Susceptibility of Chetambe Hills to Landslides and their Socio-Economic Significance in Bungoma County, Kenya
Muchuma, Kandawala Fred
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Landslides in most of the world's mountainous and hilly regions pose a substantial threat to human life and infrastructure. As geomorphological phenomena, all hills and mountains are prone to landslides. The current study sought to determine susceptibility of Chetambe Hills to landslides and their socio-economic significance in Bungoma County, Kenya. The study specifically determined the influence of slope angle and settlement changes on landslide susceptibility, determined landslide susceptibility of Chetambe Hills, examined the elements at risk in the event of landslide occurrence on Chetambe Hills and their socio-economic significance and established preventive and mitigation measures to landslide susceptibility. The study used a mixed research design involving qualitative and quantitative methods of data collection. Study design involved use of questionnaires, interviews, Focused Group Discussions, observations, photography, field survey, Remote Sensing and content analysis of secondary data. Field survey involved mapping of the Hills, measurements and observations. Remote Sensing and GIS were used to retrieve temporal Landsat images of the Hills to establish anthropogenic and land cover variability between 2000 and 2015. Questionnaires and interview schedules were used targeting households residing on and around the hills, the area Chief and officials from the Western Region Geological Centre. Land cover maps were derived from Landsat data base at 30m resolution and slope susceptibility was based on landslide occurrence and non-occurrence. Qualitative data was analysed by determination of frequencies, percentages and means and the results were presented on maps, tables, graphs and charts. Quantitative data was analysed by GIS based on explicit spatially derived variables that aid in landslide occurrence, namely land cover maps and slope. A Logistic Regression model in R was used to regress landslide occurrence and non-occurrence against slope. The statistical significance of slope stood at a p value of less than 0.05 hence making the variable slope angle to be significant for deriving the landslide susceptibility map. The study that hypothesized that Chetambe Hills had no statistically significant association between slope angle and susceptibility to landslides was rejected. However, the study hypothesis which stated that high immigration rate has an impact on settlement density and pattern, land use variability and landslide susceptibility on Chetambe Hills was accepted. The study revealed that most of the low susceptibility areas correspond to flat areas especially on the eastern slopes of the Hills, while steep slopes near Webuye town on the western side of the slopes were highly susceptible. The study recommends that the National Government should partner with the County Government and other agencies to sensitize the communities on Chetambe Hills about the risks associated with encroachment on protected areas. The study noted that existing legislation on land use policy prohibiting settlements and farming on Chetambe Hills was not fully implemented, hence continued encroachment. The study therefore recommends that families should use the land in a manner that minimizes its susceptibility to landslides. The study further recommends that the local authorities need to take their rightful role in physical planning and reclamation of Chetambe Hills through reforestation. The study finally recommends that the Ministry of Lands should promptly address the issue of land ownership on Chetambe Hills.