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Coefficient of Spillway Formula:
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The Coefficient of Spillway is a dimensionless factor that represents the efficiency of a spillway in discharging water. It is obtained through calibration and varies based on spillway design and operating conditions.
The calculator uses the spillway coefficient formula:
Where:
Explanation: The formula calculates the spillway coefficient by dividing the discharge rate by the product of spillway length and the head of water raised to the power of 3/2.
Details: Accurate spillway coefficient calculation is crucial for designing efficient spillway systems, ensuring proper water discharge capacity, and preventing dam overtopping or structural failure during flood events.
Tips: Enter discharge in m³/s, spillway length in meters, and head of water in meters. All values must be positive numbers greater than zero.
Q1: What is a typical range for spillway coefficients?
A: For ogee spillways, coefficients typically range from 1.8 to 2.3, with well-designed spillways achieving coefficients around 2.0-2.1.
Q2: How does head affect the spillway coefficient?
A: The coefficient generally increases with head up to the design head, then may decrease slightly for higher heads due to submergence effects.
Q3: What factors influence the spillway coefficient?
A: Crest shape, approach conditions, upstream head, downstream submergence, and spillway surface roughness all affect the coefficient value.
Q4: Why is the ogee spillway shape commonly used?
A: The ogee shape closely follows the profile of water flowing over a sharp-crested weir, providing high discharge coefficients and good energy dissipation.
Q5: When should field calibration be performed?
A: Field calibration is recommended after construction to verify design assumptions and account for actual site conditions that may differ from laboratory models.