A water wheel is a device that uses flowing or falling water to generate power by using paddles that are mounted around the wheel. The force of the water pushes the paddles causing the wheel to rotate, this creates a special channel which is known by a majority as the ‘mill race’ from the pond to the waterwheel.
Waterwheels are usually positioned vertically over a water source, this means that the axle is positioned horizontally. The axel transfers the energy from the falling water to a drive belt or a system of gears that then operates some sort of machine. These wheels require some source of falling or flowing water.
Hope it helped!