Accelerating shear velocity in gravel-bed channels

The behaviour of the shear velocity along a gravel-bed channel is investiga ted experimentally in the presence of a negative pressure gradient (acceler ating flow). Different methods of estimation of the sheer velocity, derived from vertical profiles of the mean longitudinal point velocity, are examin ed and a new method is proposed. Results show that the proposed method of e stimation is comparable to the St Venant and Clauser's methods. At a specif ic cross section, for constant bottom slope and relative roughness, shear v elocity increases with discharge.