Experimental Analysis of Inclined Gabion Drop Behavior in Comparison to the Standard Stilling Basins (USBR)

Controlling relative residual energy values, relative depth, and downstream Froude numbers are important issues faced by designers of inclined drop structures. In this study, 60 different experiments including three angles and two drop heights with subcritical flow at upstream were performed to investigate the effect of using gabion structure in inclined structure in comparison with using the stilling basin downstream of this structure. The results showed that for all experiments, increasing the relative critical depth increases the relative residual energy values and downstream relative depth. Relative energy values and relative downstream depth were significantly reduced when the gabion structure was used in inclined drop and the inclined gabion drop was constructed. The inclined gabion drop reduced the relative energy remained at downstream by 30, 33, 30, and 36 percent as compared to the standard type one, two, three and four stilling ponds, respectively. The average relative depth of downstream was also reduced 37, 40, 37 and 43% as compared to the standard type one, two, three and four stilling ponds, respectively. The range of Froude numbers reduced from 4.49-8.35 to 1.28-2.64. Also, some relationships were presented for estimating relative residual energy and relative depth at downstream of the gabion inclined drop structure.