Landslide Inventory in an Urban Setting in the Context of Chittagong Metropolitan Area, Bangladesh

Chittagong Metropolitan Area (CMA) is vulnerable to landslide hazards with an increasing trend in frequency and damage. Devastating landslides have hit CMA repeatedly in recent years. Under a project financed through ICIMOD of Nepal, detail survey has been conducted to prepare an inventory of landslides in CMA. Landslide events have been observed to occur at times of much higher rainfall amount compared to the monthly average. Moreover, rapid urbanization, increased population density, improper land-use, cutting of hills, indiscriminate deforestation and agricultural practices are aggravating the landslide vulnerability in CMA. A landslide inventory is helpful for landslide modelling, runoff modelling and urban land-use planning. A three step methodology, identifying past landslide events from news archive, information from local people and satellite image interpretation has been followed. An inventory of 57 landslide events has been prepared which includes landslide locations, types, dimension, activity, potential causes of landslides, triggering mechanism and slope stabilizing mechanism. This inventory is expected to be a useful resource for future landslide studies in this port city of Bangladesh

Landslide Inventory Report of Chittagong Metropolitan Area, Bangladesh

Landslides are one of the most significant natural damaging disasters in hilly environments. Chittagong Metropolitan Area (CMA), the second largest city of Bangladesh, is vulnerable to landslide hazard with an increasing trend of frequency and damage. Devastating landslides have hit CMA repeatedly in recent years. Landslide events occurred at a much higher rainfall amount compared to the monthly average. Moreover, rapid urbanization, increased population density, improper land-use, cutting of hills, indiscriminate deforestation and agricultural practices are aggravating the landslide vulnerability in CMA. Against this backdrop, it is essential to develop an early-warning system for the hilly communities of CMA incorporating local knowledge. The first step of developing early warning system is to prepare an inventory of all landslide locations. This report shows detailed information of all landslide locations of CMA. A landslide inventory has been prepared for the CMA area. To prepare inventory three steps have been followed. At first, existing achieves of landslide have been studied. Some information that could not have been found from existing achieves were collected from field survey. Participation of local people in field survey was a big part of field survey. Some other data that could not have been collected from field survey were collected through image interpretation. To prepare landslide inventory different factors have been studied, such as: landslide classification, landslide dimensions (different widths and lengths, area ), landslides activity and its distribution (advancing, enlarging, moving, widening etc.), potential causes of landslides (geological, morphological, physical, human induced etc.), landslide triggering mechanism (excessive rain, water level change, earthquake, human activities), factors influencing slope stability (gradient, slope geometry, stress, vegetation, disturbance etc.). Study results on each factor have been discussed in this inventory report. This inventory report also covers different social and physical aspects of landslide vulnerable people. This report gives a glance of road network, housing pattern, drainage condition of the adjacent areas of landslide locations. Socio economic condition of people living in landslide vulnerable areas has also been studied and presented in this report. This report presents detailed landslide conditions and possible risk that may arise from it in CMA area