Abstract:
Disasters like earthquake, tropical storm, flood or drought, etc. are increasing both in number and severity. Like other disasters, waterlogging-induced human losses are not common. But financial and infrastructural damage is increasing in different cities every year due to waterlogging. So, from the investment perspective, it is important to know about an area's vulnerability due to waterlogging. This research aimed at developing an index to identify the vulnerability of an area due to waterlogging and applying the tool to look at its consistency and relevance in real-world scenarios. Bearing those in mind two objectives have been set for this research. The first objective was to develop a composite index for waterlogging and the second objective was to apply the composite index in Chattogram City Corporation (CCC) area to find out the vulnerability of different areas of the city to waterlogging. To fulfill the first objective, through extensive literature review considering global and local factors of waterlogging 25 factors have been found. After then, from expert opinion survey five factors related to waterlogging have been identified. Those five factors were Surface Runoff, Slope, Tidal Water Effect, Distance from drainage network, and Solid waste management. Then those factors were weighted using the AHP method. Finally, the Composite water logging index (CWLI) has been developed by combining all factors and weightage related to waterlogging from expert opinion survey. To fulfill the second objective, the CWLI was applied to the CCC area to look at its consistency and relevance in real-world scenarios. The surface runoff of CCC was estimated utilizing Soil Conservation Service Curve Number (SCS-CN) method. Other four attribute map slope map, tidal water effect map, distance from drainage network map, and solid waste map also prepared using different GIS techniques. After then all layers were overlaid together using the Weighted Sum tool of ArcGIS. The weightage maps were classified into Five (5) classes using the Natural breaks (Jenks) classification method. However, from the vulnerability map it has been seen that 10% area falls into very high, 18% area falls into high, 31% area falls into moderate, 18% area falls into low and 23% of the area falls into very low vulnerable areas. Finally, based on the study it can be concluded that if the government and other concerned authorities take the necessary steps, the vulnerability of water logging can be reduced to an extent tolerable to the city people. In addition, the developed tool could be used for other cities in Bangladesh that were facing waterlogging.
Key words: Waterlogging, Vulnerability, CWLI, Surface Runoff, AHP, GIS.
