Landslide Inventory, Hazard Analysis and Prediction Mappings in the Chittagong Hill-Tracts (CHTs), Bangladesh: A Case Study of Rangamati Municipality Using GIS Techniques

Bangladesh, a disaster-prone country is frequently affected by various natural calamities including landslides. This study is centered on landslide hazard analysis and prediction mapping in Rangamati Municipality of the Chittagong Hill Tracts. The thrust has been to take a landslide inventory including identifying the factors that may have contributed to the massive landslides that occurred in the study area in 2017. To conduct the research, the present study used different categorical data such as geo-locational, geological, topological, hydrological, meteorological-rainfall, and environmental, and processed those using the GIS techniques. The vulnerability map preparation was done using the weighted overlay method. The analytic process involved fifteen causative factors responsible for landslide occurrence, i.e. elevation, slope, aspect, plan, and profile curvature, Topographic Wetness Index, Stream Power Index, distance to water, distance from the road, an array of 30 years (1988–2018) rainfall patterns, geology, distance from the fault line, NDVI, land-use and Land-cover, and population distribution data were used and re-classified into different classes. Based on the literature review and field observation, those layers and classes were assigned to different weight values. For landslide inventory mapping, a GPS machine with an accuracy of 3–5 m was also utilized to collect geographic information from 70 discrete locations. The result is a landslide vulnerability map that has been produced with three distinct vulnerable zones, i.e. low (36.95%), moderate (19.01%), and high (4.10%) including the lake (39.94%) area. The results are verified for managing landslide hazards, mitigating their effects, and planning land use for upcoming development in the region.