Hydroelectric power is produced by

Answer 1

Water piped downhill from a reservoir to create considerable pressure, drives turbines connected to alternators that generate the electricity. That is then transformed up to transmit it over long distances at high voltages hence low currents, for efficiency. ++++ [Original answer is: ] This is a small version you can build by yourself.

The water pushes a wheel, the wheel has a gear on the side of it mounted to the axle or pivot point. The larger the gear the better. The gear has a belt like one in a car engine. The belt attaches to a spindle on an alternator. The wires coming from an alternator run to a battery bank and will charge the batteries that are daisy chained together. From the batteries, it is recommended you have a power converter so you don't push too much power through the electrics you are powering. As long as the water is pushing the wheel the alternator will charge the batteries and provide power to your electronics.