Each river, waterway, or tidal inlet has its own “face.” Rivers may be large or small and may be cut in rock, sand, or clay. They all, however, have features in common, and their behavior is governed by the same physical parameters.
These factors include slope, depth, friction elements, material characteristics, material load, and water temperature. Friction elements, in turn, comprise “skin friction,” caused directly by the grains; “sill or dune friction,” caused by ripples and/or dunes; “internal distortion friction,” caused by interior eddy formation in the stream; and “meander friction” or “other irregularity friction,” caused by meander or similar effects.
The results of stream-geometry research are discussed with reference to existing regime formulas and their applications to a model river developed in the Hydraulic Experiment Station at Wallingford, England, and to field studies made by American geologists and engineers. The discussions reveal that remarkable similarities exist between flow- and stream-geometry characteristics regardless of stream size and that some differences may be explained by hydraulic considerations based on the development of bottom geometry. Also discussed are hydraulic model laws for rivers with sediment transport.