For the purpose of reaeration of polluted rivers, a mechanical surface aeration device was tested. At low flows the aerator has a tendency to recirculate the same once-aerated water within the basin. The flow concentration devices are proposed to be used with the mechanical aerator to increase the streamflow velocity and the level of stream turbulence along the approach to the aertor. This should diminish recirculation of the water due to higher velocities, and enhance the level of turbulence. This investigation reports on the hydraulic model of the proposed flow concentration devices performance in relation to the mean flow velocity and turbulence characteristics and measurements. Some of the important conclusions are: (1) The determination of hydrodynamic aspects of flow discharge, velocity distribution and turbulence characteristics of the model tested are in fair agreement with existing results. (2) It was clearly demonstrated that the technique of stream flow concentration devices provides marked increase of mean velocities along the center line of the channel. (WRSIC abstract)