Browsing by Author "Otim, Daniel"

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    Characterizing River Manafwa Floodplain and Adjacent Soils
    (East African Nature and Science Organization, 2024-04-23) Okoth, Joseph Micheal; Otim, Daniel; Kamalha, Edwin
    The objective of this study was to characterise Manafwa River floodplain and adjacent soils. Soil samples were collected from 0 - 20 cm depth in fallowed and cultivated Manafwa floodplain soils for laboratory analysis. Treatments included upland (control), floodplains fallowed for a year, floodplains fallowed for over a year, cultivated floodplains within 5 m and 50 m away from the river banks. Each treatment was replicated three times (3 blocks), and samples collected were analysed for K, Na, available P, total N, exchangeable acidity, pH, organic matter, moisture content, sand, silt, and clay. The soil sampling results were subjected to statistical Analysis of Variance (ANOVA) using Randomised Complete Block Design (RCBD), and the difference between treatment means were dictated using F-, student’s t and F-LSD/pairwise comparison tests. There was statistically no significant (p > 0.05) difference among different floodplains and uplands studied. Upland soils posted 71.67% for the highest pH and 0.09%, 0.87%, 9.74 ppm, 2.23 ppm and 7.264% for the lowest available N, organic matter, Phosphorous, Sodium and Moisture Content, respectively. Cultivated floodplain soil posted highest total P at 29.16 ppm and pH at 6.39% while fallowed floodplains lowest pH at 5.34%, highest available N at 0.32%, highest organic matter at 4.02%, highest K at 21.33%, highest Na at 13.93%, highest exchangeable acidity at 2.32 Cmol/Kg, highest clay content at 14.33%, lowest sand composition at 38.00%, highest silt composition at 54.8% and highest Moisture Content of 32.472%. As depicted by soil fertility analysis results, Manafwa River floodplain and adjacent soils have the capacity to accommodate and boost crop production and productivity. Any nutrients lost to leaching could be gained from subsequent fallowing and sustainable soil fertility management, proper drainage, crop rotation, adding organic manure, and cover cropping, among others
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    Distribution of Floods Frequency of Manafwa River, Uganda
    (East African Nature and Science Organization, 2024-01-24) Okoth, Joseph Micheal; Otim, Daniel; Kamalha, Edwin
    The objective of this study was to analyse Manafwa River flood frequency in Eastern Uganda. Analysis of Manafwa River maximum annual flows from 1949-2015 was undertaken using Log Pearson 3 distribution in comparison with Gumbel, Normal and Log Normal distributions to determine frequency of occurrence and magnitude of extreme floods. Statistical analysis including goodness of fit tests of chi-square, Kolmogorov-Smirnov and Anderson-Darling tests were used to generate the most suitable probability distribution model. The results show quantile magnitudes lowest for Log Normal distribution at 43.59 m3/s and highest for Log Pearson 3 distribution at 51.67 m3/s. The 5-year quantile estimates are highest for Normal and Log Pearson at 70.37 m3/s and 63.99 m3/s respectively. The 10-year quantile estimates are highest for Log Normal and lowest for Log Pearson 3 distributions at 87.57 m3/s and 75.13 m3/s respectively. The 100-year quantile estimates are lowest for Normal and highest for Log Normal distributions at 108.57 m3/s and 154.66 m3/s respectively. The 200-year quantile estimates are lowest for Normal and highest for Log Normal distributions respectively at 114.980 m3/s and 177.16 m3/s respectively. Log Pearson 3 distribution emerged as best fit for data. From the statistical analysis, LP 3 probability distribution presents the most accurate regression coefficient at 0.8486 and the most suitable distribution of goodness of best fit using A-D, K-S and Chi square tests followed by the Gumbel distribution. The tests yield 0.15666, 0.04855 and 0.88502 for A-D, K-S and Chi square tests respectively for the LP 3 distribution. There is an increasing upward trend of the discharges at Manafwa River floodplains at higher probabilities of exceedance across all the probability distributions due to varrying climatic changes and rapid landuse changes in the Manafwa catchment. Manafwa river floodplains have the capacity to accommodate and boost crop production and productivity. Any nutrients lost to leaching could be gained from subsequent fallowing and sustainable soil fertility management including; proper drainage, crop rotation, adding organic manure, cover cropping and among others
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    Effect of Cow Dung Ash and Recycled Concrete Aggregates on the Mechanical and Physical Properties of Concrete: Central Composite Design (CCD) Optimisation
    (East African Nature and Science Organization, 2023-11-15) Nabuuma, Racheal; Tigalana, Dan; Otim, Daniel
    Globally, concrete constructions are dependable due to their performance under diverse conditions and the availability of concrete components. However, the potential for waste concrete is high as a result of changes in human needs. For the concrete industry’s sustainable development, the ability to use recycled concrete is very important. This study aimed to investigate the effect of blending cow dung ash (CDA) with cement and waste concrete aggregates with natural coarse aggregates on concrete’s mechanical and physical properties. The approach adopted involved natural coarse aggregates (NCA) substitution with recycled coarse aggregates (RAs) derived from demolished concrete fragments as well as the use of CDA as a fractional replacement for Portland cement in the production of concrete. Response surface methodology with the central composite design (CCD) option was employed in the establishment of the effect of varying the CDA and RA on the mechanical and physical properties of concrete. Results revealed that while embedding elevated amounts of CDA lowered concrete’s compressive strength, a smaller percentage of less than 10% enriched the concrete strength past that of normal concrete. Furthermore, increases in the RA proportions from 20% to 30% translated to increases in the concrete compressive strength. The 5% CDA and 20% RA, 5% CDA and 30% RA and 10% CDA and 30% RA registered 0.88, 7.67 and 3.54% respectively greater than compressive strengths in the control experiment. In relation to water absorption, increases in proportions of CDA and RAs translated in 3.2% to 5.9% greater than water absorption rates in the control experiment. Therefore, optimised concrete of 8.80% CDA and 31.69% RA gives concrete with compressive strength of 36.82 MPa, 2315.4 kg/m3 bulk density, and 5.18% water absorption. However, CDA/RA concrete should not be used in areas where water accumulates and/ or structures that are in contact with water