Depending upon the capacity of the project, a hydro Project can be classified as:


 Total Capacity


 Upto 100 KW


 101 to 2000 KW


 2001 to 25000 KW


 Above 25000 KW to 100000 KW


 Above 100000 KW

Small hydro projects can be broadly classified in the following two types:

Small Hydro Projects on Hill Streams

Small streams with steep bed slopes are available in the hills, giving rise to medium as well as high head projects utilising small discharges. These schemes are normally run of the river type with a small diversion structure to divert the flows through the head regulator located in the intake portion of the diversion structure. The water conductor system would usually comprise of a diversion and head regulator, a power channel, a desilting basin, forebay, penstock, power house and a tail race leading from the power house to the stream.

Small Hydro Projects on Canal Falls / Dam Toe

Irrigation canals carrying relatively high but assured discharges have several falls along their route. Small hydel projects utilising low heads can be constructed at such falls. Small hydel projects can also be located just downstream of a dam, barrage or similar structure to utilise the difference in the water level in the reservoir and in the canal downstream. A bypass channel to bypass the flows adjacent to the fall structure is constructed and the power house is constructed in the bypass channel. The bypass channel is suitably connected to the main channel.

Type of  Turbine for Small Hydro Projects

Type of Turbine

 Class of Head

Head range for large/ medium sets (m)

Head range for small sets (m)

 Pelton (Impulse)

 High Head

 Above 300 m

 Above 150 m

 Francis (Reaction)

 Medium Head

 30 to 300 m

 20 to 200 m

 Kaplan (Axial Flow)

 Low Head

 3 to 50 m

 3 to 40 m

Assessment of Power Potential

Power potential can be estimated by using the following formula Where



g x Q x H x η



Power in kW



Turbine Discharge in Cu. M. per second or cumecs



Net head in meters



Overall unit efficiency



Gravitational constant generally taken as 9.81



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