Browsing by Author "Van Dongeren, Ap"
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- Introduction to RISC-KIT: resilience-increasing strategies for coastsPublication . Van Dongeren, Ap; Ciavola, Paolo; Martinez, Grit; Viavattene, Christophe; Bogaard, Tom; Ferreira, Óscar; Higgins, Ruth; McCall, RobertIn this paper an introduction is provided to the RISC-KIT project’s goals, products and applications, which is the subject of this Special Issue. Subsequent papers provide the details on the developed tools and their application on ten case study sites in Europe.
- Predicting coastal hazards for sandy coasts with a Bayesian NetworkPublication . Poelhekke, Laurens; Jager, Wiebke S.; Van Dongeren, Ap; Plomaritis, Theocharis A.; McCall, Robert; Ferreira, ÓscarLow frequency, high impact storm events can have large impacts on sandy coasts. The physical processes governing these impacts are complex because of the feedback between the hydrodynamics of surges and waves, sediment transport and morphological change. Predicting these coastal changes using a numerical model requires a large amount of computational time, which in the case of an operational prediction for the purpose of Early Warning is not available. For this reason morphodynamic predictions are not commonly included in Early Warning Systems (EWSs). However, omitting these physical processes in an EWS may lead to potential under or over estimation of the impact of a storm event.To solve this problem, a method has been developed to construct a probabilistic Bayesian Network (BN). This BN connects three elements: offshore hydraulic boundary conditions, characteristics of the coastal zone, and onshore hazards, such as erosion and overwash depths and velocities. The hydraulic boundary conditions are derived at a water depth of approximately 20 m from a statistical analysis of observed data using copulas, and site characteristics are obtained from measurements. This BN is trained using output data from many pre-computed process based model simulations, which connect the three elements. Once trained, the response of the BN is instantaneous and can be used as a surrogate for a process-based model in an EWS in which the BN can be updated with an observation of the hydraulic boundary conditions to give a prediction for onshore hazards.The method was applied to Praia de Faro, Portugal, a low-lying urbanised barrier island, which is subject to frequent flooding. Using a copula-based statistical analysis, which preserves the natural variability of the observations, a synthetic dataset containing 100 events was created, based on 20 years of observations, but extended to return periods of significant wave height of up to 50 years. These events were transformed from offshore to onshore using a 2D XBeach (Roelvink et al., 2009) model. Three BN configurations were constructed, of which the best performing one was able to predict onshore hazards as computed by the model with an accuracy ranging from 81% to 88% and predict events with no significant onshore hazards with an accuracy ranging from 90% to 95%. Two examples are presented on the use of a BN in operational predictions or as an analysis tool.The added value of this method is that it can be applied to many coastal sites: (1) limited observations of offshore hydrodynamic parameters can be extended using the copula method which retains the original observations' natural variability, (2) the transformation from offshore observations to onshore hazards can be computed with any preferred coastal model and (3) a BN can be adjusted to fit any relevant connections between offshore hydraulic boundary conditions and onshore hazards. Furthermore, a BN can be continuously updated with new information and expanded to include different morphological conditions or risk reduction measures. As such, it is a promising extension of existing EWSs and as a planning tool for coastal managers. (C) 2016 Elsevier B.V. All rights reserved.
- RISC-KIT: Resilience-increasing Strategies for CoastsPublication . Van Dongeren, Ap; Ciavola, Paolo; Martinez, Grit; Viavattene, Christophe; DeKleermaeker, Simone; Ferreira, Óscar; Costa, Cristina; McCall, RobertHigh-impact storm events have demonstrated the vulnerability of coastal zones in Europe and beyond. These impacts are likely to increase due to predicted climate change and ongoing coastal development. In order to reduce impacts, disaster risk reduction (DRR) measures need to be taken, which prevent or mitigate the effects of storm events. To drive the DRR agenda, the UNISDR formulated the Sendai Framework for Action, and the EU has issued the Floods Directive. However, neither is specific about the methods to be used to develop actionable DRR measures in the coastal zone. Therefore, there is a need to develop methods, tools and approaches which make it possible to: identify and prioritize the coastal zones which are most at risk through a Coastal Risk Assessment Framework, and to evaluate the effectiveness of DRR options for these coastal areas, using an Early Warning/Decision Support System, which can be used both in the planning and event-phase. This paper gives an overview of the products and results obtained in the FP7-funded project RISC-KIT, which aims to develop and apply a set of tools with which highly-vulnerable coastal areas (so-called "hotspots") can be identified.
- RISC-KIT: Resilience-Increasing Strategies for Coasts - toolKITPublication . Van Dongeren, Ap; Ciavola, Paolo; Viavattene, Christophe; de Kleermaeker, Simone; Martinez, Grit; Ferreira, Óscar; Costa, Cristina; McCall, RobertRecent and historic high-impact events have demonstrated the flood risks faced by exposed coastal areas. These risks will increase due to climate change and economic development. This requires a re-evaluation of coastal disaster risk reduction DRR strategies and prevention, mitigation and preparedness PMP measures. To this end, the UN Office for Disaster Risk Reduction formulated the Hyogo Framework for Action, and the EU has issued the Floods Directive. By their nature, neither is specific about the methods to be used to assess coastal risks, particularly those risks resulting from dune and structure overtopping, the non-stationarity of surge and flash flood events, and coastal morphodynamic response. This paper describes a set of open-source and open-access methods, tools and management approaches to fill this gap. A Coastal Risk Assessment Framework will assess coastal risk at a regional scale. Thus critical hotspots can be identified for which an impact-oriented Early Warning System/Decision Support System is developed. This can be applied in dual mode: as a forecast and warning system and as an ex-ante planning tool to evaluate the vulnerability. The tools are demonstrated on case study sites on a range of EU coasts with diverse geomorphic settings, land use, forcing, hazard types and socio-economic, cultural and environmental characteristics. Specific DRR plans will be developed for all sites. A management guide of PMP measures and management approaches is to be developed. The toolkit will benefit forecasting and civil protection agencies, coastal managers, local government, community members, NGOs, the general public and scientists.