COASTAL STATE INDICATORS AND COASTAL VULNERABILITY INDEXES TO IMPROVE EARLY WARNING SYSTEMS. The case study of the Catalan Coast

Half of the world's population lives within 60 km of the sea and this figure is likely to rise up to 75% by the year 2025. The extraordinary development of the built environment and of the population densities in the coastal areas are making coastal communities highly exposed. The sea level rise induced by climate change is worsening this coastal vulnerability scenario and a considerable amount of people are expected to be susceptible to and threatened by coastal flooding in the near future. Given that the northern part of the Mediterranean coastal areas is location of critical infrastructure and buildings, it represents one of the most highly exposed coastal area in the world. Its shores are indeed characterized by high rate of population densities and economic activities that extremely increase the risk of facing impacts and losses subsequent to hydro-meteorological hazards. Considering the rising values of both occurrence and magnitude of storm-induced damages, adequate assessment and forecasting tools are needed in order to enhance the resilience of coastal systems and thus the capability to reduce disaster risks and cascading effects. In particular, thanks to more sophisticated and improved numerical tools, coastal observations and data collection, it is now possible to implement in a timely manner operational morphodynamic predictions able to reduce coastal risk linked to incoming storms. In this scenario, the Integrated COastal Alert SysTem (iCoast) project has been aimed at developing a tool able to address coastal risks caused by extreme waves and high sea water levels in European coastal areas. In the framework of iCoast, a set of Coastal State Indicators (CSIs) has been developed in order to improve the forecasting and the assessment of coastal risks. CSIs are indeed parameters able to provide end-users with an essential information about coastal hazards and related impacts. CSIs have been chosen as parameters that can be retrieved from the meteorological and the hydrodynamic modules. They include both physical variables used as trigger for meteorological and flood warnings from the majority of the operational National/Regional warning systems and further essential parameters, so called ‘storm integrated’ coastal-storm indicators, which describe the physical processes that drive coastal damages, such as erosion, accumulation, flooding, destructions. With the target of improving, produce and disclose/spread more efficient general warning messages, in the iCoast approach, specific sets of CSIs have been selected subsequently to their aggregation, weighting and comparison with established thresholds. In such a way, it has been possible and easier to deliver, tailored and adapted alert messages in relation to the different end-users characteristics and requirements. In the present study, the set of CSIs chosen in the framework of the iCoast Project is presented along with their performances tested for the case study of the Spanish NW Mediterranean Coast (i.e. Catalan Coast) while hypothetic risk scenarios are subsequently delineated and analysed.