Estimate perimeter for trapezoidal, triangular, circular, or box canals. Compare sections, inspect plots, and export. Make drainage and lining decisions using dependable field values.
A canal wetted perimeter is the length of channel boundary that stays in contact with flowing water. Construction teams use it when reviewing lining quantities, hydraulic resistance, and the relationship between area and flow efficiency. A longer wetted boundary usually means more friction against the water.
This page supports four practical section types. Rectangular sections fit box channels and formed drains. Trapezoidal sections match common earth and lined canals. Triangular sections help with narrow drainage channels. Circular calculations are useful when a conduit or culvert carries open channel flow instead of full pipe flow.
The result panel also reports flow area, top width, and hydraulic radius. Those added values are useful during early design checks because hydraulic radius combines area and wetted perimeter into one measure. In many field calculations, it becomes part of Manning based flow estimation and lining comparisons.
The graph plots how wetted perimeter changes as depth changes. That visual check helps you compare section behavior before finalizing dimensions. You can also download the result as CSV or PDF for site notes, design review files, or quantity estimation records.
Rectangular canal: P = b + 2y
Trapezoidal canal: P = b + 2y√(1 + z²)
Triangular canal: P = 2y√(1 + z²)
Circular canal: P = rθ, where θ = 2cos-1((r - y) / r)
Here, P is wetted perimeter, b is bottom width, y is flow depth, z is side slope in horizontal to vertical form, r is radius, and θ is the central angle in radians.
| Section | Input values | Calculated wetted perimeter |
|---|---|---|
| Rectangular | b = 4.00 m, y = 1.50 m | 7.000 m |
| Trapezoidal | b = 3.00 m, y = 1.80 m, z = 1.00 | 8.091 m |
| Triangular | y = 2.00 m, z = 1.25 | 6.403 m |
| Circular | d = 2.40 m, y = 1.20 m | 3.770 m |
It is the boundary length touching flowing water. Designers use it to estimate resistance, compare section efficiency, and support open channel flow calculations.
It balances excavation practicality, side stability, and hydraulic efficiency. Many field canals and lined sections use this shape for that reason.
Yes. Select feet in the unit menu. The perimeter, top width, and hydraulic radius stay in feet, while flow area becomes square feet.
Hydraulic radius connects flow area and wetted perimeter. It is often needed in Manning based checks and helps compare how efficiently different sections carry water.
Yes. Enter depth equal to the diameter. The result then becomes the full internal perimeter of the circular section.
Use horizontal to vertical format. For a 1.5H:1V side, enter 1.5 as the side slope value.
The wetted boundary grows as water touches more channel surface. The chart helps you see that change across the selected depth range.
Yes. It is useful for early sizing, lining review, and comparison work. Final design should still follow project standards and verified hydraulic analysis.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.