Development of a coastal vulnerability index using analytical hierarchy process and application to Ravenna province (Italy)

The assessment of coastal vulnerability to natural hazards is a major concern in coastal areas worldwide, par-ticularly in the context of climate change and increased coastal development. In this work an index of physicalvulnerability to sea level rise and marinefloods was designed and applied over the coast of the Ravenna Province(Italy), a low-lying coastal area historically known as being susceptible to coastalflooding and erosion. Theindex is intended to be at the same time scientifically sound and easy to apply, so it is composed offive relevantvariables (elevation, dunes, artificial protection structures, shoreline change rates, and land cover) that wereweighted by using a multi-criteria decision making approach, namely the analytical hierarchy process. Theweightings were assigned by experts familiar with coastal processes in the area, and all with background inenvironmental science. This enabled a transparent approach on integrating established expert knowledge toassign the relative importance of the variables in defining vulnerability scores. Thefinal vulnerability score foreach segment along the investigated coast was calculated by applying the weighted sum of all variables. Forverification purposes, the obtained vulnerability ranking was compared to existing coastalflood hazard mapsdeveloped by regional authorities in the framework of the EU Floods Directive (2007/60/EC), and to real in-undation events generated by historical storms. The integration of this framework into geographical informationsystems resulted in informative maps, useful to a variety of end-users such as coastal managers and decisionmakers