Year: 2012
Type: article
Abstract: The consideration of risk has been a major step towards a more integrated view on the prospective impact of floods. In particular it involves flood hazard, with its magnitude and probability on the one hand, and social, economic and ecological flood vulnerability on the other. In the meantime numerous approaches to risk assessment have been developed. The increase in the number of people affected by floods and the rise in economic damage, as seen from international observations and reported by the insurance sector, indicate a significant change of risk. This calls for further advancement in science and practice for the treatment of the long-term dynamics of risk. The question is: how may future change be dealt with in flood risk management? The answer would assist the preparation for expected alterations of flood risk and ensure a reliable performance of investments in flood risk reduction measures in the future, just to mention two of the more important aspects. A closer look at the processes that generates flood risk shows a number of factors prone to change. These factors are, essentially, climate, land use, social and economic conditions, available technologies, and policy. Every change has its drivers. For instance climate change is triggered by greenhouse gas emissions. Moreover each driver has a specific dynamic ranging from a few years with respect to economic development to several decades for the changing climate. Large-scale foresight studies have been carried out in a number of regions of the world to explore the future flood risk (e.g. the UK Foresight Future Flooding, the Chinese Taihu basin and the German VERIS-Elbe research projects). They are mainly based on scenario-planning approaches using principal storylines of development to contrast, for example, a market-oriented future with a sustainable future. These studies have contributed to the understanding of the variability in the (risk) systems of countries and river basins, calculating the effects of the scenarios on flood risk. They substantiated the varying influence of the above-mentioned factors and drivers. In some cases climate change seems to be the major cause of change, whereas in other cases land use change or social developments play the most important part. The principal assumptions of societal development, the large scale of the investigations and the limited resolution of their outcomes make some of the studies difficult to interpret for local and regional decision-makers. This is particularly true if global scenarios are transferred to a regional scale without a more detailed reflection of the site-specific situation. In many cases data and tools for comprehensive exploration of local and regional systems are lacking. Therefore further efforts are needed to improve the quality and resolution of scenario-planning exercises and the practical usability of their results, with the overall aim of displaying (inherent) uncertainty of alternative scenarios and (epistemic) uncertainty from data and models especially as bandwidth in risk assessment. The quantification of uncertainties is one thing, their treatment in the societal risk management process is another. This brings the decision-making issue of dealing with future change into play. Although decision-making under uncertainty is a common item in business economics, its use is less common in the realm of public flood risk management. Reasons for that may be long-term planning procedures that involve broad stakeholder involvement and require an unambiguous budget allocation. However this should not lead to the suppression of inevitable future uncertainties. In contrast there are a number of ways of facing these challenges. An initial point of course is the acceptance and uptake of the calculated information on uncertainties, maybe with the aid of graphs and maps showing uncertainty bands with upper and lower values. It helps to specify the scope of possible developments that is sometimes reflected in the so-called uncertainty coefficient in the design level of flood defences. Another point is the analysis of risk reduction measures under different scenarios of change. Here the performance of individual measures or portfolios of measures under various boundary conditions can be designated as robustness. In addition the adaptability and flexibility of measures can be considered at which adaptability refers to a possible alteration of measures to future requirements and flexibility to the means of achieving this alteration. For example there are now dike constructions implemented that allow heightening the crest by the use of flood walls (low flexibility) or mobile elements (high flexibility). Reduction of vulnerability and increase of resilience could be a so-called ‘no regret’ option because it would have positive effects even if the future change would not significantly affect the system. However influencing vulnerability and resilience should also take the changing society into account. For example more advanced building methods are not always more resilient to flooding. External insulation of buildings can be very effective in reducing energy use but can be highly susceptible to flooding. A further key point refers to the societal management process itself. In developing strategy decision-makers need to learn how to explore the funnel of possible future development pathways and to handle resulting uncertainties. Exploiting the past as a basis for understanding the future seems to be too limited given the rapid development of society and the expected significant change of the global climate. Following implementation of explorative strategies decision-makers should apply adaptive management using information of real system performance based on monitoring. Traditionally observations have focused on flows and water levels, whereas in-depth time series of affected people and damage are often missing or limited to rough large-scale estimates only. Moreover the success of previous risk reduction measures is not always well documented so that future effects of the measures are difficult to predict. Both explorative strategies and adaptive management lead to a number of requisites for the societal risk management process, such as the long-term cooperation of actors with common learning on systems behaviour and the joint presentation of future uncertainties and agreed actions. Although flood risks should be accomplished within multisectoral, cross-border and multilevel groups in any case, collaboration with respect to future change requires particularly structured and more permanent networks. Comprehension of future change and uncertainties involved should also reach the people at risk. This assists them in the derivation of their own strategies to cope with changing conditions. However success factors for the explorative strategies and adaptive management of decision-makers, and associated public involvement are not well understood. Thus further research in this field is indispensable. This cross-disciplinary topic with its relevance for both science and practice is a typical subject for the Journal of Flood Risk Management. We are happy that we have already been able to publish a number of related international papers, and we look forward to furthering knowledge in this area through our forthcoming issues. Jochen Schanze Associate Editor
Source: Journal of Flood Risk Management
Author: Jochen Schanze
Language: English
Subfield: Global and Planetary Change
Field: Environmental Science
Domain: Physical Sciences
SDG: Climate action
Open Access status: bronze
OpenAlex ID: W2106275665