Experimental investigation of gabion broad-crested weirs under upstream partial blockage conditions

Abstract

The attention of researchers and engineers has been attracted to gabion weirs due to their environmental, hydraulic, and stability capabilities compared with solid weirs. One of the possible problems of the weirs is the partial blockage caused by sedimentation upstream of them. This research experiment investigates the hydraulic performance of gabion broad-crested weirs (GBCWs) with an upstream partial blockage. For this purpose, a total of 147 experiments were studied with different conditions for free-flow conditions. The weirs were tested with five partial blockage conditions between 0% and 100% of the weir height (0, 0.25P, 0.5P, 0.75P, and P). The results showed that increasing the partial blockage decreases the discharge coefficient. The changes in the discharge coefficients are minor for partial blockage less than 0.25P, and for partial blockage greater than 0.5P, the discharge coefficients are significantly reduced. As the partial blockage increases, the effect of filling-material size in gabion weirs decreases. Finally, a relationship was developed using the nonlinear regression analysis approach to estimate the discharge coefficient in the GBCWs with partial blockage.