Spatially Disintegrated Multi-Hazard Risk Assessment of Khulna City: A GIS Based Approach

Disaster can occur when some natural and man-caused phenomenon is able to inflict damage on a population or some type of property of human value. Disaster is generally inflicted through a mechanism (i.e., flood, cyclone, earthquake, chemical or nuclear accidents, etc.), which is called a hazard mechanism. Both the hazard mechanism and items of value must be present in the same place for significant damage to occur which can be called disaster. But within an area where a disaster is inflicted, there exists significant spatial variability in terms of the degree and magnitude of both hazard mechanism and damage caused. Besides, due to geophysical and socio-economic and socio-spatial differences, wide differences in terms of vulnerability can be observed within a disaster-inflicted area. Therefore, disaster phenomenon essentially possesses a spatial dimension. Devising an effective disaster management plan in case of any likely disaster event for any particular area fundamentally rely on a detail analysis of the disaster vulnerability of that area based on detailed geographic, socio-economic and socio-spatial information. 

GIS has emerged as a powerful and sophisticated means to manage vast amounts of spatially disaggregated geographic data. It provides a mechanism by which information on location; spatial interaction and geographic relationship of various geophysical and socio-spatial features can be processed, analyzed, and visualized for making more informed decisions which is essential for multi-hazard vulnerability analysis.  Integration of GIS with Data Base Management System (DBMS), Remote Sensing (RS), and digital survey equipment such as Global Positioning System (GPS) may further increase its automation capability and accuracy.

This research aimed at developing an integrated or unified vulnerability index for multiple hazards using GIS. Often vulnerability is assessed for different administrative units (i.e. one index for one administrative area). This is often because of the availability of census data for each administrative area. However, it is very unlikely that all places of a whole city, ward or mouza will be always similarly vulnerable due to some specific hazard. Because the socio-economic conditions, livelihood pattern, housing construction materials, topographic conditions, infrastructural conditions etc. vary significantly on urbanscape. Thus, spatial variability of vulnerability is an obvious phenomenon in urban areas. 

Vulnerability is often hazard specific (i.e. one area may be vulnerable to flooding but may not be so for the cyclones). Again, large number of factors may contribute to the overall vulnerability of Khulna City. When these factors coincide, the effects on vulnerability can be either amplified or diminished, depending on the factors themselves. Thus it is of utmost importance that we know which factors are coinciding where. This will help us identify area-specific problems, solving which vulnerability of an area would be reduced significantly. 

This research has proposed a spatially disintegrated method (not dependent on any administrative units). Moreover, using geo-spatial technologies, more spatial variables (road width, road curvature, distance from hospitals etc.) can be extracted from the maps that would be extremely helpful for revealing the spatial determinants of vulnerability as well. 

Different international and national policies have emphasized the multi-hazard vulnerability assessment. This research is developed in such a way that at the beginning vulnerability is assessed for each of the hazards separately, then all the hazards are combined together to get a multi-hazard vulnerability index. This will reveal the spatially explicit hazard-specific determinant of vulnerability. This research will be extremely useful for determining local government’s area-specific development prerogatives, which would be much more effective, pro-poor, and climate-sensitive.  

• Research Project