Stream Dynamics

the study of the movement of water and detritus in rivers, streams, and canals. The main task of stream dynamics is the study of the movement of water in a channel that is being altered under conditions of continuous interaction of the stream and channel. The channel directs the stream, forming a distribution of velocities in its various parts (a velocity field), and the stream creates for itself a channel that conforms to its velocity field. In connection with this, stream dynamics studies the kinematic structure of the stream (velocity and pressure distribution and fluctuations, turbulence and the mechanism of turbulent mixing, and the tractive resistance of the stream), the mechanism of suspension and transportation of detritus, the deformation of the stream’s bottom, and the position of the stream (river) in the plan view. Stream dynamics is based on the hydrodynamics of viscous fluid, the theory of the turbulent flow of a fluid, similarity theory, and physical experimentation.

The movement of streams in a curved channel is accompanied by a transverse circulation, because of which the detritus is moved both along the channel and across it, creating complex bottom relief. Theoretical research on streams presents significant difficulties because of the complexity and fluidity of stream flow. Because of this, physical experimentation has acquired great importance, particularly the simulation of channel processes based on similarity theory. At the same time, stream research is also conducted directly under natural conditions (in rivers and channels).

Stream dynamics began to develop as an independent science in the early 20th century on the basis of research on plains rivers for navigation purposes (begun by the Russian engineers V. M. Lokhtin and N. S. Leliavskii) and in connection with the developing hydraulic engineering construction. A great contribution to the creation and development of stream dynamics was made by the Soviet scientists M. A. Velikanov (who established the theoretical basis of the science), V. M. Makkaveev, V. N. Goncharov, and N. I. Makkaveev.

A study of stream patterns made possible not only the prediction of channel deformations but also their control. Thus, special hydraulic-engineering works may control the channels of rivers by creating conditions that promote an increase in the river’s depth to a level best suited for normal navigation. The forecasting of channel alterations has acquired particular importance in connection with the construction of hydraulic-engineering works. The most important practical concerns of stream dynamics include the precipitation of detritus in channels and settling tanks, the silting-up of reservoirs, the washing out of the bottom behind hydraulic-engineering works (a drop in the water level in the tailwater of hydraulic power systems), scouring of the river channel when it is constricted by construction (cofferdams, bridges, water intakes, and so on), the development of methods for straightening rivers for navigation purposes, and combating the harmful effect of mud flows.