The industry development and the life standards increment have caused the human feels more easement, but it also has caused an increase of energy consumption, environmental pollution and the large volume of greenhouse gases emission.
Those changes make the researchers to find out the alternative energy sources such as renewable energies. The most prominent and the oldest source of clean and renewable energies is hydropower.
There is no international consensus on the definition of small scale hydropower. In Canada 'small scale' can refer to upper limit capacities of between 20 and 25 MW, in the United States 'small scale' can mean 30 MW, however, a value of up to 10 MW total capacity is becoming generally accepted. Small scale hydropower can be further subdivided into mini hydro (usually defined as <500kW) and micro hydro (<100kW). No matter how you define it one thing remains the same, small scale hydropower is one of the most environmentally benign forms of energy generation available to us today.
 
Small scale hydropower systems capture the energy in flowing water and convert it to usable energy. Although the potential for small hydro-electric systems depends on the availability of suitable water flow, where the resource exists it can provide cheap clean reliable electricity. A well designed small hydropower system can blend with its surroundings and have minimal negative environmental impacts. Moreover, small hydropower has a huge, as yet untapped potential in most areas of the world and can make a significant contribution to future energy needs. It depends largely on already proven and developed technology, yet there is considerable scope for development and optimization of this technology. In other, more rugged regions of the country, it is possible to develop relatively higher heads without elaborate or expensive civil engineering works so that relatively smaller flows are required to develop the desired power. In these cases, it may be possible to construct a relatively simple diversion structure and obtain the highest drop by diverting flows at the top of a waterfall or steeply falling watercourse.
Small hydropower plants are a precursor for economic growth and social development. They guarantee a local, stable power supply. Small hydropower plants are often the only way to create environmentally-friendly power for electric lighting, for preparing and cooling food and for stimulating economic growth in remote regions. In developing countries, they are a good substitute for diesel-powered generators. Even in industrialized nations, small hydropower plants are in demand, as they provide a useful contribution on the whole and effectively support energy change.
In this study, has been tried to evaluate the existence and assessment the resources of this clean source of energy in Kurdistan- the northwestern province of Iran and the calculate the extraction amount of energy from this resource of energy due to the high potentials of the province.
In the evaluated small-scale hydroelectric power in this study, after full identification river and its catchment areas in terms of flow and head and after extraction of relevant maps, by using ArcGIS software, and after apply appropriate environmental, geographical and technical- economic criteria, the hydropower potential of the province from its rivers was estimated.
 The results show that Kurdistan province capable of producing around 500 megawatts of renewable power from that small-scale hydropower that it has.
As a result, 3455 small-scale hydropower plant with the average capacity of 160 kW could be located in the suggested suitable locations in the Kurdistan province. These proposed areas are selected by considering the appropriate environmental, geographical and technical- economic criteria.