Experimental study of the flow field in compound channels with converging and inclined floodplains

This paper presents experimental results of overbank flow in compound channels with converging and inclined floodplains. Velocity and boundary shear stress distributions at different selected sections along the narrowing part of the flume for two convergence angles of 3.81° and 11.31° were measured. The study indicated that the velocity and boundary shear stress increase along the flume, especially in the second half of the converging part of the flume. It was shown that the maximum velocity at the end of the converging transition can be over than twice as much as at the beginning section. By using the experimental data and force–momentum balance, the apparent shear forces at the vertical interface between the main channel and floodplains were investigated. The apparent shear forces at the vertical interface of the flume subsections increased with the increase of the convergence angle and relative depth, reached a peak at the relative depth of 0.4, and then decreased.