The width (w), depth (d), meander wavelength (l), gradient (s), shape (w/d), sinuosity (P) of stable alluvial river channels are dependent on the volume of water moving through the channel (Q_w, expressed as either mean annual or bankfull discharge or mean annual flood) and the type of sediment load conveyed through the channel (Q_s, expressed as either the ratio of bedload to total sediment load or the percentage of total sediment load that is sand size or larger):

[EQUATION]

and

[EQUATION]

Empirical equations developed from data collected along modern rivers permit calculation of the effects of changes of hydrologic regimen (Q_w, Q_s) on channel morphology. Conversely, these relations permit estimation of paleochannel gradient, meander wavelength, sinuosity, discharge, and type of sediment load from the dimensions of the paleochannel as exposed in cross section when the bed and banks of the paleochannel are composed of alluvium transported by the ancient river.

The recognition of paleochannels within valley-fill or other complex fluvial deposits is a major problem. Some criteria for the delineation of paleochannel cross-section shape and dimensions have been developed from studies of the shapes and sediment characteristics of Australian paleochannels.

Although major changes of river morphology during both historic and geologic times support the empirical relations, they, nevertheless, must be applied with caution because the effects of colonization of the land by primitive vegetation and the progressive evolution of vegetation have influenced markedly the paleohydrology of ancient drainage systems.

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