Developing recommendations for producing scenarios for natural hazard risk analysis in data-scarce environments

The development of scenarios is an essential part of many natural hazard risk analyses and assessments. Scenarios help to understand and quantify risks, identify the range of plausible consequences, and examine emerging future developments. Scenarios support informed decision-making, and the requirements to them depend on the type of decisions one wants to support. One example is the quantification of risks for the purpose of prioritizing investments, where the interest lies mainly within the expected overall losses and not the spatial distribution of the damages. By contrast, the spatial and temporal distribution of expected damage is of vital importance for tasks such as stress testing response capacities or risk mapping for spatial planning and response planning.

In data-scarce environments, where hazard and damage-forming processes are not well understood or documented, it is challenging to develop and validate models for comprehensive hazard and risk analysis. In practice, risk estimates are frequently based on a few plausible scenarios; however, it has been shown that the risk can be significantly underestimated or overestimated depending on the number and choice of scenarios that are considered (Ward et al., 2011). With the aim of developing recommendations on robust scenario selection, we structure common decision-making problems according to the demands they place on scenario selection methodologies. Using the example of an alpine catchment we illustrate constraints of some common methodologies. Based on a systematic investigation of influencing factors of the risk estimate, we propose systems of identifying scenarios for different decision-making contexts.

References:

Ward, P. J., H. de Moel, und J. C. J. H. Aerts. „How are flood risk estimates affected by the choice of return-periods?“ Natural Hazards and Earth System Sciences 11 (Dezember 2011): 3181–95. https://doi.org/10.5194/nhess-11-3181-2011.