http://41.89.164.27:8080/xmlui/handle/123456789/220 2026-04-13T11:30:44Z 2026-04-13T11:30:44Z Kondowe, Benjamin N. etl.al... http://41.89.164.27:8080/xmlui/handle/123456789/1796 2023-06-13T07:39:15Z 2022-01-01T00:00:00Z

Water quality and ecology of Lake Kanyaboli, Kenya: Current status and historical changes Kondowe, Benjamin N.; etl.al... Small waterbodies are the most threatened freshwater habitats because of the large ratio between their size and the catchment they drain. The present study assessed the current and historical changes in the physical, chemical and biological variables of Lake Kanyaboli, a satellite lake on the northern shores of Lake Victoria in west -ern Kenya. Primary and secondary data on pH, electrical conductivity (EC), dissolved oxygen (DO) concentration, temperature, Secchi depth (SD), and nitrate (NO−3), nitrite (NO−2), ammonium (NH+4 ), soluble reactive phosphorus (SRP), total nitrogen (TN), and total phosphorus (TP) and chlorophyll-a (Chl- a) concentrations were utilized in the present study. The results indicated Secchi depth and chlorophyll-a were the most erratic of all the analyzed environmental variables studied, exhibiting a range of 0.69± 0.29– 0.87 ± 0.34 m and 9.03 ± 0.81– 34.97 ± 3.36 μg/L respectively. Two- way ANOVA yielded no significant interactions between sampling sites and seasons for all the variables. Except chlorophyll-a, there also were no significant differences among the sampling sites for the studied variables. Seasonality yielded significant differences for Secchi depth, dissolved oxygen and chlorophyll-a. The Carlson Trophic Index for Chl- a and SD indicated Lake Kanyaboli is currently eutrophic, while the TP concentra-tion indicated hypereutrophic conditions. The lake, however, has fluctuated betweeneutrophic and hypereutrophic conditions over the past years. Although historical water quality data for the lake is scanty and infrequent, most physical and chemical variables reflected anthropogenic effects on a temporal scale. Interestingly, despite its eutrophic status, the general lake condition is still relatively good, attributable to the buffering effect from the extensive macrophytes fringing it. The present study identified nutrient loading, wetland reclamation and connectivity with the Yala River through a feeder canal as the management issues of critical concern. Accordingly con -tinuous monitoring of the lake's water quality to detect anthropogenic effects is rec -ommended for management intervention purposes.

2022-01-01T00:00:00Z Chepkosgei, E. Ucakuwun, E. K. Nduru, G. M. http://41.89.164.27:8080/xmlui/handle/123456789/1745 2023-02-20T07:53:12Z 2022-01-01T00:00:00Z

Mapping Landslide Susceptibility Along the Nandi Escarpment in Malava Sub-CountyKakamega County, Kenya Chepkosgei, E.; Ucakuwun, E. K.; Nduru, G. M. Landslidesmay occur in hilly terrain due to a combination of factors like deforestation, heavy precipitation, slope steepness and gravity, land use and cover. Whenever they occur, they may result in disasters such as loss of property and/or life. The frequency of landslidesin any area may be high if all the factors that trigger them are prevalent. The main objective of this study was to determine the factors that influence the occurrence of slope failure over space and time and produce a landslide susceptibility map of the Nandi Escarpment in Kabras area of Malava Sub-County. It also presents the capability of a Remote Sensing and GIS based approach to mapping the susceptibility of hilly terrains, with the Nandi escarpment as a case, to slope failure. A slope failure susceptibility map was used to help in identifying strategic points and geographically critical zones thatare prone to landslide risks. The study involved generation of landuse/ landcover maps extracted from Satellite Images, which were taken in the years 1973, 1995 and 2006. SRTM DEM 90m was used in generating slope and contour maps of the area. Soil maps were obtained as secondary data from Moi University Soil Laboratory and Soil Survey of Kenya, while rainfall maps were obtained from the Kenya Meteorological Department (KMD), Kakamega County. A slope failure risk map of Kabras region was produced by overlaying all thematic maps and analysis using GIS was conducted after assigning appropriate ranks and weights to respective variables. Focused groupsdiscussionswere used in data collection and probing historical information on land use changes in the area. The result is a map showing zones with varying degrees of susceptibility to slope failureandslopes steeper than 54owasmore susceptible to slope failures. It is opined that such a map will enable decision and policy makers to identify and implement suitable mitigation measures, with hopes of forestalling future losses in life and property in the area of study.Settlement should belimited to slopes of less than 24osince, according to this study, slopes higher than this are prone to sliding.There is needfor Kenya ministry of lands and physicalplanning to ensuresustainable land use activities are conducted in the slopes of various degrees.

2022-01-01T00:00:00Z Musonye, P. K. Ucakuwun, E. K. Munyao, T. M. http://41.89.164.27:8080/xmlui/handle/123456789/1652 2022-08-24T08:34:19Z 2022-06-01T00:00:00Z

On-Site Runoff Management, Challenges and Prospects in Amalemba, an Urban Informal Settlement in Kakamega Municipality, Kakamega County, Kenya Musonye, P. K.; Ucakuwun, E. K.; Munyao, T. M. This study investigated the challenges and prospects of on-site runoff management in Amalemba informal urban settlement in Kakamega Municipality, Kenya. The study followed a qualitative research design. Visual observations, photography, individual and focus group interviews were used to collect data. The findings indicate that on-site and institutional practices complemented each other in management of runoff. This study therefore affirmed the importance of meaningful participation of residents in runoff management interventions and approaches that sustain ‘socio-human’ capacity for response in relation to impacts of runoff in informal urban settlements. In conclusion, the benefits of catchment-scale model for runoff management, the potential of green infrastructure and the necessity for policy transition to sustainable drainage systems in Amalemba informal urban settlement are of critical importance.

2022-06-01T00:00:00Z Ontumbi, George. M. Ucakuwun, Elias. K. Munyao, Thomas, M. http://41.89.164.27:8080/xmlui/handle/123456789/1435 2021-11-03T08:20:40Z 2020-01-01T00:00:00Z

Variation of Fluoride Levels in Surface Geology: A Study of River Njoro Catchment, Kenya Ontumbi, George. M.; Ucakuwun, Elias. K.; Munyao, Thomas, M. Fluoride levels in water that is higher than the World Health Organization (WHO) recommended levels of 1.5mg/l have raised concerns to the health of human. Subsequently fluoride contamination in water is a pertinent matter that calls for concern by all people and government. This study sought to investigate variation of fluoride levels in surface geology in river Njoro catchment. This study adopted purposive longitudinal survey research designs. In this research, rock samples were collected from 11 purposively selected points along the river Njoro and its tributaries to analyse fluoride levels in the laboratory. The research adopted descriptive data analysis in evaluating fluoride changes as contained in the rocks. The study observed that despite different types of volcanic rock outcrops along Njoro River, there were minimal variations in the levels of fluoride in the river Njoro. The study identified Superficial Deposits of Volcanic Soils with highest fluoride levels (1.575 mg/l) while eutracite Welded Tuffs had the lowest fluoride levels (0.678 mg/l). In Conclusion the rocks within the River Njoro catchment have insignificant contribution to the known elevated fluoride levels contained in sub surface and water in the ground in Njoro River catchment.

2020-01-01T00:00:00Z Ontumbi, George M. Munyao, Thomas M. Ucakuwun, Elias K. http://41.89.164.27:8080/xmlui/handle/123456789/1292 2021-08-23T09:52:37Z 2020-01-01T00:00:00Z

Stratigraphy and Fluoride Levels Variation in Borehole Water: A Case of River Njoro Catchment Ontumbi, George M.; Munyao, Thomas M.; Ucakuwun, Elias K. Boreholes are main sources of water for human use in the Rift Valley. How ever these boreholes have fluoride levels higher than the World Health Or ganization (WHO) recommended levels of 1.5 mg/l and consequently have raised serious health issues. This study sought to determine the relationship between borehole stratigraphy and fluoride levels in ground water in river Njoro catchment. This study adopted purposive longitudinal survey. The study adopted descriptive analysis of the borehole stratigraphy characteristics and fluoride levels recorded. The sources of data included; field surveys which were used to collect data on the borehole fluoride levels data and qualitative analysis of the stratigraphy data. From the results of the study, it was observed that the fluoride levels in boreholes in river Njoro catchment were dependent on the stratigraphy matrix of the boreholes. Therefore lithological formations have an influence on fluoride level River Njoro catchment. This study will form a pool of knowledge to other researchers who have an interest in the study of fluoride occurrence in ground water in the Rift Valley. Further the study will help in assisting the drillers in decision making after geological surveys of where to locate the boreholes.

2020-01-01T00:00:00Z Kanule, J Ng’etich, W. Rotich, S http://41.89.164.27:8080/xmlui/handle/123456789/887 2021-03-24T07:21:34Z 2019-01-01T00:00:00Z

Environ. Res. Commun.1(2019)125003https://doi.org/10.1088/2515-7620/ab50f6PAPERComputational and experimental study of a hydro-dynamicallandslide model based on laboratoryflume tests Kanule, J; Ng’etich, W.; Rotich, S Hydrological factors such as volumetric water content(VWC)and pore-water content(PWC)havebeen cited widely as significant factors that trigger slope failures especially shallow landslides anddebrisflows. Over the years, researchers have studied these processes using a range of physically-basedmodels which in many occasions are either too complex incorporating very many parameters or fail tomimic realfield conditions. The principal objective of this study was to derive and incorporate a set ofphysically-based equations that describe the dependence of slope failures at laboratory scale on VWCinto a factor of safety expression herein referred to as the hydro-dynamical landslide model. Themodel was validated by a series of physical tests on soil samples in the laboratory using the Chep-flume. Results showed a close agreement between computational and experimental data, confirmingthe hypothesis that cohesion, internal friction angle and pore-water pressure are modulated by VWCespecially for slopes with sandy-loam soils. More so, rapid change of soil water content was observedto accelerate build-up of negative pore-water pressures(PWP)which triggers slope failure. Apart fromgiving a simplified expression for the factor of safety, the proposed model circumvents the difficultiesassociated with tedious procedures employed in the measurement of cohesive stress by limiting thetests to only three sets of parameters i.e. VWC, PWP and displacement.

2019-01-01T00:00:00Z Tiegs, Scott Masese, Frank Simiyu, Gelas http://41.89.164.27:8080/xmlui/handle/123456789/561 2020-10-23T08:07:24Z 2019-01-01T00:00:00Z

Global patterns and drivers of ecosystem functioning in rivers and riparian zones Tiegs, Scott; Masese, Frank; Simiyu, Gelas River ecosystems receive and process vast quantities of terrestrial organic carbon, the fate of which depends strongly on microbial activity. Variation in and controls of processing rates, however, are poorly characterized at the global scale. In response, we used a peer-sourced research network and a highly standardized carbon processing assay to conduct a global-scale field experiment in greater than 1000 river and riparian sites. We found that Earth’s biomes have distinct carbon processing signatures. Slow processing is evident across latitudes, whereas rapid rates are restricted to lower latitudes. Both the mean rate and variability decline with latitude, suggesting temperature constraints toward the poles and greater roles for other environmental drivers (e.g., nutrient loading) toward the equator. These results and data set the stage for unprecedented “next-generation biomonitoring” by establishing baselines to help quantify environmental impacts to the functioning of ecosystems at a global scale.

2019-01-01T00:00:00Z Kanule, J. Ng'etich, W. http://41.89.164.27:8080/xmlui/handle/123456789/544 2020-10-15T06:09:07Z 2019-01-01T00:00:00Z

Numerical modeling of translational dynamics forshallow landslides based on flume tests – specialcase of spherical-cap-shaped slope sections Kanule, J.; Ng'etich, W. Slope failures can endanger human life and cause infrastructural destruction and socioeco-nomic loss. Geoscientists have strived to develop constitutive models and real-time slopemonitoring models and systems to abate these processes. Most research studies haveproposed models which describe the dynamics of wedge-shaped soil masses which do notmimic realfield conditions. In this study, failure dynamics of spherical-cap-shaped soil masseson an inclined slope section undergoing purely translational displacement are describedusing empirical models derived from inertial forces in action for varying hydrological condi-tions. Validation of model results was done through experimental tests carried out ona laboratoryflume. Empirical models representing rainfall intensity, soil water content, pore-water pressure, factor of safety, and displacement were derived. More pertinently, theempirical model for the factor of safety is derived considering the moist unit weight of thesoil as opposed to earlier models which focused on saturated conditions only. Model andexperimental results indicate close concurrence, especially for the factor of safety with rootmean square error of 0.0385 andr2of 0.6381. Since the models are physics based, they can beapplied on a variety of rainfall-induced shallow landslides on relatively steep slopes.

2019-01-01T00:00:00Z