Fluviomorphological Processes

the sum of the processes that arise during the interaction of a stream with its channel; the processes determine the relief of the channel and the regime of its seasonal variations. The fluviomorphological processes occur in rivers and channels.

The interaction of the stream with the channel exists because the channel controls the stream, forming a velocity distribution (velocity field), and the stream creates a channel for itself that corresponds to its velocity field. The stream erodes the channel at places where the velocities are sufficiently great, transports sediment in suspension and traction, and deposits sediment where the velocities are low. The depths of the channel along the stream are therefore unevenly distributed; deep places (pools) alternate with shallow areas (river bars). A change in channel shape is imparted comparatively quickly to the kinematics of the stream, but an altered velocity distribution in the stream affects channel formation over a comparatively long period of time.

The fluviomorphological process is closely related to the physicogeographical and geomorphological conditions in drainage areas and to the peculiarities of the hydrological regime.

Prolonged interaction of the stream with the channel gives rise to relationships, called hydromorphological relationships, between the inclination of the surface of the water, the flow rate, the shape of the channel, and the dimensions of solid particles of soil. For example, a definite relation is established between width and depth of a river, and the relation is dependent on the properties of soils. Thus, the ratio of the width of a river to its depth is greater for rivers with a sandy bottom than for rivers with a clay bottom.

The most characteristic feature of the flow of a river or stream is a meandering channel at whose bends the flow is accompanied by transverse circulation resulting from centrifugal force. For this reason, sediment is moved both along and across the stream, thus creating a bottom relief with complex shapes.

The fluviomorphological process is of great importance in connection with the design and operation of hydraulic engineering installations and bridges on rivers and in dredging operations designed to improve navigating conditions. Stream dynamics deals with the study of the fluviomorphological process.