Abstract: , The mechanism of instability of non-Newtonian flow in an. open channel is studied by means of experiment and theoretical analysis. It is proved that the instability of non-Newtonian flow results essentially from the Bingham yield stress τB of the fluid. The larger the yield stress, is and the smaller the rigidity coefficient η is, the more unstable the non-New-t.onian flow will be. Based on the theory, the phenomena of "river clogging" in hypercon-centrated flow in the Yellow River and its tributories, th...