Geomorphological signatures of extreme wave events: a literature review of studies on coastal boulder deposits within the Mediterranean Region

The presence of boulders and coarse clasts on rocky coasts has been the subject of numerous studies worldwide, exploring a wide range of meteo-marine settings and site-specific geological contingency. Such coastal boulder deposits (CBD) are considered to be geomorphological signatures of erosional and depositional processes by wave action and hence, considered as important indicators in reconstructing historic impacts of wave climates and other extreme events. The scope of this paper is to review the breadth and depth of scholarly works in geomorphology (but not only), carried out on boulder deposits within the coastal regions surrounding the Mediterranean Sea. Extreme wave events are a source of hazard that may have major negative impact on human life and a vast spectrum of economic activities across many coastal Mediterranean states. Population demographics indicate an increase in the number of people living in coastal cities around the Mediterranean region, from 100 million in 1980 to 150 million in 2015 and is expected to exceed 200 million by 2030. Although population density varies across countries the highest densities are found in port cities, mainly due to higher economic opportunities associated with these areas. The aims are to analyse how the focus of studies has evolved over time in response to new findings, observations and technological advances. Understanding how such mechanisms function in terms of wave dynamics and boulder detachment and transportation may assist in the prediction of hazards and erosion. This can be done both in the short term by combining data from weather forecast and wave models and for longer timeframes by considering the cumulative effect of yearly storms, the stronger fifty year or hundred-year storm and other exceptional events.