Experimental Study on Neck Cutoff in Meandering River under Variable Discharges

Neck cutoff is a sudden phenomenon that occurs during the evolution of meandering rivers, but its process and mechanism remain unclear. In this investigation, neck-narrowing before cutoff, formation new river, appropriate conditions for under constant variable discharges were studied using experimental methods in laboratory flume. The results indicated bank erosion upstream downstream neck was main factor triggered regardless whether discharge changed. sinuosity model river approximately 7, ratio width to average reached 0.43, material nonuniform natural sand. Under unit ranged from 0.0039 0.0069 m2/s longitudinal gradient 1‰, could occur after sufficient erosion. When imminent, channel increased rotated downstream. After experienced three stages, namely, short-term scouring stage, long-term horizontal widening transverse normal slow development stage. resulting effective contributing directly affected time position. We attempted explain factors leading an energy consumption perspective. occurred when maximum value upon entry recession stage relative equilibrium To certain extent, study significant understanding cutoff.