Stone stability under non-uniform flow

The current research is aimed at finding a dimensionless stability parameter for non-uniform flow in which the effect of turbulence is incorporated. To this end, experiments were carried out in which both the bed response (quantified by a dimensionless entrainment rate) and the flow field (velocity and turbulence intensity distributions) are measured. A new stability parameter is proposed, which together with those of Shields [1], Jongeling et al. [2] and Hofland [3] was evaluated using the measured data. The focus of the evaluation is on the correlation of these stability parameters with the measured bed damage expressed in terms of the dimensionless entrainment rate. The experimental results confirm that the Shields stability parameter fails to predict bed damage for non-uniform flow conditions (R2=0.18). In contrast, Jongeling et al. [2], Hofland [3] and our new proposed stability parameters give better damage predictions (R2 = 0.77÷0.81). The results confirm the strong influence of the velocity and turbulence intensity distributions on the stability of bed material.