Ancient man-made rivers controlled the water surface by ship locks. China was the first country to build shiplocks. In the thirty-third year of Qin Shihuang (2 14 BC), a canal was dug, and a steep gate was set up, also known as Doumen (now called sluice), to adjust the water level difference before and after Doumen, so that ships could pass through the waterway with water level difference. This kind of steep gate constitutes a single brake, which is also called a half brake. During the Jingping period of the Southern Song Dynasty (AD 423-424), two steep gates were built on the Yangtze River (now Yangzi Bridge in Yangzhou City, Jiangsu Province). By opening and closing the two steep doors in turn and controlling the water level between the two steep doors, the ship can overcome the water level difference and sail up or down. During Song Yongxi's reign (984-987), two scarps were built in Xihe River (now the canal between Huai 'an and Huaiyin, Jiangsu), with a distance of 50 steps (about 76 meters). The steep gate is equipped with water conveyance equipment. This is the famous Xihe lock in the history of China, and it is the embryonic form of modern ship lock.

The waterway in Huainan is dammed to store water. I don't know when it started. According to legend, Zhao Bodai was built by Xie An in the Eastern Jin Dynasty. However, according to the relevant records in Li Ao's Record of Lainan, Zhao Bodai was still a plain river in the Tang Dynasty, and it was impossible to build a dam in Xie 'an. In the heyday, the right auxiliary pottery of the bank discharge department began to propose to build a compound sluice to adjust the water level difference, in order to solve the problem of difficulty for ships to cross the dam. At that time, Dr. Zhong Xun and Si Wen of the Ministry of Industry made Zhang Lun the main and deputy shipper. The above table requested the imperial court to promote this practice, so the gate of Zhou Zhen Courtyard was built. It can save 500 officers and1250,000 miscellaneous expenses every year. According to the old shipping method, each ship carries no more than 300 stones. After the compound gate is completed, it can initially load 400 stones. Later, the loading capacity gradually increased, and the official ship could reach 700 stones; Private boats can hold more than 800 bags, each weighing two stones. Since then, Beishen, Zhao Bo, Longzhou, Cornus and other dams have successively abolished the old system and replaced it with a new system, and the convenient function of water transportation is still playing. I once passed by Zhou Zhen during the Yuanfeng period, and found a fallen stone tablet in the mud behind Jiangting, engraved with "The Opening of the Gate in Zhou Zhen" written by Hu Wuping.