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Development should not be done in a way that endangers the environment, human life, or non-human life that depends on it. However, in Ethiopia, economic development was carried out with little or no concern for the environment or indigenous and minority groups whose livelihoods directly depended on natural resources. Based on an examination of primary and secondary sources through the lens of structural violence theory, this article argues that Ethiopia's economic growth was not equitable and happened at the expense of the country's natural resources. Using the Negede Woyto of Lake Tana as a case study, this paper investigated how economic development projects in Ethiopia impacted minority communities. The conclusion reached was that the EPRDF-led government actively worked to inflict structural violence on minority groups in the Lake Tana region, using sustainable economic development as a justification. [ABSTRACT FROM AUTHOR]

Water quality is deteriorating in the world's freshwater bodies, and Lake Tana in Ethiopia is becoming unpleasant to biodiversity. The objective of this study is to retrieve non-optical water quality data, specifically total nitrogen (TN) and total phosphorus (TP) concentrations, in Lake Tana using Machine Learning (ML) techniques applied to Landsat 8OLI imagery. TheMLmethods employed include Artificial Neural Networks (ANN), Support Vector Regression (SVR), Random Forest Regression (RF), XGBoost Regression (XGB), AdaBoost Regression (AB), and Gradient Boosting Regression (GB). The XGB algorithm provided the best result for TN retrieval, with determination coefficient (R²), mean absolute error (MARE), relative mean square error (RMSE) and Nash Sutcliff (NS) values of 0.80, 0.043, 0.52, and 0.81 mg/L, respectively. The RF algorithm was most effective for TP retrieval, with R² of 0.73, MARE of 0.076, RMSE of 0.17 mg/L, and NS index of 0.74. These methods accurately predicted TN and TP spatial concentrations, identifying hotspots along river inlets and northeasters. The temporal patterns of TN, TP, and their ratios were also accurately represented by combining in-situ, RS and ML-based models. Our findings suggest that this approach can significantly improve the accuracy of water quality retrieval in large inland lakes and lead to the development of potential water quality digital services. [ABSTRACT FROM AUTHOR]

Understanding the spatial and temporal patterns of sediment loading in water bodies is crucial for effective water quality management. Remote sensing (RS) has emerged as a valuable and reliable tool for monitoring turbidity, which can provide insights into sediment dynamics in water bodies. In this study, we investigate the potential of turbidity data derived from RS to explain simulated spatial and temporal sediment loading patterns in the Lake Tana basin, Ethiopia. Utilizing existing RS lake turbidity data from Copernicus Global Land Service (CGLS) and simulated seasonal and multiyear trends of river sediment loadings into Lake Tana from the Soil and Water Assessment Tool (SWAT + model), we estimate correlations at different river inlets into Lake Tana. The results reveal a strong positive correlation (R2 > 0.66) between the multiyear monthly average sediment load from inflow rivers and RS lake turbidity at most river inlets. This indicates that the simulated river sediment loads and lake turbidity at river inlets exhibit similar seasonal patterns. Notably, higher turbidity levels are observed at the river inlet with the highest sediment load export. These findings highlight the potential of RS turbidity products in characterizing temporal and spatial patterns of sediment loadings, particularly in data-scarce regions, contributing to a better understanding of water quality dynamics in such areas. [ABSTRACT FROM AUTHOR]

Land use and land cover (LULC) dynamics using GIS and remote sensing techniques measure extent and spatial structure, which are critical for monitoring biomes. A digital LULC detection technique with multi‐temporal satellite imagery analysis was employed at four timepoints from 1987 to 2017 and performed using supervised classifications method in ERDAS imagine 2015. For image classification, the five major LULC types included forests, built‐up land, agricultural land, water bodies and grasslands. LULC of grasslands, forests and water bodies reduced, while LULC of agricultural and built‐up lands increased. Avifaunal surveys were conducted at 11 sites across the LULC classes to compare species richness and abundance. The decrement of forests and water bodies would result in habitat loss, affecting endemic and threatened avifauna, as forests showed highest avifaunal species diversity (H′ = 3.80). Despite the decrement, grasslands demonstrated higher avifaunal species richness (107) and abundance (2767). Species richness decreased significantly from grasslands to water bodies and agricultural land (p < 0.05), and from forests to agricultural and built‐up land (p < 0.05), and water bodies (p < 0.01). Avifaunal abundance decreased significantly from grasslands to all other LULC classes. Regular LULC change assessment is integral to avifaunal habitat and biodiversity conservation efforts, particularly at Lake Tana. [ABSTRACT FROM AUTHOR]

Abstract Securely dated archaeological sites from key regions and periods are critical for understanding early modern human adaptive responses to past environmental change. Here, we report new radiocarbon dates of > 42,000 cal years BP for an intensive human occupation of Gorgora rockshelter in the Ethiopian Highlands. We also document the development of innovative technologies and symbolic behaviors starting around this time. The evidenced occupation and behavioral patterns coincide with the onset and persistence of a stable wet phase in the geographically proximate high-resolution core record of Lake Tana. Range expansion into montane habitats and the subsequent development of innovative technologies and behaviors are consistent with population dispersal waves within Africa and beyond during wetter phases ~ 60–40 thousand years ago (ka).

Securely dated archaeological sites from key regions and periods are critical for understanding early modern human adaptive responses to past environmental change. Here, we report new radiocarbon dates of > 42,000 cal years BP for an intensive human occupation of Gorgora rockshelter in the Ethiopian Highlands. We also document the development of innovative technologies and symbolic behaviors starting around this time. The evidenced occupation and behavioral patterns coincide with the onset and persistence of a stable wet phase in the geographically proximate high-resolution core record of Lake Tana. Range expansion into montane habitats and the subsequent development of innovative technologies and behaviors are consistent with population dispersal waves within Africa and beyond during wetter phases ~ 60–40 thousand years ago (ka). [ABSTRACT FROM AUTHOR]

We investigated the magnitude of reservoir sedimentation upstream and its sediment-shadow effect on a large downstream-linked lake, Lake Tana (Ethiopia). To better understand the reservoir-induced reductions of fluvial sediment downstream, sediment budgets for two scenarios were developed. The results indicated that reservoir sedimentation is extremely high, with annual storage capacity losses (1–4.2%) exceeding the global average. Consequently, unless mitigation measures are implemented, the reservoirs' dead storage volume will be filled with sediment in less than 42% of their designed life expectancy. The sediment-trapping conditions created by the reservoirs will also reduce sediment inflow from tributaries into the lake by 15–52%, overbank sedimentation on floodplains by 33–48%, and sediment deposition in Lake Tana by 16–54% annually. Overall, under the current environmental set-up, the ongoing and planned reservoir constructions could extend the expected useful lifetime of Lake Tana from 918 to 2022 years. [ABSTRACT FROM AUTHOR]

Alluvial rivers adjust their geometry in response to environmental and anthropogenic disturbances. Flow regulation results in a new geomorphic condition that affects the aquatic ecosystem and its nature. This paper examines the long-term effects of flow regulation on the geomorphic and ecological responses of the downstream river channels of the Abay River, which is the only natural outflow of Lake Tana, Ethiopia. Since 1996, the river's discharge regime has been affected by constructing a head-rise weir (Chara Chara) at its natural outlet for hydropower production and dam construction on the Lake Tana tributary rivers. Hydrologic data collected at the outlet of the river, SPOT, and Google Earth images were used for the study. River banks and bed topography were extracted via ArcGIS for selected study periods. The study revealed that existing water resource development on the tributary rivers of Lake Tana modified (decreased) the outflow discharge on the Abay River, and resulted a changed morphological and moderate level ecological impact on the river system. Future ongoing and planned water resource developments will exacerbate the pressure on the lake. Without careful management, these changes are likely to have severe morphological, ecological and social consequences.

This study assessed the performance of Pleurotus ostreatus and Lentinula edodes mushrooms on a variety of substrate combinations. Water hyacinth, rice husk, and cow dung were employed as substrates. Mushroom growth performance, yield, proximate composition, and mineral content were among the variables evaluated. The results indicate significant differences (p

This study investigates the heavy metals (HMs) and other constituents in Lake Tana around the Gulf of Bahir Dar City. The water sample was collected from areas receiving drainage water and a reference sample was collected from areas away from the urban impact, both during dry and wet seasons. Pollution sources and levels were determined using pollution indices and GIS spatial analyses. All in situ parameters were in the recommended range of the USEPA aquatic and WHO drinking water guidelines. The level of dissolved P was recorded between 0.03 and 0.9 mg/l and the level of N-NO3 ranged from 0.05 to 1.01 mg/l indicating that the limits were above USEPA aquatic criteria. The HMs varied from 0.08 to 2.85 mg/l for Cu, 0.10 to 1.60 mg/l for Fe, 0.04 to 0.22 mg/l for Cr, and Mn was below detection. Cr and Fe were above the aquatic and drinking water guideline limit. Spatially, pollution was more significant in areas receiving drainage. Also, except Cu and Fe, other parameters were higher in the rainy season indicating storm runoff pollution. The overall pollution indices of water quality status, such as water quality index 63, heavy metal pollution index 3.1, and nutrient pollution index 4.7, indicated the quality level of water to be alarming. Therefore, comprehensive regulatory and waste management practices are needed. HIGHLIGHTS This research is a first study evaluating the heavy metals (HMs) in Lake Tana.; Both HMs (Cr and Fe) and nutrients (N and P) exceeded the aquatic limit.; GIS spatial analysis shows that concentration is at a high level in urban drainage discharge area.; HMs and nutrients are at high levels in the rainy season.; The calculated pollution indices such as WQI, HPI, and NPI indicated the water quality of the lake to be alarming.;

Water quality is deteriorating in the world's freshwater bodies, and Lake Tana in Ethiopia is becoming unpleasant to biodiversity. The objective of this study is to retrieve non-optical water quality data, specifically total nitrogen (TN) and total phosphorus (TP) concentrations, in Lake Tana using Machine Learning (ML) techniques applied to Landsat 8 OLI imagery. The ML methods employed include Artificial Neural Networks (ANN), Support Vector Regression (SVR), Random Forest Regression (RF), XGBoost Regression (XGB), AdaBoost Regression (AB), and Gradient Boosting Regression (GB). The XGB algorithm provided the best result for TN retrieval, with determination coefficient (R2), mean absolute error (MARE), relative mean square error (RMSE) and Nash Sutcliff (NS) values of 0.80, 0.043, 0.52, and 0.81 mg/L, respectively. The RF algorithm was most effective for TP retrieval, with R2 of 0.73, MARE of 0.076, RMSE of 0.17 mg/L, and NS index of 0.74. These methods accurately predicted TN and TP spatial concentrations, identifying hotspots along river inlets and northeasters. The temporal patterns of TN, TP, and their ratios were also accurately represented by combining in-situ, RS and ML-based models. Our findings suggest that this approach can significantly improve the accuracy of water quality retrieval in large inland lakes and lead to the development of potential water quality digital services.

The Lake Tana area is located within a complex volcano-tectonic basin on the northwestern Ethiopian plateau. The basin is underlain by a thick succession of Oligocene transitional basalts and sub-alkaline rhyolites overlain in places, particularly south of the lake, by Quaternary alkaline to mildly transitional basalts, and dotted with Oligo-Miocene trachyte domes and plugs. This paper presents the results of integrated field, petrographic, and major and trace element geochemical studies of the Lake Tana area volcanic rocks, with particular emphasis on the Oligocene basalts and rhyolites. The studies reveal a clear petrogenetic link between the Oligocene basalts and rhyolites. The Oligocene basalts are: (1) plagioclase, olivine, and/or pyroxene phyric; (2) show an overall decreasing trend in MgO, Fe2O3, and CaO with silica; (3) have relatively low Mg#, Ni and Cr contents and high Nb/La and Nb/Yb ratios; and (4) show LREE enriched and generally flat HREE patterns. All these imply the origin of the Oligocene basalts by shallow-level fractional crystallization of an enriched magma sourced at the asthenospheric mantle. The Oligocene rhyolites: (1) are enriched in incompatible while depleted in compatible trace elements, P and Ti; (2) show a strong negative Eu anomaly; (3) contain appreciable amounts of plagioclase, apatite, and Fe-Ti oxides; and (4) show clear geochemical similarity with well-constrained rhyolites from the Large Igneous Province (LIP) of the northwestern Ethiopian plateau. Low-pressure fractional crystallization of mantle-derived basaltic magma in crustal magma chambers explains the origin of these rhyolites. Our study further shows that the Oligocene basalts and rhyolites are co-genetic and the felsic rocks of the Lake Tana area are related differentiates of the flood basalt volcanism in the northwestern Ethiopian plateau. [ABSTRACT FROM AUTHOR]

Abstract Lake Tana, which is the largest Lake in Ethiopia, has been invaded by water hyacinths since 2011. Although the government and the community have devoted considerable time and energy over a long period to removing the invasive weed mechanically and manually, the weed has been increasing significantly. Accurate, reliable, and timely information on the spatiotemporal distribution and extent of water hyacinth is crucial to determine its evolution, propagation, and potentially vulnerable areas of the Lake. Therefore, comprehensive information on the spatial distribution of water hyacinths and their annual and seasonal variability is essential for Lake Tana’s water resource planning, development, and management. This study aims to evaluate the spatiotemporal pattern of water hyacinth and its dynamics with seasonal climate variability and impact on evapotranspiration. Landsat 7 ETM+, Landsat 8 OLI, and Sentinel 2 and meteorological datasets were employed. Supervised and manual digitization image classification methods were applied to prepare Land-use/ Land-cover in the Lake. The Mann–Kendall trend test and Pearson correlation coefficient were used to evaluate the trend of water hyacinth and the impact of climate variability on water hyacinth distribution respectively. Besides, the evapotranspiration and water losses were estimated using the FAO-56 Penman–Monteith method. The surface extent of the water hyacinth in Lake Tana has increased by 96% in 2019 from 2011. However, the surface area of the Lake has declined. That means 1603 ha of water surface area has been changed to land surface from 2011 to 2019. The average volume of water loss in Lake Tana was 0.21% of the volume of the Lake from September 2016 to December 2018.

This study quantified the total evapotranspiration (ET) flux of three major types of macrophytes that cover lacustrine fringe wetlands in Lake Tana, Ethiopia during the dry season, April and May, 2022. This study was conducted to understand lacustrine wetland macrophytes' ET rates and provide an important guideline for designing their conservation and restoration plans. To assess ET rates during the peak dry season, three macrophytes of lacustrine wetlands in Lake Tana were chosen: Eichhornia crassipes (water hyacinth), Cyperus papyrus, and Echinochloa stagnina. Three replicate lysimeters for each of the three treatment types (macrophytes) and one control type (open water) were applied to measure ET. To calculate reference evapotranspiration (ET o), FAO's ET o Calculator Version 3.2 was applied. All statistical analyses were carried out using R software. The results of ET rates from wetland macrophytes (9.05mm/day) were considered to be significantly higher than open water evaporation (5.90mm/day). There was a significant difference in mean ET among the macrophytes [F (3, 488) = 194.6, p < 2e-16 ***]. In this study, crop coefficient (K c1) (1.99 ± 0.65) referenced to FAO Penman–Monteith ET o is greater than K c2 (1.58 ± 0.59) referenced to open water evaporation (E ow). In terms of wetland macrophyte type, E. crassipes had the maximum mean Kc values (K c1 = 2.51±0.70 and K c2 = 2.02±0.67). E. stagnina had the minimum mean Kc values (K c1 = 1.52±0.32 and K c2 = 1.19±0.24). Except for open water which strongly correlated with sunshine hours (r = 0.61) and solar radiation (r = 0.60), the correlation among daily ET values and meteorological variables was found to be weak. The result of our research indicated that the presence of floating macrophytes of E. crassipes will increase the ET flux during the dry season more than emergent macrophytes and open water surfaces. Our findings could provide an important guideline for designing conservation and restoration plans for C. papyrus and E. stagnina to reverse the spread of E. crassipes and maintaining lacustrine fringe wetlands for fish breeding ground and sediment control. [ABSTRACT FROM AUTHOR]

Lake Tana, which is the largest Lake in Ethiopia, has been invaded by water hyacinths since 2011. Although the government and the community have devoted considerable time and energy over a long period to removing the invasive weed mechanically and manually, the weed has been increasing significantly. Accurate, reliable, and timely information on the spatiotemporal distribution and extent of water hyacinth is crucial to determine its evolution, propagation, and potentially vulnerable areas of the Lake. Therefore, comprehensive information on the spatial distribution of water hyacinths and their annual and seasonal variability is essential for Lake Tana's water resource planning, development, and management. This study aims to evaluate the spatiotemporal pattern of water hyacinth and its dynamics with seasonal climate variability and impact on evapotranspiration. Landsat 7 ETM+, Landsat 8 OLI, and Sentinel 2 and meteorological datasets were employed. Supervised and manual digitization image classification methods were applied to prepare Land-use/ Land-cover in the Lake. The Mann–Kendall trend test and Pearson correlation coefficient were used to evaluate the trend of water hyacinth and the impact of climate variability on water hyacinth distribution respectively. Besides, the evapotranspiration and water losses were estimated using the FAO-56 Penman–Monteith method. The surface extent of the water hyacinth in Lake Tana has increased by 96% in 2019 from 2011. However, the surface area of the Lake has declined. That means 1603 ha of water surface area has been changed to land surface from 2011 to 2019. The average volume of water loss in Lake Tana was 0.21% of the volume of the Lake from September 2016 to December 2018. [ABSTRACT FROM AUTHOR]

Excess sediment and nutrient losses from intensifying agriculture degrade water quality and boost plant growth. The relationship between circulation patterns, spatial water quality degradation, and water hyacinth infestation is not adequately studied. The objective of this study is, therefore, to investigate the effect of lake circulation patterns on sediment and nutrient distribution and its implication on the spread of water hyacinth in a tropical lake. This study was carried out in Lake Tana, the largest freshwater lake in Ethiopia, where sediment and nutrient concentrations are increasing, and water hyacinths have become a challenge since 2011. The lake circulation pattern was simulated by the Delft3D model based on a bathymetry survey, discharge, and meteorological forcings. To predict the transport path of sediments and dissolved nutrients, an inert tracer was released in the four main river inlets of the lake. Observed lake water level measurements were used to validate the model. Our results show that the lake circulation pattern could explain the transport path of sediment and nutrients and the location of the water hyacinths found in the northeast of the lake. Sediments and nutrients from the largest river, Gilgel Abay, in the southeast of Lake Tana, flow through the two outlets nearby with little sediment deposition due to the relatively short retention time. The phosphorus-rich sediments of the 24 h at 105 °C remaining three main rivers joining the lake at the north and east are transported to the northeast. Thus, the management and control of water hyacinths should focus on the northern and eastern catchment areas of Lake Tana. [ABSTRACT FROM AUTHOR]

In the past decade, streamflow data remain inaccessible for most river gauges in Ethiopia due to a lack of updated stage–discharge relationships, also called rating curves. In this study, researchers and hydrologic technicians collaborated to fill the recent streamflow data gaps at three gauging stations in the Lake Tana sub-basin of the Nile River. We conducted extensive field campaigns to improve the coverage of stage–discharge measurements for rating curve development. We evaluated the rating curve uncertainty during the time of its establishment and the sensitivity of the rating curves to sample size. The stage–discharge measurements conducted by the hydrological agency during the period 2016–2020 were found inadequate in number and coverage to establish reliable rating curves. Hence, converting recent water level measurements to discharge data was made possible using the rating curves developed in this study. The converted discharge data will be accessible to researchers to investigate the sub-basin's hydrology. Our study emphasizes the need to improve the stage–discharge measurement frequency to keep up with frequent changes in the morphology of the rivers' channels. The study demonstrated that collaboration between the data provider and data users can improve streamflow data availability and accessibility, which has become an increasing global challenge. HIGHLIGHTS The hydrology agency would benefit from revising its strategy and practice of stage–discharge measurement.; Data users' willingness to share the burden of data collection by hydrologic agencies has immense value in streamflow data availability for the study of water and climate change.; Cross-validation was applied to evaluate the adequacy of stage–discharge data for rating curve establishment.;

Pesticide use has increased in the Lake Tana sub-basin due to increased agricultural activity, potentially endangering nontargeted organisms. To assess its potential impact on fish health and fish-consuming human populations, pesticide concentrations in the fillet and liver tissue of three fish species, namely Labeobarbus megastoma, Labeobarbus tsanensis, and Oreochromis niloticus, were investigated in Lake Tana. Fish samples were taken from the lake near the rivers of Ribb and Gumara, which flow through agricultural areas where considerable amounts of pesticides have been applied. A total of 96 fish samples were collected. Liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) revealed the presence of ten pesticides. Pyrimethanil was frequently detected in 96% of liver and 65% of fillet samples at a median concentration of 33.9 µg kg−1 and 19.7 µg kg−1, respectively. The highest concentration of pyrimethanil was found in L. megastoma (1850.0 µg kg−1). Labeobarbus megastoma also had the highest concentration of oxamyl (507.0 µg kg−1) and flazasulfuron (60.1 µg kg−1) detected in the liver tissue. The highest concentration of carbaryl (56.5 µg kg−1) was found in the liver tissue of O. niloticus. Fish tissue samples from the two study sites contained pyrimethanil, oxamyl, carbaryl, and flazasulfuron. Only pyrimethanil showed a statistically significant difference between the two sites and the species L. megastoma and L. tsanensis. The amounts of pesticides found in the fish species pose no direct risk to the health of fish consumer human population. However, the results show that the lake ecosystem needs immediate attention and regular monitoring of the rising pesticide usage in the lake watershed. [ABSTRACT FROM AUTHOR]

This study aimed at assessing the characteristics of water hyacinth biomass in Lake Tana. Explanatory research design was used based on biomass samples and satellite images acquired along with field observation and literature reviews. The results showed that high amount of N and P nutrients, shallow nature of the Lake and suitable climatic conditions of the area are the causes for the weeds’ proliferation. The mean NDVI values were −0.542 to 0.828 and −0.628 to 0.877 in the dry and wet seasons, respectively. The spatial distribution of the weed was 2126.9 ha and 592.4 ha during the wet and dry seasons. The weed has recorded a mean leaf length of 9.3 cm, petiole length of 28.1 cm, root shoot ratio of 3.3, leaf blade area of 55.6 cm2 and leaf area index of 11343.9 cm2. In addition, a mean of 10.9 leaves per plant and 18.6 plants per 0.25m2 was found. Furthermore, the biomass analysis revealed 1,990,787.8 tons of wet and 554,523.8 tons of dry water hyacinth biomass can be harvested from the Lake per year. Stakeholders shall work on control of water hyacinth biomass as a short-term measure and reduction of nutrient inflow into the Lake as a long-term measure.

Halo Yohans, Birhan Agmas Mitiku, Habtamu Tassew Department of Veterinary Science, School of Animal Science and Veterinary Medicine, College of Agriculture and Environmental Science, Bahir Dar University, Bahir Dar, EthiopiaCorrespondence: Halo Yohans, Department of Veterinary Science, School of Animal Science and Veterinary Medicine, College of Agriculture and Environmental Science, Bahir Dar University, Bahir Dar, Ethiopia, Email yohanshalo12@gmail.comIntroduction: Microbiological contamination in fish origin foods is the leading risk for public health. Among the range of pathogenic bacterial species that cause fish food borne diseases is Escherichia coli. The pathogenic strains of Escherichia coli cause diarrhea by producing and releasing toxins and can also be the cause of food spoilage in fish.Methods: A cross-sectional study was conducted to assess hygienic practices of fish handlers, to evaluate bacterial load and antimicrobial resistance patterns of Escherichia coli along the fish value chain in Northwest Ethiopia. Systematic and purposive sampling techniques were used for uncooked and cooked fish samples respectively.Results: From a total of 180 fish samples, 36 (20%) were positive for Escherichia coli. From 115 uncooked and 65 cooked fish samples examined, 27 (23.5%) and 9 (13.8%) had E. coli respectively. The highest mean bacterial count was observed in raw fish samples (6.13 × 105 cfu/g), followed by cooked fish samples (2.81 × 104 cfu/g). Among the interviewed fish handlers, 83.3%, 76.7% and 80% of respondents had good knowledge and attitude towards using a clean cutting-and-filleting board, storing raw and cooked foods separately and using an apron for reducing the risk of fish contamination, respectively. All 36 isolates were 100% sensitive to ciprofloxacin and gentamycin. Of the Escherichia coli isolates subjected to tetracycline, 55.6% were resistant, 8.3% were intermediate and 36.1% were susceptible.Conclusion and Recommendation: This study revealed that there was a lack hygienic practice and high Escherichia coli profiles were observed. Hence, it could be wise to advise the fish harvesters, fish traders, hotels and restaurants about fish food safety practices from harvesting to consumption to improve fish food safety practices and quality standards of fish harvested and sold in northwest Ethiopia.Keywords: Escherichia coli, fish food, hygienic practice, Lake Tana

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. [ABSTRACT FROM AUTHOR]

Lake Tana is a well-known tourist spot in northern Ethiopia that lures both domestic and foreign tourists. The lake's value is still underrated, despite the site's immense potential for recreation and tourism. In this study, the recreational value of Lake Tana is estimated, and the consumer characteristics associated with recreational demand are analyzed. The study employs a Zero-Truncated Poisson (ZTP) regression model for data generated by the Individual Travel Cost Method (ITCM) and draws information from 1094 on-site surveys. According to ZTP regression results, variables that are significantly and positively associated with demand for Lake Tana recreation include the monthly income and age of the visitors and their preference for other recreation destinations such as Tis-Abay and Gondar Fasiledes Royal Castle. However, respondents' leisure time, overall cost, and residential distance from the recreational site are all negatively associated with the demand for recreation. It is also evident that Lake Tana is endowed with a wealth of attributes, ranging from natural beauty to ancient religious and cultural heritages, making the lake a highly desirable recreation destination. According to the estimation, Lake Tana has a yearly recreational value of around USD 68.5 million. However, it also demonstrates that if lake settings were to improve in quality, the value of Lake Tana would rise considerably, reaching USD 151 million. The value of sentimental attachment implies that determining Lake Tana's recreational value is a key element in the resource's sustainable utilization and management. To make greater use of Lake Tana's recreational amenities, however, uncontrolled waste disposal, favorable recreation facilities, and the spread of water hyacinth should be addressed immediately. Furthermore, it is imperative to maintain the lake's diverse attributes, as the integration of these attributes is what gives the lake its primary appeal. [ABSTRACT FROM AUTHOR]

Abstract The Blue Nile’s source, Lake Tana, is the biggest lake in Ethiopia and offers multiple services to local, regional, and international communities. The first step to effectively, efficiently, and sustainably utilizing the services that the lake may provide is to understand its water balance using accurate estimations of its water balance parameters, including direct rainfall. Direct rainfall to Lake Tana is one of the most important water balance terms of the Lake that needs a precise estimate. This study tries to analyze the spatial and temporal variability of direct rainfall to the Lake and estimate the mean annual and mean monthly direct rainfall amount to the lake using sufficient data and appropriate methodologies. 30 years (1986–2015) monthly and mean annual data from 13 meteorological stations were collected and used to analyses the spatial and temporal variability. Spatial and statistical tools were used for data processing, analysis, and presentation. Five interpolation techniques:- Thiessen polygon, spline, isohyetal, inverse distance weighting, and Kriging were considered and their performances were assessed and compared using evaluation criteria. The results indicate that the Isohytal method is slightly better than the other four methods and it is also easy to implement in a geographic information system (GIS) with Geostatic Analysis in ArcGIS. Further, the analysis has shown that the mean annual direct rainfall to Lake Tana is 1313.43 mm with a standard deviation of 259.01. Besides, it has been seen that there is a significant spatial and temporal variability of direct rainfall on Lake Tana. In terms of spatial variability, the Lake gets maximum direct rainfall in its southeastern part with an annual mean value of 1720 mm and a minimum value in its northwest parts with an annual mean value of 860 mm. In terms of Temporal variability, maximum direct rainfall is estimated in July as 374.11 mm in the Summer season and the minimum is less than 12.3 mm depth in December, January, February, and March in Winter.

Abstract Lake Tana is the largest freshwater body in Ethiopia. Currently, the lake has been facing alarming environmental degradation and loss of biodiversity due to the invasion of water hyacinth. Although the weed is invasive, it can be converted into various benefits. Hence, this study was conducted in North Eastern Lake Tana, Sheha Gomengie Kebele. The main objective is compost preparation in terms of its drying periods, analyses, and user perception. Physicochemical and nutrient analyses were performed according to the standard procedures. Acid digestion was used for heavy metal analyses. From the result, the pH measurements ranged from 7.619 ± 0.195 to 7.719 ± 0.261, and the moisture content ranged from 38.712 ± 0.680 to 49.60 ± 9.06%. The mean electrical conductivity (EC) values of all treatments of matured compost ranged from 2.780 ± 0.542 to 3.51 ± 0.971 ds/m. The TN values of the matured compost ranged from 0.420 ± 0.379 to 0.754 ± 0.194 on a dry weight basis. The overall mean values of the C:N ratio for all the treatments were 11.60 which is within an acceptable range. A high amount of available P concentrations was observed in all compost treatments which ranged from 2.740 ± 0.190 to 2.940 ± 1.410 g/kg. Moreover, the concentrations of heavy metals in all treatments were below the permissible limit of different agencies and there was also no significant difference in the mean values of analysis of variance at (P

Lake Tana, the largest lake in Ethiopia, has been severely threatened by water hyacinth infestation over the last decade, especially along the northeastern shore. Since this invasive weed is extremely difficult to eradicate, sustainable management strategies should be put in place to reduce negative impacts on local ecological and socio-economic systems; this requires a better understanding of the population dynamics. In this paper, we review the seasonal change of water hyacinth coverage in Lake Tana and explore its linkages with various environmental factors. During the rainy seasons, increased nutrient concentrations, humidity, and especially water level can promote the formation of extensive water hyacinth mats. In the dry season, diminishing lake water in surrounding floodplains, along with concomitantly increased temperature and solar radiation, may support seed germination and lead to the next life cycle. Currently, water hyacinth mainly occurs in northeastern Lake Tana due to coastal eutrophication, lake topography and westerlies. Expansion of the infested area is slowing down. However, further spread of water hyacinth is still possible in other parts of the lake basin due to changing climate and environmental conditions. Integrated control methods should be put in place in the near future to prevent water hyacinth infestation in Lake Tana, and upstream basin management is vital to reduce nutrients transportation into the lake as a long-term plan. [ABSTRACT FROM AUTHOR]

Lake Tana is the largest freshwater lake in Ethiopia and is the source of the Blue Nile. The lake shorelines and those of its tributary river, Gilgel Abay, are characterized by the occurrence of extensive papyrus swamps (Cyperus papyrus L). While such papyrus swamps are highly recognized for their outstanding ecological and economical importance, their historical and current spatial distribution and size in the Lake Tana sub basin have not yet been systematically assessed. The primary goal of this study was to estimate the spatial distribution and temporal dynamics of papyrus swamps in the Lake Tana sub basin at five-year intervals over a period of 35 years (1985–2020). Our analyses revealed that the total surface area of the papyrus swamps in the study area declined by almost 55% (from 152 km² to 64 km²) during the last 35 years. The small patches of papyrus swamps that existed in the northern and eastern parts of the study area prior to the 1990s appear to have disappeared in recent years as well. Our data suggest that the strong decline of papyrus swamps mainly resulted from the expansion of crop farming, livestock overgrazing, drainage, and biomass overharvesting, all of which are increasing over time. [ABSTRACT FROM AUTHOR]

Temperature and precipitation trend fluctuations influence the components of the hydrological cycle and the availability of water supplies and result shift in the balance of lake water (lake level). Lake Tana is one of the water resources potential providing many services and threatened by human-induced and natural factors in Upper Blue Nile Basin, Ethiopia. So assessing the impacts of climate change on this water resource is a primary activity for water resource managers, researchers, and stakeholders to understand its potential for the water resource. This study was therefore conducted to examine the implications of the influence of climate change on the water balance of Lake Tana (water level) using potential simulated climate production downscaled by a regional CORDEX climate model powered by GCM-RCM ensembles under the Eastern Africa domain CIMP5 archive (AFR44) and RCP scenarios (RCP4.5, and RCP8.5) for future climate data prediction. Quantile mapping has been used to correct temperature biases, and power transformation was applied for rainfall correction. The performance of the HBV model was evaluated through calibration and validation using objective functions (relative volume error (RVE), Nash-Sutcliffe Efficiency (NSE) and provide RVE of 3.7%, -1.27%, 1.05%, -0.72%, 8.9% and -0.68 during calibration and RVE of -1.5%, 6.93%, -3.04%,8.796%, -5.89% and 8.5% during validation for Gumara, Kiltie, Koga, Gilgel Abay, Megech and Rib respectively. While the model provided NS of 0.79, 0.63, 0.72, 0.803, 0.68 and 0.797 during calibration and NSE of 0.8, 0.64, 0.7, 0.82, 0.801 and 0.82 during validation for Gumara, Kiltie, Koga, Gilgel Abay, Megech, and Rib respectively. The simulated Lake level showed adequate agreement to the observed with NS and RVE of 0.7 and 6.44% respectively. The result showed that lake evaporation and rainfall increase for all future scenarios. The ungauged surface inflow is also increased shortly scenarios while gauged surface inflow increased for RCP4.5 (the 2070s) and RCP8.5 (2040s) and decreased for RCP4.5 (2040s) and RCP8.5 (2070s). The decrease in gauged surface water inflow is due to a decrease in inflow for Gilgel Abay, Koga and Gumara gauged catchments. The results showed that the Lake storage will decrease in all future scenarios of all-time horizons. As the study's revealed climate model minimized the level of uncertainty, especially with the use of more RCMs than GCMs, future studies should therefore use more than one regional climate model and also use fine resolution data like (CMIP 6). [ABSTRACT FROM AUTHOR]

The colonization of freshwater lakes by invasive alien species is increasingly alarming primarily owing to nutrient loads from the watersheds. For the sustainable management of invasive weeds, preventive methods, such as watershed management and sustainable agricultural practices, are recommended. Watershed protection activities by the upstream local community are believed to be effective measures to reduce nutrient loading to the receiving water bodies and hence help prevent the spread of water hyacinth. However, their willingness and potential contributions determine the effectiveness of watershed management activities. The objective of this study is, therefore, to evaluate the preferences and contributions (willingness to pay and willingness to contribute labor) of the local community for the management of water hyacinth in Lake Tana (Ethiopia). A contingent valuation method for a hypothetical market "prevention of water hyacinth infestation of Lake Tana through watershed management program" was used to collect data from 560 randomly selected households. A multivariable interval regression model was used to identify factors affecting the contribution of local people. The mean yearly willingness to pay and to contribute labor of the respondents was 435.4 Ethiopian Birr (US$ 10) and 22.4 man-days, respectively. The place of residence (rural/urban), educational level, private farm plot area, annual income, and water hyacinth-related conference participation significantly influenced the willingness to pay. Similarly, the willingness to contribute labor was strongly associated with place of residence, location, educational level, and household family size. The economic value derived from this study reflects community preferences, which could be an input for informed and evidence-based decision-making regarding the prevention of weed expansion and sustainable use of ecosystem services. Therefore, local, regional, and national authorities are advised to mobilize the local community to contribute labor and/or money so as to halt the expansion of the weed. [ABSTRACT FROM AUTHOR]

This document is a corrigendum for an article titled "Advancing non-optical water quality monitoring in Lake Tana, Ethiopia: insights from machine learning and remote sensing techniques." The corrigendum addresses errors in Figure 9 and Figure 10 of the published article, where the captions did not correctly describe the part labels. The authors apologize for the error and state that it does not change the scientific conclusions of the article. The original article has been updated. [Extracted from the article]

Excess sediment and nutrient losses from intensifying agriculture degrade water quality and boost plant growth. The relationship between circulation patterns, spatial water quality degradation, and water hyacinth infestation is not adequately studied. The objective of this study is, therefore, to investigate the effect of lake circulation patterns on sediment and nutrient distribution and its implication on the spread of water hyacinth in a tropical lake. This study was carried out in Lake Tana, the largest freshwater lake in Ethiopia, where sediment and nutrient concentrations are increasing, and water hyacinths have become a challenge since 2011. The lake circulation pattern was simulated by the Delft3D model based on a bathymetry survey, discharge, and meteorological forcings. To predict the transport path of sediments and dissolved nutrients, an inert tracer was released in the four main river inlets of the lake. Observed lake water level measurements were used to validate the model. Our results show that the lake circulation pattern could explain the transport path of sediment and nutrients and the location of the water hyacinths found in the northeast of the lake. Sediments and nutrients from the largest river, Gilgel Abay, in the southeast of Lake Tana, flow through the two outlets nearby with little sediment deposition due to the relatively short retention time. The phosphorus-rich sediments of the 24 h at 105 °C remaining three main rivers joining the lake at the north and east are transported to the northeast. Thus, the management and control of water hyacinths should focus on the northern and eastern catchment areas of Lake Tana.

AbstractRural households in Ethiopia are characterized by subsistence agriculture, while empirical evidence reveals that rural livelihoods are limited. The aim of this study was to assess the rural livelihoods diversification with evidence of households surrounding Lake Tana. Data was collected using a survey from 413 households. The results of the study revealed that the mean overall asset score of the households was 0.313. Crop production, livestock rearing and employment were the major livelihood strategies. The households practiced a mean of three livelihood strategies, and the evenness score of the households was 0.18 referring to the dominance of small livelihood strategies. The mean annual income of the households was 26,696 ETB which was found to have a strong positive correlation with the asset possession of the households (r = 0.56). In addition, the Simpson diversification index result showed that 46.3%, 43.8% and 9.9% of households were low, medium and high-income diversifiers, respectively. Diversification groups have shown a significant difference in asset holdings but not in the income of the households. Moreover, significant variations were observed between Tana Zuria Rice and Tana Zuria livelihood zone households in asset, number of strategies, income and diversification status. The study concludes that the asset ownership of the households is limited. Development of rural livelihood assets is recommended to improve rural livelihoods and, as a result, household income.

Lake Tana is one of the largest freshwater bodies in East Africa, with its 18 Labeobarbus species being the world's last remaining Cyprinid species flock. Many of them feed and grow in Lake Tana and migrate to the tributaries of the lake to reproduce. The construction of irrigation structures is increasing in the tributary rivers, however, without due attention being given to the spawning migration routes and critical spawning habitats. The present study examined the impacts of the Gilgel Abay Weir on the spawning migration of these species and discusses possible interactions with other human‐related impacts and potential mitigation measures. Fish samples were taken twice monthly from July to November 2019, both below and above the weir with gillnets. No spawning migration to the upstream of the weir has occurred since its construction, with the weir being a barrier to their spawning migration route of Lake Tana fisheries. Of the 11 species caught, only Labeobarbus intermedius (a habitat generalist) was observed above the weir, with the species diversity being significantly higher below the weir (p < 0.05) than above it. The total number of species observed during the present study was also lower, compared with previous reports. The fisheries impacts may also have been exacerbated by other contributing factors such as habitat destruction, river system degradation, destructive fishing practices and weed infestation, a situation which may lead to the collapse of Lake Tana fisheries and ultimately the lake's ecology. Reversing this situation is crucial, noting the implementation of such measures as habitat restoration and improvement, replacing the weir with environmentally friendly technologies, prohibition of illegal fishing, and construction of fish ladders could definitely alleviate the observed negative impacts of the Gilgel Abay Weir on the fisheries. [ABSTRACT FROM AUTHOR]

The Blue Nile's source, Lake Tana, is the biggest lake in Ethiopia and offers multiple services to local, regional, and international communities. The first step to effectively, efficiently, and sustainably utilizing the services that the lake may provide is to understand its water balance using accurate estimations of its water balance parameters, including direct rainfall. Direct rainfall to Lake Tana is one of the most important water balance terms of the Lake that needs a precise estimate. This study tries to analyze the spatial and temporal variability of direct rainfall to the Lake and estimate the mean annual and mean monthly direct rainfall amount to the lake using sufficient data and appropriate methodologies. 30 years (1986–2015) monthly and mean annual data from 13 meteorological stations were collected and used to analyses the spatial and temporal variability. Spatial and statistical tools were used for data processing, analysis, and presentation. Five interpolation techniques:- Thiessen polygon, spline, isohyetal, inverse distance weighting, and Kriging were considered and their performances were assessed and compared using evaluation criteria. The results indicate that the Isohytal method is slightly better than the other four methods and it is also easy to implement in a geographic information system (GIS) with Geostatic Analysis in ArcGIS. Further, the analysis has shown that the mean annual direct rainfall to Lake Tana is 1313.43 mm with a standard deviation of 259.01. Besides, it has been seen that there is a significant spatial and temporal variability of direct rainfall on Lake Tana. In terms of spatial variability, the Lake gets maximum direct rainfall in its southeastern part with an annual mean value of 1720 mm and a minimum value in its northwest parts with an annual mean value of 860 mm. In terms of Temporal variability, maximum direct rainfall is estimated in July as 374.11 mm in the Summer season and the minimum is less than 12.3 mm depth in December, January, February, and March in Winter. [ABSTRACT FROM AUTHOR]

Lake Tana is one of the biosphere reserves in Ethiopia registered by the United Nations Educational, Scientific, and Cultural Organization (UNESCO). Water hyacinth is expanding in the lake owing to increased nutrient load from the watershed. As efforts from the government alone could not bring the anticipated change, local peoples’ engagement and contribution are believed to sustainably and effectively manage the watershed and prevent the weed’s spreading. This study, therefore, aims to estimate households’ contribution (willingness to pay–WTP–and willingness to contribute labor–WTCL–) to prevent and control water hyacinth and hence improve lake ecosystem services through a hypothetical watershed management in Lake Tana. This study applied quantitative and qualitative methods. It was conducted among 560 randomly selected households of the Libo-kemkem district using a contingent valuation method from March to April/2021. Eleven key informant interviews were also conducted. Bivariable and multivariable interval regression models were used to identify the determinants of households’ potential contribution. Thematic analysis was used to analyze the qualitative data. As the weed is believed negatively impact the ecosystem services provided by the lake, 72% of the respondents showed willingness to contribute to the proposed management program. About 32 and 39% of the respondents were willing to pay in cash and to contribute labor, respectively, to prevent weed infestation. On the other hand, 28% of them were neither willing to contribute in cash nor in labor to the hypothetical market. The findings showed respondents’ mean annual WTP and WTCL were 632.8 Ethiopian birr and 30.1 man-days per household, respectively. The place of residence, educational status, farm plot area, household income, family size, and conference participation significantly influenced WTP and/or WTCL. In this hypothetical improvement scenario, an estimated annual WTP and WTCL of nearly 12 million Ethiopian birr and 700 man-days per year, respectively, are reported considering the total households in the study area. Therefore, collaborative efforts by different stakeholders are the next steps to realize the hypothetical contributions.

Lake Tana is the largest freshwater body in Ethiopia. Currently, the lake has been facing alarming environmental degradation and loss of biodiversity due to the invasion of water hyacinth. Although the weed is invasive, it can be converted into various benefits. Hence, this study was conducted in North Eastern Lake Tana, Sheha Gomengie Kebele. The main objective is compost preparation in terms of its drying periods, analyses, and user perception. Physicochemical and nutrient analyses were performed according to the standard procedures. Acid digestion was used for heavy metal analyses. From the result, the pH measurements ranged from 7.619 ± 0.195 to 7.719 ± 0.261, and the moisture content ranged from 38.712 ± 0.680 to 49.60 ± 9.06%. The mean electrical conductivity (EC) values of all treatments of matured compost ranged from 2.780 ± 0.542 to 3.51 ± 0.971 ds/m. The TN values of the matured compost ranged from 0.420 ± 0.379 to 0.754 ± 0.194 on a dry weight basis. The overall mean values of the C:N ratio for all the treatments were 11.60 which is within an acceptable range. A high amount of available P concentrations was observed in all compost treatments which ranged from 2.740 ± 0.190 to 2.940 ± 1.410 g/kg. Moreover, the concentrations of heavy metals in all treatments were below the permissible limit of different agencies and there was also no significant difference in the mean values of analysis of variance at (P < 0.05). Therefore, the prepared compost can be recommended for better agricultural purposes. Considering users' understanding of compost preparation as an opportunity, converting WH into compost is promising in terms of its rich supply and the possibility of preparing in the dry season where labor is abundant. Therefore, it can be one way of sustainably reducing WH adverse effects on the Lakeshore. [ABSTRACT FROM AUTHOR]

Despite the fact that rice was only recently brought to Ethiopia, the Ethiopian government has dubbed it the "millennium crop" because of its importance as a food security crop, as well as a source of revenue and job possibilities. Rice production is being practiced on wetland areas and floodplains; however, no attention has been given to the sustainability of these wetlands, or to the integration of different previous indigenous activities, such as livestock rearing and farming of different crops in the area. This study aims to investigate the impact of rice expansion on traditional wetland management in the Fogera floodplain wetlands of the Lake Tana basin. Data were generated via interviews and the application of GIS and remote sensing. The survey questionnaire was administered to 385 rice-producing farmers. The respondents (87%) confirmed that increases in the price of rice encouraged them to shift from the cultivation of conventional crops to rice farming. Subsequently, between the years 1973 and 2014, wetland areas have been reduced from 3114 ha to 1060 ha, accompanied by a high rate of expansion in rice production in the area. Major activities being pursued in the wetlands of the study area do not consider environmental impacts. As a result, the diverse ecosystem services available in the past have been compromised through time. Sense of ownership of wetland resources and their benefit shall be communicated to reduce abusive utilization. Therefore, the policies, strategies, and development activities implementation need to consider environmental issues in rice production enhancement endeavors. [ABSTRACT FROM AUTHOR]

Monitoring the dynamics of land use land cover (LULC) is crucial for the sustainable use of natural resources. This study was intended to analyze the impact of water hyacinth on LULC on Lake Tana, Ethiopia. Satellite images and key informants interview (KII) were sources of the data. Satellite images were captured in October 2010 and 2019 from USGS, and KIIs were conducted with officials and local leaders. Maximum likelihood classification and post-classification were used to analyze the data, and ArcGIS 10.4, Envi 5.3, QGIS 3.12.1 plug in CSP and Excel were tools of data analysis. Spectral separability analysis of endmember files showed that clear windows to separate water hyacinth from other LULC classes were Band 7 VRE, Band 8 NIR and Band 8a Narrow NIR for Sentinel 2 images. The overall classification accuracies of classified images were found to be 95.84% to 98.91%, while the kappa value ranged from 0.93 to 0.97. The land-use land-cover change (LULCC) analysis displayed important changes in the study area. The water hyacinth proliferated from zero in 2010 to 1360.78 ha in 2019 at the expense of water, agricultural land, bare land and other vegetation. The general LULCC of the area from 2010 to 2019 revealed the expansion of water hyacinth, other vegetation and forest with annual rate of 136.08, 312.09 and 58.01 ha, respectively. On the other hand, reduction of area coverage was recorded in agricultural land (115.54 ha/year), water (154.82 ha/year) and bare land (235.8 ha/year). The study concludes that significant LULCC is caused by the water hyacinth, while a continuous assessment of the weed and restoration of healthy the LULC in the lake and surrounding areas is recommended. [ABSTRACT FROM AUTHOR]

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.

Labeobarbus brevicephalus is one of the 17 endemic migratory large African barb species making up a species flock in Lake Tana (Ethiopia). The multiple constructions of dams and irrigation weirs on the tributary rivers of Lake Tana have become detrimental to the upstream spawning migration of these fishes. Considering worst-case scenarios of obstruction of all-natural migratory routes, artificial spawning emulation structures were designed and developed at the Bahir Dar Fisheries and Other Aquatic Life Research Center (BFALRC) to emulate the upstream spawning migration routes and habitats. A pond was constructed to emulate the lake and a canal was connected to the pond emulating tributary rivers. The setups were to enable the fishes to migrate out of the pond and spawn at the upper area (pool) of the canal. At the upstream of the canal, gravel beds were prepared on which the L. brevicephalus could spawn. Running (ready for spawning (stage 5)) male and female L. brevicephalus were placed in the pond. After a day long-acclimatization period lake water was pumped into the canal at a discharge rate of 250–1000 liters/min. Stimulated by the flow, 86 male and 24 female L. brevicephalus moved out of the pond migrated to the upper part of the canal made 16 spawning on the gravel beds, and returned to the pond. The fertilized oocytes (zygotes) were collected and it was possible to hatch them in aquariums in the laboratory.