Snow avalanches and debris flows in the Mediterranean conditions of the southern coast of the Crimean Mountains: Dendrogeomorphic reconstruction

Abstract

The southern coast of the Crimean Mountains is affected by both debris flows and snow avalanches. However, there is no systematic record of these dangerous natural hazards. Therefore, this study is aimed at compiling a chronology of snow avalanches and debris flows at one of the most exposed sites on the southern coast of the Crimean Mountains. Dendrogeomorphic analysis of 310 individuals of black pine (Pinus nigra ssp. Pallasiana) revealed 639 growth disturbances induced by 55 debris flow events (since 1705) and three snow avalanche events (since 1959). A multidisciplinary approach combining precise intra-seasonal tree-ring dating, event-response index thresholds, geomorphological mapping, and testing of spatial patterns of disturbed trees was used to distinguish the two processes. This method has confirmed more than 85% of the known events and has thus proven to be highly effective and can thus be used to compile a catalogue of natural hazards in the region of interest. A limitation for dating snow avalanches was the inertia of growth disturbances induced by debris flows preceding avalanche events. Based on the analysis of meteorological data, possible triggers and predisposing factors for the occurrence of the events of both studied processes are also discussed.