Waterwheel Park, the unique-shaped Water Wheel has a long history and the first reference to it appeared in the Ming Dynasty. Lanzhou is the only city through which the Yellow River flows; there are thus many irrigation machines in the city. The waterwheel invented by Duan Xu in the Ming Dynasty (1368 - 1644) is the oldest one. Duan Xu learnt from the irrigation machines in Yunnan Province and invented a distinctive style with the appearance of chariot wheels and a diameter ranging from 10 to 20 meters (32.8 to 65.6 feet). Until 1952, about 252 waterwheels stood along the river in Lanzhou, and at that time, the city was reputed to be the "City of Waterwheels."
It is an ancient irrigation device that uses flowing or falling water to create power by means of a set of paddles mounted around a wheel. The force of the water moved the paddles, and the consequent rotation of the wheel is transmitted to machinery via the shaft of the wheel.
In the garden, two huge waterwheels with striking appearances stand uprightly on the south bank of the Yellow River. They are modeled on the antique waterwheel, having quadrate buckets and a diameter of 16.5 meters (54.1 feet). In high water periods, they are driv en by flowing water from the river; in low water periods, they are driven by water gathered by cofferdam. Owing to the two waterwheels and an advantaged position, the Waterwheel Teahouse attracts a lot of tourists.