Influential Factors of Landslide Occurrence in the South-Eastern Part of Bangladesh

Abstract

Landslides pose an intensifying and recurring hazard in the southeastern region of Bangladesh, especially in Cox’s Bazar district. It mainly occurs due to various causative, triggering, and anthropogenic factors. This study investigated the significant causes of landslide incidents in high, moderate, and less landslide-vulnerable locations of Ramu, Ukhiya, and Teknaf subdistricts in Cox’s Bazar district. The research used primary and secondary data regarding the determinants of landslides. As a part of primary data collection, a triangulated approach involving soil analysis on 22 soil samples, topographic mapping on slope angle and elevation, and a semi-structured questionnaire survey on 300 respondents was used for this study. Monthly total rainfall data (2000-2018) were collected from the Bangladesh Meteorological Department as secondary data. Findings revealed that sandy loam or loamy sand soils with low cation exchange capacity (4.9-9.4 cmolc/kg) and slightly acidic pH (4.9-5.7) and steep slopes (12°–21°) at elevations ranging from 89 to 177 meters were the common characteristics of high landslide vulnerable locations in the study area. Survey responses attributed that heavy rainfall in June was identified as the primary triggering factor in 63.7% of landslides in the study area. Regression analysis also showed a strong correlation between monthly total rainfall and the percentage of monthly landslide incidence. Deforestation, jhum cultivation, hill cutting, and refugee settlement were also identified as significant anthropogenic activities that are related to landslide occurrence. The findings of the study can be applied in disaster risk reduction, urban planning, environmental management, and geotechnical engineering. It offers a scientific foundation for policymakers, local authorities, and development agencies to implement slope stabilization, strengthen environmental regulations, and promote community awareness. Overall, it supports the development of integrated resilience strategies for landslide-prone regions in hilly areas at the national and international level.