The KULTURisk Regional Risk Assessment methodology for water-related natural hazards – Part 2: Application to the Zurich case study

Abstract

Abstract. The main objective of the paper is the application of the KULTURisk Regional Risk Assessment (KR-RRA) methodology, presented in the companion paper (Part 1, Ronco et al., 2014), to the Sihl River valley, in Switzerland. Through a tuning process of the methodology to the site-specific context and features, flood related risks have been assessed for different receptors lying on the Sihl River valley including the city of Zurich, which represents a typical case of river flooding in urban area. After characterizing the peculiarities of the specific case study, risk maps have been developed under a 300 years return period scenario (selected as baseline) for six identified relevant targets, exposed to flood risk in the Sihl valley, namely: people, economic activities (including buildings, infrastructures and agriculture), natural and semi-natural systems and cultural heritage. Finally, the total risk index map, which allows to identify and rank areas and hotspots at risk by means of Multi Criteria Decision Analysis tools, has been produced to visualize the spatial pattern of flood risk within the area of study. By means of a tailored participative approach, the total risk maps supplement the consideration of technical experts with the (essential) point of view of the relevant stakeholders for the appraisal of the specific scores and weights related to the receptor-relative risks. The total risk maps obtained for the Sihl River case study are associated with the lower classes of risk. In general, higher relative risks are concentrated in the deeply urbanized area within and around the Zurich city centre and areas that rely just behind to the Sihl River course. Here, forecasted injuries and potential fatalities are mainly due to high population density and high presence of old (vulnerable) people; inundated buildings are mainly classified as continuous and discontinuous urban fabric; flooded roads, pathways and railways, the majority of them referring to the Zurich main train station (Hauptbahnhof), are at high risk of inundation, causing huge indirect damages. The analysis of flood risk to agriculture, natural and semi-natural systems and cultural heritage have pointed out that these receptors could be relatively less impacted by the selected flood scenario mainly because their scattered presence. Finally, the application of the KR-RRA methodology to the Sihl River case study as well as to several other sites across Europe (not presented here), has demonstrated its flexibility and possible adaptation to different geographical and socio-economic contexts, depending on data availability and peculiarities of the sites, as well as for other hazard scenarios.

Cumulative Impact Index for the Adriatic Sea: Accounting for interactions among climate and anthropogenic pressures

“…Compared to traditional regional risk assessment approaches (Ronco et al, 2015;Torresan et al, 2016;Sperotto et al, 2016) and to the recent study proposed by Furlan et al (2018), the methodology for the calculation of the CI-Index applies advanced MCDA functions (Demirel et al, 2018;Gain and Giupponi, 2015;Giupponi et al, 2013;Zabeo et al, 2010;Grabisch and Roubens, 2000) for modelling the potential synergies between endogenic and exogenic pressures affecting the marine environment.…”

The KULTURisk Regional Risk Assessment methodology for water-related natural hazards – Part 1: Physical–environmental assessment

“…On the other hand, as per the 2014 IPCC AR5 report, the expert judgement (using specific criteria) must be used to "integrate the diverse information sources relating to the severity of consequences and the likelihood of occurrence into a risk evaluation, considering exposure and vulnerability in the context of specific hazards" in order to cope with the fact that "data are seldom sufficient to allow direct estimation of probabilities of a given outcome" (IPCC, 2014). Furthermore, the methodology can be further improved by taking into consideration the complex dynamics of feedbacks between physical, social and political factors that relevant end-users, decision makers and local experts frequently pose (see the companion paper, Part 2, Ronco et al, 2014). In this sense, the characterization of the vulnerability patterns for (selected) communities and areas through the combination of different drivers, such as collective memory, risk-taking attitudes and trust in protection measures, as proposed by Viglione et al (2014), or by considering its temporal evolution as proposed by Mazzorana et al (2012), represent a new, challenging, frontier for the next generation of risk assessment methodologies.…”

“…It further compares the baseline scenario with alternative scenarios, where different structural and/or non-structural mitigation measures are planned and eventually implemented. As demonstrated in the companion paper (Part 2, Ronco et al, 2014), risk maps, along with related statistics, allow one to identify and classify, on a relative scale, areas at risk which are more likely to be affected by floods and support the development of strategic adaptation and prevention measures to minimizing flood impacts. In addition, the outcomes of the RRA can be eventually used for a further socio-economic assessment, considering the tangible and intangible costs as well as the human dimension of vulnerability.…”

“…), the review demonstrated that there are very few examples of methodologies that consider the complete suite of elements at risk pointed out by the FD encompassing the entire varieties of risk dimensions (i.e. physical/environmental, social and economic) (Di Baldassarre et al, 2009;Di Baldassarre et al, 2010;Rotach et al, 2012). Most of the available methodologies, in fact, only targeted "classical" receptors, such as buildings, infrastructure or population (e.g.…”

“…Finally, the article will also present a simple but effective algorithm, based on multi-criteria decision analysis (MCDA), to combine the receptor-related relative risks into a single general (total) risk index. The (ultimate) objective of the methodology, successfully applied in several case studies across Europe (see the companion paper, Part 2, Ronco et al, 2014), is to identify and prioritize areas and targets at risk in the considered region, in order to evaluate the benefits of different risk prevention scenarios to support relevant stakeholders in knowledge-based (land-use) planning and decision making. 2 The KULTURisk Regional Risk Assessment (KR-RRA) methodology…”