This study aimed to characterize the topographic effect on landslides attributes and explore the implications on risk management in a tropical mountainous environment. A database was constructed based on landslide inventory from field surveys supplemented by desk research. The topographic parameters were derived from STRM DEM of a 30 m resolution for the study area. The analysis of the data was conducted in Arc GIS 10.5 environment. The relationship between landslides and topographic conditioning factors was analysed using the Frequency Ratio model. Results revealed that most landslides were distributed within the altitudinal range of 1500 to 1800 m a.s.l. on moderately steep slopes (15 o-20o) in concave curvatures (hollows). Shallow slides mainly debris flows and debris slides were predominant. Most slope failures were initiated on mid to upper slope positions in either new or old scars. Some runout depositions of large slides ended in streams thus undermining water quality. The findings on topographic parameters have implications and yet landslide risk management by the local population was generally inadequate. Any efforts toward effective landslide risk management should prioritise greening the sensitive topographic hollows and old scars particularly on mid to upper slope positions.

Analyzing the dominant forms and extent of land cover changes in the Mount Elgon region is important for tracking conservation efforts and sustainable land management. Mount Elgon’s rugged terrain limits the monitoring of these changes over large areas. This study used multitemporal satellite imagery to analyze and quantify the land cover changes in the upper Manafwa watershed of Mount Elgon, for 42 years covering an area of 320 km2. The study employed remote sensing techniques, geographic information systems, and software to map land cover changes over four decades (1978, 1988, 2001, 2010, and 2020). The maximum likelihood classifier and post-classification comparison technique were used in land cover classification and change detection analysis. The results showed a positive percentage change (gain) in planted forest (3966%), built-up (890%), agriculture (186%), and tropical high forest low-stocked (119%) and a negative percentage change (loss) in shrubs (−81%), bushland (−68%), tropical high forest well-stocked (−50%), grassland (−44%), and bare and sparsely vegetated surfaces (−14%) in the period of 1978–2020. The observed changes were concentrated mainly at the peripheries of the Mount Elgon National Park. The increase in population and rising demand for agricultural land were major driving factors. However, regreening as a restoration effort has led to an increase in land area for planted forests, attributed to an improvement in conservation-related activities jointly implemented by the concerned stakeholders and native communities. These findings revealed the spatial and temporal land cover changes in the upper Manafwa watershed. The results could enhance restoration and conservation efforts when coupled with studies on associated drivers of these changes and the use of very-high-resolution remote sensing on areas where encroachment is visible in the park.

This study aimed to characterize the topographic effect on landslides attributes and explore the implications on risk management in a tropical mountainous environment. A database was constructed based on landslide inventory from field surveys supplemented by desk research. The topographic parameters were derived from STRM DEM of a 30 m resolution for the study area. The analysis of the data was conducted in Arc GIS 10.5 environment. The relationship between landslides and topographic conditioning factors was analysed using the Frequency Ratio model. Results revealed that most landslides were distributed within the altitudinal range of 1500 to 1800m a.s.l. on moderately steep slopes (15 o -20 o ) in concave curvatures (hollows). Shallow slides mainly debris flows and debris slides were predominant. Most slope failures were initiated on mid to upper slope positions in either new or old scars. Some runout depositions of large slides ended in streams thus undermining water quality. The findings on topographic parameters have implications and yet landslide risk management by the local population was generally inadequate. Any efforts toward effective landslide risk management should prioritise greening the sensitive topographic hollows and old scars particularly on mid to upper slope positions.

Landslides continue to occur in the Elgon region despite interventions such as tree planting initiatives aimed at restraining them. The current study assessed the mechanical properties of six selected agroforestry tree roots on slope stability with a keen focus on root tensile strength, soil shear strength, and index of root binding. A standard deviation ellipse method was applied to model the spatial distribution patterns of selected agroforestry trees. Tree-landslide relationship was tested using the Pearson correlation method while root tensile and soil shear strength with a one-way (ANOVA) and descriptive statistics respectively. Species distribution results indicate a high dispersion rate of Croton macrostachyus and Markhamia luteaacross the study area and high concentration of Albizia coriaria downstream. A weak negative correlation (r = -0.20 < 0.01) was reported between diameter at breast height and landslide size. Tensile strength results observed a significant difference among species with (F (5, 573) = [18.161], p < 0.001) and Grevillea robusta (3.02±1.217kg/mm²), Albizia coriaria (2.53±1.382kg/mm²), and Markhamia lutea (2.28±1.01kg/mm²) as the best performers. The best shearing species was Albizia coriaria with average shear strength (52.46±10.24) kpa followed by Markhamia lutea (50.70±15.47) kpa. The Eucalyptus spp. on the other hand underperformed with average shear strength of (46.75±12.92) kpa. In conclusion, the presence of trees reduces landslide risk in an area and DBH is a very important guiding factor. Grevillea robusta, Albizia coriaria, andMarkhamia lutea emerged as best performers in terms of root tensile strength and soil shear strength hence their suitability for enhancing slope stability. However, Eucalyptus Spp., which is widely favoured in the region for its rapid growth was the worst performer with very low shear strength. Therefore, careful consideration of the tree characteristics is essential during promotion campaigns for slope stability in fragile environments.

Globally landslides occurrence is reportedly frequent particularly in the mountainous regions causing both direct and indirect effects to various sectors including the road transport. Existing literature reveals limited assessment of road vulnerability to landslides in the mountain regions in Africa. The objective of this study was to investigate the risk to different segments of the road network in the Mt Elgon region. A Fuzzy logic model was used to assess and map the landslide susceptibility of the study area. A total of 478 landslide sites were used in the model development. Ten conditional factors were applied for generating the dataset for training and validation of the model. The results reveal that mid to high altitude steep and rugged areas are more susceptible to landslides. The model performance was good as revealed by high Area Under the Curve (AUC) of 83% and thus can be relied upon in landslide susceptibility mapping. The hotspot segments, which are high risk sections of the road network need to be prioritized for monitoring so as to initiate and strength existing risk mitigation strategies.