Stable Channels with Mobile Gravel Beds

Regime type equations for mobile gravel-bed rivers are presented based on data obtained from 62 stable gravel-bed river reaches in the United Kingdom. Multiple regression techniques are applied to derive equations relating reach average and riffle values of width, mean and maximum depth, slope, velocity, sinuosity and riffle spacing to bankfull discharge, bed and bank material characteristics, valley slope, bank vegetation type and an independent estimate of bankfull bed load transport rates. Although discharge has a dominant control on channel geometry, these equations indicate that bed load discharge also has a significant influence, particularly with regard to channel slope. Bank vegetation has a major control on width and velocity while depth, velocity and slope are strongly affected by bed material size. Reasons for these results are considered in terms of the physical processes controlling channel adjustment. The application of these regime equations is discussed, and particular consideration is given to the design of sinuous channels with a pool-riffle bed topography.