Evolutionary leap in large‐scale flood risk assessment needed

Abstract

Current approaches for assessing large‐scale flood risks contravene the fundamental principles of the flood risk system functioning because they largely ignore basic interactions and feedbacks between atmosphere, catchments, river‐floodplain systems, and socioeconomic processes. As a consequence, risk analyses are uncertain and might be biased. However, reliable risk estimates are required for prioritizing national investments in flood risk mitigation or for appraisal and management of insurance portfolios. We review several examples of process interactions and highlight their importance in shaping spatiotemporal risk patterns. We call for a fundamental redesign of the approaches used for large‐scale flood risk assessment. They need to be capable to form a basis for large‐scale flood risk management and insurance policies worldwide facing the challenge of increasing risks due to climate and global change. In particular, implementation of the European Flood Directive needs to be adjusted for the next round of flood risk mapping and development of flood risk management plans focusing on methods accounting for more process interactions in flood risk systems. WIREs Water 2018, 5:e1266. doi: 10.1002/wat2.1266 This article is categorized under: Science of Water > Water Extremes Science of Water > Hydrological Processes Engineering Water > Planning Water

Challenges, Opportunities, and Pitfalls for Global Coupled Hydrologic‐Hydraulic Modeling of Floods

“…Operational global‐ and continental‐scale flood forecasting systems are currently based on a weather prediction module and a rainfall‐runoff hydrological module (Emerton et al, ). However, inclusion of two‐dimensional hydraulic models into large‐scale flood forecast and risk assessment systems has been advocated by a number of studies (e.g., Falter et al, ; Falter et al, ; Huang & Hattermann, ; Schumann et al, ; Vorogushyn et al, ; Zhao et al, ) because it enables more accurate predictions of floodplain inundation dynamics. Moreover, Bates et al () highlighted the need to use hydraulic models to predict the duration of flooding, as this parameter largely affected the impacts of flood events in a number of recent disasters, such as the floods in Queensland (Australia) in 2010–2011, in Thailand in 2011, in England and Wales (UK) in 2014, and, more recently, the 2017 hurricane floods in the United States.…”

Accounting for the uncertain effects of hydraulic interactions in optimising embankments heights: Proof of principle for the IJssel River

“…These studies show the relevance of taking into account the effects of hydraulic system behaviour in flood risk analysis and suggest that its inclusion may lead to different decisions and alternative investment schemes. However, a due consideration of hydraulic system behaviour in the design and planning of flood risk management measures is still lacking: current plans are usually based on flood risk analyses which assume hydraulic loads at each embankment as being independent from those nearby or upstream (De Bruijn, Diermanse, Van Der Doef, & Klijn, ; Vorogushyn et al, ). For instance, flood protection standards in the Netherlands are based on a well‐known and successfully applied embankment height optimization model which was first introduced by van Dantzig () and then developed further by, for example, Brekelmans and den Hertog () and Eijgenraam, Brekelmans, Den Hertog, and Roos ().…”

The role of atmospheric rivers in compound events consisting of heavy precipitation and high storm surges along the Dutch coast

“…To close this gap, this study focuses on the large-scale climatologic conditions leading to the simultaneous occurrence of heavy precipitation and high surge levels. In particular, the study aims to identify the importance of one atmospheric phenomenon that has been suggested to potentially be involved in coastal CEs due to its association with high precipitation and strong near-surface winds, namely atmospheric rivers (Waliser and Guan, 2017).…”