Question

Low-head hydropower involves ___________ dams on ___________ rivers.

Answer 1

I think that the Low-head hydropower involves small dams on minor rivers. 
Low head hydropower plants are those that operate with a water level difference of 30 feet or less. The systems that generate electricity involve diverting water from a river that is delivered to a power house containing a turbine, generator or other equipment that convert mechanical energy to electrical energy.