Journal Articles

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An assessment of the impact of construction activities on the environment in Uganda: a case Study of Iganga Municipality
(Journal of Construction Engineering and Project Management., 2012-11-15) Muhwezi, Lawrence; Kiberu, Faisal; Kyakula, Michael; Batambuze, Alex O.
Construction while being an economic activity that provides facilities and infrastructure, it is beneficial to man in some aspects and detrimental in others. There have been environmental concerns related to construction activities globally which mainly focus on atmospheric emissions, depletion of natural resources and energy issues. This study was carried out to assess the impacts of construction activities on the environment in Iganga Municipality and to propose measures for their mitigation. The methodology included: review of relevant literature, observations of the general environmental effects of construction activities, focus groups and a survey conducted among construction industry role players to determine their perceptions and opinions regarding environmental impact of construction activities. The collected data was presented in tabular form and analysed by description of responses to questions. The study revealed that forests were the most greatly degraded due to high demand of timber for construction followed by wetlands degradation. The findings of this study will be useful to architects, designers and builders in order to carefully design buildings and other infrastructure that are environmentally friendly and sustainable. Construction materials and their mode of acquisition are harmful threats to the environment. There is need to reduce the consumption of these materials through recycling and reusing wastes to reduce on waste generation, use of virgin materials and the subsequent waste of energy used in new material production.
Occupational safety training and practices in selected vocational training institutions and workplaces in Kampala, Uganda
(Taylor&Francis: International Journal of Occupational Safety and Ergonomics, 2015-12-23) Denis, Kintu; Kyakula, Michael; Kikomeko, Joseph
Several industrial accidents, some of them fatal, have been reported in Uganda. Causes could include training gaps in vocational training institutions (VTIs) and workplaces. This study investigated how occupational safety training in VTIs and workplaces is implemented. The study was carried out in five selected VTIs and workplaces in Kampala. Data were collected from instructors, workshop technicians, students, workshop managers, production supervisors, machine operators and new technicians in the workplaces. A total of 35 respondents participated in the study. The results revealed that all curricula in VTIs include a component of safety but little is practiced in VTI workshops; in workplaces no specific training content was followed and there were no regular consultations between VTIs and industry on safety skills requirements, resulting in a mismatch in safety skills training. The major constraints to safety training include inadequate funds to purchase safety equipment and inadequate literature on safety.
An advanced continuum damage mechanics model for predicting the crack progress process based on the consideration of the influence of crack direction under quasi-static load
(Elsevier: International Journal of Mechanical Sciences., 2017-09) Yun, Kumchol; Wang, Zhenqing; Ronald, Sakaya; Pak, Yongchol
In reality the wrong crack path can be generally obtained in the case of arbitrary crack propagation by traditional continuum damage mechanics (CDM). In this paper a novel advanced continuum damage mechanics (ACDM) method is proposed, which can predict the crack propagation and fracture behavior correctly for the structures. The material property degradation method, which is usually used when simulating the structures within the framework of CDM, is advanced based on considering the influence of crack direction. The maximum tensile stress criterion is used to predict the damage initiation and crack propagation direction and the advanced CDM used to predict the damage evolution process in meso-level under the quasi-static load. It can directly evaluate the propagation process of the discrete crack and the fracture strength for structures using the continuum model as well as not using discontinuum model. The algorithm for the application of our advanced CDM theory in the numerical simulation based on finite element method (FEM) is presented. ACDM model is not only a simple and useful model which can easily be used in FEM framework but also a phenomenological model based on the concept of crack propagation. The simulation results by our ACDM are compared with the experiment results and the ones and from cohesive zone method and extended finite element method for good agreements to be achieved.
African food insecurity in a changing climate: the roles of science and policy
(Wiley Online Library: Food and Energy Security, 2018-12-12) Onyutha, Charles
African population is projected to double to 2.48 billion people by 2050. The population increase poses a serious challenge of increasing food supply to meet the future demand. This challenge is compounded by climate change impacts on agriculture. In this paper, how poverty contributes to household food insecurity is explored and measures suggested to help address this challenge. To plan adaptation measures, linkages among food insecurity, poverty, and illiteracy should be considered. For the sub-Saharan Africa (SSA), adaptation (focused on poverty alleviation) should be prioritized and preferred to mitigation. Enhancement of adaptive capacity should not only be tailored toward empowerment of women but also made highly localized to household levels. Generally, efforts could be geared toward yield gap closure, addressing challenges regarding food distribution, promoting non-farm income-generating activities, and unification of government priorities in agriculture and food security. Government in each country of the SSA should ensure that governance strongly embraces transparency, accountability, and integrity otherwise as it is said a fish rots from the head down. Estimates of uncertainty in predicting future climate and their implications on expenditure related to adaptation should to always be made in an integrated way and reported to support actionable policies. To increase credibility in climate prediction especially at local scales, advances toward improving climate models (for instance by refining spatiotemporal scales, enhancing models’ capacity to reproduce observed natural variability in key climatological variables like rainfall) should be made, and this requires support from the investment in climate science. Science–policy interfacing is required in planning and implementation of measures for adapting to climate change impacts. In summary, food insecurity and persistent poverty especially in the SSA should be of direct relevance and concern at a global scale. Thus, global collaboration in science is key to achieve food security in the SSA.
Osmotic consolidation of expansive soil
(Japanese Geotechnical Society Special Publication, 2019) Sam, Bulolo; E.C., Leong
The mechanical behavior of expansive soils is influenced by the concentration of salts in their pore water. Research has shown that volume change of soil can occur due to a difference in salt concentration in the pore water between different zones of the soil as a result of either osmotically-induced consolidation or osmotic consolidation. The effect of the salt concentration of the pore water in unsaturated soil mechanics can be expressed as osmotic suction. Very little work has been done to quantify the mechanical equivalence of osmotically-induced and osmotic consolidation. This study attempts to quantify the mechanical stress equivalence of consolidation of an expansive soil submerged in a salt solution. Two remoulded soil samples of kaolin - bentonite mixture in proportions of 70% – 30% and 90% - 10%, (kaolin – bentonite) by dry mass were submerged in different concentrated salt solutions to investigate the effect of osmotic suction. Results showed that osmotic suction caused an additional settlement over the consolidation settlement under a mechanical stress but does not affect the soil compressibility. The osmotic coefficient of volume change (mπ) is only a fraction of the coefficient of volume change (mv).
Hydrological model supported by a step-wise calibration against sub-flows and validation of extreme flow events
(MDPI, 2019-01-31) Onyutha, Charles
Most hydrological models have fixed structures and their calibrations are typified by a conventional approach in which the overall water balance closure is considered (without a step-wise focus on sub-flows’ variation). Eventually, hydrological modelers are confronted with the difficulty of ensuring both the observed high flows and low flows are accurately reproduced in a single calibration. This study introduced Hydrological Model focusing on Sub-flows’ Variation (HMSV). Calibration of HMSV follows a carefully designed framework comprising sub-flow’s separation, modeling of sub-flows, and checking validity of hydrological extremes. The introduced model and calibration framework were tested using hydro-meteorological data from the Blue Nile Basin of Ethiopia in Africa. When the conventional calibration approach was adopted through automatic optimization strategy, results from the HMSV were found highly comparable with those of five internationally well recognized hydrological models (AWBM, IHACRES, SACRAMENTO, SIMHYD, and TANK). The new framework enhanced the HMSV performance for reproducing quantiles of both high flows and low flows. The combination of flow separation and step-wise calibration of hydrological model against sub-flows enhances the modeler’s physical insight in identifying which areas need focus in modeling to obtain meaningful simulation results, especially of extreme events. The link for downloading the HMSV is provided
A computational methodology for simulating quasi-brittle fracture problems
(Elsevier: Computers & Structures, 2019-04-15) Yun, Kumchol; Wang, Zhenqing; Chang, Mengzhou; Liu, Jingbiao; Kim, Tae-Jong; Son, Namjin; Ji, Kyongsu; Ronald, Sakaya
The paper focuses on an efficient and simple methodologies for simulating the three dimensional (3D) quasi-brittle fracture problems. Strain-softening is performed on the elements by a developed anisotropic continuum damage model that has more effective capability in crack path prediction and is easily available in standard finite elements. In the present damage model, the damaged stiffness tensor is constructed to form a crack surface, and the energy dissipation in the damaged element is only allowed in the direction perpendicular to the crack plane. Crack surface is divided into crack lines and crack triangles based on the first introduced crack surface discretization, and the application scope of local tracking algorithm is extended from two dimension to 3D. The present tracking algorithm not only guarantees the continuity and stability of the predicted crack path by solving the topological problems but also has low computational cost, keeping the advantages of local tracking. The method does not identify the crack plane within each element, but it couples well with smeared crack method by identifying all the elements through which the crack surface passes. The high efficiency and stability of the present approach are verified by resolving several 3D benchmark problems in failure analysis.
Dynamically dimensioned search embedded with piecewise opposition-based learning for global optimization
(2019-05-26) Xu, Jianzhong; Yan, Fu; Yun, Kumchol; Ronald, Sakaya; Li, Fengshu; Guan, Jun
Dynamically dimensioned search (DDS) is a well-known optimization algorithm in the field of single solution-based heuristic global search algorithms. Its successful application in the calibration of watershed environmental parameters has attracted researcher’s extensive attention. The dynamically dimensioned search algorithm is a kind of algorithm that converges to the global optimum under the best condition or the good local optimum in the worst case. In other words, the performance of DDS is easily affected by the optimization conditions. Therefore, this algorithm has also suffered from low robustness and limited scalability. In this work, an improved version of DDS called DDS-POBL is proposed. In the DDS-POBL, two effective methods are applied to improve the performance of the DDS algorithm. Piecewise opposition-based learning is introduced to guide DDS search in the right direction, and the golden section method is used to search for more promising areas. Numerical experiments are performed on a set of 23 classic test functions, and the results represent significant improvements in the optimization performance of DDS-POBL compared to DDS. Several experimental results using different parameter values demonstrate the high solution quality, strong robustness, and scalability of the proposed DDS-POBL algorithm. A comparative performance analysis between the DDS-POBL and other powerful algorithms has been carried out by statistical methods by using the significance of the results. The results show that DDS-POBL works better than PSO, CoDA, MHDA, NaFA, and CMA-ES and gives very competitive results when compared to INMDA and EEGWO. Moreover, the parameter calibration application of the Xinanjiang model shows the effectiveness of the DDS-POBL in the real optimization problem.
Contribution of climatic variability and human activities to stream flow changes in the Haraz River basin, Northern Iran
(Journal of Hydro-environment Research, 2019-06) Pirnia, Abdollah; Darabi, Hamid; Choubin, Bahram; Omidvar, Ebrahim; Onyutha, Charles; Haghighi, Ali Torabi
In northern Iran’s Haraz River basin between 1975 and 2010, hydrological sensitivity, double mass curve, and Soil and Water Assessment Tool (SWAT) methods were applied to monitoring and analysing changes in stream flow brought on by climatic variability and human activities. Applied to analyse trends in annual and seasonal runoff over this period, the sequential MK test showed a sudden change point in stream flow in 1994. The study period was, therefore, divided into two sub-periods: 1975–1994 and 1995–2010. The SWAT model showed obvious changes in water resource components between the two periods: in comparison to the period of 1975–1994, sub-watershed-scale stream flow and soil moisture decreased during 1995–2010. Changes in evapotranspiration were negligible compared to those in stream flow and soil moisture. The hydrological sensitivity method indicated that climatic variability and human activities contributed to 29.86% and 70.14%, respectively, of changes in annual stream flow, while the SWAT model placed these contributions at 34.78% and 65.21%, respectively. The double mass curve method indicated the contribution of climatic variability to stream flow changes to be 57.5% for the wet season and 22.87% for the dry season, while human activities contributed 42.5% and 77.13%, respectively. Accordingly, in the face of climatic variability, measures should be developed and implemented to mitigate its impacts and maintain eco-environmental integrity and water supplies.
Combined use of graphical and statistical approaches for analyzing historical precipitation changes in the black sea region of Turkey
(MDPI: Water, 2020-03-05) Cengiz, Taner Mustafa; Tabari, Hossein; Onyutha, Charles; Kisi, Ozgur
Many statistical methods have been developed and used over time to analyze historical changes in hydrological time series, given the socioeconomic consequences of the changes in the water cycle components. The classical statistical methods, however, rely on many assumptions on the time series to be examined such as the normality, temporal and spatial independency and the constancy of the data distribution over time. When the assumptions are not fulfilled by the data, test results are not reliable. One way to relax these cumbersome assumptions and credibilize the results of statistical approaches is to make a combined use of graphical and statistical methods. To this end, two graphical methods of the refined cumulative sum of the difference between exceedance and non-exceedance counts of data points (CSD) and innovative trend analyses (ITA)-change boxes alongside the classical statistical Mann–Kendall (MK) method are used to analyze historical precipitation changes at 16 stations during 1960–2015 in the Black Sea region of Turkey. The results show a good match between the results of the graphical and statistical methods. The graphical CSD and ITA methods, however, are able to identify the hidden trends in the precipitation time series that cannot be detected using the statistical MK method.
Analyses of precipitation and evapotranspiration changes across the lake Kyoga basin in East Africa
(MDPI: Water, 2020-04-16) Onyutha, Charles; Acayo, Grace; Nyende, Jacob
This study analyzed changes in CenTrends gridded precipitation (1961–2015) and Potential Evapotranspiration (PET; 1961–2008) across the Lake Kyoga Basin (LKB). PET was computed from gridded temperature of the Princeton Global Forcings. Correlation between precipitation or PET and climate indices was analyzed. PET in the Eastern LKB exhibited an increase (p > 0.05). March–April–May precipitation decreased (p > 0.05) in most parts of the LKB. However, September–October–November (SON) precipitation generally exhibited a positive trend. Rates of increase in the SON precipitation were higher in the Eastern part where Mt. Elgon is located than at other locations. Record shows that Bududa district at the foot of Mt. Elgon experienced a total of 8, 5, and 6 landslides over the periods 1818–1959, 1960–2009, and 2010–2019, respectively. It is highly probable that these landslides have recently become more frequent than in the past due to the increasing precipitation. The largest amounts of variance in annual precipitation (38.9%) and PET (41.2%) were found to be explained by the Indian Ocean Dipole. These were followed by precipitation (17.9%) and PET (21.9%) variance explained by the Atlantic multidecadal oscillation, and North Atlantic oscillation, respectively. These findings are vital for predictive adaptation to the impacts of climate variability on water resources.
Suitability of averaged outputs from multiple rainfall-runoff models for hydrological extremes: a case of River Kafu catchment in East Africa
(Springer link:International Journal of Energy and Water Resources., 2020-05-26) Onyutha, C.; Amollo, C. J.; Nyende, J.; Nakagiri, A.
In this study, seven rainfall-runoff models were applied to model daily River Kafu flows from 1952 to 1981. Among others, models from the rainfall-runoff library of the eWater toolkit were applied. Optimal parameters of each model were obtained based on an automatic calibration strategy. Averaging in terms of simple arithmetic mean, hereinafter taken as the multi-model ensemble (MME), was performed to independently and identically distributed events separately extracted from the outputs of the individual models. How well the MME captured variation and frequency of observed hydrological extremes was assessed. Models performed better for high flows than low flows. Absolute model average biases on quantiles with return periods from 1 to 30 years were over the ranges 5.5–83.6% and 11.6–57.7% for high flows and low flows, respectively. It is envisaged that making model structures flexible and performing calibration with objective functions constrained to extreme events can enhance simultaneous capturing of high flows and low flows. The amount of variance in annual maxima series that could be explained by the multi-model ensemble was 73.4% and ranged from 35.1 to 82.5% for the individual models. This made the multi-model ensemble better than outputs from six of the seven models. For the annual minima flows, the multi-model ensemble yielded the smallest root mean squared error but the third largest coefficient of determination. Notably, the suitability of the multi-model ensemble in capturing the hydrological extremes depends on the selected goodness-of-fit measure, approach for combination of model outputs, number of models considered and length of data used.
Suitability of averaged outputs from multiple rainfall-runoff models for hydrological extremes: a case of River Kafu catchment in East Africa
(International Journal of Energy and Water Resources., 2020-05-26) Onyutha, C.; Amollo, C. J.; Nyende, J.; Nakagiri, A.
In this study, seven rainfall-runoff models were applied to model daily River Kafu flows from 1952 to 1981. Among others, models from the rainfall-runoff library of the eWater toolkit were applied. Optimal parameters of each model were obtained based on an automatic calibration strategy. Averaging in terms of simple arithmetic mean, hereinafter taken as the multi-model ensemble (MME), was performed to independently and identically distributed events separately extracted from the outputs of the individual models. How well the MME captured variation and frequency of observed hydrological extremes was assessed. Models performed better for high flows than low flows. Absolute model average biases on quantiles with return periods from 1 to 30 years were over the ranges 5.5–83.6% and 11.6–57.7% for high flows and low flows, respectively. It is envisaged that making model structures flexible and performing calibration with objective functions constrained to extreme events can enhance simultaneous capturing of high flows and low flows. The amount of variance in annual maxima series that could be explained by the multi-model ensemble was 73.4% and ranged from 35.1 to 82.5% for the individual models. This made the multi-model ensemble better than outputs from six of the seven models. For the annual minima flows, the multi-model ensemble yielded the smallest root mean squared error but the third largest coefficient of determination. Notably, the suitability of the multi-model ensemble in capturing the hydrological extremes depends on the selected goodness-of-fit measure, approach for combination of model outputs, number of models considered and length of data used.
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.
Does training improve sanitary inspection answer agreement between inspectors? Quantitative evidence from the Mukono district, Uganda
(MDPI, 2020-10-10) King, Richard; Okurut, Kenan; Herschan, Jo; Lapworth, Dan J.; Malcolm, Rosalind; McKeown, Rory Moses; Moses, Rory
Sanitary inspections (SIs) are checklists of questions used for achieving/maintaining the safety of drinking-water supplies by identifying observable actual and potential sources and pathways of contamination. Despite the widespread use of SIs, the effects of training on SI response are understudied. Thirty-six spring supplies were inspected on two occasions, pre- and post-training, by an instructor from the research team and four local inspectors in the Mukono District of Uganda. SI score agreement between the instructor and each inspector was calculated using Lin’s concordance correlation coefficient. Average SI score agreement between the instructor and all inspectors increased post-training for the Yes/No answer type (0.262 to 0.490). For the risk level answer type (e.g., No, Low, Medium, High), average SI score agreement between the instructor and all inspectors increased post-training (0.301 to 0.380). Variability of SI scores between the four inspectors was calculated using coefficient of variation analysis. Average SI score variability between inspectors reduced post-training for both answer types, Yes/No (21.25 to 16.16) and risk level (24.12 to 19.62). Consistency of answer agreement between the four inspectors for each individual SI question was calculated using index of dispersion analysis. Average answer dispersion between inspectors reduced post-training for both answer types, Yes/No (0.41 to 0.27) and risk level (0.55 to 0.41). The findings indicate that training has a positive effect on improving answer agreement between inspectors. However, advanced training or tailoring of SI questions to the local context may be required where inconsistency of responses between inspectors persists, especially for the risk level answer type that requires increased use of inspector risk perception. Organisations should be aware of the potential inconsistency of results between inspectors so that this may be rectified with appropriate training and, where necessary, better SI design and customisation.
Graphical-statistical method to explore variability of hydrological time series
(Hydrology Research, 2021-02) Onyutha, Charles
Due to increasing concern on developing measures for predictive adaptation to climate change impacts on hydrology, several studies have tended to be conducted on trends in climatic data. Conventionally, trend analysis comprises testing the null hypothesis H0 (no trend) by applying the Mann–Kendall or Spearman's rho test to the entire time series. This leads to lack of information about hidden short-durational increasing or decreasing trends (hereinafter called sub-trends) in the data. Furthermore, common trend tests are purely statistical in nature and their results can be meaningless sometimes, especially when not supported by graphical exploration of changes in the data. This paper presents a graphical-statistical methodology to identify and separately analyze sub-trends for supporting attribution of hydrological changes. The method is based on cumulative sum of differences between exceedance and non-exceedance counts of data points. Through the method, it is possible to appreciate that climate variability comprises large-scale random fluctuations in terms of rising and falling hydro-climatic sub-trends which can be associated with certain attributes. Illustration on how to apply the introduced methodology was made using data over the White Nile region in Africa. Links for downloading a tool called CSD-VAT to implement the presented methodology were provided.
Negative emotions about climate change are related to insomnia symptoms and mental health: cross-sectional evidence from 25 countries
(Current Psychology : Springer, 2021-02-16) Ogunbode, Charles Adedayo; Pallesen, Ståle; Böhm, Gisela; Doran, Rouven; Bhullar, Navjot; Aquino, Sibele; Marot, Tiago; Schermer, Julie Aitken; Wlodarczyk, Anna; Lu, Su; Jiang, Feng; Salmela-Aro, Katariina; Hanss, Daniel; Maran, Daniela Acquadro; Ardi, Rahkman; Chegeni, Razieh; Tahir, Hajra; Ghanbarian, Elahe; Park, Joonha; Tsubakita, Takashi; Tan, Chee-Seng; Broek, Karlijn L. van den; Chukwuorji, JohnBosco Chika; Ojewumi, Kehinde; Reyes, Marc Eric S.; Lins, Samuel; Enea, Violeta; Volkodav, Tatiana; Sollar, Omas; Navarro-Carrillo, Ginés; Torres-Marín, Jorge; Mbungu, Winfred; Onyutha, Charles; Lomas, Michael J.
Climate change threatens mental health via increasing exposure to the social and economic disruptions created by extreme weather and large-scale climatic events, as well as through the anxiety associated with recognising the existential threat posed by the climate crisis. Considering the growing levels of climate change awareness across the world, negative emotions like anxiety and worry about climate-related risks are a potentially pervasive conduit for the adverse impacts of climate change on mental health. In this study, we examined how negative climate-related emotions relate to sleep and mental health among a diverse non-representative sample of individuals recruited from 25 countries, as well as a Norwegian nationally-representative sample. Overall, we found that negative climate-related emotions are positively associated with insomnia symptoms and negatively related to self-rated mental health in most countries. Our findings suggest that climate-related psychological stressors are significantly linked with mental health in many countries and draw attention to the need for cross-disciplinary research aimed at achieving rigorous empirical assessments of the unique challenge posed to mental health by negative emotional responses to climate change.
Changes in precipitation and evapotranspiration over Lokok and Lokere catchments in Uganda
(Bulletin of Atmospheric Science and Technology volume : Springer Link, 2021-03-24) Mubialiwo, Ambrose; Chelangat, Cyrus; Onyutha, Charles
This study analysed long-term (1948–2016) changes in gridded (0.25° × 0.25°) Princeton Global Forcing (PGF) precipitation and potential evapotranspiration (PET) data over Lokok and Lokere catchments. PGF-based and station datasets were compared. Trend and variability were analysed using a nonparametric technique based on the cumulative sum of the difference between exceedance and non-exceedance counts of data. Seasonal (March-April-May (MAM), June-July-August (JJA), September-October-November (SON), December-January-February (DJF)) and annual precipitation exhibited negative trends (p < 0.05). Positive anomalies in precipitation occurred in the 1950s as well as in the early 2000s till 2016. Negative anomalies existed between 1960 and 2000. Both seasonal and annual PET mainly exhibited increasing trend with alternating positive and negative anomalies for the entire period, except in the southern region. The H0 was rejected (p < 0.05) for SON PET in the North and South of the study area. The H0 was rejected (p < 0.05) for DJF PET in the North. However, H0 was not rejected (p > 0.05) for MAM, JJA and annual PET. Positive and negative correlations were observed between PGF and station precipitation varying from one location to another. The PGF-based PET were lower than the observed PET at Kotido by about 40%. Besides, a close agreement was noticeable between PGF-based and MODIS PET from May to November. This showed the need to improve on the quality of PGF data in reproducing the observed climatic data in areas with low meteorological stations density. Nevertheless, the findings from this study are relevant for planning of predictive adaptation to the effects of climate variability on the water resources management applications. Impacts of human factors and climate change on the hydrology of the study area should be quantified in future research studies.
Water availability trends across water management zonesin Uganda
(Atmospheric Science Letters, 2021-06-21) Onyutha, Charles; Asiimwe, Arnold; Muhwezi, Lawrence; Mubialiwo, Ambrose
This study assessed trends in gridded (0.25° × 0.25°) Climate Forecast System Reanalysis (CFSR) precipitation, potential evapotranspiration (PET), and precipitation minus PET (PMP) across the four water management zones (WMZs) in Uganda including Kyoga, Victoria, Albert, and Upper Nile. The period considered was 1979–2013. Validation of CFSR datasets was conducted using precipitation observed at eight meteorological stations across the country. Observed precipitation trend direction was satisfactorily reproduced by CFSR data extracted at five out of eight stations. Negative (positive) values of long-term PMP mean were considered to indicate areas characterized by water scarcity (surplus). Areas with large positive PMP were confined to Lake Victoria and mountains such as Rwenzori and Elgon. The largest negative PMP values were in the arid and semi-arid areas of north and northeastern Uganda. The null hypothesis H0 (no trend) was rejected (p < 0.05) for increasing annual precipitation trends across the various WMZs except in the extreme eastern parts of the Upper Nile, Kyoga, and Victoria WMZs (or areas along the boundary of Uganda and Kenya). The H0 (no trend) was rejected (p < 0.05) for decreasing trends in annual PET over West Nile region of the Upper Nile, western parts of Victoria, and the Albert WMZs. For increasing trend in PMP, the H0 (no trend) was rejected (p < 0.05) across the various WMZs except around the Mount Elgon area. The study findings are relevant for planning of water resources management across the different WMZs in the country.
Long-term climatic water availability trends and variability across the African continent
(Theoretical and Applied Climatology : Springer Link, 2021-06-29) Onyutha, Charles
This study analyzed trends and variability in climatic water availability (CWA) across the African continent using monthly precipitation and potential evapotranspiration (PET) over the period 1901–2015. Climatic water availability was characterized in terms of precipitation minus PET totals. Predictability of the variation in CWA was tested using climate indices. Large positive values of the CWA (or few drought incidents) were confined to areas (such as sub-region along the Gulf of Guinea, the western part of the equatorial region, and the Ethiopian Highlands) that receive large amounts of precipitation. Drought incidence in these areas was generally low and characterized by severity in the range 0–44% indicating moderate to extreme wetness. Areas which experienced increasing CWA or wetting trends were confined within the Tropics. These wetting trends were mostly insignificant (p > 0.05). Drying trends (or decreasing CWA) occurred mainly in areas outside the Tropics. These drying trends (especially in the CWA of the months from April to September) were mainly significant (p < 0.05) over the Sahara desert. CWA variability in the southern and eastern parts of Africa was negatively and positively correlated with Niño 3, respectively. Variability of the East African CWA was also positively correlated with the Indian Ocean Dipole (IOD). CWA variability in West Africa (or Sahel) was negatively correlated with Niño 3. Variability of West African CWA was also linked to changes in the sea surface temperature over the Atlantic Ocean. Based on multiple linear regression, predictability of variation in CWA using combinations of climate indices varied across regions and among time scales. For instance, using combination of IOD and Niño 3 as predictors, up to about 40% and less than 10% of the total variance in CWA across East Africa and area north of the Sahel belt could be explained, respectively.

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