Document Type : Original Article
Abstract
Construction of weirs in river bends results in non-uniformity of water flow across a channel bend and can reduce the performance of intake structures on both sides of the river. It was hypothesized that more uniform distribution of flow across the bend can be achieved by changing the weir-crest profile from horizontal to sloping. The present study tested the performance of horizontal and sloping broad-crested weirs in a channel bend to achieve the most uniform distribution of unit flow rates across the river bend. The results indicate that horizontal crested weirs were sufficient at the entrance and exit of the bend, but within the bend reach, sloping crest weirs provided better convergence of the unit flow rates across the bend. It is recommended that the slope of the weir crest incline 2º to 5º toward the outer bank of the bend. The best location for the weir inside the bend is at that angular sections at 30°, 60°, and 45°, respectively. The flow equation over the weir was derived using mathematical and dimensional analysis. Discharge coefficient Cd was examined for free to submerged flow as a function of the position of the weir along the bend, geometry of the weir, upstream head water, and downstream tail water.
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