The role of multigelation in the development of river banks

Abstract

The development of river banks is conditioned by a few factors: fluvial erosion, mass movements and subaerial processes. Many researchers believe that the subaerial phenomena are more preparatory processes to actual erosion than the erosion itself. Among the subaerial phenomena, freezing and thawing play a key role. Multigelation affects the stability and sustainability of river banks, not only in the northern reaches of Eurasia andNorth Americabut also in temperate latitudes. Susceptibility to change in bank morphology, however, is extremely selective. Within the same layer, at a distance of 1 metre the intensity of frost erosion can be very different. This is the result of many factors determining the rate of bank retreat. These include: the height of the bank, its structure and texture, physical and chemical properties of the material from which it is built, environmental conditions, soil moisture, water pressure in the pore spaces, porosity and density of the soil, organic matter content in the soil, temperature, vegetation, as well as thickness and duriation of snow cover. An important objective is therefore to show the differences in the rate of retreat of the river banks, and above all characterized by varying degrees of density and grain size of the material it is build of.