ENGINEERING – HYDRAULIC & OPEN CHANNEL FLOW CALCULATOR
Culvert Capacity
A precise tool.
What is the Culvert Capacity & How does it work?
Culverts convey water beneath roadways, railways, or embankments and their capacity depends on whether the flow is governed by inlet or outlet control. In inlet‑controlled conditions the upstream head drives water through the opening, while outlet‑controlled flow is limited by the pipe’s ability to convey water under gravity. For inlet control the discharge is estimated with the orifice equation, where a discharge coefficient Cd accounts for energy losses at the entrance. The governing expression is When outlet control dominates, Manning’s equation for pipe flow is applied. The pipe’s roughness (n), hydraulic radius (R) and slope (S) together determine the maximum conveyance.
Q = C_d A \sqrt{2 g H}
Q = discharge (m³/s) A = flow area (m²) g = 9.81 m/s² H = head causing flow (m)
Parameters
Result
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Frequently Asked Questions
What is the difference between inlet-controlled and outlet-controlled flow in a culvert?
Inlet-controlled flow is driven by upstream head, while outlet-controlled flow is limited by the pipe’s ability to convey water under gravity.
How do you calculate the discharge coefficient (Cd) for a culvert?
The discharge coefficient (Cd) accounts for energy losses at the entrance and typically ranges between 0.6 and 0.9, depending on the flow conditions and culvert design.
What factors affect the capacity of a culvert?
Culvert capacity is affected by factors such as pipe diameter, slope, length, material, and whether the flow is inlet or outlet controlled.
How do you determine if a culvert is inlet-controlled or outlet-controlled?
A culvert is inlet-controlled if the upstream head drives water through the opening; it is outlet-controlled if the pipe’s ability to convey water under gravity limits the flow.
Can you explain the role of the orifice equation in culvert capacity calculations?
The orifice equation is used to estimate discharge for inlet-controlled conditions, where a discharge coefficient (Cd) accounts for energy losses at the entrance.
Results are for informational purposes only and do not constitute professional advice.