The role of extreme winter storms in the overall retreat pattern of an actively eroding eolianite coastal cliff-line in the eastern Mediterranean

Eolianite cliffs along the Mediterranean coast of Israel form an actively eroding 55-km-long linear feature with local average retreat rates of up to 0.3 m/year over the past 60 years. Here, we investigate the effect of extreme winter storms with decadal-scale recurrence intervals, on the overall retreat pattern of this 'soft rock' coastal cliff-line. Repeat high resolution ground based LiDAR surveys before and after an extreme '20-year' winter storm that occurred in the eastern Mediterranean during December 2010 allowed us to characterize syn- and post-storm erosional effects at cm-km scales. Our results reveal a complex cliff retreat pattern that continued to evolve several months after the storm. Storm-induced retreat occurs primarily as discrete catastrophic cliff-failure events. Failure initiated with forming of syn-storm basal notches and then propagated up-cliff during the months that follow. In places, storm induced cliff retreat reached up to 7 m, which is comparable to the maximum total retreat previously documented along this coastal stretch during the past 60 years. Yet it is observed that spatially cliff retreat associated with the December 2010 storm accounts for <5% of the total retreat documented in this coastal stretch over the past 60 years, thus implying only a secondary role for extreme winter storms in the overall volumetric retreat of the cliff line. Nonetheless, the preferred occurrence of peak storm-associated erosion at local capes along the cliff line suggests that extreme winter storms may in fact have a governing role in maintaining the large-scale linearity of the coastal cliff-line.