Landslide
Landslides have started to become a major hazard especially in hilly areas of the country which make up 18% of the total area of the country. Usually triggered by heavy rainfall, landslides can cause extensive damage to human settlements and activities on the slopes (National Plan for Disaster Management, 2020).
FOREWARN Bangladesh developed an experts group for landslide who supports the development of Landslide Vulnerability Analysis in Bandarban and Rangamati district in Bangladesh. A landslide susceptibility map was developed using a frequency ratio model. The landslide susceptibility map of the study area showed very low, low, moderate, high, and very high landslide susceptibility zones of the study area. The model established the relationship between landslide conditioning factors and landslide distribution map by integrating several factors, such as elevation, slope aspect, slope curvature, topographic wetted index (TWI), rainfall, normalised differential vegetation index (NDVI) and land use and land cover (LULC) etc. The analysis also revealed the socio-economic, political instability and vulnerability of the selected areas.
Forecast
The early warning system issues alerts based on soil moisture and rainwater supply thresholds to warn the public and authorities about landslide hazards. In Bangladesh, there is currently no specific landslide warning system, but the Bangladesh Meteorological Department (BMD) monitors and predicts all climate and meteorological phenomena, including rainfall. The Bangladesh University of Engineering and Technology-Japan Institute of Disaster Prevention and Urban Safety (BUET-JIDPUS) initiated the development of an information system in 2014 to provide landslide early warning alerts to vulnerable communities. Recommendations, including precipitation threshold values, were established for Cox’s Bazar and Teknaf municipalities, along with corresponding alert systems for the target communities.
Impact
The urbanised hilly areas of Chattogram and Chattogram hill tracts, with elevations of 60-150 metres and 600-900 metres above sea level, are highly susceptible to landslides. Prolonged rainfall, especially during the monsoon season (568 mm to 1404 mm), triggers 83% of landslides in these vulnerable regions. Notably, a major landslide in 2017 caused 171 casualties and resulted in a humanitarian response plan addressing $2.23 billion in economic loss, 98,491 affected people, 4,484 displaced individuals, and 22,851 damaged houses. Previous reports indicate at least 10 smaller landslides between 1990 and 2012, claiming the lives of 404 individuals. The calculated risk index for landslides, based on seven indicators, indicates very high impact in 2 (40.0%) districts, medium impact in 2 (40.0%) districts, and low impact in 1 (20.0%) district, making landslides a major concern for the hilly areas of the country.