Journal Articles

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Sensitivity of streamflow to changing rainfall and evapotranspiration in catchments across the Nile Basin
(MDPI, 2024-11-25) Onyutha, Charles; Ayugi, Brian Odhiambo; Sian, Kenny Thiam Choy Lim Kam; Babaousmail, Hassen; Arineitwe, Wenseslas; Akobo, Josephine Taata; Chelangat, Cyrus; Mubialiwo, Ambrose
This research focuses on the complex dynamics governing the sensitivity of streamflow to variations in rainfall and potential evapotranspiration (PET) within the Nile basin. By employing a hydrological model, our study examines the interrelationships between meteorological variables and hydrological responses across six catchments (Blue Nile, El Diem, Kabalega, Malaba, Mpanga, and Ribb) and explores the intricate balance between rainfall, PET, and streamflow. Nash Sutcliffe Efficiency (NSE) for calibration of the hydrological model ranged from 0.636 (Ribb) to 0.831 (El Diem). For validation, NSE ranged from 0.608 (Ribb) to 0.811 (Blue Nile). With rainfall kept constant while PET was increased by 5%, the streamflows of the Blue Nile, El Diem, Kabalega, Malaba, Mpanga, and Ribb decreased by 7.00, 5.08, 2.49, 4.10, 1.84, and 7.67%, respectively. With the original PET data unchanged, increasing rainfall of the Blue Nile, El Diem, Kabalega, Malaba, Mpanga, and Ribb by 5% led to an increase in streamflow by 9.02, 9.87, 5.38, 4.34, 6.58, and 8.32%, respectively. The research reveals that the rate at which a catchment losing water to the atmosphere (determined by PET) substantially influences its drying rate. Utilizing linear models, we demonstrate that the surplus rainfall available for increasing streamflow (represented by model intercepts) amplifies with higher rainfall intensities. This highlights the pivotal role of rainfall in shaping catchment water balance dynamics. Moreover, our study stresses the varied sensitivities of catchments within the basin to changes in PET and rainfall. Catchments with lower PET exhibit heightened responsiveness to increasing rainfall, accentuating the influence of evaporative demand on streamflow patterns. Conversely, regions with higher PET rates necessitate refined management strategies due to their increased sensitivity to changes in evaporative demand. Understanding the intricate interplay between rainfall, PET, and streamflow is paramount for developing adaptive strategies amidst climate variability. By examining these relationships, our research contributes essential knowledge for sustainable water resource management practices at both the catchment and regional scales, especially in regions susceptible to varying sensitivities of catchments to climatic conditions.
Evaluation of Factors Influencing Performance of Building Construction Projects in Uganda: A Case Study of Masaka City
(East African Journal of Engineering, 2024-11-10) Hakizimana, Venust; Muhwezi, Lawrence; Acai, Joseph
The construction industry has gained rapid growth for the past decade due to population growth resulting in housing and infrastructure demand. In Uganda, over twelve percent (12%) of the gross domestic product (GDP) is contributed by the building construction sector and is of great significance in the current economy. Despite this contribution to the sector, building construction fails due to performance issues as previously conducted studies have indicated and there are various reasons and factors which contribute to these performance issues. Therefore, there is a need to have a deeper understanding of the major factors attributing to this trend for better performance improvement. This study aimed to establish strategies to improve the performance of building construction projects in Uganda cities, a case study of Masaka city. The study employed a survey research design and targeted a population of 420 participants from which a sample of 201 respondents was selected. Data were collected using a questionnaireand interview guide. SPSS version 21 and Excel were used in data analysis. The following factors were established; cost factors, health and safety factors, time factors, quality factors productivity factors, project stakeholders’ factors, environmental factors and resource factors. The regression analysis conducted confirmed time factors, quality factors and cost factors to have evidence of a significant impact on the performance of building construction projects in Masaka city. A framework for improving the performance of building construction projects was developed based on factors with significant impact. These findings highlight the need to prioritize these factors with significant impact when evaluating and managing building construction projects in Masaka City.
Space–time prediction of residual chlorine in a water distribution network using artificial intelligence and the EPANET hydraulic model
(Water Practice & Technology, 2024-09-10) Kwio-Tamale, Julius Caesar; Onyutha, Charles
Insufficient knowledge of physical models and difficulty in fitting statistical models impair the choice of models to regulate residual chlorine in water distribution. This paper compared the performance of physical and statistical models in predicting residual chlorine concentrations in drinking water distribution. Drinking water was sampled from the downstream 128 water points water pipeline. Online chlorine concentrations were determined at water draw-off points. EPANET, the physical model, was used because of its efficiency in tracking dissolved chemicals. Statistical models used were regression, decision tree, random forest and artificial neural network. In the whole distribution network, the artificial neural network performed at R2 of 94%, multi-linear regression (62%), random forest (55%), decision tree (41%), and EPANET (24%). However, EPANET yielded improved performance with R2 above 70% when separately applied to individual sub-distribution networks; hence, is recommended for secondary chlorination in small distribution networks. For modelling large distribution networks, statistical models, especially an artificial neural network, are recommended. However, such cases still need support from confirmatory systems of interpretable parametric or hydraulic models that can achieve good performance with R2 80%. Water utilities can use these results to deploy model(s) for managing residual chlorine within safe limits of residual chlorine concentration in water distribution practice.
Amplification of compound hot-dry extremes and associated population exposure over East Africa
(Climatic Change, 2024-09-09) Ayugi, Brian Odhiambo; Onyutha, Charles; Zhu, Huanhuan; Babousmail, Hassen; Chung, Eun-Sung; Sian, Kenny Thiam Choy Lim Kam
Quantifying the vulnerability of population to multi-faceted climate change impacts on human well-being remains an urgent task. Recently, weather and climate extremes have evolved into bivariate events that heighten climate risks in unexpected ways. To investigate the potential impacts of climate extremes, this study analyzes the frequency, magnitude, and severity of observed and future compound hot-dry extremes (CHDEs) over East Africa. The CHDE events were computed from the observed precipitation and maximum temperature data of the Climatic Research Unit gridded Timeseries version five (CRU TS4.05) and outputs of climate models of Coupled Model Intercomparison Project Phase 6 (CMIP6). In addition, this study quantifies the population exposure to CHDE events based on future population density datasets under two Shared Socioeconomic Pathways (SSPs). Using the 75th/90th and 25th/10th percentile of precipitation and temperature as threshold to define severe and moderate events, the results show that the East African region experienced multiple moderate and severe CHDE events during the last twenty years. Based on a weighted multi-model ensemble, projections indicate that under the SSP5-8.5 scenario, the frequency of moderate CHDE will double, and severe CHDE will be 1.6 times that of baseline (i.e., an increase of 60%). Strong evidence of an upward trajectory is noted after 2080 for both moderate and severe CHDE. Southern parts of Tanzania and northeastern Kenya are likely to be the most affected, with all models agreeing (signal-to-noise ratio, SNR > 1), indicating a likely higher magnitude of change during the mid- and far-future. Consequentially, population exposure to these impacts is projected to increase by up to 60% for moderate and severe CHDEs in parts of southern Tanzania. Attribution analysis highlights that climate change is the primary driver of CHDE exposure under the two emission pathways. The current study underscores the urgent need to reduce CO2 emissions to prevent exceeding global warming thresholds and to develop regional adaptation measures.
Mathematical Modeling of Traffic Flow in Kampala City Using the Moving Observer Method
(East African Journal of Interdisciplinary Studies, 2024-08-25) Okiza, Humphrey; Muhwezi, Lawrence; Okello, Joseph Omwonylee; Awichi, Richard Opaka; Nuwagaba, Savannah
The purpose of the study was to investigate the variables affecting traffic flow in Kampala Central Business District (CBD), employing a quantitative approach. The rapid urbanization has led to a huge increase in the number of vehicles, resulting in traffic congestions, delays, and financial losses especially in the Kampala CBD area. Data on traffic density, speeds, and driver behaviors were collected for a period of 20 days from five selected road sections leading into and out of the city which included traffic on Entebbe Road, Jinja road, Sir Apollo Kaggwa Road, Yusuf Lule and Wandegeya roads using the moving observer method. Regression analysis was done to identify the relationships between the variables, leading to the development of a predictive model for traffic flow. The study found out that the flow tends to increase as the day progresses and as well flow rate increases with increase in density. As the week progressed, the flow rate decreased as number of people coming to town on weekends is low since there is no work. A mathematical model was generated which could be used to predict the traffic intensity on the road at a given day and time. The model shows that changing from weekdays to weekend, the flow decreases by about 29%, and as density increases by 1%, the flow also increases by 1.5% over time. The study recommends prioritizing public transportation improvement, establishment of out of city parking yards, utilizing the other various means of transport other than road and promoting non-motorized modes of transportation in order to reduce traffic density on the road and subsequently manage congestion.
Remaking the Late Holocene Environment of Western Uganda: Archaeological Perspectives on Kansyore and Later Settlers
(Springer Link, 2024-07-09) Schmidt, Peter R.; Walz, Jonathan R.; Besigye, Jackline N.; Krigbaum, John; Oteyo, Gilbert; Lejju, Julius B.; Asiimwe, Raymond; Ehret, Christopher; Crowther, Alison; Mwebi, Ogeto; Dunne, Julie; Schmidt, Jane; Okeny, Charles; Niwahereza, Amon; Yeko, Doreen; Bermudez, Katie; Echoru, Isaac
Archaeological and environmental research by an international and interdisciplinary team opens new perspectives into the settlement histories of Kansyore, Early Iron Age, and Bigo period peoples in the once forested regions of the Ndali Crater Lakes Region (NCLR) of western Uganda. The research examines the role of Kansyore agropastoralists and their Early Iron Age and Bantu-speaking contemporaries in remaking a once forested environment into a forest-savannah mosaic from circa 500 BC to the end of the first millennium AD. Archaeological settlement and subsistence evidence is examined within a framework of social interaction of Sudanic speakers with Bantu speakers, drawing on historical linguistics and environmental studies to arrive at a new synthesis of late Holocene history in western Uganda. This perspective also unveils the significance and chronology of Boudiné ware, a long enigmatic ceramic tradition that we identify as contemporary to Transitional Urewe and deeply influenced through social interactions with those making Kansyore ceramics and inhabiting the same landscape. Using archaeological evidence from fifteen sites and multiple burials spanning from 400 to 1650 calAD, new views of ceramic histories, lifeways, and symbolic values are revealed, including Bigo period settlements that arose in what was an environmental refugium beginning in the early fourteenth century AD. This research also shows that the Kansyore of the forested region east of the Rwenzori Mountains had greater affinities to late Holocene archaeological evidence from western Equatoria, in the southern South Sudan, and Kansyore Island, Uganda, than it does to the Kansyore in eastern Kenya.
Urban Sanitation: New Terminology for Globally Relevant Solutions?
(Environmental Science & Technology, 2023-10-11) Strande, Linda; Evans, Barbara; Sperling, Marcos Von; Bartram, Jamie; Harada, Hidenori; Nakagiri, Anne; Nyuyen, Viet-Anh
Progress toward Sustainable Development Goals for global access to safesanitation is lagging significantly. In this Feature, we propose that misleading terminologyleads to errors of categorization and hinders progress toward sanitation service provision inurban areas. Binary classifications such as “offsite/onsite” and “sewered/nonsewered” do notcapture the need for “transport to treatment” or the complexity of urban sanitation andshould be discarded. “Fecal sludge management” is used only in the development context oflow- or middle-income countries, implying separate solutions for “poor” or “southern”contexts, which is unhelpful. Terminology alone does not solve problems, but rather thanusing outdated or “special” terminology, we argue that a robust terminology that is globallyrelevant across low-, middle-, and upper-income contexts is required to overcomeincreasingly unhelpful assumptions and stereotypes. The use of accurate, technically robustvocabulary and definitions can improve decisions about management and selection oftreatment, promote a circular economy, provide a basis for evidence-based science andtechnology research, and lead to critical shifts and transformations to set policy goals aroundtruly safely managed sanitation. In this Feature, the three current modes of sanitation are defined, examples of misconceptions basedon existing terminology are presented, and a new terminology for collection and conveyance is proposed: (I) fully road transported,(II) source-separated mixed transport, (III) mixed transport, and (IV) fully pipe transported. KEYWORDS: city-wide inclusive sanitation, fecal sludge, onsite, septic tank, pit latrine, sewer, sustainable development goals, wastewater.
Investigating the cost of mechanized unpaved road maintenance operations in Uganda
(Elsevier, 2024-05) Obeti, Andrew Moses; Muhwezi, Lawrence; Kakitahi, John Muhumuza
Force Account Mechanism (FAM) is the predominant road maintenance system in Uganda’s local government setup and a similar, though slightly different approach, is used in some large private sector agriculture plantations. With the Uganda Road Fund (URF) 2021/2022 annual report and previous research citing challenges in cost management and efficiency of the FAM method of road maintenance, it becomes paramount to analyse how FAM is implemented in government-led operations, in comparison to similar private sector approaches, while proposing possible solutions to these challenges. This research offered to analyse unpaved road maintenance cost drivers alongside providing a cost model solution to improve on cost prediction of the FAM system. Gulu District Local Government (DLG) and Kakira Sugar Limited (KSL) were selected as case study areas. Two descriptive research methods were used: observations and case study approach. The selected case study areas were accessible and reachable in terms of data. Control parameters affecting unpaved mechanized road maintenance were identified as machine repair costs, tool costs, labour costs, material costs, fuel costs and machine fuel costs. Unpaved mechanized road maintenance costs at KSL and Gulu DLG were computed as a cost/km ratio of 26,442,032Ugx/km (6,958.4USD/km) and 32,674,895Ugx/km (8,598.65USD/km) respectively. The Uganda National Roads Authority (UNRA) unpaved road maintenance costs were calculated as an average of 34,987,122.9Ugx/km (9,165USD/km) while the World Bank ROCKS database provided a comparable figure of 7,971USD/km (30,553,440.83Ugx/km). A USD to Ugx conversion rate of 3,800 was used. Two linear regression cost models with a 0.679 and 0.687 R2 value were computed, and these can be used in preliminary road maintenance cost prediction. The study recommends the need for an effective, digital road maintenance cost database system for mechanized unpaved road maintenance works, cost driver analytics and management, alongside improvement in aspects of maintenance processes at both the DLG and KSL. Further research can be conducted on equipment condition level prediction and analytics in the private sector and at the DLG.
Investigating equipment productivity in feeder road maintenance in Uganda
(Elsevier, 2023-01) Obeti, Andrew Moses; Muhwezi, Lawrence; Kakitahi, John Muhumuza
Rural roads form the largest part of Uganda’s road network (approximately 50.2%) and is therefore a critical part of economic growth in an agriculturally dependent country like Uganda. With Uganda’s rural population standing at approximately 76% of the total population and agriculture still employing approximately 72% of Uganda’s population, this underscores the need to fix loopholes in road maintenance strategies in Uganda with emphasis on rural roads. This study sought to conduct a detailed cost analysis with a view to determining whether productivity is at an optimum for specific road maintenance equipment in Uganda, with emphasis on mechanized agricultural plantation access road maintenance works. Two descriptive research methods were used: observations and case study approach. Control parameters affecting machine production were identified as machine repair costs, maintenance costs, machine depreciation costs, worker’s salaries, machine insurance costs, and machine fuel costs. Machine downtime was mainly affected by delays in procuring spares. The total hourly machine production costs were calculated to be 699,602 Ugx (185.84USD). This cost calculation can be improved upon in subsequent studies. The study recommends the need for an effective centralised electronic database where all feeder road maintenance data is collected, analysed, and recorded.
Drought severity across Africa: a comparative analysis of multi-source precipitation datasets
(Springer, 2024-04) Lim Kam Sian, Kenny Thiam Choy; Onyutha, Charles; Ayugi, Brian Odhiambo; Njouenwet, Ibrahim; Ongoma, Victor
An accurate analysis of climate extremes is essential for impact assessment and devising appropriate adaptation measures. There is an urgent need to assess precipitation products in capturing the increasing occurrence of climate extremes. This study evaluates the ability of 20 observational datasets, including gauge-based, satellite-based and reanalyses, in representing different drought severity (moderate, severe and extreme drought) over Africa and its nine sub-regions at varying time scales (3-, 6- and 12-months) during 1983–2014. Drought is represented using the Standardized Precipitation Index (SPI). The results demonstrate that while most datasets are suitable for drought studies over the continent, the African Rainfall Climatology version 2 (ARC2) and Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks Climate Data Records (PERSIANN_CDR_v1r1) are less fitted for such investigations. Moreover, regions such as the Sahara (SAH), Central Africa (CAF) and North Eastern Africa (NEAF) show a larger disparity among the datasets, requiring more caution when selecting a dataset for use in such areas. Generally, the datasets present low agreement toward the lower end of the range (5–30%) because the individual datasets estimate varying drought severities at different grids and months. This is observed in the coefficient of variation of 20–25% of the datasets falling outside the ± 1 standard deviation range. Therefore, using an ensemble to represent the datasets remains an indispensable tool. The datasets present better agreement in the timing of drought events than the spatial distribution. The findings provide valuable insights into the complexity of drought assessment using diverse precipitation datasets. Furthermore, the results highlight the significance of considering spatial and temporal dimensions, as datasets may capture drought events at varying locations and times, revealing subtle variations in drought impact.
Changes in extreme precipitation over Mpologoma catchment in Uganda, East Africa
(Heliyon, 2023-02-17) Ambrose, Mubialiwo; Adane, Abebe; Charles, Onyutha
Changes of five Extreme Precipitation Indices (EPIs) over Mpologoma catchment were examined. The EPIs were obtained from the long-term (1948–2016) gridded (0.25◦ × 0.25◦ ) Princeton Global Forcing (PGF) daily precipitation dataset. The number of days with precipitation intensity greater than 5 mm/day (NWD5) and 10 mm/day (NWD10) were part of the five EPIs. Trend and variability analyses were by the nonparametric technique based on the cumulative sum of the difference between exceedance and non-exceedance counts of data. The simple multiplicative bias correction method was employed to bias correct the PGF dataset using observed rainfall from nine weather stations. The number of wet days were decreasing although insignificant (p > 0.05). On the other hand, the annual total precipitation considering days with rainfall intensities greater than 5 mm/day (SPre5) exhibited a significant (p < 0.05) decrease. However, annual maxima rainfall (ANMS) increased even though insignificant. This indicates that less frequent rains are received over the study area but some events having high intensity. The insights from the findings of this study constitute a good baseline for predictive planning of water resources management applications across Mpologoma catchment.
Influence of physical and water quality parameters on residual chlorine decay in water distribution network
(Heliyon, 2024-05-07) Julius, Caesar Kwio-Tamale; Charles, Onyutha
Chlorine is the most common disinfectant in drinking water distribution practice. World Health Organization recommends 0.2–5.0 mg/l of residual chlorine in drinking water. This paper analyzed influence of physical and water quality parameters on chlorine decay in drinking water distribution. Principal component analysis, directed tree and regression were used to investigate influence of these parameters on chlorine from water treatment plant to water consumption points. Results show that initial chlorine, electrical conductivity and distance explain 62 % of chlorine decay with estimated error of 0.045 mg/l. The decision-tree feature importance scores of initial chlorine and electrical conductivity were 0.47 and 0.23 respectively. The combined feature importance scores of physical parameters of distance (0.09), pipe diameter (0.06), flow velocity (0.03), pressure (0.02) and travel time (0.046) were less than that for initial chlorine concen- tration (0.47) alone. These results show that conventional chlorination at water treatment plants removes largely fast inorganic reactants leaving traces of slow organic reactants as the dominant secondary contaminants in water distribution system. The key policy recommendation is to use water quality parameters more than physical parameters in order to enable water utility man- agers maintain residual chlorine within safe public health standards.
Improving household water treatment: using zeolite to remove lead, fluoride and arsenic following optimized turbidity reduction in slow sand filtration
(Sustainable Environment Research, 2024-03) Charles, Onyutha; Emmanuel, Okello; Rebecca, Atukwase; Pamella, Nduhukiire; Michael, Ecodu; Japheth, Nkiriyehe Kwiringira
Despite the United Nations 2030 agenda, large number of both urban and rural dwellers in low-income countries continue to lack access to improved water. Thus, increased effort is required towards enhancing low-cost drinking water treatment technologies especially for developing countries. Slow sand filter (SSF) is one of the most commonly used low-cost and efficient technologies for treating household drinking water. However, effectiveness of SSF is sub- stantially affected by very high turbidity and relatively large amounts of dissolved heavy metals. To enhance removal of both turbidity and heavy metals, this study optimized sand bed depth (SBD) of SSF and investigated the potential of natural zeolite from Uganda for removal of lead, arsenite (As(III)) and fluoride ions from water. To remove lead ions, the zeolite was used in its natural form. However, to remove As(III) and fluoride, the natural zeolite was modified using hexadecyltrimethylammonium bromide solution. Removal of high turbidity was found to require a large optimal SBD. Furthermore, efficiency of treating synthetic turbid water increased with increasing initial turbidity. Variation of final turbidity with SBD was found to be best described by an exponential function. Optimal SBDs on top of an underdrain gravel layer of 0.2 m were 453, 522, 561, and 580 mm for turbidity of 60, 80, 100, and 120 NTU, respectively. Opti- mized SBD used achieve at least 95% efficiency in removing suspended particles from water with turbidity 120 NTU was found to save up to 35% of the total cost for acquiring sand volume required by a conventional SSF. For a par- ticular zeolite mass, removal efficiencies of lead, As(III) and fluoride generally increased with increasing contact time. Removal efficiencies of lead, As(III), and fluorides were also shown to increase with increasing zeolite mass. Lead removal efficiencies using natural zeolite were 75 and 98% under 20 and 40 min, respectively. Removal of As(III) using modified zeolite mass was 91% within contact time of 10 min. Adsorption of fluoride on modified zeolite was 80% within 5 min. Adsorption of lead, As(III), and fluorides indicated promising potential of natural zeolites from Uganda for treating polluted water.
Turbidity reduction efficacies of seed kernels of Mango (Mangifera indica) genotypes in Uganda
(Elsevier, 2023-10) Onyutha, Charles; Auma, Nancy
Alum and ferric salts as traditional chemical coagulants for turbidity removal in water and wastewater are expensive, and have known harmful effects. Thus, attempts to replace the chemical coagulants with safe and effective natural solutions are increasingly being made in terms of research studies to investigate the coagulation efficacies of various plants one of which is Mango (Mangifera indica). It is worth noting that M. indica has various genotypes of different origins across the world. In this study, eight (8) common M. indica genotypes in Uganda were identified, protein contents of their seed kernels determined, and coagulating efficacies investigated. Coagulation solution of each selected genotype was obtained by dissolving 5 g powder of the selected Mango seed kernel sample in 100 mL of distilled water. Next, 5 mL of this coagulant (or stock) solution was used to treat 200 mL of turbid water with turbidity ranging from 15 to 120 NTU. Using 0.01 M hydrochloric acid as an extraction solvent, protein contents of selected genotypes including Apple mango, Kate, Kent, Bire, Doodo red, Takataka, Kagoogwa, and Tommy Atkins were 38.02 %, 30.66 %, 15.94 %, 22.11 %, 21.50 %, 16.98 %, 16.36 %, and 17.87 %, respectively. Efficacies of coagulant from Apple mango, Kate, Kent, Bire, Doodo red, Takataka, Kagoogwa, and Tommy Atkins seed kernel samples were 92.2, 89.3, 66.0, 78.7, 76.9, 71.1, 68.9, and 73.1 %, respectively. Apple mango was the best performing genotype as a coagulant and this was followed by Kate. Coagulation efficacy was generally found to increase with increasing turbidity and/or coagulant’s concentration. For instance, Apple Mango coagulant removed 16.7 %, 50.3 %, and 92.2 % of initial turbidity 15, 65 and 120 NTU, respectively. Kent removed 57.5, 66, and 69 % of initial turbidity 120 NTU using 5, 20, and 30 mL of stock solution, respectively. This study demonstrated the influence of the choice of a plant genotype on coagulation efficacy.
Dam breach analysis of Kibimba Dam in Uganda using HEC-RAS and HEC-GeoRAS
(Springer, 2023-10) Kiwanuka, Moses; Chelangat, Cyrus; Mubialiwo, Ambrose; Lay, Francis Joel; Mugisha, Ayubu; Mbujje, Webster Joel; Mutanda, Hosea Eridadi
Dam failures have severe consequences on human life and property. In the case of an earth filled Kibimba Dam located in Eastern Uganda, the occurrence of a food equal to or larger than the probable maximum food (PMF) could result in catastrophic economic losses including loss of human life. This study utilized the USACE Hydrologic Engineering Center’s River Analysis System (HEC-RAS) and Hydrologic Engineering Center’s Geographic River Analysis System (HEC-GeoRAS) to analyze the potential dam break of Kibimba Dam, considering overtopping and piping failure scenarios. The results of the analysis revealed that the spillway of Kibimba Dam possesses sufficient capacity to safely discharge a food resulting from a probable maximum food peak of 400 m3/s. Therefore, the dam is not susceptible to breach under the overtopping failure mode. However, the dam failed under the piping failure mode. To assess the downstream impact of the dam break, the breach hydrographs resulting from piping failure were examined. Consequently, the study investigated the effects of food propagation downstream of the dam. This resulted in varying inundation depths of up to 6 m and velocities ranging from 1.2 to 10 m/s. These findings highlight the devastating consequences of Kibimba Dam’s failure, particularly affecting rice field plantations, infrastructure, and other economic activities in the downstream area. Therefore, the outcomes of this study are crucial for the development of Emergency Action Plans that incorporate dam breach and food routing analyses specific to the affected downstream regions. Keywords Dam breach, HEC-RAS, HEC-GeoRAS, Kibimba
COVIDiStress diverse dataset on psychological and behavioural outcomes one year into the COVID-19 pandemic
(Scientific data, 2022) angélique, M. Blackburn; Sara, Vestergren; The COVIDiStRESS II Consortium
During the onset of the COVID-19 pandemic, the COVIDiSTRESS Consortium launched an open-access global survey to understand and improve individuals’ experiences related to the crisis. a year later, we extended this line of research by launching a new survey to address the dynamic landscape of the pandemic. this survey was released with the goal of addressing diversity, equity, and inclusion by working with over 150 researchers across the globe who collected data in 48 languages and dialects across 137 countries. The resulting cleaned dataset described here includes 15,740 of over 20,000 responses. the dataset allows cross-cultural study of psychological wellbeing and behaviours a year into the pandemic. It includes measures of stress, resilience, vaccine attitudes, trust in government and scientists, compliance, and information acquisition and misperceptions regarding COVID-19. Open- access raw and cleaned datasets with computed scores are available. Just as our initial COVIDiStRESS dataset has facilitated government policy decisions regarding health crises, this dataset can be used by researchers and policy makers to inform research, decisions, and policy.
Field-based methods for measuring greenhouse gases emissions from on-site sanitation systems: A systematic review of published literature
(Heliyon, 2023-04) Prativa, Poudel; Anish, Ghimire; Guy, Howard; Barbara, Evans; Miller, Camargo-Valero A.; Freya, Mills; Olivia, Reddy; Subodh, Sharma; Sarana, Tuladhar; Abraham, Geremew; Kenan, Okurut; Baba, Ngom; Manish, Baidya; Sheila, Dangol
On-site sanitation systems (OSS) are a source of greenhouse gas (GHG) emissions. Although ef- forts have been made recently to measure and quantify emissions from septic tanks using various field-based methods, the vast majority of published literature reporting GHG emissions from OSS units (e.g., pits and tanks) is based on non-empirical evidence. This systematic review presents an overview and limitations of field-based methods used for the quantification of GHG emissions from OSS. Papers published in English were searched in three databases: Google Scholar, PubMed, and Directory of Articles and Journals. Peer-reviewed papers that reported field-based methods applied to containment units in OSS were included in this study. Only eight out of 2085 papers met the inclusion criteria with septic tanks as the sole technology reported and were thus, considered for the review. Most of the studies have been conducted in middle- and high- income countries. Field-based measurements of GHGs are conducted using a flux chamber (FC) and the most commonly used FC methods are (a) the modified simple static FC, (b) automated static FC, and (c) floating FC. Data reported in published studies do not provide sufficient in- formation on the calibration and validation of the results from the FCs used. The complex FC designs, laborious fieldwork operations, and reliance on expensive, specialist equipment, suggest that such methods may not be suitable in Low and Middle-Income countries (LMICs), where re- sources and access to laboratory facilities are limited. Also, the complexity of pits and tank ty- pology in LMICs (i.e., unstandardised designs and sizes) may be a challenge to the use of FCs with fixed dimensions and set operational conditions. The variation in the quantification methods and resulting emission rates among the studies indicates that gaps prevail in the use of existing methods. Therefore, there is still a need for a simple field-based, easily adaptable FC method with adequate calibration and validation that can help in reliably quantifying the emissions from different OSS in any LMICs.
The potential for citizen science to improve the reach of sanitary inspections
(MDPI- Resources, 2020-10) Jo, Herschan; Richard, King; Theresa, Mkandawire; Kenan, Okurut; Dan, J. Lapworth; Rosalind, Malcolm; Katherine, Pond
To achieve Sustainable Development Goals (SDGs) 6, universal and equitable access to safe and affordable drinking-water quality and sanitation for all, and 10, to reduce inequality within and among countries, additional and urgent work is required. Efforts to achieve these Goals in the context of small drinking-water supplies, which are the furthest behind in regards to progress, are of particular need. Reasons for this disparity in progress include the remoteness of access to small drinking-water supplies and the lack of technical and financial capacity for monitoring supplies. The World Health Organization promote the use of Sanitary inspection (SI) as an on-site assessment of risk. Despite the potential to increase the body of knowledge and information on supplies in a region, there has been limited research into the role of citizen science and SIs. To meet SDG targets, we need to improve the reach of SIs. This study uses a mixed methods approach of quantitative on-site SI data collection and remote SI data collection via photographic images, together with qualitative data collection, collected by non-expert students, who are citizens of Malawi, as well as a panel of experts in the field of SI. Results indicate that, although further research into the topic is required prior to widescale implementation, the potential exists for citizens to conduct SI, with remote expert verification of the results using photographic images of supplies. Further documentation or guidance is required to support citizens in this process. The results highlight a critical gap in the availability of appropriate documentation for unprotected spring sources which is urgently required. The use of citizen science for SI data collection is in its infancy. However, this study indicates that there is potential to explore the use of citizen science in this area, which will contribute to achieving SDGs 6 and 10.
Progress of using risk assessment to manage small drinking-water supplies in Rwanda: a preliminary study
(MDPI- Processes, 2023-03) Jo, Herschan; Aime, Tsinda; Kenan, Okurut; Rosalind, Malcolm; Daniel, J. Lapworth; Katherine, Pond
The World Health Organization promotes risk assessment and risk management through Water Safety Plans (WSPs) as the most effective way to manage drinking-water supplies. Despite proven advantages of this approach in other regions, WSPs are still not widely used across small drinking-water supplies in Sub Saharan Africa. The aim of this research is to identify good practices and related gaps which may assist with formal uptake of WSPs for small drinking-water supplies in Rwanda. Through semi-structured interviews with the key stakeholders involved in small drinking-water supply management across Rwanda, the aim is achieved through the investigation of the following: (i) current drinking-water management challenges; (ii) stakeholder collaboration and data management activities including reporting of information; and (iii) the regulatory and policy environment. The use and awareness of WSPs in Rwanda was confirmed as low. However certain drinking-water management activities which align with the WSP methodology are being carried out. These include catchment management and stakeholder collaboration. Although legislation and policy are in place in Rwanda, communication and training of methods to implement WSPs are required to sustainably embed WSPs into practice. Several elements, including community engagement, systematic review of risks and data management, require greater focus to align with the WSP methodology. Respondents highlighted key drinking-water management challenges, including reactive budgeting and lack of sector prioritization, which could benefit from formal WSP implementation.
Abating eutrophication on urban lakes: a case study of Kabaka's Lake, Uganda
(IWA Publishing Water Practice & Technology, 2023-07) Anne, Nakagiri; Abel, Mutyaba; Charles, Onyutha; Kenan, Okurut
Eutrophication of water bodies is a challenge in many urban areas. This study measured and modelled quantitatively the pollutant nutrient load of an urban lake (80,596 m2), and assessed both external (constructed wetland) and internal (dredging) eutrophication extenuation measures. For the past 25 years, there has been redistribution (p < 0.005) of the lake's catchment land use, with built-up area increasing by 78.5%, and a reduction in vegetated (37.2%) and water surface (1.8%) areas. A 92.2% reduction in the lakes receiving wetland footprint (p = 0.000003) was noted, with increased nutrient load. The lake's light attenuation was found to be dominated by algae, limited by nitrogen and classified under the oligotrophic class (Trophic State Index < 40), with a threat of eutrophication in an estimated 25 years. Scenario analyses show that the construction of a wetland in the remaining 0.54 hectares of natural wetland will reduce total phosphorus by 35% and total nitrate by 45% (p = 0.05), whereas dredging the lake could reduce them by 80% each (p = 0.0005). Watershed management is the only sustainable solution to control nutrient flow into the lake and enable self-cleansing, factoring in the design of the receiving wetland and groundwater sources.

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