Drainage & Stormwater Structures
Inlets, catch basins, storm sewers, open channels, and detention elements that convey or attenuate stormwater runoff. Design flows follow rainfall-runoff relations, and conveyance follows open-channel hydraulics.
Engineering Application
Catchment runoff estimated with the Rational Method sets the design flow for storm sewers and culverts; channels and pipes then carry that flow at acceptable velocities, with detention volume where attenuation is required.
Key Parameters
| Parameter | Unit |
|---|---|
| Design flow | L/s |
| Rainfall intensity | mm/h |
| Runoff coefficient | — |
| Channel velocity | m/s |
Related Engineering Tools
Open Channel Flow (Manning′) Calculator
Compute open-channel velocity and discharge with Manning’s equation for trapezoidal, rectangular, and circular channels.
v = (1/n) × R^(2/3) × S^(1/2) · Q = v × A Pipe Flow Velocity & Sizing Calculator
Size a pipe to carry a target flow within a recommended velocity range, or check velocity for a given diameter.
D = √(4Q / (π·v)) · v = Q / A Stormwater Runoff (Rational Method) Calculator
Estimate peak stormwater runoff with the Rational Method (Q = C·i·A) for drainage design and storm sewer sizing.
Q = 2.78 × C × i × A (L/s, A in ha, i in mm/h)