved when the number of partitioned subbasins was increased. This finding indicates that the distributed models are especially applicable for the complex watershed because of its physical heterogeneity. In general, integrating these three models may be suitable for water resources assessment.
13 Tigabu, T. B.; Hormann, G.; Wagner, P. D.; Fohrer, N. 2020. Statistical analysis of rainfall and streamflow time series in the lake Tana Basin, Ethiopia. Journal of Water and Climate Change, 11(1):258-273. [doi: https://doi.org/10.2166/wcc.2018.008]
Lakes ; Water levels ; Rain ; Stream flow ; Hydrometeorology ; Meteorological stations ; Catchment areas ; Land use ; Rivers ; Discharges ; Wet season ; Dry season ; Time series analysis / Ethiopia / Lake Tana Basin
(Location: e-copy only Call no: e-copy only Record No: H049650)
(0.94 MB)
This research focuses on the statistical analyses of hydrometeorological time series in the basin of Lake Tana, the largest freshwater lake in Ethiopia. We used autocorrelation, cross-correlation, Mann–Kendall, and Tukey multiple mean comparison tests to understand the spatiotemporal variation of the hydrometeorological data in the period from 1960 to 2015. Our results show that mean annual streamflow and the lake water level are varying significantly from decade to decade, whereas the mean annual rainfall variation is not significant. The decadal mean of the lake outflow and the lake water level decreased between the 1990s and 2000s by 11.34 m3/s and 0.35 m, respectively. The autocorrelation for both rainfall and streamflow were significantly different from zero, indicating that the sample data are non-random. Changes in streamflow and lake water level are linked to land use changes. Improvements in agricultural water management could contribute to mitigate the decreasing trends
14 Abera, A.; Verhoest, N. E. C.; Tilahun, S.; Inyang, H.; Nyssen, J. 2021. Assessment of irrigation expansion and implications for water resources by using RS and GIS techniques in the Lake Tana Basin of Ethiopia. Environmental Monitoring and Assessment, 193(1):13. [doi: https://doi.org/10.1007/s10661-020-08778-1]
Irrigation water ; Water resources ; Remote sensing ; Geographical information systems ; Techniques ; Land use ; Irrigated land ; Farmland ; Land cover ; Water use ; Water management ; Water requirements ; Satellite imagery ; Landsat ; Vegetation index ; Rain ; Evapotranspiration ; Irrigation schemes / Ethiopia / Lake Tana Basin / Abay Basin
(Location: IWMI HQ Call no: e-copy only Record No: H050148)
(5.94 MB)
Understanding irrigation expansion and its implications on water availability is critical for development of decision support tools for sustainable water resources planning. Irrigation expansion in the Lake Tana Basin of Ethiopia from 1986 to 2016 was examined using image classification from thematic maps and remote sensing imagery (Landsat5-8 TM/ETM+, OLI). The soil-adjusted vegetation index (SAVI) imagery was used to identify irrigated cropland based on greenness. Irrigation water consumption was determined by calculating irrigation water requirements of the major crops grown with irrigation and using the estimated irrigated land size of the basin. Irrigated croplands have increased in area from 55 to 65 % in the last past 30 years (from 1986 to 2016). The classification obtained is accurate to the level of 89.6% and Kappa coefficient of 0.83. The Landsat imagery is useful in tracking of the spatiotemporal patterns of irrigated croplands for water management purposes, especially in data deficient areas dotted sparsely by small holder irrigated farms. The results indicated that irrigation consumption in the basin increased from 0.380 km3 year-1 in 1986 to 0.798 km3 year-1 in 2016. It is found that the available water cannot sustain the projected irrigation expansion unless alternative water sources are found. Also, more precise irrigation technologies have to be implemented to minimize water losses.
15 Assaye, H.; Nyssen, J.; Poesen, J.; Lemma, H.; Meshesha, D. T.; Wassie, A.; Adgo, E.; Frankl, A. 2021. Curve number calibration for measuring impacts of land management in sub-humid Ethiopia. Journal of Hydrology: Regional Studies, 35:100819. [doi: https://doi.org/10.1016/j.ejrh.2021.100819]
Land management ; Subhumid zones ; Catchment areas ; Land use ; Land cover ; Farmland ; Hydrology ; Forecasting ; Models ; Rain ; Runoff ; Soil erosion ; Vegetation / Ethiopia / Lake Tana Basin / Enkulal Catchment
(Location: IWMI HQ Call no: e-copy only Record No: H050402)
https://www.sciencedirect.com/science/article/pii/S2214581821000483/pdfft?md5=811f24334ecf439a5dd45030e6fb5ebc&pid=1-s2.0-S2214581821000483-main.pdf
https://vlibrary.iwmi.org/pdf/H050402.pdf
https://vlibrary.iwmi.org/pdf/H050402.pdf
(7.40 MB) (7.40 MB)
Study Region: We investigate the event runoff response in six sub-catchments in the Lake Tana sub-basin, headwater of the Blue Nile basin, northwest Ethiopia. Steep and mountainous terrains surround floodplains, imposing runoff and soil erosion in the upper catchments and flooding and sedimentation at floodplains. This study was conducted in the upland runoff source catchments.
Study Focus: The focus is to investigate catchment characteristics that control the event runoff response in upland catchments, and how recent land management practices may have contributed to improved hydrological conditions. Event rainfall and runoff data were obtained at five-minute time steps through automated divers and tipping bucket rain gauges and related to catchment characteristics.
New Hydrological Insights for the Region: Our results show that the catchment event quickflow response was controlled by different factors of both natural and anthropogenic nature of which forest and shrubs, bund density and soil organic matter content were found to be the most important to reduce event quickflow. On the contrary, increase in cropland area caused an increase in quickflow. Through least square fitting procedure of the Natural Resources Conservation Service Curve Number method (NRCS-CN), a site specific abstraction ratio ( ) value of 0.01, rather than the commonly used 0.2 or 0.05, was found to be most appropriate for the sub-humid highlands of Ethiopia.
Study Focus: The focus is to investigate catchment characteristics that control the event runoff response in upland catchments, and how recent land management practices may have contributed to improved hydrological conditions. Event rainfall and runoff data were obtained at five-minute time steps through automated divers and tipping bucket rain gauges and related to catchment characteristics.
New Hydrological Insights for the Region: Our results show that the catchment event quickflow response was controlled by different factors of both natural and anthropogenic nature of which forest and shrubs, bund density and soil organic matter content were found to be the most important to reduce event quickflow. On the contrary, increase in cropland area caused an increase in quickflow. Through least square fitting procedure of the Natural Resources Conservation Service Curve Number method (NRCS-CN), a site specific abstraction ratio ( ) value of 0.01, rather than the commonly used 0.2 or 0.05, was found to be most appropriate for the sub-humid highlands of Ethiopia.
16 Anteneh, M. 2022. Climate variability patterns and farmers’ perceptions of its impact on food production: a case study of the Gelda Watershed in the Lake Tana Basin in Northwest Ethiopia. Air, Soil and Water Research, 15:1-11. [doi: https://doi.org/10.1177/11786221221135093]
Climate variability ; Food production ; Farmers ; Watersheds ; Catchment areas ; Agroecology ; Rain ; Households ; Case studies / Ethiopia / Lake Tana Basin / Gelda Watershed
(Location: IWMI HQ Call no: e-copy only Record No: H051537)
https://journals.sagepub.com/doi/epdf/10.1177/11786221221135093
https://vlibrary.iwmi.org/pdf/H051537.pdf
https://vlibrary.iwmi.org/pdf/H051537.pdf
(0.87 MB) (892 KB)
This study looked at patterns of erratic climate and farmer perceptions in the Gelda watershed of Lake Tana Basin in northwestern Ethiopia. The National Meteorological Agency of Ethiopia provided essential climatic data for the period between 1981 and 2011. A household survey and focus group discussions were also used to understand about local communities’ perceptions of climate variability and its impact on food production. Time series trend analysis of observed rainfall and temperature conditions was detected using linear regression analysis. To compare the means of climatic parameters and determine whether the average difference was significantly different from zero, the paired sampled t-test was used. The study found that the average annual temperature trend increased by 1.1°C, while the amount and distribution of annual and monthly rainfall decreased, varied across the catchment, and fluctuated during the study periods (1981–2011) at mean temperature rise with an average rate of 0.17°C in the last decade. The variability of annual and monthly rainfall in terms of intensity and distribution has decreased and varied across the watershed. The analysis revealed that annual rainfall variability was variable in the upper catchment (CV > 11.7%) and lower catchment (CV > 14.4%). The amount and intensity of temperature, on the other hand, increased throughout the study watershed, despite observed variation both spatially and temporally (stated decades). Farmers’ understanding and expression of climate variability in terms of erratic rainfall distribution, decreasing amount, and increasing temperature over the last three decades, however, matched the observed data. Moreover, farmers are pointed out that high population pressure; deforestation and intensified agriculture are responsible factors for the variability of climate in the study watershed. Therefore, based on the findings, scientist and policymakers has to design appropriate adaptation measures that can tackle the aggravation of climate variability for future.
17 Bogale, A. G.; Adem, A. A.; Mekuria, Wolde; Steenhuis, T. S. 2023. Application of geomorphometric characteristics to prioritize watersheds for soil and water conservation practices in the Lake Tana Basin, Ethiopia. Geocarto International, 38(1):2184502. [doi: https://doi.org/10.1080/10106049.2023.2184502]
Watersheds ; Soil conservation ; Water conservation ; Geographical information systems ; Remote sensing ; Soil erosion ; Resuspended sediments ; Lakes / Ethiopia / Lake Tana Basin
(Location: IWMI HQ Call no: e-copy only Record No: H051832)
https://www.tandfonline.com/doi/epdf/10.1080/10106049.2023.2184502?needAccess=true&role=button
https://vlibrary.iwmi.org/pdf/H051832.pdf
https://vlibrary.iwmi.org/pdf/H051832.pdf
(4.06 MB) (4.06 MB)
This study employed geomorphometric analysis to characterize the four major watersheds (Gilgel Abay, Gumara, Rib, and Megech) of Lake Tana sub-basin, Ethiopia, and prioritize the watersheds for the implementation of SWC practices using GIS and remote sensing techniques. Also, the study analyzed streamflow and sediment data recorded at the outlets of each watershed to associate the geomorphometric prioritization result with recordings of the watersheds. Geomorphometric analysis results indicated that the Rib watershed is the most susceptible watershed for soil erosion and should be prioritized for the implementation of SWC practices. The analysis of streamflow and suspended sediment concentration suggest that the Rib watershed had the second maximum sediment yield (14.3 t ha-1 yr-1) compared to the other three watersheds. This is because of the low streamflow response of the watershed compared with the Gumara watershed which had the highest sediment yield (18.9 t ha-1 yr-1).
18 Sishu, F. K.; Tilahun, Seifu A.; Schmitter, Petra; Steenhuis, T. S. 2023. Investigating nitrate with other constituents in groundwater in two contrasting tropical highland watersheds. Hydrology, 10(4):82. (Special issue: Editorial Board Members’ Collection Series: Integrated Surface Water and Groundwater Resources Management) [doi: https://doi.org/10.3390/hydrology10040082]
Groundwater table ; Nitrates ; Watersheds ; Highlands ; Volcanic areas ; Aquifers ; Wells ; Precipitation ; Rainfall ; Chlorides ; Ammonia ; Fertilizers ; Runoff / Africa South of Sahara / Ethiopia / Lake Tana Basin / Dangishta Watershed / Robit Bata Watershed
(Location: IWMI HQ Call no: e-copy only Record No: H051839)
https://www.mdpi.com/2306-5338/10/4/82/pdf?version=1680523739
https://vlibrary.iwmi.org/pdf/H051839.pdf
https://vlibrary.iwmi.org/pdf/H051839.pdf
(8.28 MB) (8.28 MB)
Nitrate is globally the most widespread and widely studied groundwater contaminant. However, few studies have been conducted in sub-Saharan Africa, where the leaching potential is enhanced during the rainy monsoon phase. The few monitoring studies found concentrations over drinking water standards of 10 mg N-NO3 - L -1 in the groundwater, the primary water supply in rural communities. Studies on nitrate movement are limited to the volcanic Ethiopian highlands. Therefore, this study aimed to evaluate the transport and fate of nitrate in groundwater and identify processes that control the concentrations. Water table height, nitrate, chloride, ammonium, reduced iron, and three other groundwater constituents were determined monthly in the groundwater in over 30 wells in two contrasting volcanic watersheds over two years in the Ethiopian highlands. The first watershed was Dangishta, with lava intrusion dikes that blocked the subsurface flow in the valley bottom. The water table remained within 3 m of the surface. The second watershed without volcanic barriers was Robit Bata. The water table dropped rapidly within three months of the end of the rain phase and disappeared except near faults. The average nitrate concentration in both watersheds was between 4 and 5 mg N-NO3 - L -1 . Hydrogeology influenced the transport and fate of nitrogen. In Dangishta, water was blocked by volcanic lava intrusion dikes, and residence time in the aquifer was larger than in Robit Bata. Consequently, nitrate remained high (in several wells, 10 mg N-NO3 - L -1 ) and decreased slowly due to denitrification. In Robit Bata, the water residence time was lower, and peak concentrations were only observed in the month after fertilizer application; otherwise, it was near an average of 4 mg N-NO3 - L -1 . Nitrate concentrations were predicted using a multiple linear regression model. Hydrology explained the nitrate concentrations in Robit Bata. In Dangishta, biogeochemistry was also significant.
19 Alaminie, A.; Amarnath, Giriraj; Padhee, Suman; Ghosh, Surajit; Tilahun, S.; Mekonnen, M.; Assefa, G.; Seid, Abdulkarim; Zimale, F.; Jury, M. 2023. Application of advanced Wflow_sbm Model with the CMIP6 climate projection for flood prediction in the data-scarce: Lake-Tana Basin, Ethiopia [Abstract only]. Paper presented at the European Geosciences Union (EGU) General Assembly 2023, Vienna, Austria and Online, 24-28 April 2023. 1p. [doi: https://doi.org/10.5194/egusphere-egu23-1113]
Flood forecasting ; Climate change ; Hydrological modelling ; Climate models / Ethiopia / Lake Tana Basin
(Location: IWMI HQ Call no: e-copy only Record No: H051891)
https://meetingorganizer.copernicus.org/EGU23/EGU23-1113.html?pdf
https://vlibrary.iwmi.org/pdf/H051891.pdf
https://vlibrary.iwmi.org/pdf/H051891.pdf
(0.28 MB) (289 KB)
20 Sishu, F. K.; Tilahun, S. A.; Schmitter, Petra; Assefa, G.; Steenhuis, T. S. 2022. Pesticide contamination of surface and groundwater in an Ethiopian highlands’ watershed. Water, 14(21):3446. [doi: https://doi.org/10.3390/w14213446]
Pesticides ; Chemical contamination ; Surface water ; Groundwater ; Water pollution ; Highlands ; Watersheds ; Lakes ; Ecotoxicity ; Aquatic organisms ; Fish ; Human health ; Risk assessment ; Farmers / Africa South of Sahara / Ethiopia / Lake Tana Basin / Robit Bata Watershed
(Location: IWMI HQ Call no: e-copy only Record No: H052844)
https://www.mdpi.com/2073-4441/14/21/3446/pdf?version=1667996326
https://vlibrary.iwmi.org/pdf/H052844.pdf
https://vlibrary.iwmi.org/pdf/H052844.pdf
(4.12 MB) (4.12 MB)
Agricultural intensification in sub-Saharan African countries has significantly increased pesticide applications. Information on pesticide residues and their transport in groundwater and streams is needed to properly manage and reduce any harm to the ecosystem and environment. This information is lacking in the volcanic soils of Ethiopian highlands. Therefore, this study was conducted to assess pesticide concentrations in ground and surface water and their risk to humans and aquatic life. The 9 km2 rural watershed Robit Bata in the Lake Tana Basin was selected. Crops were grown under rainfed and irrigated conditions. Pesticide use was assessed, and groundwater samples were collected from eight wells and surface water samples at the outlet twice in the rain phase and once in the dry phase. Samples were analyzed for chlorpyrifos, dimethoate, (a and ß) endosulfan, profenofos, NO- 3 , and pH. Chlorpyrifos and endosulfan, which are strongly adsorbed and slowly degrading pesticides, were found in nearly all surface and groundwater samples, with maximum concentrations in surface water of 8 µg L-1 for chlorpyrifos and 3 µg L-1 endosulfan. Maximum groundwater concentrations were only slightly lower. The weakly adsorbed and fast degrading pesticides, dimethoate, and profenofos were detected only in the rain phase after spraying in the groundwater, indicating preferential transport to groundwater at depths of up to 9 m. The average concentration was 0.38 µg L-1 for dimethoate in surface waters and 1.24 µg L-1 in groundwater. Profenofos was not detected in surface water. In the groundwater, the average concentration was 0.05 µg L-1 . Surface water concentrations of chlorpyrifos and endosulfan were highly toxic to fish. The World Health Organization banned these pesticides worldwide. It should be phased out for use in Ethiopia to safeguard the ecological health of Lake Tana, which is rich in biodiversity and endemic fish species.
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