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River Discharge Rate Calculator

River Discharge Rate

Calculate river flow rate (discharge) using channel cross-section area and average velocity with Manning equation for open channel flow.

Formula

V = (1/n) x R^(2/3) x S^(1/2) (Manning Equation); Q = V x A; R = A / P (Hydraulic Radius); A = Width x Depth; P = Width + 2 x Depth

Frequently Asked Questions

What is Manning equation?
Manning equation calculates flow velocity in open channels based on the hydraulic radius, channel slope, and a roughness coefficient (n). It is one of the most widely used formulas in hydraulic engineering.
What affects river discharge?
River discharge depends on channel size (width and depth), slope, and roughness. Rainfall, snowmelt, land use, and upstream dams also affect how much water flows through a river at any given time.
What is hydraulic radius?
Hydraulic radius is the cross-sectional area of flow divided by the wetted perimeter. For wide, shallow channels, it approximately equals the average depth. It is a key parameter in flow calculations.

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