Development and application of flood vulnerability indices for various spatial scales

Human population world wide is vulnerable to natural disasters, which are increasing due tothe consequences of socio-economical and land-use developments and due to climate change.In recent years the impacts of floods have gained importance because of the increasingamount of people who are affected by its adverse effects.In this study a methodology to compute a flood vulnerability index, based on indicators, isdeveloped, aiming at assessing the conditions which favour flood damages at various levels:river basin, sub-catchment and urban area. This methodology can be used as a tool fordecision making to direct investments at the most needed sectors. Its implementation couldguide policy makers to analyse actions towards better dealing with floods.The methodology involves two concepts. First, vulnerability, which covers three relatedconcepts called factors of vulnerability: exposure, susceptibility and resilience. The otherconcept concerns the actual flooding; understanding which elements of a system is sufferingfrom this natural disaster. Four main components of a system are recognized which areaffected by flooding: social, economical, environmental and physical components. Theinteraction between the vulnerability factors and the components serves as the base of theproposed methodology.The developed methodology distinguishes different spatial scales of flood vulnerability: riverbasin, sub-catchment and urban area. This allows a more in-depth interpretation of localindicators and pinpoints actions to diminish focal spots of flood vulnerability. The largerscales in international committees to identify and develop necessary plans actions to deal withfloods and flooding. The smaller scales aim to improve the (local) decision making process byselecting action plans to reduce vulnerability at local and regional levels.The methodology has been applied in various case studies spatial scales, which resulted ininteresting observations on how vulnerability can be reflected by quantifiable indicators. Thetesting results indicate that the FVI of a river basin as a whole can be better reflected by theaverage FVI of its sub-catchments, thereby improving decision-making processes at regionallevels. However, the average FVI of urban areas does not reflect the FVI of the sub-catchmentor river basin in which they are located.To fully understand the capacity of the FVI methodology, it is recommended to continue withadditional case studies to carry on with the search for more useful indicators, refinement ofthe equations and enhancement of the concepts. In addition, an international network ofknowledge institutes could contribute to the further development of flood vulnerability atdifferent spatial scales