Dams are often builds across rivers to tap on the river energy to generate hydroelectric power. Hydroelectric power plants convert the kinetic energy contained in falling water into electricity. Hydropower is currently the world's largest renewable source of electricity, accounting for 6% of worldwide energy supply or about 15% of the world's electricity. In Canada, hydroelectric power is abundant and supplies 60% of our electrical needs.
Hydroelectric power plants capture the energy released by water falling through a vertical distance, and transform this energy into useful electricity. In general, falling water is channeled through a turbine, which converts the water's energy into mechanical power. The rotation of the water turbines is transferred to a generator, which produces electricity. The amount of electricity, which can be generated at a hydroelectric plant, is dependent upon two factors. These factors are (1) the vertical distance through which the water falls, called the "head", and (2) the flow rate, measured as volume per unit time.
Irrigation has been practiced throughout the world. There are modern ways to obtain water from the river as well as traditional ways. Irrigation is very important to areas where there is long period of drought, areas with seasonal rainfall. Irrigation has helped farmers to have double or even up to triple cropping per year.
Fertile alluvial soil
Floodplain and delta are good agricultural land, which have fertile alluvial soil. The alluvial is increased when the river floods. The flat and low-lying floodplain and delta makes it easier for people to build settlement and farm. Many urban settlements start in the fertile floodplain. Bangkok in the Menam Chao Phraya Delta of Thailand is one good example.
Famous rivers are popular tourist attraction. Tourist comes to see the spectacular view of the various landforms in the river. Many people flock to North America to see the Niagara fall on the Niagara River. The Singapore River is also one of the tourist attraction in Singapore.
Rivers are also places that provide a very good enviroment for whitewater rafting and various other water sport.