Risk assessment and management of rainfall‑induced landslides in tropical regions: a review

Excessive rainfall is considered the major landslide triggering mechanism, especially in tropical climate regions. During rainfall, water infiltrates into the subsurface; reducing the matric suction, increasing pore water pressure, and decreasing the shear strength of the soil. The prevailing unfavourable ground and geomorphological conditions can further exacerbate the vulnerability and severity of catastrophic landslides. Hence, it is vital to identify different landslide mechanisms, key drivers for rainfall-induced landslides, and risk assessment methods for adopting appropriate failure mitigation strategies. This study captures a comprehensive review and in-depth analysis based on 200 articles published in literature including authors own case studies to describe the risk management strategies of rain-induced landslides in tropical countries. First, a clear relationship between the rainfall patterns and the landslide events has been proposed through the comprehensive data sets reviewed. Then key influencing factors for landslides in the tropical region have been identified with in-depth discussion from past reported studies. Moreover, landslide risk assessment and management framework are discussed with the key steps involved. The framework provides a better-structured approach to discuss on identifying, analysing, evaluating, and managing risk associated with landslides. The complex geological conditions, lack of rainfall and impact data, and rapid change in land use make quantitative risk assessment challenging in the tropical region. The review finally recommends effective risk mitigation strategies from the authors' experience on past projects and reported literature case studies. The outcomes from the review are beneficial for engineers and authorities for adopting risk mitigation approaches in tropical regions.