Discharge Calculator
A discharge calculator will take a cross section and a speed. Then it will give the flow in cubic meters per second…
A discharge calculator will take a cross section and a speed. Then it will give the flow in cubic meters per second or liters per second. It will make field checks quick. It will help you plan pumps, drains, and irrigation.
From my own experience, that kind of quick answer keeps a job on track.
Why you must calculate discharge now
Example,
An engineer is teaching a small crew beside a concrete channel. She wants the team to size a pump. She asks her learner to measure depth and speed. They read depth and speed on simple tools.
They want to know how much water will reach the pump. So they use the discharge method. This helps them pick the right pump and avoid trouble. I have done this on sites. Quick math saved us time and money.
Calculate discharge — step by step
First, know the simple formula.
Q = A × v
Q is discharge (m³/s).
A is cross-section area (m²).
v is velocity (m/s).
Second, pick a real example. A teacher measures a small rectangular channel. Width is 2 m. Depth is 0.5 m. Velocity is 0.8 m/s. She tells the learner to write values down.
Third, find the area. Area = width × depth.
Area = 2 m × 0.5 m = 1.0 m².
Fourth, plug into the formula. Q = A × v.
Q = 1.0 m² × 0.8 m/s = 0.8 m³/s.
Fifth, convert to liters per second if you want. 1 m³ = 1000 L.
0.8 m³/s × 1000 = 800 L/s.
So the team sees the pump must handle about 800 L/s. They will pick gear that can move that much water. That choice will make the system run well.
Practical tips from my fieldwork:
Always check velocity in a few spots. Flow can change fast. Use a small float or a hand-held velocity meter. If the channel shape is odd, break it into pieces and add areas. Use the calculator for quick checks, and then verify with a simple test.
FAQs
Q: What units should I use?
A: Use meters and seconds for m³/s. Convert to L/s by ×1000.
Q: Can I use this for a pipe?
A: Yes. For full pipe use area = πD²/4 and the same formula.
Q: What if flow is uneven?
A: Take several velocity readings. Then use the average.
Final Words
A neat trick for manual checks is to measure width, depth and a few speed points. Multiply to get Q. A discharge calculator will save time and cut errors, but a quick hand check will keep you safe on site.
