Chapter 48 Section 2 The Rise of Ancient Seawalls

In the thirty-seventh year of Qin Shihuang (210 BC), Qiantang County was established, and the seat of the government is now at the foot of Lingyin Mountain in Hangzhou. "Tang, embankment also." The ancient Tangtang is common.Taking Qiantang as the name of the county, there may have been seawalls at that time.The legend also holds that the Qin Dynasty built seawalls along the Qiantang River in order to conquer tidal surges. "Shui Jing Zhu · Zhejiang Water" quotes such a legend in "Qian Tang Ji", to the effect that: About one mile east of Qiantang County, there is a "big anti-sea pond" named Qian Tang.The origin of the name of Qiantang has something to do with Cao Hua crediting money to lure people to build the pond.Cao was a native of the Han and Wei dynasties, and declared: "Anyone who can send a piece of Dendrobium soil will be given a thousand dollars." During the ten-month period, there were many people who came.Later, because Huaxin was untrustworthy, it falsely claimed that it would pay everyone after the completion of the seawall.In a rage, everyone abandoned the earth and left by the river.As a result, a section of seawall was piled up, named Qiantang.This story reflects that when "Qiantang Ji" was written, there was already a seawall on the Qiantang River.

The records about seawalls in northern Jiangsu were first seen in the middle of the 6th century.At that time, there was an official of the Northern Qi Dynasty named Du Bi. When he was working in Haizhou (where the government is located in the southwest of Lianyungang City, Jiangsu Province), he "built a long weir in the east of the state to lead the sea, to contain the salty tide outside and to divert fresh water inside." ("Northern Qi Book·Du Bi Biography") The tide-suppressing long dike here is the tidal-proof long dike.If the aforementioned seawalls on the Qiantang River during the Qin and Han Dynasties are not credible because of place names and legends, then there is no doubt about the seawalls in Haizhou.This is the earliest and clearest record of seawall construction in my country.

Some people believe that during the Xianhe period of the Eastern Jin Dynasty (326-334 A.D.), Wu Neishi Yutan built the Hudu Fort at the front of the Yangtze River Delta, which is the earliest and most accurate record of seawall construction in my country.Professor Tan Qixiang, a well-known historical geographer, put forward different opinions in his book "Changshui Collection". The fort is not a seawall, but a castle. This project is not to prevent "sea sand", but to prevent sea copying.Haichao is pirates.Tan's opinion is correct. During the Sui and Tang Dynasties, with the gradual development of the coastal areas of Jiangsu, Shanghai, and Zhejiang, the population and arable land here have increased, and the losses caused by tidal surges have become increasingly serious.Therefore, the construction of moisture-proof projects has attracted more and more attention.From the north bank of the Qiantang River to the south bank of the Yangtze River, a 124-mile long seawall was built according to "New Book of Tang Geography Five".It starts from Yanguan (now Haining, Zhejiang Province) in the south, passes through Pinghu, Jinshan, Huating (now Songjiang County, Shanghai), Fengxian, Nanhui, and ends at the mouth of Wusong River in the north.This is an earlier and longer sea wall that was recorded, and it defends the towns and farmlands between Shanghai and Zhejiang that are vulnerable to tidal surges.

In northern Jiangsu, during the Zongdali period of the Tang Dynasty (766-779 AD), Li Cheng, the deposed emissary of Huainan, also built a relatively important seawall.It starts from Tongzhou in the south (where the government is located in today's Nantong City) and ends in Yancheng in the north, with a length of 142 li.In addition, in order to resist the tide, a Yong'an embankment was also built in Haizhou, which is seven miles long. From the Qin and Han Dynasties to the Sui and Tang Dynasties, it was the initial construction stage of seawalls in my country.At this stage, they were basically earthen ponds, or rammed soil near the coast to form ponds; or they were built by plate-building methods like building walls.This kind of earth pond is relatively easy to build, and soil can be taken from the spot, saving labor and labor, and the technology is relatively simple.But it cannot withstand the impact of the tide, and it must be repaired frequently at ordinary times.