Geological and geomorphological control of river meanders formation and morphology

Abstract

Channel studies at the Aldan, Dnestr and Vilyui rivers revealed that geologic and geomorphic factors not always influence river meanders formation and morphology in the same way. Within a series of entrenched and free meanders a transition can be seen from passive adaptation to geologic structure towards active transformation of the structure, different factors may be of primary importance under different conditions. The main cause of meanders active development is a certain hydrodynamic characteristics of the flow at channel's bend, which accounts for asymmetry of both channel and valley profiles within the meander zone. With reference to clayey channels the author demonstrates the channel floor resistance to erosion to be the main factor controlling both rate and direction of meander development.