A synthetic framework for wave energy resource variability assessment

Wave energy variability plays a crucial role both in characterizing wave-energy resources and in defining the wave climate of exposed coasts. On the one hand, the temporal variability of the resource is a key factor in assessing the economic viability of wave energy extraction projects. On the other hand, it is well known that the short-term morphodynamic response of sandy beaches is intimately related to the temporal succession of sea states. The aim of this manuscript is therefore to propose a simple method for the quantitative characterization of wave energy variability. The method relies on a synthetic variability index, based on the use of the Gini coefficient, aimed at quantifying the temporal concentration of wave energy. The method is applied to the case study of the Mediterranean and Black Seas in order to demonstrate its feasibility, applicability, and reliability. The results highlight that both wave energy availability and variability should be considered in the preliminary identification of suitable areas for wave energy exploitation and in the definition of coastal and offshore planning strategies.