Browsing by Author "Okoth, Joseph Micheal"

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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