Work out head and flow for hydro instantly with clear inputs, formula shown and shareable results.
Rearranging the hydro power equation gives the flow needed for a target output: Q = P / (9.81 x net head x efficiency). Net head is gross head less penstock friction, which typically consumes 5-10%. Head and flow together determine the turbine type through specific speed.
Required flow
Q (m3/s) = P (kW) / (9.81 x net head x overall efficiency)
Net head
Net head = gross head x (1 - penstock loss %)
Abstraction volumes, environmental flows and licence conditions govern what may actually be diverted. Confirm with the water authority before design.
No. An environmental or compensation flow must be left in the river, and abstraction is usually licensed with a hands-off flow below which no water may be taken. Design around the flow duration curve, not the peak.
Larger diameter pipe, smoother lining and fewer bends. Doubling the diameter cuts friction loss by a factor of about 32, which usually justifies the extra pipe cost on long penstocks.