Alluvial friction in the transition zone

Laboratory experiments carried out in the transition zone between upper and lower regime flows are described. The results of these experiments imply that the transition zone consists of a family of curves that fill the area and that the trajectory of a flow through the transition zone it is suggested that use is made of the parameter Ue. This parameterisation should be based on experimental data, were available, but in the absence of such data an approximation is presented. This should enable the calculation of flows within the transition zone.