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Climate predictions using recent and high-resolution climate models are becoming important for effective decision-making and for designing appropriate climate change adaptation and mitigation strategies. Due to highly variable climate and data scarcity of the upper Blue Nile Basin, previous studies did not detect specific unified trends. This study discusses, the past and future climate projections under CMIP6-SSPs scenarios for the basin. For the models’ validation and selection, reanalysis data were used after comparing with area-averaged ground observational data. Quantile mapping systematic bias correction and Mann–Kendall trend test were applied to evaluate the trends of selected CMIP6 models during the 21st century. Results revealed that, ERA5 for temperature and GPCC for precipitation have best agreement with the basin observational data, MRI-ESM2-0 for temperature and BCC-CSM-2MR for precipitation were selected based on their highest performance. The MRI-ESM2-0 mean annual maximum temperature for the near (long)-term period shows an increase of 1.1 (1.5) °C, 1.3 (2.2) °C, 1.2 (2.8) °C, and 1.5 (3.8) °C under the four SSPs. On the other hand, the BCC-CSM-2MR precipitation projections show slightly (statistically insignificant) increasing trend for the near (long)-term periods by 5.9 (6.1)%, 12.8 (13.7)%, 9.5 (9.1)%, and 17.1(17.7)% under four SSPs scenarios.
Addis Alaminie; Seifu Tilahun; Solomon Legesse; Fasikaw Zimale; Gashaw Tarkegn; Mark Jury. Evaluation of Past and Future Climate Trends under CMIP6 Scenarios for the UBNB (Abay), Ethiopia. Water 2021, 13, 2110 .
AMA StyleAddis Alaminie, Seifu Tilahun, Solomon Legesse, Fasikaw Zimale, Gashaw Tarkegn, Mark Jury. Evaluation of Past and Future Climate Trends under CMIP6 Scenarios for the UBNB (Abay), Ethiopia. Water. 2021; 13 (15):2110.
Chicago/Turabian StyleAddis Alaminie; Seifu Tilahun; Solomon Legesse; Fasikaw Zimale; Gashaw Tarkegn; Mark Jury. 2021. "Evaluation of Past and Future Climate Trends under CMIP6 Scenarios for the UBNB (Abay), Ethiopia." Water 13, no. 15: 2110.
There is an increasing need globally to establish relationships among flow, ecology, and livelihoods to make informed decisions about environmental flows. This paper aimed to establish the ecological foundation for a holistic environmental flow assessment method in the Gumara River that flows into Lake Tana in Ethiopia and the Blue Nile River. First, the ecological conditions (fish, macro-invertebrate, riparian vegetation, and physicochemical) of the river system were characterized, followed by determining the hydrological condition and finally linking the ecological and hydrological components. The ecological data were collected at 30 sites along the Gumara River on March 2016 and 2020. River hydrology was estimated using the SWAT model and showed that the low flow decreased over time. Both physico-chemical and macroinvertebrate scores showed that water quality was moderate in most locations. The highest fish diversity index was in the lower reach at Wanzaye. Macroinvertebrate diversity was observed to decrease downstream. Both the fish and macroinvertebrate diversity indices were less than the expected maximum, being 3.29 and 4.5, respectively. The normalized difference vegetation index (NDVI) for 30 m and 60 m buffer distances from the river decreased during the dry season (March–May). Hence, flow conditions, water quality, and land-use change substantially influenced the abundance and diversity of fish, vegetation, and macroinvertebrate species. The pressure on the ecology is expected to increase because the construction of the proposed dam is expected to alter the flow regime. Thus, as demand for human water consumption grows, measures are needed, including quantification of environmental flow requirements and regulating river water uses to conserve the ecological status of the Gumara River and Lake Tana sub-basin.
Wubneh Abebe; Seifu Tilahun; Michael Moges; Ayalew Wondie; Minychl Dersseh; Workiye Assefa; Demesew Mhiret; Anwar Adem; Fasikaw Zimale; Wuletawu Abera; Tammo Steenhuis; Michael McClain. Ecological Status as the Basis for the Holistic Environmental Flow Assessment of a Tropical Highland River in Ethiopia. Water 2021, 13, 1913 .
AMA StyleWubneh Abebe, Seifu Tilahun, Michael Moges, Ayalew Wondie, Minychl Dersseh, Workiye Assefa, Demesew Mhiret, Anwar Adem, Fasikaw Zimale, Wuletawu Abera, Tammo Steenhuis, Michael McClain. Ecological Status as the Basis for the Holistic Environmental Flow Assessment of a Tropical Highland River in Ethiopia. Water. 2021; 13 (14):1913.
Chicago/Turabian StyleWubneh Abebe; Seifu Tilahun; Michael Moges; Ayalew Wondie; Minychl Dersseh; Workiye Assefa; Demesew Mhiret; Anwar Adem; Fasikaw Zimale; Wuletawu Abera; Tammo Steenhuis; Michael McClain. 2021. "Ecological Status as the Basis for the Holistic Environmental Flow Assessment of a Tropical Highland River in Ethiopia." Water 13, no. 14: 1913.
This study was conducted at the Dangishta watershed in the Ethiopian highlands to evaluate irrigation potential from surface and groundwater sources under different farming and water application systems. Daily streamflow and the groundwater table were monitored from 2015 to 2017. Shallow groundwater recharge was estimated using the water table fluctuation method. Automated baseflow separation techniques were used to determine the amount of runoff and baseflow from the total streamflow records. The potential of groundwater and runoff to sustain dry season irrigation (i.e., low flow) was evaluated considering two tillage systems (i.e., conservation agriculture, CA; and conventional tillage, CT), and water application (i.e., drip and overhead) systems for major irrigated crops (i.e., onion, garlic, cabbage, and pepper) grown in the Dangishta watershed. We found that the annual groundwater recharge varied from 320 to 358 mm during the study period, which was about 17% to 22% of the annual rainfall. The annual surface runoff depth ranged from 192 to 268 mm from 2015 to 2017. The results reveal that the maximum seasonal irrigable land from groundwater recharge was observed under CA with drip irrigation (i.e., 2251 and 2992 ha from groundwater recharge and surface runoff, respectively). By comparison, in the CT practice with overhead irrigation, the lowest seasonal irrigable land was observed (i.e., 1746 and 2121 ha from groundwater and surface runoff, respectively). From the low flow analysis, about 199 and 173 ha of one season’s irrigable land could be irrigated using the CA and CT systems, respectively, both with drip irrigation. Similarly, two-season overhead irrigation potential from low flow under CA and CT was found to be about 87 and 76 ha, respectively. The dry season irrigable land using low flow could be increased from 9% to 16% using the CA system for the various vegetables, whereas drip irrigation could increase the irrigable land potential by 56% compared to overhead irrigation. The combined use of groundwater recharge and runoff could sustain up to 94% of the dry season low flow irrigation through the combination of the CA system and drip irrigation. Decision makers must consider the introduction of feasible and affordable technologies to make use of groundwater and direct runoff, to maximize the potential of dry season production through efficient and appropriate CA and water management practices.
Abdu Yimam; Tewodros Assefa; Feleke Sishu; Seifu Tilahun; Manuel Reyes; P.V. Prasad. Estimating Surface and Groundwater Irrigation Potential under Different Conservation Agricultural Practices and Irrigation Systems in the Ethiopian Highlands. Water 2021, 13, 1645 .
AMA StyleAbdu Yimam, Tewodros Assefa, Feleke Sishu, Seifu Tilahun, Manuel Reyes, P.V. Prasad. Estimating Surface and Groundwater Irrigation Potential under Different Conservation Agricultural Practices and Irrigation Systems in the Ethiopian Highlands. Water. 2021; 13 (12):1645.
Chicago/Turabian StyleAbdu Yimam; Tewodros Assefa; Feleke Sishu; Seifu Tilahun; Manuel Reyes; P.V. Prasad. 2021. "Estimating Surface and Groundwater Irrigation Potential under Different Conservation Agricultural Practices and Irrigation Systems in the Ethiopian Highlands." Water 13, no. 12: 1645.
This study assessed farmers’ soil and irrigation water management practices, perceptions, and major constraints at Koga, a large-scale irrigation scheme in Ethiopia. Key informant interviews, structured and semi-structured questionnaires, focus group discussions, and field visits were used for data collection. Soil samples were collected for the assessment of soil properties and a comparison with the respondents’ perception of soil-related constraints. A total of 385 respondents were involved in the questionnaire. All of the respondents had a good perception of soil acidity and its management strategies. Respondents’ perception was in line with the mean soil pH, soil texture, infiltration rate, exchangeable acidity, and soil organic carbon obtained from lab analysis and field tests. Soil acidity, unwise use of water, water scarcity, and lack of market linkages hampered the performance of the Koga irrigation scheme. Yet, respondents had a low awareness of irrigation water management. Farmers never used irrigation scheduling, but apply the same amount of water regardless of the crop type. As a result, low yield and water use efficiency were reported. To reduce soil acidity, an adequate lime supply for farmers with hands-on training on how to apply it would be desirable. Farmers should be aware of how to design effective irrigation scheduling and adopt water-saving management strategies.
Desale Asmamaw; Pieter Janssens; Mekete Dessie; Seifu Tilahun; Enyew Adgo; Jan Nyssen; Kristine Walraevens; Derbew Fentie; Wim Cornelis. Soil and Irrigation Water Management: Farmer’s Practice, Insight, and Major Constraints in Upper Blue Nile Basin, Ethiopia. Agriculture 2021, 11, 383 .
AMA StyleDesale Asmamaw, Pieter Janssens, Mekete Dessie, Seifu Tilahun, Enyew Adgo, Jan Nyssen, Kristine Walraevens, Derbew Fentie, Wim Cornelis. Soil and Irrigation Water Management: Farmer’s Practice, Insight, and Major Constraints in Upper Blue Nile Basin, Ethiopia. Agriculture. 2021; 11 (5):383.
Chicago/Turabian StyleDesale Asmamaw; Pieter Janssens; Mekete Dessie; Seifu Tilahun; Enyew Adgo; Jan Nyssen; Kristine Walraevens; Derbew Fentie; Wim Cornelis. 2021. "Soil and Irrigation Water Management: Farmer’s Practice, Insight, and Major Constraints in Upper Blue Nile Basin, Ethiopia." Agriculture 11, no. 5: 383.
Accelerated sediment concentration has become a pervasive feature in developing countries and has substantially impacted lake ecosystem functioning. Despite this, very few comprehensive studies have examined the changes in sedimentation over the time that agriculture intensified greatly with the increasing population. The study aims to fill this gap using historical and recent bathymetric surveys to determine sediment deposition and link these to watershed development. With its unique ecology, Lake Tana that was pristine less than 100 years ago, is one of these systems experiencing increasing sediment concentrations. A detailed bathymetric survey was conducted in late 2017 and compared with bathymetric surveys conducted in 1940, 1987, and 2006. The result shows that in the past 77 years, Lake Tana's depth decreased an average of 28 ± 11 cm, equivalent to nearly 0.9 ± 0.4 Tg (million tons). Sediment deposition was 2.8± 2.3 mm a‐1 between 1940 and 1987, when the agricultural intensification started. It almost doubled to 5.0 ± 3.7 mm a‐1 after that. Spatially, the sediment deposition was most significant in areas near the major river inlets where 2 to 10 km long peninsulas were formed. The increase in sediment deposition is primarily driven by newly formed valley bottom gullies formed after deforestation disturbed the hydrological equilibrium, and watershed outflow increased.
Mebrahtom G. Kebedew; Seifu A. Tilahun; Mulugeta A. Belete; Fasikaw A. Zimale; Tammo S. Steenhuis. Sediment deposition (1940–2017) in a historically pristine lake in a rapidly developing tropical highland region in Ethiopia. Earth Surface Processes and Landforms 2021, 46, 1521 -1535.
AMA StyleMebrahtom G. Kebedew, Seifu A. Tilahun, Mulugeta A. Belete, Fasikaw A. Zimale, Tammo S. Steenhuis. Sediment deposition (1940–2017) in a historically pristine lake in a rapidly developing tropical highland region in Ethiopia. Earth Surface Processes and Landforms. 2021; 46 (8):1521-1535.
Chicago/Turabian StyleMebrahtom G. Kebedew; Seifu A. Tilahun; Mulugeta A. Belete; Fasikaw A. Zimale; Tammo S. Steenhuis. 2021. "Sediment deposition (1940–2017) in a historically pristine lake in a rapidly developing tropical highland region in Ethiopia." Earth Surface Processes and Landforms 46, no. 8: 1521-1535.
Small-scale irrigation in Ethiopia is a key strategy to improve and sustain the food production system. Besides the use of surface water for irrigation, it is essential to unlock the groundwater potential. It is equally important to use soil management and water-saving systems to overcome the declining soil fertility and the temporal water scarcity in the region. In this study, the solar MajiPump was introduced to enable dry season crop production in Ethiopia using shallow groundwater sources. The capacity of the MajiPumps (MP400 and MP200) was tested for the discharge head and discharge using three types of solar panels (150 W and 200 W rigid, and 200 W flexible). Besides, drip irrigation and conservation agriculture (CA) farming systems were evaluated in terms of water productivity and crop yield in comparison to the farmers’ practice (overhead irrigation and tilled farming system). Results indicated that the maximum discharge head capacity of the MajiPumps was 18 m, 14 m, 10 m when using MP400 with 200 W rigid, MP400 with 200 W flexible, and MP200 with 150 W rigid solar panels, respectively. The corresponding MajiPump flow rates ranged from 7.8 L/min. to 24.6 L/min., 3 L/min. to 25 L/min., and 3.6 L/min. to 22.2 L/min., respectively. Compared to farmer’s practice, water productivity was significantly improved under the CA farming and the drip irrigation systems for both irrigated vegetables (garlic, onion, cabbage, potato) and rainfed maize production. The water productivity of garlic, cabbage, potato, and maize was increased by 256%, 43%, 53%, and 9%, respectively, under CA as compared to conventional tillage (CT) even under overhead irrigation. Thus, farmers can obtain a significant water-saving benefit from CA regardless of water application systems. However, water and crop productivity could be further improved in the combined use of MajiPump with CA and drip irrigation (i.e., 38% and 33% water productivity and 43% and 36% crop productivity improvements were observed for potato and onion, respectively). Similarly, compared to CT, the use of CA significantly increased garlic, cabbage, potato, and maize yield by 170%, 42%, 43%, and 15%, respectively under the MajiPump water-lifting system. Overall, the solar-powered drip irrigation and CA farming system were found to be efficient to expand small-scale irrigation and improve productivity and livelihoods of smallholder farmers in Ethiopia.
Tewodros T. Assefa; Temesgen F. Adametie; Abdu Y. Yimam; Sisay A. Belay; Yonas M. Degu; Solomon T. Hailemeskel; Seifu A. Tilahun; Manuel R. Reyes; P. V. Vara Prasad. Evaluating Irrigation and Farming Systems with Solar MajiPump in Ethiopia. Agronomy 2020, 11, 17 .
AMA StyleTewodros T. Assefa, Temesgen F. Adametie, Abdu Y. Yimam, Sisay A. Belay, Yonas M. Degu, Solomon T. Hailemeskel, Seifu A. Tilahun, Manuel R. Reyes, P. V. Vara Prasad. Evaluating Irrigation and Farming Systems with Solar MajiPump in Ethiopia. Agronomy. 2020; 11 (1):17.
Chicago/Turabian StyleTewodros T. Assefa; Temesgen F. Adametie; Abdu Y. Yimam; Sisay A. Belay; Yonas M. Degu; Solomon T. Hailemeskel; Seifu A. Tilahun; Manuel R. Reyes; P. V. Vara Prasad. 2020. "Evaluating Irrigation and Farming Systems with Solar MajiPump in Ethiopia." Agronomy 11, no. 1: 17.
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.
Muluken L. Alemu; Abeyou W. Worqlul; Fasikaw A. Zimale; Seifu A. Tilahun; Tammo S. Steenhuis. Water Balance for a Tropical Lake in the Volcanic Highlands: Lake Tana, Ethiopia. Water 2020, 12, 2737 .
AMA StyleMuluken L. Alemu, Abeyou W. Worqlul, Fasikaw A. Zimale, Seifu A. Tilahun, Tammo S. Steenhuis. Water Balance for a Tropical Lake in the Volcanic Highlands: Lake Tana, Ethiopia. Water. 2020; 12 (10):2737.
Chicago/Turabian StyleMuluken L. Alemu; Abeyou W. Worqlul; Fasikaw A. Zimale; Seifu A. Tilahun; Tammo S. Steenhuis. 2020. "Water Balance for a Tropical Lake in the Volcanic Highlands: Lake Tana, Ethiopia." Water 12, no. 10: 2737.
East African riparian countries have debated sharing Nile River water for centuries. To define a reasonable allocation of water to each country, the United Nations’ Watercourse Convention could be a key legal instrument. However, its applicability has been questioned given its overly generalized guidance and non-quantifiable factors. This study identified and evaluated appropriate indicators that best describe reasonable and equitable principles and factors detailed under Article 6 of the convention in order to allocate Nile River water among the states. Potential indicators (n = 75) were defined based on multiple sources that can address conflicting interests specific to this basin context. A questionnaire based on these indicators was developed and distributed to 215 prominent experts from five professional groups on five continents. To analyze the presence of agreements or disagreements within and outside of the basin, as well as differences across expert groups, a k-mean clustering analysis and statistical tests (ANOVA and t-test) were employed. The results imply agreement on 75% of the proposed indicators by all experts across all continents. However, a significant difference in identifying the importance and relevance of many indicators between experts from Egypt and other countries was evident. This study thus demonstrates how the UN watercourse convention principles can be quantified and applied to transboundary water allocation, and ideally lead to informed discourse between basin countries in conflict.
Yared Gari; Paul Block; Getachew Assefa; Muluneh Mekonnen; Seifu Tilahun. Quantifying the United Nations’ Watercourse Convention Indicators to Inform Equitable Transboundary River Sharing: Application to the Nile River Basin. Water 2020, 12, 2499 .
AMA StyleYared Gari, Paul Block, Getachew Assefa, Muluneh Mekonnen, Seifu Tilahun. Quantifying the United Nations’ Watercourse Convention Indicators to Inform Equitable Transboundary River Sharing: Application to the Nile River Basin. Water. 2020; 12 (9):2499.
Chicago/Turabian StyleYared Gari; Paul Block; Getachew Assefa; Muluneh Mekonnen; Seifu Tilahun. 2020. "Quantifying the United Nations’ Watercourse Convention Indicators to Inform Equitable Transboundary River Sharing: Application to the Nile River Basin." Water 12, no. 9: 2499.
Lakes hold most of the world’s fresh surface water resources. Safeguarding these resources from water quality degradation requires knowledge of the relationship between lake morphometry and water quality. The 3046-km2 Lake Tana in Ethiopia is one of the water resources in which the water quality is decreasing and water hyacinths have invaded. The objective of this study is to understand the interaction between the lake morphometry and water quality and specifically the phosphorus dynamics and their effect on the water hyacinths. A bathymetric survey was conducted in late 2017. Various morphometric parameters were derived, and both these parameters and sediment available phosphorus were regressed with the dissolved phosphorus. The results show that, with a wave base depth that is nearly equal to a maximum depth of 14.8 m, the bottom sediments were continuously suspended in the water column. As a result of the resuspension mixing, we found that the dissolved phosphorus in the water column decreased with lake depth and increased with sediment available phosphorus (R2 = 0.84) in the northern half of the lake. This relationship is not as strong in the south due to a large flow of Gilgel Abay to the outlets. Water hyacinths were found where the lake was shallow and the available phosphorus was elevated. The large reservoir of sediment phosphorus will hamper any remedial efforts in removing the water hyacinths.
Mebrahtom G. Kebedew; Aron A. Kibret; Seifu A. Tilahun; Mulugeta A. Belete; Fasikaw A. Zimale; Tammo S. Steenhuis. The Relationship of Lake Morphometry and Phosphorus Dynamics of a Tropical Highland Lake: Lake Tana, Ethiopia. Water 2020, 12, 2243 .
AMA StyleMebrahtom G. Kebedew, Aron A. Kibret, Seifu A. Tilahun, Mulugeta A. Belete, Fasikaw A. Zimale, Tammo S. Steenhuis. The Relationship of Lake Morphometry and Phosphorus Dynamics of a Tropical Highland Lake: Lake Tana, Ethiopia. Water. 2020; 12 (8):2243.
Chicago/Turabian StyleMebrahtom G. Kebedew; Aron A. Kibret; Seifu A. Tilahun; Mulugeta A. Belete; Fasikaw A. Zimale; Tammo S. Steenhuis. 2020. "The Relationship of Lake Morphometry and Phosphorus Dynamics of a Tropical Highland Lake: Lake Tana, Ethiopia." Water 12, no. 8: 2243.
Smallholder agriculture constitutes the main source of livelihood for the Ethiopian rural community. However, soil degradation and uneven distribution of rainfall have threatened agriculture at present. This study is aimed at investigating the impacts of conservation agriculture on irrigation water use, nutrient availability in the root zone, and crop yield under supplementary irrigation. In this study, conservation agriculture (CA), which includes minimum soil disturbance, grass mulch cover, and crop rotation, was practiced and compared with conventional tillage (CT). We used two years’ (2018 and 2019) experimental data under paired-t design in the production of a local variety green pepper (Capsicum annuum L.). The results showed that CA practices significantly (α = 0.05) reduced irrigation water use (13% to 29%) and runoff (29% to 51%) while it increased percolated water in the root zone (27% to 50%) when compared with CT practices under the supplementary irrigation phase. In addition, CA significantly decreased NO3-N in the leachate (14% to 44%) and in the runoff (about 100%), while PO4-P significantly decreased in the leachate (33% to 50%) and in the runoff (16%) when compared with CT. Similarly, CA decreased the NO3-N load in the leachate and in the runoff, while the PO4-P load increased in the leachate but decreased in the runoff. The yield return that was achieved under CA treatment was 30% higher in 2018 and 10% higher in 2019 when compared with the CT. This research improves our understanding of water and nutrient dynamics in green pepper grown under CA and CT. Use of CA provides opportunities to optimize water use by decreasing irrigation water requirements and optimize nutrient use by decreasing nutrient losses through the runoff and leaching.
Sisay Belay; Tewodros Assefa; P. Prasad; Petra Schmitter; Abeyou Worqlul; Tammo Steenhuis; Manuel Reyes; Seifu Tilahun. The Response of Water and Nutrient Dynamics and of Crop Yield to Conservation Agriculture in the Ethiopian Highlands. Sustainability 2020, 12, 5989 .
AMA StyleSisay Belay, Tewodros Assefa, P. Prasad, Petra Schmitter, Abeyou Worqlul, Tammo Steenhuis, Manuel Reyes, Seifu Tilahun. The Response of Water and Nutrient Dynamics and of Crop Yield to Conservation Agriculture in the Ethiopian Highlands. Sustainability. 2020; 12 (15):5989.
Chicago/Turabian StyleSisay Belay; Tewodros Assefa; P. Prasad; Petra Schmitter; Abeyou Worqlul; Tammo Steenhuis; Manuel Reyes; Seifu Tilahun. 2020. "The Response of Water and Nutrient Dynamics and of Crop Yield to Conservation Agriculture in the Ethiopian Highlands." Sustainability 12, no. 15: 5989.
Water hyacinth originated from the Amazon Basin and has expanded to other parts of the world since the 1800s. In Ethiopia, the weed is affecting the socio-economic activities of the people whose livelihood is directly or indirectly dependent on Lake Tana. Still, the area covered by water hyacinth and the impact of water level fluctuation on the expansion of water hyacinth has not been known clearly. Therefore, the main objective of this study was to determine the spatiotemporal distribution of water hyacinth and relation with lake-level fluctuation. The area covered by water hyacinth was determined using monthly Sentinel-2 images, which were collected from November 2015 to December 2019. The impact of water level fluctuation on the expansion of water hyacinth was evaluated using hourly water level data converted to a monthly average to correlate with the area covered by the water hyacinth. In addition, MOD13Q1.006 data was used to evaluate the trend of the Normalized Difference Vegetation Index (NDVI) and its linkage with the weed. The maximum areas covered by water hyacinth were 278.3, 613.6, 1108.7, 2036.5, and 2504.5 ha in Feb 2015, October 2016, September 2017, December 2018, and in December 2019, respectively. Its areal coverage was declining from the northern corridors and increasing in eastern shores of the lake. The lake-level fluctuation was observed in the range of 1.5 to 3.98 m in this study. The annual mean maximum spatial values of the NDVI were in the range of 0.27 and 0.47. The area covered by water hyacinth was increasing significantly (P < 0.05) and positively correlated with the seasonal lake-level fluctuation. High water level enabled the expansion of the weed by extending its suitable habitat of shallow water to the flood plain. Based on the results of this study, lake-level fluctuations can have an adverse impact on the expansion of the weed.
Minychl G. Dersseh; Seifu A. Tilahun; Abeyou W. Worqlul; Mamaru A. Moges; Wubneh B. Abebe; Demesew A. Mhiret; Assefa M. Melesse. Spatial and Temporal Dynamics of Water Hyacinth and Its Linkage with Lake-Level Fluctuation: Lake Tana, a Sub-Humid Region of the Ethiopian Highlands. Water 2020, 12, 1435 .
AMA StyleMinychl G. Dersseh, Seifu A. Tilahun, Abeyou W. Worqlul, Mamaru A. Moges, Wubneh B. Abebe, Demesew A. Mhiret, Assefa M. Melesse. Spatial and Temporal Dynamics of Water Hyacinth and Its Linkage with Lake-Level Fluctuation: Lake Tana, a Sub-Humid Region of the Ethiopian Highlands. Water. 2020; 12 (5):1435.
Chicago/Turabian StyleMinychl G. Dersseh; Seifu A. Tilahun; Abeyou W. Worqlul; Mamaru A. Moges; Wubneh B. Abebe; Demesew A. Mhiret; Assefa M. Melesse. 2020. "Spatial and Temporal Dynamics of Water Hyacinth and Its Linkage with Lake-Level Fluctuation: Lake Tana, a Sub-Humid Region of the Ethiopian Highlands." Water 12, no. 5: 1435.
Gully erosion has many negative impacts on both cultivated and grazing lands in Ethiopian highlands. The present study was conducted in Chentale watershed, Ethiopia, to quantify the contribution of gully erosion, and to assess its temporal changes. Within the Chentale watershed, we selected a sub-watershed (104.6 ha) and nested gully catchment, and gauged for stream flow and sediment concentration data in 2015 and 2016. We measured gully dimensions before and after the onset of the rainy season in 2016 to determine soil loss due to gully erosion. The temporal changes of gully expansion were determined by digitizing gully plain area from Google earth images taken in 2005 and 2013. The results support that gullies were expanding at higher rate in recent years. Area covered by gullies in the watershed increased from 1.84 to 3.43 ha between 2005 and 2013, indicating that the proportion of the watershed covered by gullies was nearly doubled in the investigated period. The estimated soil loss from the main watershed and gullies catchment was 6 and 2 t ha−1 year−1 in 2015, and was 7 and 9 t ha−1 year−1 in 2016, respectively. The results support that gullies were the main contributors of soil erosion in the watershed, and that integrated soil and water conservation measures are required to reduce soil erosion.
Alemsha Bogale; Dessalew Aynalem; Anwar Adem; Wolde Mekuria; Seifu Tilahun. Spatial and temporal variability of soil loss in gully erosion in upper Blue Nile basin, Ethiopia. Applied Water Science 2020, 10, 1 -8.
AMA StyleAlemsha Bogale, Dessalew Aynalem, Anwar Adem, Wolde Mekuria, Seifu Tilahun. Spatial and temporal variability of soil loss in gully erosion in upper Blue Nile basin, Ethiopia. Applied Water Science. 2020; 10 (5):1-8.
Chicago/Turabian StyleAlemsha Bogale; Dessalew Aynalem; Anwar Adem; Wolde Mekuria; Seifu Tilahun. 2020. "Spatial and temporal variability of soil loss in gully erosion in upper Blue Nile basin, Ethiopia." Applied Water Science 10, no. 5: 1-8.
A field experiment consists of conservation agriculture (CA) and conventional tillage (CT) practices were set up in two areas, Robit and Dangishta, in sub-humid Ethiopian highlands. Irrigation water use, soil moisture, and agronomic data were monitored, and laboratory testing was conducted for soil samples, which were collected from 0 to 40 cm depth before planting and after harvest during the study period of 2015–2017. Calculation of crop coefficient (Kc) revealed a significant decrease in Kc values under CA as compared to CT. The result depicted that CA with a drip irrigation system significantly (α = 0.05) reduced Kc values of crops as compared to CT. Specifically, 20% reductions were observed for onion, cabbage, and garlic under CA whereas 10% reductions were observed for pepper throughout the crop base period. Consequently, irrigation water measurement showed that about 18% to 28% of a significant irrigation water savings were observed for the range of vegetables under CA as compared to CT. On the other hand, the results of soil measurement showed the CA practice significantly (α = 0.05) increased soil moisture (4%, 7%, 8%, and 10% increment for onion, cabbage, garlic, pepper) than CT practice even if irrigation input was small in CA practice. In addition, CA was found to improve the soil physico-chemical properties with significant improvement on organic matter (10%), field capacity (4%), and total nitrogen (10%) in the Dangishta experimental site. CA with drip irrigation is evidenced to be an efficient water-saving technology while improving soil properties to support sustainable intensification in the region.
Abdu Y. Yimam; Tewodros T. Assefa; Nigus F. Adane; Seifu A. Tilahun; Manoj K. Jha; Manuel R. Reyes. Experimental Evaluation for the Impacts of Conservation Agriculture with Drip Irrigation on Crop Coefficient and Soil Properties in the Sub-Humid Ethiopian Highlands. Water 2020, 12, 947 .
AMA StyleAbdu Y. Yimam, Tewodros T. Assefa, Nigus F. Adane, Seifu A. Tilahun, Manoj K. Jha, Manuel R. Reyes. Experimental Evaluation for the Impacts of Conservation Agriculture with Drip Irrigation on Crop Coefficient and Soil Properties in the Sub-Humid Ethiopian Highlands. Water. 2020; 12 (4):947.
Chicago/Turabian StyleAbdu Y. Yimam; Tewodros T. Assefa; Nigus F. Adane; Seifu A. Tilahun; Manoj K. Jha; Manuel R. Reyes. 2020. "Experimental Evaluation for the Impacts of Conservation Agriculture with Drip Irrigation on Crop Coefficient and Soil Properties in the Sub-Humid Ethiopian Highlands." Water 12, no. 4: 947.
Sediment concentration of rivers in developing countries has been increasing greatly over the last 50 years due to the conversion of forest to continuously cultivated land with the increasing population. Few studies have addressed its effect on sedimentation and water quality of the lakes by analyzing bottom sediment characteristics. In this study, the objective was to investigate the spatial distribution (and their interrelationships) of the bottom sediment characteristics in the largest lake in Ethiopia, Lake Tana where water hyacinths have been spreading rapidly during the last decade. Sediment samples were collected from the lake bottom at 60 locations and analyzed for texture, organic matter, total nitrogen, and available phosphorus. Bottom sediment samples had a median of 75% clay, 13% silt, and 9% sand. Clay was greatest in the northwestern part and smallest in the areas near the major rivers entering or exiting the lake. Clay percentage and lake depth were strongly correlated. The mean organic matter content of bottom sediment was 16 g kg−1, total nitrogen 0.8 g kg−1, and Olsen available phosphorus 19 mg kg−1. Phosphorus concentrations peaked where water hyacinths were found in the northeastern part of the lake. This study will serve as a baseline for future water quality and sedimentation changes in Lake Tana. In particular, it might aid in explaining the spread of the water hyacinths.
Mebrahtom G. Kebedew; Seifu A. Tilahun; Fasikaw A. Zimale; Tammo S. Steenhuis. Bottom Sediment Characteristics of a Tropical Lake: Lake Tana, Ethiopia. Hydrology 2020, 7, 18 .
AMA StyleMebrahtom G. Kebedew, Seifu A. Tilahun, Fasikaw A. Zimale, Tammo S. Steenhuis. Bottom Sediment Characteristics of a Tropical Lake: Lake Tana, Ethiopia. Hydrology. 2020; 7 (1):18.
Chicago/Turabian StyleMebrahtom G. Kebedew; Seifu A. Tilahun; Fasikaw A. Zimale; Tammo S. Steenhuis. 2020. "Bottom Sediment Characteristics of a Tropical Lake: Lake Tana, Ethiopia." Hydrology 7, no. 1: 18.
The sustainable development of water resources includes retaining some amount of the natural flow regime in water bodies to protect and maintain aquatic ecosystem health and the human livelihoods and wellbeing dependent upon them. Although assessment of environmental flows is now occurring globally, limited studies have been carried out in the Ethiopian highlands, especially studies to understand flow-ecological response relationships. This paper establishes a hydrological foundation of Gumara River from an ecological perspective. The data analysis followed three steps: first, determination of the current flow regime—flow indices and ecologically relevant flow regime; second, naturalization of the current flow regime—looking at how flow regime is changing; and, finally, an initial exploration of flow linkages with ecological processes. Flow data of Gumara River from 1973 to 2018 are used for the analysis. Monthly low flow occurred from December to June; the lowest being in March, with a median flow of 4.0 m3 s−1. Monthly high flow occurred from July to November; the highest being in August, with a median flow of 236 m3 s−1. 1-Day low flows decreased from 1.55 m3 s−1 in 1973 to 0.16 m3 s−1 in 2018, and 90-Day (seasonal) low flow decreased from 4.9 m3 s−1 in 1973 to 2.04 m3 s−1 in 2018. The Mann–Kendall trend test indicated that the decrease in low flow was significant for both durations at α = 0.05. A similar trend is indicated for both durations of high flow. The decrease in both low flows and high flows is attributed to the expansion of pump irrigation by 29 km2 and expansion of plantations, which resulted in an increase of NDVI from 0.25 in 2000 to 0.29 in 2019. In addition, an analysis of environmental flow components revealed that only four “large floods” appeared in the last 46 years; no “large flood” occurred after 1988. Lacking “large floods” which inundate floodplain wetlands has resulted in early disconnection of floodplain wetlands from the river and the lake; which has impacts on breeding and nursery habitat shrinkage for migratory fish species in Lake Tana. On the other hand, the extreme decrease in “low flow” components has impacts on predators, reducing their mobility and ability to access prey concentrated in smaller pools. These results serve as the hydrological foundation for continued studies in the Gumara catchment, with the eventual goal of quantifying environmental flow requirements.
Wubneh B. Abebe; Seifu A. Tilahun; Michael M. Moges; Ayalew Wondie; Minychl G. Derseh; Teshager A. Nigatu; Demesew A. Mhiret; Tammo S. Steenhuis; Marc Van Camp; Kristine Walraevens; Michael E. McClain. Hydrological Foundation as a Basis for a Holistic Environmental Flow Assessment of Tropical Highland Rivers in Ethiopia. Water 2020, 12, 547 .
AMA StyleWubneh B. Abebe, Seifu A. Tilahun, Michael M. Moges, Ayalew Wondie, Minychl G. Derseh, Teshager A. Nigatu, Demesew A. Mhiret, Tammo S. Steenhuis, Marc Van Camp, Kristine Walraevens, Michael E. McClain. Hydrological Foundation as a Basis for a Holistic Environmental Flow Assessment of Tropical Highland Rivers in Ethiopia. Water. 2020; 12 (2):547.
Chicago/Turabian StyleWubneh B. Abebe; Seifu A. Tilahun; Michael M. Moges; Ayalew Wondie; Minychl G. Derseh; Teshager A. Nigatu; Demesew A. Mhiret; Tammo S. Steenhuis; Marc Van Camp; Kristine Walraevens; Michael E. McClain. 2020. "Hydrological Foundation as a Basis for a Holistic Environmental Flow Assessment of Tropical Highland Rivers in Ethiopia." Water 12, no. 2: 547.
Comprehensive spatially referenced soil data are a crucial input in predicting biophysical and hydrological landscape processes. In most developing countries, these detailed soil data are not yet available. The objective of this study was, therefore, to evaluate the detail needed in soil resource inventories to predict the hydrologic response of watersheds. Using three distinctively different digital soil inventories, the widely used and tested soil and water assessment tool (SWAT) was selected to predict the discharge in two watersheds in the headwaters of the Blue Nile: the 1316 km2 Rib watershed and the nested 3.59 km2 Gomit watershed. The soil digital soil inventories employed were in increasing specificity: the global Food and Agricultural Organization (FAO), the Africa Soil Information Service (AfSIS) and the Amhara Design and Supervision Works Enterprise (ADSWE). Hydrologic simulations before model calibration were poor for all three soil inventories used as input. After model calibration, the streamflow predictions improved with monthly Nash–Sutcliffe efficiencies greater than 0.68. Predictions were statistically similar for the three soil databases justifying the use of the global FAO soil map in data-scarce regions for watershed discharge predictions.
Anwar A. Adem; Yihun T. Dile; Abeyou W. Worqlul; Essayas K. Ayana; Seifu A. Tilahun; Tammo S. Steenhuis. Assessing Digital Soil Inventories for Predicting Streamflow in the Headwaters of the Blue Nile. Hydrology 2020, 7, 8 .
AMA StyleAnwar A. Adem, Yihun T. Dile, Abeyou W. Worqlul, Essayas K. Ayana, Seifu A. Tilahun, Tammo S. Steenhuis. Assessing Digital Soil Inventories for Predicting Streamflow in the Headwaters of the Blue Nile. Hydrology. 2020; 7 (1):8.
Chicago/Turabian StyleAnwar A. Adem; Yihun T. Dile; Abeyou W. Worqlul; Essayas K. Ayana; Seifu A. Tilahun; Tammo S. Steenhuis. 2020. "Assessing Digital Soil Inventories for Predicting Streamflow in the Headwaters of the Blue Nile." Hydrology 7, no. 1: 8.
Feeding nine 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 three months out of the eight month long dry season.
Seifu A. Tilahun; Debebe L. Yilak; Petra Schmitter; Fasikaw A. Zimale; Simon Langan; Jennie Barron; Jean‐Yves Parlange; Tammo S. Steenhuis. Establishing irrigation potential of a hillside aquifer in the African highlands. Hydrological Processes 2019, 34, 1741 -1753.
AMA StyleSeifu A. Tilahun, Debebe L. Yilak, Petra Schmitter, Fasikaw A. Zimale, Simon Langan, Jennie Barron, Jean‐Yves Parlange, Tammo S. Steenhuis. Establishing irrigation potential of a hillside aquifer in the African highlands. Hydrological Processes. 2019; 34 (8):1741-1753.
Chicago/Turabian StyleSeifu A. Tilahun; Debebe L. Yilak; Petra Schmitter; Fasikaw A. Zimale; Simon Langan; Jennie Barron; Jean‐Yves Parlange; Tammo S. Steenhuis. 2019. "Establishing irrigation potential of a hillside aquifer in the African highlands." Hydrological Processes 34, no. 8: 1741-1753.
The spatio-temporal characteristic of rainfall in the Beles Basin of Ethiopia is poorly understood, mainly due to lack of data. With recent advances in remote sensing, satellite derived rainfall products have become alternative sources of rainfall data for such poorly gauged areas. The objectives of this study were: (i) to evaluate a multi-source rainfall product (Climate Hazards Group Infrared Precipitation with Stations: CHIRPS) for the Beles Basin using gauge measurements and (ii) to assess the spatial and temporal variability of rainfall across the basin using validated CHIRPS data for the period 1981–2017. Categorical and continuous validation statistics were used to evaluate the performance, and time-space variability of rainfall was analyzed using GIS operations and statistical methods. Results showed a slight overestimation of rainfall occurrence by CHIRPS for the lowland region and underestimation for the highland region. CHIRPS underestimated the proportion of light daily rainfall events and overestimated the proportion of high intensity daily rainfall events. CHIRPS rainfall amount estimates were better in highland regions than in lowland regions, and became more accurate as the duration of the integration time increases from days to months. The annual spatio-temporal analysis result using CHIRPS revealed: a mean annual rainfall of the basin is 1490 mm (1050–2090 mm), a 50 mm increase of mean annual rainfall per 100 m elevation rise, periodical and persistent drought occurrence every 8 to 10 years, a significant increasing trend of rainfall (~5 mm year−1), high rainfall variability observed at the lowland and drier parts of the basin and high coefficient of variation of monthly rainfall in March and April (revealing occurrence of bimodal rainfall characteristics). This study shows that the performance of CHIRPS product can vary spatially within a small basin level, and CHIRPS can help for better decision making in poorly gauged areas by giving an option to understand the space-time variability of rainfall characteristics.
Ashebir Sewale Belay; Ayele Almaw Fenta; Alemu Yenehun; Fenta Nigate; Seifu A. Tilahun; Michael Mehari Moges; Mekete Dessie; Enyew Adgo; Jan Nyssen; Margaret Chen; Ann Van Griensven; Kristine Walraevens. Evaluation and Application of Multi-Source Satellite Rainfall Product CHIRPS to Assess Spatio-Temporal Rainfall Variability on Data-Sparse Western Margins of Ethiopian Highlands. Remote Sensing 2019, 11, 2688 .
AMA StyleAshebir Sewale Belay, Ayele Almaw Fenta, Alemu Yenehun, Fenta Nigate, Seifu A. Tilahun, Michael Mehari Moges, Mekete Dessie, Enyew Adgo, Jan Nyssen, Margaret Chen, Ann Van Griensven, Kristine Walraevens. Evaluation and Application of Multi-Source Satellite Rainfall Product CHIRPS to Assess Spatio-Temporal Rainfall Variability on Data-Sparse Western Margins of Ethiopian Highlands. Remote Sensing. 2019; 11 (22):2688.
Chicago/Turabian StyleAshebir Sewale Belay; Ayele Almaw Fenta; Alemu Yenehun; Fenta Nigate; Seifu A. Tilahun; Michael Mehari Moges; Mekete Dessie; Enyew Adgo; Jan Nyssen; Margaret Chen; Ann Van Griensven; Kristine Walraevens. 2019. "Evaluation and Application of Multi-Source Satellite Rainfall Product CHIRPS to Assess Spatio-Temporal Rainfall Variability on Data-Sparse Western Margins of Ethiopian Highlands." Remote Sensing 11, no. 22: 2688.
The Ethiopian highlands suffer from severe land degradation, including erosion. In response, the Ethiopian government has implemented soil and water conservation practices (SWCPs). At the same time, due to its economic value, the acreage of eucalyptus has expanded, with croplands and pastures converted to eucalyptus plantations. The impact of these changes on soil loss has not been investigated experimentally. The objective of this study, therefore, is to examine the impacts of these changes on stream discharge and sediment load in a sub-humid watershed. The study covers a nine-year period that included installation of SWCPs, a three-fold increase from 1.5 ha in 2010 to 5 ha in 2018 in eucalyptus, and the upgrading of an unpaved to the paved road. Precipitation, runoff, and sediment concentration were monitored by installing weirs at the outlets of the main and four nested watersheds. A total of 867 storm events were collected in the nine years. Runoff and sediment concentration decreased by more than half in nine years. In the main watershed W5, we estimated that evapotranspiration by eucalyptus during the dry phase (November to May) increased approximately from 30 mm a−1 in 2010 to 100 mm a−1 in 2018. In watershed W3 it increased from 2 mm a−1 to 400 mm a−1, requiring more rainfall before saturation excess runoff began in the rain phase. The reduction in runoff led to a decreased sediment load from 70 Mg ha−1 a−1 in 2010 to 2.8 Mg ha−1 a−1 in 2018, though the reduction in discharge may have negative impacts on ecology and downstream water resources. SWCPs became sediment-filled and minimally effective by 2018. This indicates that these techniques are either inappropriate for this sub-humid watershed or require improved design and maintenance.
Demesew A. Mhiret; Dessalegn C. Dagnew; Tilashwork C. Alemie; Christian D. Guzman; Seifu A. Tilahun; Benjamin F. Zaitchik; Tammo S. Steenhuis. Impact of Soil Conservation and Eucalyptus on Hydrology and Soil Loss in the Ethiopian Highlands. Water 2019, 11, 2299 .
AMA StyleDemesew A. Mhiret, Dessalegn C. Dagnew, Tilashwork C. Alemie, Christian D. Guzman, Seifu A. Tilahun, Benjamin F. Zaitchik, Tammo S. Steenhuis. Impact of Soil Conservation and Eucalyptus on Hydrology and Soil Loss in the Ethiopian Highlands. Water. 2019; 11 (11):2299.
Chicago/Turabian StyleDemesew A. Mhiret; Dessalegn C. Dagnew; Tilashwork C. Alemie; Christian D. Guzman; Seifu A. Tilahun; Benjamin F. Zaitchik; Tammo S. Steenhuis. 2019. "Impact of Soil Conservation and Eucalyptus on Hydrology and Soil Loss in the Ethiopian Highlands." Water 11, no. 11: 2299.
Intensification of rainfed agriculture in the Ethiopian highlands has resulted in soil degradation and hardpan formation, which has reduced rooting depth, decreased deep percolation, and increased direct runoff and sediment transport. The main objective of this study was to assess the potential impact of subsoiling on surface runoff, sediment loss, soil water content, infiltration rate, and maize yield. Three tillage treatments were replicated at five locations: (i) no tillage (zero tillage), (ii) conventional tillage (ox-driven Maresha plow, up to a depth of 15 cm), and (iii) manual deep ripping of the soil’s restrictive layers down to a depth of 60 cm (deep till). Results show that the posttreatment bulk density and penetration resistance of deep tillage was significantly less than in the traditional tillage and zero-tillage systems. In addition, the posttreatment infiltration rate for deep tillage was significantly greater, which resulted in significantly smaller runoff and sedimentation rates compared to conventional tillage and zero tillage. Maize yields were improved by 6% under deep tillage compared to conventional tillage and by 29% compared to no tillage. Overall, our findings show that deep tillage can be effective in overcoming some of the detrimental effects of hardpans in degraded soils.
Misbah Abidela Hussein; Habtamu Muche; Petra Schmitter; Prossie Nakawuka; Seifu A. Tilahun; Simon Langan; Jennie Barron; Tammo S. Steenhuis. Deep Tillage Improves Degraded Soils in the (Sub) Humid Ethiopian Highlands. Land 2019, 8, 159 .
AMA StyleMisbah Abidela Hussein, Habtamu Muche, Petra Schmitter, Prossie Nakawuka, Seifu A. Tilahun, Simon Langan, Jennie Barron, Tammo S. Steenhuis. Deep Tillage Improves Degraded Soils in the (Sub) Humid Ethiopian Highlands. Land. 2019; 8 (11):159.
Chicago/Turabian StyleMisbah Abidela Hussein; Habtamu Muche; Petra Schmitter; Prossie Nakawuka; Seifu A. Tilahun; Simon Langan; Jennie Barron; Tammo S. Steenhuis. 2019. "Deep Tillage Improves Degraded Soils in the (Sub) Humid Ethiopian Highlands." Land 8, no. 11: 159.