        MyCTMainForum  Open water flow rate

Civil Engineering index               The Manning formula is evaluated to give flow speed, using a substitution of A/P for the hydraulic radius. The volumetric flow rate is also given, by use of the discharge formula (Q=AV, where Q=discharge rate and V= velocity).              Cross-sectional area m² --- METRIC --- nm² µm² mm² cm² km² -- IMPERIAL -- square inches sqare feet square yards square miles --- OTHER --- hectares acres dunams square chains tennis courts Wetted perimeter m --- METRIC --- pm nm microns (µm) mm cm km -- IMPERIAL -- mil 1/16 inch inches feet yards miles - SCIENTIFIC - Planck Bohrs Angstrom light-seconds light-years au parsecs --- OTHER --- points cubits fathoms rods chains football fields furlongs Roman miles nautical miles leagues Slope (linear head loss) Coefficient of roughness Flow velocity m/s --- METRIC --- cm/s km/s -- IMPERIAL -- inches/second feet/second feet/minute - RECIPROCAL - min/mile min/km min/5 km min/10 km --- OTHER --- km/h mph miles/second knots furl's/f'night Mach c (light speed) Discharge rate m³/s mL/min liter/min liter/s m³/min cu ft/s cu ft/min gal(US)/min gal(UK)/min   The Manning equation is used to find the flow or discharge (volume) rate of an open flow such as a river, stream, or irrigation channel. Flow occurs as a consequence of gravity and the slope of the conduit. While the Manning formula is convenient, it can easily give errors of up to 20%.
The Manning coefficient of roughness varies between ~0.02 for smooth, straight sides and ~0.075 for meandering flows with very uneven bottoms and banks.          