Work out pump discharge for field instantly with clear inputs, formula shown and shareable results.
One millimetre of water over one hectare is 10 cubic metres. Multiply the area by the depth to get the net volume, divide by application efficiency for the gross volume the pump must lift, then divide by the hours available to get the discharge rate the pump and delivery pipe have to sustain.
Volume
Net volume (m3) = area (ha) x 10,000 x depth (mm) / 1000
Discharge
Discharge (m3/h) = net volume / efficiency / hours; L/s = m3/h / 3.6
Take the required L/s with your total head (suction lift + delivery height + friction losses) to a pump curve. Hydraulic power in kW is roughly 9.81 x L/s x head (m) / 1000, divided by pump and motor efficiency.
Water lost to runoff, wind drift and deep percolation never reaches the root zone, so more must be pumped than the crop receives. Efficiency turns the crop requirement into a pumping requirement.