Assessing human vulnerability to urban flood hazard using the analytic hierarchy process and geographic information system

Recurrent floods are severely affecting the built assets and people of numerous Indian cities. Urban flood being a comparatively nascent area of research is often dealt with strategies apt for other disasters. The conventional approach of hazard zonation lacks vital information on human vulnerability. This paper addresses this lacuna by identifying vulnerable population and their precise cause of vulnerability for a case study of the city of Guwahati. It is the largest urban and financial centre of north-east India, a disaster hotspot and exclusive link connecting the region and the mainland. Guwahati's 31 municipal wards were gradedparallel for flood hazard and human vulnerability in five categories each (very high to very low). Analytic Hierarchy Process based survey with 16 domain experts and Geographic Information System were used for hazard mapping using factors causing urban flood grouped under environment and urbanization. For vulnerability mapping, questionnaire survey, based on the Human Development Index and other published disaster vulnerability indices, was carried out with 1023 citizens. For 38.70% cases, wards descended by one category from hazard grouping to vulnerability grouping i.e. a ward prone to flooding may not be perceived as equally vulnerable. A strong correlation of 73.5% validated this fact. For obtaining a holistic picture, the top-down approach from experts was tallied with its bottom-up counterpart of citizen's observation. The knowledge will help in making focused policies and prioritize funds for development planning, that are critical for cities of developing countries which lack resources to tackle the growing wrath of urban floods.