Cliff dynamics in western Crimea

Abstract

The paper considers the long-term dynamics of clayey cliffs of the Western Crimea in view of the problem of further recreational development of the Crimean Peninsula. Open-source satellite imagery and long-term (over 40 years) cliff section measurements were analyzed. The paper provides data on the geomorphology of individual coastal sites. It is shown that landslides are the main mechanism causing the cliff retreat on the larger part of the coastline. Slumps are typical for the southern part of the region and their movement episodes are relatively rare. Landslides become more active during the winter — spring period, when the moisture content of clayey cliff rocks increases substantially and the abrasion intensifies. Landslides can also be triggered by short-term heavy precipitation, which is usually observed in the summer. There is no definite relationship between the amount of annual precipitation, storm activity and landslide activity, either synchronous or with a time lag. No regularity in landslide dynamics was identified. It was found that the average long-term rates of cliff edge retreat are 0.1–1.2 m/year. In the northern part of the coast, the rates are the highest, decreasing towards the southern part of the region. The obtained average annual rates of cliff edge retreat are significantly less than those previously reported in the literature. There is a decrease in the beach-forming sediment supply due to a reduction in the stretch of the cliffs. Out of 50 km coastline with cliffs, only 39 km are left in the study area due to being covered by various structures and terracing. The paper also discusses anthropogenic activity, which leads to the formation and movement of man-made landslides and an increase in natural landslide activity. It is shown that the construction of transverse beach-retaining structures leads to blocking of littoral sediment transport, and to increase in the cliff retreat rate outside the protected reach.