The impact of spillway curvature on discharge coefficient and the hydraulic behavior of the approach channel, case study: Germichai spillway

The ogee spillway with an arc plan has a longer crest length. Therefore, in a specific reservoir water level, it can discharge higher flow rate compared to a straight one and due to this reason is preferred in applicable plans. The aim of this research was to laboratory investigation on the effect of the curvature of the ogee overflow weir on distribution of flow discharge, determination of discharge coefficient and study the overall hydraulic behavior. This research was executed on Germichai Dam spillway physical model which was constructed in the Soil Conservation and Water Management Research Institute hydraulic lab. Results showed the need of correction on initial design and that the discharge coefficient of this free overflow is nine percent in average, less than ogee spillways with straight axis On the other hand, the geometry of the downstream conveyance conduit forces the spillway to act in a submerged condition for discharges higher than 1.3 times the design discharge And the discharge coefficient presented a decreasing trend with the upstream weir head.