What it does
LMNO Engineering provides calculators for open channels, culverts, flow measurement, pipes and related water-resource questions.
LMNO separates open channels, culverts, pressurised pipes and hydraulic-control models. Its Manning calculator selects an unknown from area, wetted perimeter, slope, roughness, velocity and discharge, with feet/seconds or metre/second units. The rectangular-channel model assumes uniform steady flow in a long, unchanged cross-section; water depth is normal to the channel bottom. Hydraulic radius is area divided by wetted perimeter, and the selected units are converted through SI for calculation. Inputs must be positive. Free tools are marked separately from PIN-restricted calculations. Purchased access uses browser cookies and time/computer limits: 7 days, 90 days or a year for up to five computers, or 30 days for up to 30 computers. Keep a culvert inlet/outlet-control problem separate from a simple Manning normal-flow calculation.
Strengths
- Detailed hydraulic calculation categories
- Catalogue marks free and PIN-restricted tools
Watch out for
- Some calculators require a purchased PIN for full functionality
Best for
- Reviewing a defined hydraulic model
Sources
- LMNO Engineering, Research, and Software (Oct 26, 2026)
- LMNO Manning Inputs and Uniform-Flow Model (Oct 26, 2026)
- LMNO Rectangular Channel Geometry and Input Bounds (Oct 26, 2026)
- LMNO PIN Cookie, Duration and Computer Scope (Oct 26, 2026)