Best Hydraulic Section Designer

Design the most efficient open-channel section — the one with the least wetted perimeter for the flow — for a given design discharge, Manning n and bed slope. Pick the shape and the app finds the depth and proportions, then the area, velocity, Froude number and flow regime.

⭐ Free to use · Balance … EP

① Section shape

Side slope z (horizontal : 1 vertical)

Leave blank for the overall best trapezoid (z = 1/√3 ≈ 0.5774 — a half-hexagon). Enter a value to get the best section for that fixed side slope.

② Design flow

Discharge Q (m³/s)

Manning n

Bed slope S (m/m)

Q = (1/n)·A·R^(2/3)·S^(1/2). Typical n: smooth concrete 0.013, rough concrete 0.017, earth 0.025, masonry 0.020.

🏞️ Best section

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Geometry

Flow depth y

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Bottom width b

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Top width T

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Flow area A

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Wetted perimeter P

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Hydraulic radius R

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Flow

Mean velocity V

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Froude number

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Check discharge

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Worked solution

⚠️ Study/estimating aid. The "best" section minimises the wetted perimeter (least lining/excavation per unit flow); add freeboard and check permissible velocity, side-slope stability and practical widths before final design. Verify against your course references.