Utilization of Open Source Spatial Data for Landslide Susceptibility Mapping at Chittagong District of Bangladesh—An Appraisal for Disaster Risk Reduction and Mitigation Approach

Abstract

Since creation of spatial data is a costly and time consuming process, researchers, in this domain, in most of the cases rely on open source spatial attributes for their specific purpose. Likewise, the present research aims at mapping landslide susceptibility at the metropolitan area of Chittagong district of Bangladesh utilizing obtainable open source spatial data from various web portals. In this regard, we targeted a study region where rainfall induced landslides reportedly causes causalities as well as property damage each year. In this study, however, we employed multi-criteria evaluation (MCE) technique i.e., heuristic, a knowledge driven approach based on expert opinions from various discipline for landslide susceptibility mapping combining nine causative factors-geomorphology, geology, land use/land cover (LULC), slope, aspect, plan curvature, drainage distance, relative relief and vegetation in geographic information system (GIS) environment. The final susceptibility map was devised into five hazard classes viz., very low, low, moderate, high, and very high, representing 22 km 2 (13%), 90 km 2 (53%); 24 km 2 (15%); 22 km 2 (13%) and 10 km 2 (6%) areas respectively. This particular study might be beneficial to the local authorities and other stake-holders, concerned in disaster risk reduction and mitigation activities. Moreover this study can also be advantageous for risk sensitive land use planning in the study area.

A Case Study Based Slope Stability Analysis at Chittagong City, Bangladesh

“…The reason behind selecting the power based regressive curve is that the highest value of the coefficient R 2 was found for power curve compared to other curves like linear, logarithmic, exponential, etc. Again, Islam et al (2017) showed that all the failed slopes in the Chittagong City has slope angle (β) > 15 o . Therefore, we assumed the FS values below the crossing point of the line representing tan15 o and the best-fit curve as unsafe and the FS values above the point as safe in terms of rainfall induced landslide hazard in the study region.…”

“…Chittagong city, in the southeastern hilly region of Bangladesh, is a landslide prone city, where almost every year devastating landslides result in casualties and damage to properties (Islam et al, 2017, Mia et al, 2017. Table 1 represents some of the major historic and recent landslide events.…”

“…Unsafe construction on the hills or foothills is the major cause for the worst scenario of landslide events. It is documented that excessive rainfall triggers the landslide phenomenon in Bangladesh, and is more facilitated in many places by hill cutting and deforestation Islam et al, 2017;Mia et al, 2017). Population is growing in this city as well in the hill sites due to continuously incoming population for livelihood and therefore constructions are made more rapidly on the hills and foothills (Islam et al, 2017).…”

“…It is documented that excessive rainfall triggers the landslide phenomenon in Bangladesh, and is more facilitated in many places by hill cutting and deforestation Islam et al, 2017;Mia et al, 2017). Population is growing in this city as well in the hill sites due to continuously incoming population for livelihood and therefore constructions are made more rapidly on the hills and foothills (Islam et al, 2017). Therefore, determination of appropriate and site specific real factor of safety (FS), based on geotechnical parameters of the slope materials where there the hazard has already been taken place, is important and would be really useful for inferring the degree of strength required for slope design.…”

“…km area with a total population of about 2,068,082 (Bangladesh Population Census, 2011). This tropical region experiences monsoon mostly from the month of June to October, with average rainfall recorded more than 2540 mm in this period (Islam et al, 2017).…”