Weirs are normally provided for water level and flood control, flow measurement, environmental enhancement and channel stabilization. In engineering expression a weir must be able to satisfy the fundamental requirements such as; hydraulic performance, structural stability and environmental impacts. Due to the extensive use of weirs in hydraulic systems, more investigations are needed on such structures. Weirs in channel are left; LINE-HEIGHT: normal; MARGIN: 0in 0in 0pt; mso-layout-grid-align: none" align=left Key Words Discharge coefficient, Experimental model, Free flow, Piano-Key weir, Submerged flow, Threshold submergence.
