Development of a regional risk assessment methodology for climate change impact assessment and management in coastal zones

Abstract

Today there is new and stronger evidence that global warming is likely to have profound impacts on coastal communities and ecosystems. Accelerated sea-level rise, increased storminess, changes in water quality and coastal erosion as a consequence of global warming, are projected to pose increasing threats to coastal population, infrastructure, beaches, wetlands, and ecosystems. Coastal zones represent an irreplaceable and fragile ecological, economic and social resource that need to be preserved from the increasing coastal resources depletion, conflicts between uses, and natural ecosystems degradation. Accordingly, there is a growing importance of innovative integrated and multidisciplinary approaches to support the preservation, planning and sustainable management of coastal zones, considering the envisaged effects of global climate change. Climate change impacts in coastal zones are very dependent on regional geographical and environmental features, climate, and socio-economic conditions. Impact studies should therefore be performed at the local or at most at the regional level. In order to provide effective information that can assist coastal communities in planning sustainable adaptation measures to the effects of climate change, the main aim of this thesis is to develop a GIS-based Regional Risk Assessment (RRA) methodology for the integrated assessment of climate change impacts in coastal zones at the regional scale. The main aim of the RRA is to evaluate and rank the potential impacts, vulnerabilities and risks of climatic changes on coastal systems. Moreover the methodology allows the identification of key vulnerable receptors in the considered region and of homogeneous vulnerable and risk areas, that can be considered as homogeneous geographic sites for the definition of adaptation and management strategies. The present thesis complies with the research activities of the Euro-Mediterranean Centre for Climate Change (CMCC) and was implemented in a Decision support System for Coastal climate change impact assessment (DESYCO). In order to characterize climate related hazards and vulnerable receptors the RRA approach integrates downscaled climate, circulation and wave models output for the construction of future climate change scenarios and includes the analysis of site-specific physical, ecological and socio-economic characteristics of the territory (e.g. coastal topography, geomorphology, presence and distribution of vegetation cover, location of artificial protection). The RRA methodology was applied to the coastal area of the North Adriatic sea, in order to analyze the potential consequences of sea-level rise, relative sea-level rise inundation and coastal erosion impacts on multiple coastal receptors (i.e. beaches, river mouths, wetlands, terrestrial biological systems, protected areas, urban areas and agricultural areas) and compare the results based on multiple climate change scenarios. The main output of the analysis include exposure, susceptibility, risk and damage maps that could be used to support coastal authorities in the implementation of sustainable planning and management processes. Exposure maps obtained for the permanent inundation impacts (i.e. sea-level rise and relative sea-level rise) in 2100 allowing identification of coastal areas where the territory would be more submerged by projected water levels (i.e. areas surrounding the Po River Delta and the hinterland region between the Northern Venice lagoon and the Grado-Marano lagoons). Future exposure scenarios of coastal erosion depict a worse situation in winter and autumn for the future period 2070-2100 and highlight hot-spot exposure areas surrounding the Po River Delta. Susceptibility maps highlighted that the receptors more susceptible to coastal erosion are the beaches with about 94% of the territory identified by the very high and high susceptibility class. Risk maps showed that receptors with very high risk scores for the sea-level rise impact are wetlands, agricultural areas, protected areas and river mouths. The municipalities more interested by potential loss of beaches due to relative sea-level rise inundation are Ariano nel Polesine, Porto Viro, Porto Tolle, and Caorle. The receptors at higher risk for coastal erosion are the beaches where the percentage of the territory with higher risk scores is about 72% in the winter, 21% in the spring, 14% in the summer and 41% in autumn. Finally, the damage assessment phase showed that the receptors with by higher percentages of the territory in the medium and high damage classes are wetlands, agricultural areas, protected areas and river mouths for the sea-level rise inundation; beaches, wetlands and river mouths for the coastal erosion impact.

I cambiamenti climatici arrecheranno crescenti impatti sulle aree costiere e gli ecosistemi connessi attraverso un possibile aumento del livello del mare e dei processi di erosione costiera. Allo scopo di eseguire una valutazione integrata di questi impatti su diversi bersagli e guidare la definizione di strategie di adattamento a scala regionale è stata sviluppata una metodologia di Analisi di Rischio Regionale (ARR) su base GIS. Tale metodologia si avvale degli output di modelli climatici e idrodinamici per costruire scenari di pericolo legato al cambiamento climatico a scala regionale e analizza le caratteristiche intrinseche del territorio (es. aspetti bio-fisici, ecologici e socio-economici) per valutarne la vulnerabilità. I risultati dell'analisi comprendono mappe di esposizione, suscettibilità, rischio e danno utili per identificare, visualizzare e prioritizzare bersagli ed aree a rischio nella stessa regione e per guidare la definizione di strategie per la gestione dei rischi.