Experimental Investigation and Assessment of Turbidity Current Head Dynamic Over a Mobile Bed

Turbidity current phenomenon is one of the most important factors in reservoir sedimentation and sediment distribution, which causes management and operational problems and decreases dam’s useful life. Study and investigation of progressive section (head of turbidity current), as the most significant and considerable section is essential for sustainable management of dam reservoirs. So far, most of the studies have been conducted under experimental conditions on rigid beds. But In this study, in order to achieve more realistic results regarding natural conditions in rivers and reservoirs, the experiments were carried out on an erodible and mobile bed. So dynamic of turbidity current head was analyzed on rigid and erodible beds for different effective hydraulic conditions. It was shown that erodible bed increased the head velocity of turbidity current and Keulegan coefficient up to about 20% and also, increased the relative forehead height up to about 40% with increasing flume bed slope. In addition, in order to estimate the averaged head velocity, an equation with correlation coefficient of 0.86, was developed using multivariate linear regression and effective dimensionless parameters. Finally sensitivity analysis of the equation’s dimensionless parameters showed that the most effective parameter in estimation of the head velocity average is Richardson number.