Dynamics of gabion weirs and its comparison to reinforced concrete weirs
Keywords:Gabion weir, non-porous weir, seepage, scouring, sedimentation, flow profile, discharge coefficient.
AbstractWeir is one of the important water divergence structure. Different types of weirs have different hydraulics on upstream as well as downstream resulting in various construction costs and necessary arrangements for safe operation. This study presents the hydraulic comparison of two different types of weirs namely Reinforced concrete weir and Gabion weir. These weirs were compared using different hydraulic parameters like downstream scouring, upstream sedimentation, discharge coefficient, water surface profile and seepage along the weir and its foundation. Experimental analysis was carried out to estimate scouring, discharge coefficient and sedimentation. Similarly, Seepage analysis was performed using the SEEP/w software whereas water surface profile is drawn using HEC-RAS. After analyses, it is found that the upstream sedimentation and downstream scouring were maximum for concrete weir as compared to Gabion weir due to the fact that the later type is allowing some sediments to pass through its body. It is also concluded that foundation and body seepage of Gabion weir is reduced by almost 95 % when replaced with reinforced concrete weir. The HEC-RAS results showed that the water surface elevation for concrete weir is much higher than the Gabion weir. Likewise, low Discharge Coefficient was observed for concrete weir as compared to the Gabion weir. At the end it is concluded that concrete weir is more efficient in raising the water level and reducing seepage and are also durable but needs better arrangement to control scouring and sedimentation.
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