Setting up of indices to measure vulnerability of structures During a flood

Abstract

Computation of flood extents and identification of vulnerable elements help to take mitigatory measures effectively and efficiently during a disaster. This is a baseline study carried out to examine how effectively the vulnerability of a small administrative division that depend on the type and facilities of existing structures can be assessed. In this study the flood extent of upper reaches of Kalu-Ganga River in Sri Lanka for a rainfall of 100 year return period was derived using HEC-HMS and HEC-RAS software. Building vulnerability within the administrative divisions affected by floods were derived using census data. Subsequently, flood risk maps with respect to structures due to 100 year return period rainfall were developed based on vulnerability derived from census data and the developed flood hazard maps. This approach could be used to identify high risk administrative divisions during a disastrous flood event to organize relief aids. It further helps in taking post disaster mitigatory measures according to the vulnerability levels of the buildings in each administrative division. Identification of crucial factors that influence vulnerability helps to reduce vulnerability and to mitigate the risks involved in future flood events.