Water power is power derived from the fall of water from a higher to lower level, and extracted by the passing of this falling water through turbines.
This kind of power, is commonly known as Hydro-electric power.
Hydro-electricity is the most widely used renewable energy resource. Its availability depends upon an assured supply of fast-flowing water which may be obtained from rainfall spread evenly throughout the year or by building dams and storing water in large reservoirs.
The initial investment costs and levels of technology needed to build new dams and power stations, to install turbines and to erect pylons and cables for the transport of the electricity to often-distant markets, are high. However, once a scheme is operative, the 'natural', continual, renewable flow of water makes its electricity cheaper than that produced by fossil fuels.
Although the production of hydro-electricity is perceived as 'clean', it can still have very damaging effects upon the environment. The creation of reservoirs can mean large areas of vegetation being cleared, wildlife habitats and agricultural land being lost, and people being forced to move home. Where new reservoirs drown vegetation, the resultant lake is likely to become acidic and anaerobic. Dams can be a flood risk if they collapse or overflow and have been linked to increased earthquake activity.
Despite these negative aspects, many countries rely upon large, sometimes prestigious, schemes or, increasingly in less developed countries, on smaller projects using more appropriate levels of technology.