Basal Stress Fluctuation: Reply to Comment by Cagnoli on "Slope-Break Collisions: Comment on 'Insight Into Granular Flow Dynamics Relying on Basal Stress Measurements: From Experimental Flume Tests' by K. Li et al."

In the comment, Cagnoli (2022) disagrees with our experimental conclusion that the enhanced particle agitation related to the high magnitude basal fluctuating stresses contributes to the granular flow mobility. Instead, he argues that the slope-break model used in our experiments prevents the granular flows from being as mobile as they could be. In this reply, we restate our viewpoints by further clarifying the experimental variables and evaluating the effects of the additional phenomena raised in our experiments. By considering the granular flow velocities before the slope-break, a linear correlation between the depth-average velocity and equivalent friction coefficient is established, indicating that an increasing flow mobility with decreasing fractal dimension D has already been initiated before the slope-break. Thus, the slope-break collision has no significant effect on the general trend of the flow mobility versus grain size and the positive correlation between stress fluctuation and granular flow mobility is still valid.