A Geotechnical Assessment of Collapsible and Dispersive Soils for Landslide Risk Evaluation: A Case Study of Soche Hill, Blantyre, Malawi

Landslides pose a significant threat to infrastructure, livelihoods, and ecosystems in Sub-Saharan Africa, particularly in regions with complex geological and climatic conditions. This study investigates the geotechnical properties of soils on Soche Hill, Blantyre, Malawi, to evaluate their role in landslide susceptibility. Soil samples (SPs) from five locations were analyzed for key geotechnical parameters, including collapsibility, dispersivity, moisture content, dry unit weight, and Atterberg limits. Results indicate that soils with lower clay content (e.g., SP.2 and SP.3) exhibit high collapsibility, while those with elevated clay content (e.g., SP.4 and SP.1) demonstrate increased cohesion but higher dispersive tendencies. The Atterberg limits reveal that SP.3, with a high plasticity index, is particularly prone to shrink-swell behavior, increasing slope instability risk. Laboratory tests confirm that most soils in the study area exhibit high dispersivity, exacerbating erosion and slope failure risks. Regional climate models predict an increase in extreme rainfall events, further heightening the vulnerability of these soils. The findings underscore the urgent need for targeted geotechnical interventions, including slope reinforcement, improved drainage systems, and vegetation-based stabilization strategies. Future research should integrate hydrological modeling, real-time monitoring, and advanced soil stabilization techniques to enhance landslide risk mitigation efforts.