Flexi Says: Hydroelectric power, or hydropower, harnesses the energy of water moving down a stream. Hydropower is the most widely used form of renewable energy in the world. This abundant energy source provides almost one fifth of the world’s electricity. The energy of waves and tides can also be used to produce water power. At this time, wave and tidal power are rare. Hydroelectric power's dependency on adequate water resources is mandate. Water cycle play an important role to maintain these water resources, specially in the water scarcity areas. If there is no plentiful rains the dams over streams would not able to generate enough of hydroelectric power.