Mechanical Anthropogenic Impact on Natural Slopes of Coastal Dunes

The results of a series of experimental works on controlled human trampling on natural slopes of coastal dunes are summarized. Intensification of anthropogenic impact on coastal dunes, including the growth of local tourism, together with modern climatic changes, leads to degradation of coastal aeolian-marine complexes. The impact of human foot traffic on dune slopes triggers a chain of morphodynamic processes that ultimately lead to sand activation and migration. The morphodynamic effect of human trampling depends on the initial moisture content of the sand and the depth of the dried layer, which expires in streams before reaching the natural slope and leads to a localized change in moisture content due to instantaneous mixing. The morphodynamic effect of multiple successive human descents is to form a trough of disturbed sands, within which there is a slow outflow of dry sand moved by slow displacement. In both cases, the displacement process is similar to that of a “flowing wedge”, where under the action of surface pressure in a local depression there is a correlated movement of particles confined to a region defined by the length of the stress chains. The processes of subsequent relaxation cause the crumbling of microform walls of the footprint formed by the moistened sand layer and the formation of the natural slope in new, “shifted”, conditions.