Vulnerabilidad Costera Cerdeña

The main goal of this work is to provide a probabilistic regional assessment of the coastal vulnerability of Sardinian sandy beaches to storm impacts.

We considered the beaches as coastal units and we have assessed the geomorphic coastal vulnerability taking into account the intensity of storm induced hazards (Run up elevation, Volume of beach eroded and Beach retreat) and the adaptation capacity of the system. The methodology aplied allows to calculate quantitatively-in to separate manner-the erosion and inundation hazards induced by the storms associated to a given probability of occurrence. The practical application of this method is to provide information that allows stakeholders to manage resource allocation and mitigate consequences.

This framework has been developed by covering the following steps:

(i) Defined forcing conditions for the Sardinian coast using storm classification method; to obtain this we have divided the Sardinian coast in 4 different sectors. For each sector storm events have been defined from wave hindcast data obtained for the period between 1979-2012 by ECMWF (European Centre for Medium-Range Weather Forecasts).

(ii) Find out the beach induced response to each storm class measured by the quantification of the flooding and erosion hazards. In each sector sandy beaches have been characterized in terms of their slope, height of foot and crest dune, widht and lenght.

(iii) Estimation of to coastal vulnerability index formulated in terms of these two intermediate variables by means of a linear function that ranges from a minimum value of 0 (optimum state) to a maximum of 1 (failure state), defining 5 qualitative categories (Very Low, Low,. Medium, High and Very High).

(iv) Assessment and mapping of the coastal vulnerability index along different sectors of the island.

In terms of prospective analysis we have built to projected timeline of beach hazard based on existing storm data fitted into an extreme probability function. Once the probability of occurrence of the flooding and erosion hazards have been assessed and a risk level defined by the stakeholders, the spatial distribution of vulnerabilities associated to selected probability level will permit to "robustly" compare areas along the coast to identify the most endangered zones. The results show that Sardinian beaches are more vulnerable to erosion than inundation phenomena and that tha most vulnerable areas of the island are Sassari and Oristano provinces.

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