In the rahat system of irrigation, there is a bull which is tied to a pole and it moves the pole round and round. the pole is connected to a wheel and as a result of moving the pole the wheel also moves.
Below the wheel is a well. there are buckets attached to the wheel which go into the well and get filled with water.
When on top of the wheel, the buckets are slanted and the water falls into thin canals and get transported to the fields.