Your search found 6 records
1 Tilahun, S. A.; Yilak, D. L.; Schmitter, Petra; Zimale, F. A.; Langan, Simon; Barron, Jennie; Parlange, J.-Y.; Steenhuis, T. S. 2020. Establishing irrigation potential of a hillside aquifer in the African highlands. Hydrological Processes, 34(8):1741-1753. [doi: https://doi.org/10.1002/hyp.13659]
Aquifers ; Highlands ; Sloping land ; Groundwater table ; Groundwater recharge ; Irrigation water ; Wells ; Water budget ; Water storage ; Water availability ; Water levels ; Hydrometeorology ; Monitoring ; Infiltration ; Runoff ; Discharges ; Rain ; Watersheds ; Small scale systems ; Farmer-led irrigation ; Models / Africa South of Sahara / Ethiopia / Lake Tana / Robit Bata Watershed
(Location: IWMI HQ Call no: e-copy only Record No: H049535)
https://onlinelibrary.wiley.com/doi/epdf/10.1002/hyp.13659
https://vlibrary.iwmi.org/pdf/H049535.pdf
https://vlibrary.iwmi.org/pdf/H049535.pdf
(3.92 MB) (3.92 MB)
Feeding 9 billion people in 2050 will require sustainable development of all water resources, both surface and subsurface. Yet, little is known about the irrigation potential of hillside shallow aquifers in many highland settings in sub-Saharan Africa that are being considered for providing irrigation water during the dry monsoon phase for smallholder farmers. Information on the shallow groundwater being available in space and time on sloping lands might aid in increasing food production in the dry monsoon phase. Therefore, the research objective of this work is to estimate potential groundwater storage as a potential source of irrigation water for hillside aquifers where lateral subsurface flow is dominant. The research was carried out in the Robit Bata experimental watershed in the Lake Tana basin which is typical of many undulating watersheds in the Ethiopian highlands. Farmers have excavated more than 300 hand dug wells for irrigation. We used 42 of these wells to monitor water table fluctuation from April 16, 2014 to December 2015. Precipitation and runoff data were recorded for the same period. The temporal groundwater storage was estimated using two methods: one based on the water balance with rainfall as input and baseflow and evaporative losses leaving the watershed as outputs; the second based on the observed rise and fall of water levels in wells. We found that maximum groundwater storage was at the end of the rain phase in September after which it decreased linearly until the middle of December due to short groundwater retention times. In the remaining part of the dry season period, only wells located close to faults contained water. Thus, without additional water sources, sloping lands can only be used for significant irrigation inputs during the first 3 months out of the 8 months long dry season.
2 Alemu, M. L.; Worqlul, A. W.; Zimale, F. A.; Tilahun, S. A.; Steenhuis, S. 2020. Water balance for a tropical lake in the volcanic highlands: Lake Tana, Ethiopia. Water, 12(10):2737. (Special issue: Hydrology and Sedimentology of Hilly and Mountainous Landscapes) [doi: https://doi.org/10.3390/w12102737]
Water balance ; Lakes ; Rivers ; Water levels ; Runoff ; Water loss ; Evaporation ; Irrigation ; Precipitation ; Weather data ; Rain gauges ; Watersheds ; Groundwater ; Highlands ; Models / Ethiopia / Lake Tana / Blue Nile Basin
(Location: IWMI HQ Call no: e-copy only Record No: H050064)
(4.57 MB) (4.57 MB)
Lakes hold most of the freshwater resources in the world. Safeguarding these in a changing environment is a major challenge. The 3000 km2 Lake Tana in the headwaters of the Blue Nile in Ethiopia is one of these lakes. It is situated in a zone destined for rapid development including hydropower and irrigation. Future lake management requires detailed knowledge of the water balance of Lake Tana. Since previous water balances varied greatly this paper takes a fresh look by calculating the inflow and losses of the lake. To improve the accuracy of the amount of precipitation falling on the lake, two new rainfall stations were installed in 2013. The Climate Hazards Group Infrared Precipitation Version two (CHIRPS-v2) dataset was used to extend the data. After reviewing all the previous studies and together with our measurements, it was found that the period of 1990–1995 likely had the most accurate gauged discharge data. During some months in this period, the lake water balance was negative. Since the river inflow to the lake cannot be negative, water was either lost from the lake via the subsurface through faults, or the outflow measurements were systematically underestimated. Based on the evaporation rate of 1650 mm, we found that unaccounted loss was 0.6 km3 a-1, equivalent to 20 cm of water over the lake area each year. This implies the need for reliable rainfall data and improved river discharge measurements over a greater portion of the basin both entering and exiting the lake. Also, integrated hydrological and geologic investigations are needed for a better understanding of the unaccounted water losses and quantifying the amount of subsurface flow leaving the lake.
3 Tiruye, A. E.; Belay, S. A.; Schmitter, Petra; Tegegne, Desalegn; Zimale, F. A.; Tilahun, S. A. 2022. Yield, water productivity and nutrient balances under different water management technologies of irrigated wheat in Ethiopia. PLOS Water, 1(12):e0000060. [doi: https://doi.org/10.1371/journal.pwat.0000060]
Crop yield ; Irrigation water ; Water productivity ; Nutrient balance ; Water management ; Technology ; Wheat ; Irrigated farming ; Irrigation schemes / Ethiopia / Koga Irrigation Scheme
(Location: IWMI HQ Call no: e-copy only Record No: H051887)
https://journals.plos.org/water/article/file?id=10.1371/journal.pwat.0000060&type=printable
https://vlibrary.iwmi.org/pdf/H051887.pdf
https://vlibrary.iwmi.org/pdf/H051887.pdf
(1.01 MB) (1.01 MB)
Development of irrigation technologies and agricultural water management systems holds significant potential to improve productivity and reduce vulnerability to climate change. Our study dealt with the behavior of irrigation water productivity, partial nutrient balance and grain yield of wheat under the application of different irrigation water management technologies in the Koga irrigation scheme in Ethiopia. For our analysis, we considered three nutrient fluxes entering and leaving farmers’ fields. Our experimental design had three irrigation blocks with three different irrigation water management practices (wetting front detector, Chameleon soil moisture sensor and farmers’ practice as control) on three farm plots replicated in each block. To calculate irrigation water productivity and grain yield of wheat, the amount of irrigation water applied and the agronomic attributes of wheat yield were recorded during the irrigation period. Further, three input and output variables were considered to determine the partial nutrient balances of nitrogen (N), phosphorus (P) and potassium (K). The results showed that the amount of irrigation water used was 33% and 22% less with a wetting front detector and Chameleon sensors, respectively, compared to the farmers’ practice. The wetting front detector (WFD) and Chameleon sensor (CHS) treatments gave a 20% and 15.8% grain yield increment, respectively, compared to the farmers’ practice plot. The partial nutrient balances of N and K were negative for the wetting front detector and chameleon sensor practices while it was positive for P in the control (farmers’ practice) treatment. We conclude that irrigation water management with appropriate technologies can improve yield, water productivity and the nutrient utilization. However, further research needs to be conducted on the suitability of irrigation management technologies to achieve full nutrient balance.
4 Leggesse, E. S.; Zimale, F. A.; Sultan, D.; Enku, T.; Srinivasan, R.; Tilahun, Seifu A. 2023. Predicting optical water quality indicators from remote sensing using machine learning algorithms in tropical highlands of Ethiopia. Hydrology, 10(5):110. [doi: https://doi.org/10.3390/hydrology10050110]
Water quality ; Indicators ; Prediction ; Remote sensing ; Machine learning ; Algorithms ; Neural networks ; Modelling ; Total dissolved solids ; Turbidity ; Chlorophyll A ; Landsat ; Satellite imagery ; Monitoring ; Highlands ; Lakes / Ethiopia / Lake Tana
(Location: IWMI HQ Call no: e-copy only Record No: H051963)
https://www.mdpi.com/2306-5338/10/5/110/pdf?version=1684396571
https://vlibrary.iwmi.org/pdf/H051963.pdf
https://vlibrary.iwmi.org/pdf/H051963.pdf
(3.60 MB) (3.60 MB)
Water quality degradation of freshwater bodies is a concern worldwide, particularly in Africa, where data are scarce and standard water quality monitoring is expensive. This study explored the use of remote sensing imagery and machine learning (ML) algorithms as an alternative to standard field measuring for monitoring water quality in large and remote areas constrained by logistics and finance. Six machine learning (ML) algorithms integrated with Landsat 8 imagery were evaluated for their accuracy in predicting three optically active water quality indicators observed monthly in the period from August 2016 to April 2022: turbidity (TUR), total dissolved solids (TDS) and Chlorophyll a (Chl-a). The six ML algorithms studied were the artificial neural network (ANN), support vector machine regression (SVM), random forest regression (RF), XGBoost regression (XGB), AdaBoost regression (AB), and gradient boosting regression (GB) algorithms. XGB performed best at predicting Chl-a, with an R2 of 0.78, Nash–Sutcliffe efficiency (NSE) of 0.78, mean absolute relative error (MARE) of 0.082 and root mean squared error (RMSE) of 9.79 µg/L. RF performed best at predicting TDS (with an R2 of 0.79, NSE of 0.80, MARE of 0.082, and RMSE of 12.30 mg/L) and TUR (with an R2 of 0.80, NSE of 0.81, and MARE of 0.072 and RMSE of 7.82 NTU). The main challenges were data size, sampling frequency, and sampling resolution. To overcome the data limitation, we used a K-fold cross validation technique that could obtain the most out of the limited data to build a robust model. Furthermore, we also employed stratified sampling techniques to improve the ML modeling for turbidity. Thus, this study shows the possibility of monitoring water quality in large freshwater bodies with limited observed data using remote sensing integrated with ML algorithms, potentially enhancing decision making.
5 Fenta, H. M.; Aynalem, D. W.; Malmquist, L.; Haileslassie, Amare; Tilahun, Seifu A.; Barron, J.; Adem, A. A.; Adimassu, Z.; Zimale, F. A.; Steenhuis, T. S. 2024. A critical analysis of soil (and water) conservation practices in the Ethiopian Highlands: implications for future research and modeling. Catena, 234:107539. [doi: https://doi.org/10.1016/j.catena.2023.107539]
Soil conservation ; Water conservation ; Highlands ; Soil loss ; Erosion ; Sediment ; Ecosystem services ; Environmental monitoring ; Land use ; Crop yield ; Modelling / Africa / Ethiopia / Ethiopian Highlands
(Location: IWMI HQ Call no: e-copy only Record No: H052323)
(8.68 MB)
Soil and water conservation have been traditionally part of farming practices for thousands of years. Despite massive efforts to implement modern soil and water conservation practices (SWCPs) in the Ethiopian Highlands, soil erosion increased after the 1970s when social and political events led to a remarkable change in land use. This review aims to critically analyze the impact of conservation practices on soil loss and crop yield and highlight research and modeling gaps. In doing so, 120 published articles on experimental and simulated soil losses in the Ethiopian Highlands were retrieved from the refereed literature. We found that most published experimental studies evaluating SWCPs lasted less than five years in areas of less than 100 ha. Most modeling studies were over short periods, too; some models simulated soil loss over large areas. The literature analysis for these short-term experimental studies showed that SWCP decreased soil loss on individual sites and increased crop yield in semi-arid regions. Simulated sediment concentration increased as a function of watershed size, while observed soil losses did not follow this trend. Moreover, the decrease in soil loss due to the soil and water conservation practices on small plots was also greatly overestimated. Consequently, past research and current modeling techniques are inconclusive on the effectiveness of SWCPs in large catchments over periods exceeding five years and those with active gullies. Additional long-term experimental studies in catchments are required to evaluate whether SWCPs can decrease sediment loads.
6 Taye, Meron Teferi; Zimale, F. A.; Woldesenbet, T. A.; Kebede, M. G.; Amare, S. D.; Tegegne, G.; Mekonnen, K.; Haile, Alemseged Tamiru. 2023. Priority research topics to improve streamflow data availability in data-scarce countries: the case for Ethiopia. Hydrology, 10(12):220. [doi: https://doi.org/10.3390/hydrology10120220]
Stream flow ; Monitoring ; Data management ; Research ; Developing countries ; Hydrology ; Remote sensing ; Stakeholders ; Institutions ; Runoff ; Data collection ; Capacity development ; Citizen science ; Education / Ethiopia
(Location: IWMI HQ Call no: e-copy only Record No: H052410)
https://www.mdpi.com/2306-5338/10/12/220/pdf?version=1700708664
https://vlibrary.iwmi.org/pdf/H052410.pdf
https://vlibrary.iwmi.org/pdf/H052410.pdf
(2.26 MB) (2.26 MB)
Lack of consistent streamflow data has been an increasing challenge reported by many studies in developing countries. This study aims to understand the current challenges in streamflow monitoring in Ethiopia to prioritize research topics that can support sustained streamflow monitoring in the country and elsewhere. A workshop-based expert consultation, followed by a systematic literature review, was conducted to build a collective understanding of the challenges and opportunities of streamflow monitoring in Ethiopia. The experts’ consultation identified the top ten research priorities to improve streamflow monitoring through research, education, remote sensing applications, and institutions. The experts’ views were supported by a systematic review of more than 300 published articles. The review indicated scientific investigation in Ethiopian basins was constrained by streamflow data gaps to provide recent and relevant hydrological insights. However, there is inadequate research that seeks solutions, while some researchers use experimental methods to generate recent streamflow data, which is an expensive approach. Articles that attempted to fill data gaps make up less than 20% of the reviewed articles. This study identified research priorities that can benefit streamflow data providers and the research community in alleviating many of the challenges associated with streamflow monitoring in countries such as Ethiopia.
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