FLOW CHARACTERISTICS OF GABION WEIR FOR FREE FLOW CONDITION – AN EXPERIMENTAL APPROACH

Traditional solid weirs are a water tight body build of impervious materials across the stream, to raise the water level and control the flow. However, it obstructs the longitudinal travel of aquatic life and other materials causing adverse effect on hydroenvironment. A Gabion weir serves as a hydro-friendly structure because of its porosity which allows the Aquatic life as well as other materials to pass through them. Gabion weirs can be used as an easy substitute to the solid weirs in case of flow with low afflux and restricted flood mitigation. In this study, sets of laboratory experiments were carried out in order to study the flow characteristics over gabion weirs. The experiment has been conducted in a tilting flume of length 5.36m, 0.245m width and 0.450m depth, for a wide range of discharge, height, weir length, upstream water depth and different size aggregates for filling gabion. The outcome of the gabion weir were compared with solid weirs having equal size and found that the flow characteristics over solid and Gabion weir is different. A linear regression analysis has been performed to find the equation for discharge coefficient in terms of dimensionless parameters and using the proposed equation the discharge has been calculated over the gabion weir for given range of data and found that the calculated discharge is within ±5% of the observed ones.