Introduction to Yuliang Dam: Yuliang Dam is the largest stone rolling dam on the Xin'an River. There are three grooves about 10 meters wide on the dam, called water gates. The three water gates on the dam gradually decrease from north to south: the water passing through the water gate at the southern end rushes straight to the Longjing Mountain wall 150 meters away from the dam, encounters a stone wall extending more than 30 meters wide into the river, and then turns to the northeast and flows down. , This not only greatly reduces the flow of incoming water, but also makes it difficult for sand moraine to accumulate on the north bank, making the area around the Long Shipyard under the dam an ideal berthing place for ships. The two water gates at the north end and the middle ensure that the Lianjiang River still has a large water discharge capacity when the water level is high, and can regularly wash away part of the siltation left by the turning of the river surface. The structure of the dam body is also very particular. The multi-layered stone strips are mostly connected with dovetail stone mortise and tenon joints. Vertical stone piers are inserted every 1.5 meters or so for reinforcement.