Hydraulic Characteristics of the Crump Gabion Weirs for Free Flow Conditions

In contrast with conventional impermeable weirs, Solid objects and dissolves substances can pass through gabion weirs. Thus, due to its minimal negative attributes, gabion weirs are considered environmentally friendly structures. This study aimed to assess the effect of upstream and downstream side slopes of the crump gabion weirs on the discharge coefficient for free flow conditions and compare it with those of impermeable weirs. To achieve this objective, a general non dimensional relationship was developed. Eight different Gabion weir models and 3 impermeable weir models were examined in a horizontal flume, 15.0m long, 0.3m wide, and 0.5m deep, respectively. Multiple, methodical experiments were performed using various discharge rates including: discharge, upstream and downstream depths, material size, and upstream and downstream slopes. It was observed that under the free flow conditions, a decrease in the upstream and downstream slopes led to an increase in the weir and a decrease in the discharge coefficient. Furthermore, an increase in the material size caused a decrease in the head on the weir and an increase in the coefficient development of a relationship to predict the gabion crump weirs’ discharge coefficient (R2=0.97) was achieved through dimensional analysis.