Multi-hazard risk and the asynergies of structural disaster risk reduction measures: a case study of Afghanistan

Abstract:

Many countries face the risk of multiple hazards. The UNDRR’s Global Platform for Disaster Risk Reduction have called upon the science community for an increased understanding of the complexities of multi-hazard risk (UNDRR 2019). Nonetheless, in the currently prevailing risk assessment paradigm, risk is often represented as static and fragmented in terms of hazard types. While positively influencing the risk of one hazard, DRR measures can have adverse effects on the risk of another hazard type thereby increasing the vulnerability of the built environment, exacerbating impacts and potentially causing compound or cascading disasters. For example, wood-frame buildings tend to perform well under ground shaking but are likely to sustain higher damages due to an inundation than concrete buildings. We refer to these negative impacts between hazards as the asynergy of a DRR measure. Due to the predominantly single-hazard approach, the potential asynergies of DRR measures remain poorly understood.

In a case study of Afghanistan, we calculate the asynergies of structural, building-level DRR measures for floods and earthquakes. To this extent, we develop two scenarios where DRR measured are aimed at either decrease flood or earthquake risk. These scenarios are used to assess the asynergies and to illustrate to what degree a reduction of one risk may actually be offset by an increase in the other hazard’s risk. This is then used to show which type of measure is worthwhile in which area.

An improved capability of understanding risk more holistically would strongly benefit first responders, aid organizations, urban planners and decision makers in designing sustainable DRR measures. We discuss several key potential asynergies of building level DRR measures for floods and earthquakes tailored to decrease the risk of one hazard on the risk of the other hazard.