Indicator-based risk assessments for urban hazard resilience: an application for flash floods

Urban resilience to environmental hazards can be substantially improved if proactive planning is mainstreamed as a risk mitigation strategy. To enable such transition, a resource-efficient and transparent framework is urgently needed for undertaking vulnerability and risk assessments, to consequently inform risk-aware proactive planning on spatially variable assets with very diverse characteristics. This study proposes an indicator-based risk-assessment framework, for efficiently treating the spatially distributed diverse physical and social components comprising a city network. The proposed framework decomposes the risk to its three main dimensions, i.e. hazard, exposure and vulnerability; with the latter accounting for both the susceptibility of the city network to the considered hazard and its capacity to cope. The inclusion of the capacity to cope as a distinct element, that accounts for both city and building-block level preparatory actions, is a unique feature, much sought in Decision Support Systems, that allows to directly quantify their effectiveness towards risk mitigation. The outcome of spatially variable risk estimates, could be exploited by urban planners and city authorities for undertaking risk-aware urban design, development and resilience enhancement decisions. The framework is demonstrated herein for the case of flash floods but could be tailored to accommodate other types of environmental hazards.