Fluctuating Frequency of Live Bed Scour Depth around Submerged Weirs at Equilibrium Stages

Abstract

Previous studies have primarily focused on the estimation of equilibrium scour depths around weirs, while overlooking the details of the temporal evolution of the live bed scour process of submerged weirs at the equilibrium stage. This study aims to investigate the relationships between fluctuating frequencies of the approaching bedforms and live bed scour depths around submerged weirs. The average fluctuating frequencies of approaching bedforms, upstream scour depth, and downstream scour depth are quantified from measured topographic time-series data. The frequency of upstream scour depth variations is found to be almost the same as that of bedforms, while the fluctuating frequencies of the scour depth variations downstream of the weir are found to be 0.38–0.68 times the approaching bedform frequencies in the scour equilibrium stage. New empirical equations are proposed to predict the fluctuating frequencies of live bed scour depth variations in the scour equilibrium stage.