Abstract: As river restoration idea transfers from canal-dominated back to nature-oriented, instream flow control structure, as a proactive bank protection measure, is drawing increasing attention due to its unique ecological benefits. The main categories, working characteristics, applicability and research progress of in-stream flow control structure in China and abroad are summarized in this paper.On this basis,the 3D hydraulic characteristics in a 193° sharp bending flume before and after stream barbs are arranged in backflow direction are studied and comparedthrough numerical simulation. The working mechanism and effectiveness of stream barbs in bend flume are investigated preliminarily. Results demonstrate that stream barbs could achieve the purpose of bank stabilization by adjusting the secondary flow structure and deflecting the high speed flow far away from the concave bank. Nevertheless, stream barbs would give rise to backwater in the bend and deviate the high speed flow on the convex bank side. The backwater level and deviation degree are closely related with the layout pattern of stream barbs. The study is of referential significance for upcoming researches on eco-hydraulic engineering structures in river ecological restoration field.

Key words: medium and small river, in-stream flow control structures, stream barbs, hydraulic characteristic, numerical simulation