Effects of geomorphic processes and land use activities on slope stability in Mount Elgon region, Eastern Uganda
Gumisiriza, Turyabanawe Loy
MetadataAfficher la notice complète
This study assessed the effects of geomorphic processes and land use activities on slope stability in Mount Elgon region, in Eastern Uganda. The main objective was to assess the stability of slopes in Mount Elgon so as to map the instability prone areas. To achieve this, the study investigated geomorphic processes and land use practices taking place on slopes and the role of geomorphic processes and land use activities in rendering such slopes unstable. In addition, zonation and mapping of slope instability risk areas, assessment of peoples‟ perception and attitude towards slope failure as well as response to evacuation programmes put in place by government were assessed. Data was collected through field surveys as well as interpretation and analysis of aerial photographs and Landsat imagery. Interaction with land users, planners and local authorities was conducted through questionnaire administration, conducting interviews, and focus group discussions. Data analysis involved both qualitative and quantitative techniques. Qualitative analysis involved computation of non-arithmetic relations. Descriptive statistics and percentages were used while correlation coefficients and chi- square tests were computed to determine the forms and strengths of underlying relationships. The study established that Mount Elgon is a naturally unstable environment with regard to slope stability. Geomorphic processes especially weathering and undercutting of slopes by rivers was found to contribute directly and indirectly to slope instability experienced in the region. Land use activities such as cultivation, construction and associated clearance of forests have aided natural processes to destabilize the already unstable slopes triggering slope failure. The study classified the slopes in the area into slope instability hazard areas according to when slope failure was last experienced and slope instability risk areas based on slide potential as seen from slope gradient. Even though majority (70%) of the respondents expressed awareness of the unstable and landslide prone environment they are living in, they have over time developed an attitude that has led them to ignore landslides even though they disrupt their life when they occur. The coping mechanisms adopted as well as the people‟s response to evacuation programmes following slope failure were established to be popularly in favour of staying (84.5%) rather than evacuation (15.5%) from the risk areas. The study concludes that although natural prerequisites for slope failure are ample and of overruling importance in Mount Elgon, human activities need to be regulated or better still prohibited in order to address the situation. The study provides a landslide inventory and slope stability database upon which policies regarding use of land in slope instability hazard areas can be formulated. The intervention strategies recommended by this study could also offer practical short term and long term remedies where ever a similar problem is experienced. Following such a study, studies on landslide vulnerability assessment, resilience and coping mechanisms related to landslides need to be conducted in the area and other areas that face similar hazards.