Discharge characteristics of a trench weir

Trench weirs are commonly adopted in boulder streams for diverting water for use in hydropower, irrigation and water supply schemes etc. Here, a trench is built across the river below its bed level. The top level of this trench is covered with bars to prevent the entry of sediment into the trench. Discharge characteristics of this weir apart from flow conditions also depend on the geometric characteristics of the bars used. Generally round bars are used, however, from a structural consideration, flat bars are preferred over round bars as flat bars have more flexural rigidity. In the present paper, the results of an experimental study on the discharge characteristics of a trench weir consisting of flat bars under free and submerged flow conditions are reported.