Fluviatile fining-upwards cycles and the magnitude of palaeochannels

Abstract

SummaryThe bankfull width (w) of modern meandering rivers (sinuosity >1.7) is related to bankfull depth (h) by the equation w = 6.8h1.54. The equation may be used to calculate limits for the bankfull widths of palaeochannels that deposited alluvial fining-upwards cycles. Calculated bankfull widths and measured bankfull widths from epsilon cross stratification are further used to state ranges of values for meander wavelength and mean annual discharge using existing empirical equations. The empirical equations directly relating width/depth ratios to sediment load and sinuosity are shown to be generally valid only for small rivers because of the increase of width/depth ratios as meandering rivers increase in size.