Lake Hawassa Research Articles

Investigating the nexus of urban expansion, wetlands, and livelihoods from 1991 to 2021: evidence from Hawassa, Ethiopia

ABSTRACT Urban expansion in Ethiopia, particularly informal construction, has led to complex and dynamic changes in livelihoods and wetlands. This study examined the effects of urban expansion on the Cheleleka Wetland and the livelihood of the peripheral community in Hawassa. A mixed research design was used to quantitatively analyze Landsat imagery (1991, 2001, 2011, 2021) and socioeconomic data. Key informant interviews and focus group discussion data were narrated qualitatively. The built-up area substantially increased from 718.11 ha in 1991 to 4820.71 ha in 2021. However, agricultural and wetland areas decreased from 8807.58 ha and 8177.04 ha in 1991 to 6382.44 ha and 7030.26 ha in 2021, respectively. Water and forest areas fluctuated. Built-up areas had a significant advantage over other land use and cover classes, with agricultural, wetland, and forest areas being converted into built-up areas throughout the study period. As a result, the area of Lake Hawassa expanded. Currently, the Cheleleka Wetland has been negatively impaired by overgrazing, cutting of grass, animal dung dumps, eucalyptus plantations, agricultural expansion, and urban expansion. Urban expansion has exacerbated social and economic divisions, resulting in the concentration of poor-quality neighborhoods in the peripheral community. To protect the wetlands, alternative livelihoods and participatory land-use planning are crucial.

Correction to “Object‐Based Image Analysis (OBIA)‐based gully erosion dynamics, sediment loading rate and sediment yield study in Lake Hawassa Subbasin, Ethiopia”

Correction to “Object‐Based Image Analysis (OBIA)‐based gully erosion dynamics, sediment loading rate and sediment yield study in Lake Hawassa Subbasin, Ethiopia”

Ecosystem services provision through nature-based solutions: A sustainable development pathway to environmental stewardship as evidenced in the Protecting Lake Hawassa Partnership in Ethiopia

Ecosystem services provision through nature-based solutions: A sustainable development pathway to environmental stewardship as evidenced in the Protecting Lake Hawassa Partnership in Ethiopia

Occurrence of microplastics in commercial fish species from the Ethiopian rift valley's Lake Hawassa, Ethiopia.

Microplastics (MPs) have recently been detected as emergent pollutants in the Ethiopian rift valley lakes located close to rapidly expanding towns. We provide the first study of MPs ingestion of commercial fish species from Lake Hawassa, Ethiopia: Catfish (Clarias gariepinus) and Nile Tilapia (Oreochromis niloticus). A total of 60 individual fish species was collected from three sampling sites of lake Hawassa in October 2020. Across all sampling sites, there was a significant difference in ingested MPs between benthic omnivore catfish and pelagic phytoplanktivorous Tilapia (χ2 = 15.864, p < 0.001). The most common size of ingested MPs (84.6%) was 0.5-1mm, with fragments (59.5%) dominating, followed by fibers (25.4%). On average, 4.03 ± 1.33 MPs with sizes ranging between 60μm and 10.53mm were detected per individual. White and yellow MPs were particularly numerous, accounting for 36.8% and 26.4% of the total, respectively. Because Lake Hawassa's fishery is so significant, the potential impact of MP pollution on the lake biota in general, and economically valuable fish species in particular, deserves attention, additional research, and, if possible, early mitigation.

Hybridization of deep learning, nonlinear system identification and ensemble tree intelligence algorithms for pan evaporation estimation

A reliable pan evaporation (Epan) estimation over a daily scale is vital for sustainable water and agriculture management, especially for designing water use allocations, irrigation system management, and demand and utilization assessments. However, designing a reliable computational methodology is a challenging task for Epan estimation due to its stochastic and random characteristics. In this study, the potential of five machine learning (ML) models namely Hammerstein-Weiner (HW), Random Forest (RF), Boosted Regression Tree (BRT), Long Short-Term Memory (LSTM), and Stepwise Linear Regression (SWLR) models were evaluated for Epan modeling in Lake Hawassa catchment, Ethiopia. Afterward, hybrid SWLR-LSTM, SWLR-RF, SWLR-BRT, and SWLR-HW models were developed to benefit from the strength of the non-linear and linear characteristics of the models. The estimation results were evaluated using determination coefficient (R2), Nash-Sutcliffe efficiency (NSE), mean absolute error (MAE) and Root Mean Square Error (RMSE), Index of Agreement (IA) and Kling-Gupta efficiency (KGE). The performance analysis result of individual models showed that the RF model led to more accurate estimation with NSE = 0.938, IA = 0.956, R2 = 0.94, KGE = 0.852, RMSE = 0.483 mm/day and Pbias = -1.193 mm/day during the validation phase. Among the hybrid models, SWLR-RF provides the best predictive performance improving SWLR, HW, LSTM, BRT and RF by 26.563 %, 21.348 %, 15.577 %, 9.091 % and 3.514 %, respectively based on the validation phase NSE value. Generally, the results of the current study demonstrated the capability of deep learning, ensemble tree and hybrid linear-nonlinear models for Epan estimation in the data-scarce catchment.

The impact of Ethiopian Green Legacy Initiative (GLI) on landscape functionality and plant species diversity in Lake Hawassa watershed, Ethiopia

AbstractAs one of the responses to the global commitments against climate change, the Ethiopian Government launched a nationwide Green Legacy Initiative (GLI) in 2019, which largely focused on forest tree plantations with some inclusion of fruit trees. Despite its tremendous efforts and investments, its effectiveness and impacts have not been studied. This paper attempted to address this necessity by conducting a cross‐sectional quasi‐experiment in three randomly selected woredas/districts of Lake Hawassa Watershed from August 20 to September 2, 2023. The research hypothesized the likely impacts of GLI on four dependent variables (hydrological regulation, soil stability, nutrient cycling and plant species diversity). To achieve this, the research considered the two variants of GLI practices (plantation with and without soil and water conservation measures) and the corresponding control sites. Having three sites and three treatments with five replications, the study involved a total of forty‐five quadrats of the same size (20 m × 20 m). The first three parameters were analysed using the landscape functionality analysis method, while the fourth employed Shannon's diversity index. Results of ANOVA showed that, on average 87% of randomly selected quadrats were found to significantly improve the local hydrology (runoff potential) (≈ 83.3% with Av. p = 0.012), soil stability (≈100% with Av. p = 0.002), nutrient cycling (≈83.3% with Av. p = 0.017) and plant species diversity (≈83.3% with Av. p = 0.012). The research revealed positive results from the Ethiopian Green Legacy Initiative. The small number of samples is acknowledged as a limitation of the research.

Sensitivity analysis on stormwater management response to land cover dynamics and urban expansion of developing City in Lake Hawassa watershed, Ethiopia

AbstractHawassa is a rapidly developing city in Lake Hawassa watershed of Ethiopia. Analyzing the effect of land cover dynamics on surface runoff remains imperative to adaptive urban stormwater management. This study quantified spatial variation of land cover and sensitivity of stormwater management response. Historical 30 years of daily annual rainfall, three satellite imageries, DEM, and hydrological soil group data were analyzed. A statistical‐based combined approach of geospatial techniques and Soil Conservation Service‐Curve Number (SCS‐CN) model was employed. CN and surface runoff depth for the delineated urban watersheds were determined. The result revealed that the built‐up area increased by 30.9 km2, where the rate varies spatially. The variation of impervious land cover explains 58.6% of change in CN with coefficient of 0.352. While CN is inversely correlated with agricultural and vegetation land cover variations. The finding suggests CN explains 96.78% of the change in surface runoff with a significant correlation coefficient of 3.91. The proposed integrated model approach justifies the potential to reorganize the relationship between the spatial effect of land cover variation on surface runoff at the urban watersheds. Thus, suitable local‐specific solutions can be devised for effective management of flood risk and optimize the drainage system of urban areas.

Organochlorine, organophosphorus, and carbamate pesticide residues in an Ethiopian Rift Valley Lake Hawassa: occurrences and possible ecological risks.

Currently, pesticide production and use are on the rise globally. This trend is certain to continue in the coming decades with residues posing risks to the environment and human health even at low levels. Although various aspects of pesticides and their possible implications have widely been studied, such studies have mostly been carried out in developed countries leaving the rest of the world with little scientific information. We present here the results of a study on the occurrences, concentrations, and ecological risks of 30 pesticide residues (PRs) in water and sediment samples from a tropical freshwater Lake Hawassa in the Ethiopian Rift Valley. A total of 54 composite samples of water and sediment were collected from three sampling sites on three occasions. The samples were prepared by quick, easy, cheap, effective, rugged, and safe (QuEChERS) technique, and analyzed using GC-MS at Bless Agri Food Laboratory Service located in Addis Ababa, Ethiopia. The study applied the risk quotient (RQ) method to scrutinize the risks posed to aquatic biota by the detected PRs. The results showed occurrences of 18 and 20 PRs in the water and sediment samples, respectively. The majority, 78 and 75% of the detected PRs in water and sediment samples, respectively represent the organochlorine chemical class. Concentrations of heptachlor epoxide were significantly (p ≤ 0.001) higher than those of the remaining pesticides in both matrices. Of the pesticides detected, 77% were present in water and 83% in sediment samples and pose a serious risk (RQ ≥ 1) to the Lake Hawassa biota. This calls for further research to investigate the risks to human health posed by the PRs. The findings of this study can contribute to the development of global protocols, as they support the concerns raised about the ecological and public health impacts of PRs on a global level.

Integrated assessment and mapping of provisioning services for sustainable management of natural resources, the case of Lake Hawassa Basin, Ethiopia

Lake Hawassa Basin (LHB)-the study area is known for its rich and diverse aquatic and terrestrial natural resource base. However, the prevailing environmental and social problems, such as land degradation, deforestation, pollution, resource exploitation, etc. impacted the existing provisioning services (PS), and the effect becomes remarkable unless sound management is in place. The study aimed at the assessment and mapping of PS to suggest development options for decision-makers. The study employed various methods including primary and secondary data collection, including existing Land Use Land Cover (LULC), desk review, stakeholder consultations, site visits, expert judgment matrix, and ArcGIS v10.1. The study results include 6 PS identified and prioritized from the existing 14 PS, mapping of the spatial pattern of the selected 6 PS at the basin scale, and alternative development options recommended for the decision-making process conducted by decision-makers and development partners to ensure efficient management of ecosystem services in LHB. The importance of this study, as well as the simplicity and user-friendly nature of the methods and approach adopted, enables interested parties to replicate while conducting similar studies in different places within the country or globally. The intervention of adopting this study approach helps also to avoid or minimize the aforesaid biophysical and socioeconomic environmental problems and ensure development activities planned or implemented in the respective study area are environmentally friendly, and socially acceptable, through sustainable management of natural resources. In this regard, decision-makers and development partners shall provide adequate consideration for this study approach and the result of demonstrating basin scale spatial variability of PS. This plays a vital role in the sustainable management of natural resources as well as provisioning services existing in the study area to benefit the community members, ensure human well-being, and secure the livelihood of the people residing within or around the Lake Hawassa Basin.

Isolation and characterisation of potential bacterialpathogens from Oreochromis niloticus (Linnaeus, 1758) of Lake Hawassa, Ethiopia

The aim of the current study was to isolate and identify potential bacterial pathogens from Nile tilapia, Oreochromis niloticus (Linnaeus, 1758) in Lake Hawassa, Ethiopia. The study was conducted during January to December 2021. A total of 360 Nile tilapia were sampledfrom Lake Hawassa and subjected to bacteriological investigations. The results showed 64.2% prevalence of bacterial infection in Nile tilapia from the lake. Potential bacterial pathogens such as Aeromonas hydrophila, Escherichia coli, Edwardsiella tarda, Vibrio sp,,Bacillus sp., Staphylococcus sp., Salmonella sp., Flavobacterum sp., Pseudomonas sp. and Shigella sp. were isolated. The prevalence of infection in female fish (52.4%) was higher compared to male fish (47.6%). Comparatively higher prevalence was recorded in thesmaller fish group than in the larger ones. The average bacterial loads recorded in various organs such as intestine, skin, gill, liver and kidney were, 4.86±0.56 x 105, 4.72±0.48 x 105, 4.14±0.53 x 105, 3.45±0.23 x 105 and 2.63±0.324 x 105 CFU ml-1 respectively. Significantly high bacterial loads were recorded from the intestine (5.81±0.01 x 105 CFU ml-1) of fishduring the summer season (p&lt;0.05). The results of the study indicated that there is a risk of occurrence of disease outbreak under stressful situations. Moreover, the recovery of these bacteria in the fish which are potentially pathogenic to humans, suggests that if the fish are improperly handled, undercooked or consumed raw, may cause diseases to susceptible individuals. Keywords:Bacterial pathogens, Lake Hawassa, Oriochromis niloticus, Prevalence

Awareness and Disposal Practices of Medicines among the Community in Hawassa City, Ethiopia

Despite the enormous benefits medicines provide to humanity, their improper disposal frequently leads to detrimental consequences on the environment. Lack of awareness and malpractices concerning expired, leftover, or unused (ELU) medicines have become concerns worldwide. This study assessed community awareness and practices regarding the disposal of ELU medicines in Hawassa City, Ethiopia. A community-based descriptive cross-sectional survey design was used among the urban population of Hawassa City. Multistage sampling procedures were employed to select 405 household (HH) respondents, and purposive sampling techniques were used to select key experts (KEs) and key informants (KIs). A pretested questionnaire was designed for HHs, KEs, and KIs. The results of the study showed that analgesics and antibiotics, used in 52 and 27% of the HHs, respectively, were the most commonly consumed medicines in this city. The vast majority (95.5%) of the HHs did not store expired medicines but disposed of them. Only 10% of the HHs were well informed on how to dispose of ELU medicines. Most (70%) KEs and KIs revealed that there were no awareness-creation mechanisms for the safe disposal of ELU medicines. A significantly high p &lt; 0.05 percentage (76%) of the HH respondents who were well informed on how to dispose of ELU medicines had higher education, but most (95%) of them indicated that they would not be willing to be involved in “ELU-take-back” programs even if there had been such a mechanism. Field observations confirm significant amounts of medical waste improperly discarded in various areas, including the shores of Lake Hawassa near Hawassa City. The study has shown that awareness of the management of ELU medicines is critically lacking in the community of Hawassa City, posing environmental and human health risks. Moreover, the majority of households practice unsafe disposal of ELU medicines, leading to human health threats and environmental risk.

Assessment of Length-weight Relationship, Sex Ratio, Condition Factor and Socioeconomic Values of Nile tilapia in Lake Hawassa

The length – weight relationship, condition factor and sex ratio in Lake Hawassa were evaluated over a period of seven weeks from May to June 2019. The growth coefficient ‘b’ obtained for male, female and combined sexes were 3.17, 3.17 and 3.19 respectively. The ‘b’ value differed significantly (p&lt;0.05) from the value of ‘3’ for all the male, female and combined sexes, indicating a positive allometric growth. The condition factors ‘K’ for male, female and combined sex were 0.97, 1 and 0.94 respectively. There was a significant difference in condition factor between the male, female and combined sexes (ANOVA, p&lt; 0.001). The sex ratio of male and female O. niloticus significantly different (χ2 = 5.78, p&lt; 0.05) from the expected 1:1 ratio. The study conducted to reveal the potential of Nile tilapia to produce fishmeal showed that at least 15.12% of Nile tilapia fish which otherwise would have been discarded as a waste product have the potential to become a fishmeal, such that Lake Hawassa has the potential to produce 27.66 tons of fish meal from annual catch of 182.94 tons of Nile tilapia. The impact of socioeconomic values of Nile tilapia both on fishermen and consumers have been shown as the livelihood of 88% of the fishermen respondents is based on fishery activity with no other source of income with nearly two thirds of the respondents have a monthly income between 1000 to 2000 birr and annual median income of 18,000 birr. This study also revealed that 90% of the fishermen respondents have been given awareness or training that improves their fishing practices. More than three quarter of the fishermen agreed that the long distance of fish markets from residential areas have reduced the accessibility of the fish resource to the consumers. And also there is strong statistical evidence that supports unhygienic fish processing practices contributed more to the problems and constraints of the socioeconomic values of Nile tilapia. On the other hand consumers’ spending capacity depends on their monthly income and also consumers’ consumption habit depends on factors like the cost of fish, proximity of the fish market and buying power. Further research needs to be undertaken to address some of the problems facing the fishery activity such as lack of proper fish processing, storage and marketing facilities.

Social and political contexts of religious conversion in Sidaama, Ethiopia, 1891-1974

This article discusses religious conversion in Sidaama, Ethiopia, 1891-1974. The Sidaama area is in Southern Ethiopia, southeast of Lake Hawassa and northeast of Lake Abaya in the Rift Valley of Ethiopia. Most of the population belongs to the ethnic group Sidaama, speakers of the Cushitic language Sidaamu Afoo. The region became incorporated into the Ethiopian Empire during the twentieth century. The article will first provide a historical overview of religious change in the area. Next, the paper will present theoretical approaches to religious conversion. The article's main content focuses on the interreligious encounter between the indigenous Sidaama religion and varieties of christianity. The paper will discuss how the interreligious encounter initiated a process of conversion to Christianity. The conversion process occurred at the intersection between indigenous Sidaama converts and various forms of Christianity and was influenced by internal social tensions and inequalities in Sidaama.

Ecohydrological nature-based solution for climate resilience and biodiversity enhancement in water-limited ecosystem: Perspectives and proof of concepts

Following the declaration of the UN Decade on Ecosystem Restoration, nature-based solutions (NbS) are at the forefront of the sustainability discourse. However, this solution needs operational clarity to avoid the commonly mentioned vagueness of the concept. This paper highlighted application of the ecohydrological principles to guide the conception, planning, designing, implementation, and monitoring of nature-based solutions. The paper proposed an ecohydrological nature-based solution that is emanated from the natural sequence of self-regulating patch-interpatch at the hillslope scale to restore highly degraded hillslope in Lake Hawassa sub-basin of Ethiopian Rift Valley Basin. The active restoration site is found to have a landscape organization index value of 0.94 (= 94% of the gradsect is consisting of resources conserving patches) as compared to 0.16 at the passive site. In terms of landscape functionality, the active site showed significant stability (p(x≤T) = 0.01), infiltration (p(x≤T) = 0.001), and nutrient cycling (p(x≤T)=0.005). It also exhibited significant improvement in soil moisture (p(x≤T) = 0.001). Ecologically, the active site is found to be more diverse (richness index 18 (active) vs. 8 (passive); heterogeneous (Shannon diversity index=1.22 (active) vs. 0.44 (passive)); well distributed (Simpson's index= 0.62 (active) vs. 0.28 (passive)); less dominance of few species (Evenness index (0.99 (passive) vs. 0.96 (active)). Limitation of this study is linked with the short span of the restoration period which tends to be not adequate to observe the full ‘dual’ regulation between hydrology and biota. For this, the research can be considered as a prerequisite towards full restoration of the landscape.

Development of macroinvertebrate based multimetric index for ecological health monitoring in Lake Hawassa, Ethiopia

Little information is available on the use and applicability of biotic indices in aquatic resource conservation and management in Eastern Africa, especially in lentic ecosystems. The aim of this study was to develop a macroinvertebrate multimetric index (MMIH) to assess the ecological condition of Lake Hawassa. Sampling sites were clustered based on percentage disturbance score (PDS) and categorized into minimally (three sites), moderately (three sites) and highly disturbed (three sites). Physicochemical and invertebrate sampling was done at these clustered sites along the lakeshore area from February to November 2015 and 2016. Out of a total of 35 macroinvertebrate candidate metrics, ten core metrics were selected based on redundancy analysis, metrics response to environmental parameters, percent discriminatory efficiency (%DE) and box and whisker plots, and incorporated in the development of MMIH. The developed MMIH index performed well and showed a clear demarcation between the reference and non-reference sites and between the three-disturbance levels. The validation of the MMIH index performed well in discriminating the independent data sets taken from Lake Hawassa and L. Ziway. Besides, it also showed a strong but inverse relation with PDS (R2 = 0.91, P = 0.0003). Hence, in a lentic ecosystem, this index should be considered as a starting point in terms of lake bio-assessment in Ethiopia, but additional data in all ecoregions of the country are necessary to determine the long-term reliability and usefulness of the MMIH. In the short-term, this index will provide resource managers and aquatic environmentalists with a tool to assess the ecological condition of freshwater lakes.

Evaluation of a multi-staged bias correction approach on CHIRP and CHIRPS rainfall product: a case study of the Lake Hawassa watershed

Abstract A promising future development area to improve the accuracy of satellite rainfall estimates (SREs) is accessing merits from different sources of data through combining algorithms. The main objective of this study is to assess the accuracy and importance of the fused multistage approach of bias correction. Accordingly, two versions of resampled and spatially bias-corrected Climate Hazards Group Infrared Precipitation (CHIRP) estimates were merged with ground measurements using a conditional merging procedure. Results of applied performance measures (i.e. seven) on corrected and merged CHIRP SREs show that the Percent of Detection (POD) and Percent Volume Error (PVE) have improved. Depending on the combination of coupled stations for validation, up to 70 and 50% PVE improvement was achieved at some stations for wet and dry periods, respectively. Moreover, the bias-corrected and conditionally merged CHIRP SREs have outperformed the estimates by resampling CHIRP with station dataset (CHIRPS) over the sparsely populated western part of the watershed. However, the devised method was limited in considering dry-day events during bias correction, which in turn has affected the performance of the bias correction of the CHIRPS product. Finally, future research should concentrate on such methods of fusing to understand the benefits of various approaches and produce more precise rainfall records.

Integrated use of GIS, RS and USLE model for LULC change analysis and soil erosion risk mapping in the Lake Hawassa Watershed, Southern Ethiopia

Soil erosion is a worldwide problem leading to loss of nutrient rich top soil resulting in reduction of agricultural productivity that threatens the livelihood of agrarian societies. Assessment of soil loss due to water-induced erosion using Models is essential to quantify and map erosion prone areas for possible application of soil conservation measures. In the current study, GIS, RS, and USLE model were integrated with the aim to quantify LULC classes, estimate soil loss rates, and identify priority areas for conservation in the Lake Hawassa Watershed for the two temporal instants, 1975 and 2020. The use of thematic recoding and model maker during LULC classification process has improved the accuracy of thematic classes, producing more than 89% for both classified images. The LULC change analysis showed that agricultural land and built-up area expanded by 0.44% and 15.26% per annum, respectively over the last 45 years. The declines in vegetation cover coupled with steep slopes have contributed to the increase in soil loss from 1975 to 2020 by 65%. The model estimated annual soil erosion rate in 1975 that ranged from nil to 158.77 t ha−1 yr−1 with a mean annual soil loss rate of 25.16 t ha−1 yr−1. Likewise, the annual soil loss estimated for the year 2020 varied from zero to 262.48 t ha−1 yr−1 with a mean annual soil loss rate of 28.20 t ha−1 yr−1. Generally, a total of 23,580.59 and 27,783.35 tons of soil have been lost per annum for the year 1975 and 2020, respectively, which is a direct reflection of vegetation clearance. The identified highest three severity classes combined accounted for 50.54% in 1975 and 55.40% of the entire soil loss in 2020 and these losses occurred on areas less than 2% in both 1975 and 2020 periods. Besides, 23.48% and 31.04% of soil loss rates exceeded the established tolerable limit of soil loss for the study area. The integrated use of USLE model, GIS and RS have identified erosion risk areas that could help apply conservation measures.

Integrated modelling techniques to implication of demographic change and urban expansion dynamics on water demand management of developing city in Lake Hawassa Watershed, Ethiopia

Hawassa is a rapidly developing city in the Lake Hawassa watershed of Ethiopia that is a continuous change in the face of an urban environment. The urban development has been increasing the challenge to maintain urban services and surrounding environmental quality. These exert a new challenge to the growing gap between urban water demand and supply balance. Correlating urban growth and water demand to a rapidly growing population remains imperative to adaptive urban planning and decision-making. This study quantified urban development with demographic change and urban expansion dynamics. The population statistics and satellite imageries of historical years 1991–2021 and projections to the year 2051 were analysed using the exponential increase model and geospatial techniques. Multiple empirical modelling approaches were employed to link urban water demand with the explanatory variable. The study findings revealed the projected urban population reach more than one million and 79.2% of urbanization by 2051. With the current trend of 8.9% built-up growth rate, urban area will cover 73.6 km2 (45.9%) for the predicted period. The demographic variables and the sprawl of urban expansion jointly influence the water demand with statistically significant (f = 0.000, at α = 0.05) association. An increase in urban water use efficiency also reduces the water demand by increasing the availability of water supplies. Thus, the proposed model can be applied to reset the emerging relationship between the explanatory variables and water demand management. A detailed consideration of the spatially explicit effect on access to and optimization of the urban water supply system is vital to a local-specific solution. Integrating urban land planning with water demand management, therefore, has the potential to minimize the need to construct additional water supply infrastructure and cheer a sustainable urban environment.

The impact of sewage effluents on water quality of Lake Hawassa, Ethiopia

The physicochemical characteristics of water samples from Lake Hawassa was determined with the aim of pointing out possible impacts of industrial effluents, agricultural chemicals and domestic sewage on the water quality of the lake. For this, a total of 15 physicochemical parameters were measured in 72 water samples collected from four different locations on the lake that are adjacent to areas involved in various human activities including agriculture (Tikur Wuha), resort hotel (Haile Resort), public recreation (Gudumale) and referral hospital (Hitita). Samples were collected over a period of six months covering the dry and wet seasons in 2018/19. One-way analysis of variance revealed the presence of significant difference in the physicochemical quality of the lake’s water across the four study areas and the two seasons. Principal component analysis identified the most discriminating characteristics that differentiate the studied areas according to the nature and level of pollution status. Tikur Wuha area was found to be characterized by high levels of EC and TDS, the values of these parameters were about twice or more than that measured in the other areas. This was ascribed to contamination of the lake by runoff water from the surrounding farmlands. On the other hand, the water around the other three areas was characterized by high nitrate, sulfate and phosphate. Hierarchical cluster analysis classified the sampling areas in to two groups, where Tikur Wuha constituted one group and the other three locations the second group. Linear discriminant analysis provided 100% correct classification of the samples into the two cluster groups. The measured values of turbidity, fluoride and nitrate were found to be significantly higher than the standard limits set by national and international guidelines. These results show that the lake has been facing serious pollution problems from various anthropogenic activities.

Assessment of Climate Change Impact on Water Balance of Lake Hawassa Catchment

Assessment of Climate Change Impact on Water Balance of Lake Hawassa Catchment