Browsing by Author "Joel Webster Mbujje"

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Flood analysis and hydraulic competence of drainage structures along Addis Ababa light rail transit
(Journal of Environmental Science and Sustainable Development, 2025-02-11) Moses Kiwanuka; Seleshi Yilma; Joel Webster Mbujje; John Bosco Niyomukiza
The occurrence of flooding events and the associated risks are increasing in the urban areas of most developing countries. Flooding in any circumstance causes major stresses on affected area’s economic, social and environmental regimes. Therefore, the current study presents a flood analysis and hydraulic competence of existing drainage structures on some selected roads of Addis Ababa City, after integration with Addis Ababa Light Rail Transit (AALRT) Drainage Systems. The existing side drains and cross drainage structures located within the study area were inspected and assessed to ascertain different aspects relating to their performance. Different watersheds were delineated. Hydrological analysis was then carried out using Geospatial tools such as ARCGIS, ARCSWAT, and HEC GEOHMS to determine the different watersheds contributing to the flows. The flows were obtained from the rational method for areas less than 0.5 km2 and HEC HMS for areas greater than 0.5 km2. The hydraulic analysis was carried out using HY-8 for the culvert and the Hydraulic toolbox for side drains. It was found from field surveys and measurements that the existing side drain of 900 mm circular pipe could not convey the maximum flow. The existing box culvert, which comprised of one barrel was able to convey the design flow of 29.52 m3/s with a headwater elevation of 2300.94 m. The existing box culvert was sufficient in conveying the designed flow since its headwater elevation was lower than that of the roadway elevation. However, observations like the presence of accumulated silt, debris within most side drains, and an undersized side drain reduced its hydraulic competence. The undersized side drain was redesigned by increasing its diameter to 1200 mm. The study acts as a yardstick for drainage assessment, especially for existing structures, an indicator for identifying the most flood-prone areas along the railway track. It recommended an intermediate cross culvert before Lancha, regular desilting, and putting screens at inlets of side drains and some distance before the entrance of the culverts. Periodic maintenance of the existing drainage structures and widening of the pipe conduits for the side drains to about 1200 mm for easy maintenance is also necessary
Investigation on the potential use of waste paper to produce papercrete bricks
(AIP Conference Proceedings, 2025-02-17) John Bosco Niyomukiza; Bernard Joseph Odeke; David Owori; Paul Tiboti; Moses Kiwanuka; Joel Webster Mbujje
A significant demand has been placed on the building material industry, especially in the last decade due to the increasing population, which causes a chronic shortage of building materials. The current study aims at utilizing waste paper to produce papercrete bricks and study their engineering properties, a step towards sustainable development. Papercrete is rapidly gaining popularity in the building construction industry worldwide because of its environmental friendliness, low-cost and lightweight. The study considered literature and related ideas up to conceptualization and design of the trial ratio used in testing. Trial mixes of paper sludge, sand, and cement at different proportions made papercrete bricks of dimensions 220×110×102 mm. The tests conducted included compressive strength and water absorption. The mixes of paper sludge, sand, and cement in the ratio of 50, 35, and 15%, respectively, gave the best results. The compressive strength increased with the increase in the curing period. The rate at which the papercrete bricks absorbed water reduced as the curing period increased for all the papercrete trial mixes. It was concluded that percentages of paper sludge less than 50% are recommended for non-load bearing walls such as parapet walls and partition walls.