Calculate normal depth for open channels and pipes using Manning's equation. Iteratively solve for the depth at which uniform flow occurs. Supports circular, rectangular, trapezoidal, and triangular sections.
Normal depth is the depth at which uniform flow occurs in an open channel. At normal depth, the energy slope equals the channel bed slope, meaning gravitational forces are balanced by frictional resistance.
Manning's equation for uniform flow:
This calculator iteratively solves for the depth that satisfies Manning's equation for the given discharge.
| Material | n Value |
|---|---|
| Concrete pipe | 0.012 - 0.015 |
| Corrugated metal pipe | 0.022 - 0.027 |
| HDPE pipe | 0.010 - 0.012 |
| Concrete channel | 0.013 - 0.017 |
| Earth channel (clean) | 0.022 - 0.033 |
| Grass-lined channel | 0.030 - 0.050 |
Source: Chow (1959), HEC-22 Table 7-1.
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