The fact that friction significantly modifies long barotropic waves was first demonstrated by Sverdrup (1927) and Fjeldstad (1929) in their analyses of the semi-diurnal tides on the North Siberian Shelf. Features such as reduced phase speed, decreasing am plitude as the waves progress and phase lag between maximum current and high water were found to result from the effect of friction. For this reason, long, friction-modified barotropic waves in a rotating viscous ocean are often referred to as Sverdrup wa ves. The mean mass transport in Sverdrup waves is a non-linear phenomenon and it is confined to the viscous boundary layer at the sea bottom. Here friction is the source of mean secondary vorticity. The associated mean m otion in the bottom layer result from abalance between the viscous force and the Coriolis force. Also Sverdrup waves along the interface separating lighter and heavier water (baroclinc Sverdrup waves) will induce a mean mass transport in the bottom bounda ry layer. The non-linear, mean mass transport in Sverdrup waves will be investigated both analytically and numerically. In particular, it is focused on how these currents depend on the modelling of the bottom turbulence. The ability of these currents to t ransport b ottom sediments in supension is addressed, and the consequences for offshore engineering activities at the ocean bottom are discussed.