Transverse mixing of solute and suspended sediment from a river outfall during over bank flow

Laboratory experiments have been undertaken on a large scale compound channel to investigate the transverse mixing of solute and suspended sediment in effluent plumes under river flood conditions. Attention has been focused on the effect of a cross-stream depth variation from main channel to flood plain on the lateral variation of local transverse mixing coefficient in the near and mid field zones. Preliminary experimental results are presented for the transverse variation of solute and suspended sediment concentrations. Both tracers were injected simultaneously above the mid point of a side slope of the main channel. These show in this particular case that there is little difference between the transverse mixing of solute and suspended sediment. An analytical solution provides a potentially powerful technique to obtain the width averaged transverse mixing coefficient that may also determine the lateral variation of transverse mixing coefficient.