Tongjiyan - A Thousand Years of Water Conservancy, Creating the Bihu Plain.
Tongjiyan, a World Irrigation Heritage Site, is located in Yantou Village, Bihu Town, Lishui City, near the confluence of the Oujiang River and Songyin Creek. Construction began in the fourth year of Emperor Liang's Tianjian reign (505 AD) during the Southern Dynasties.
Tongjiyan consists of an arched dam, water intake gates, channels, stone boxes, leaf holes, sluice gates, and lakes and ponds. The Bihu Plain is higher in the southwest and lower in the northeast, with a drop of 20 meters. Tongjiyan was built according to this geographical feature, achieving gravity irrigation without external support.
There are 72 sluice gates of various sizes on the canal, which regulate water flow. There are also numerous lakes and ponds along the canal, which store water in case of drought. This forms a bamboo-shaped water network, with irrigation as the main focus, supplemented by storage and drainage.
The World's Earliest Arched Dam
Before the Southern Dynasties, Songyin Creek in Zhejiang often flooded during the rainy season. In the fourth year of Emperor Liang's Tianjian reign (505 AD), the first official large-scale dam construction project in history began. After enduring hardships, an arched dam with a curved exterior was built on Songyin Creek. Today, the earliest known arched dam outside of China is the Alqueva Dam built by the Spanish in the 16th century, and the Ponte della Maddalena Dam built by the Italians in 1612. The Tongjiyan arched dam predates these by a full millennium!
The Tongjiyan arched dam is a rainbow-shaped arch dam composed of multiple semicircular small arch dams. Its rounded top faces the incoming water, allowing the surging creek water to flow to both sides along the arch's center, effectively increasing the dam's flood peak capacity. Here, water flows from natural to regulated, from chaos to order, and flows into the Bihu Plain. As a result, the Bihu Plain has become one of the most important grain-producing areas in the upper reaches of the Oujiang River.
The World's Oldest Water Interchange Bridge
In the early years of Emperor Huizong's reign in the Northern Song Dynasty (1111 AD), Wang Mo, then magistrate of Lishui, visited Yantou Village to understand the local people's needs. He learned that the Tongjiyan canal and a mountain stream called Quankeng met at the entrance of Yantou Village, forming a cross-shaped intersection. Both then flowed forward in their respective directions. Due to the higher elevation of the Quankeng Riverbed and the lower elevation of the Tongjiyan canal, the seasonal mountain stream, which often experienced sudden rises and falls, would carry a large amount of silt and sand, causing blockages in the lower-lying canal. This resulted in frequent dredging work for the villagers of Yantou.
Wang Mo was determined to eliminate this burden for the people. Soon, a cross-shaped water trough was built, mainly using stone slabs and supplemented with wooden boards. It was open at both ends and on top. The total length was over 18 meters, and the net span was over 10 meters. Due to its resemblance to a box, which is also called a "han" in Chinese, and its construction using stone slabs, it was named "Stone Box." From then on, Quankeng water flowed into Songyin Creek through the upper trough of the Stone Box, while Tongjiyan water flowed downstream through the other trough. "Creek water does not interfere with canal water," preventing silt and sand blockages and ensuring smooth flow in the canal. Later, stone bridges were built on both the east and west sides of the Stone Box, forming a three-dimensional "water interchange bridge" - people walked on the upper level, creek water flowed on the middle level, and canal water flowed on the lower level. They did not interfere with each other, yet they were inseparable.
One of the World's Earliest Agricultural Water Conservancy Regulations
Tongjiyan's continued prosperity after a thousand years is inseparable from its scientific management system. To this day, in the Temple of the Two Sima of the Southern Jin Dynasty in Yantou Village, there are still stone tablets engraved with various regulations for the canal, such as how to manage, divide labor, supervise, and punish violators. The source of these rules comes from a Southern Song Dynasty stone inscription, which is 165 cm high, 86 cm wide, and has faded lettering.
In the third year of Emperor Gaozong's reign in the Southern Song Dynasty (1167 AD), Fan Chengda, a 41-year-old poet, was appointed governor of Chuzhou (present-day Lishui City). He believed that a scientific and comprehensive management system was necessary. With the guarantee of rule-based governance, everyone would consciously comply, and the water from the canal could be pooled and adjusted, flowing smoothly to its destination. This would achieve the grand goal of benefiting the people and promoting prosperity for a thousand years. Therefore, Fan Chengda wrote 20 regulations for the canal: from the establishment of management institutions and water allocation systems to the source and expenditure of funds, and even details such as the starting and finishing times for cutting firewood and grass in the mountains. All were stipulated in a detailed, fair, and feasible manner.
According to research, the "Tongjiyan Stele" is one of the earliest known ancient agricultural water conservancy regulations in the world, and it is also the oldest extant physical inscription of a canal regulation stele. At that time, copies of the "Tongjiyan Stele" were distributed to various dams in Chuzhou, becoming the blueprint for Chuzhou's canal regulations.
Long Temple (also known as the Temple of the Two Sima of the Southern Jin Dynasty) is located at No. 71, Yantou Village, Bihu Town, Lotus District. It is a building from the Republic of China period. Inside the hall, there are thirteen stone tablets, recording events related to Tongjiyan from the Yuan Dynasty to the Republic of China period.
Fan Chengda's "Stele of the Rebuilt Tongjiyan Regulations and Postscript" in the Long Temple is the world's earliest stone inscription of canal regulations, and it is also Fan Chengda's earliest extant genuine work.
There are several famous figures in the history of Tongjiyan, who played important roles in its construction and management. The following is information about some key figures:
* Sima Zhan (Sima Zhi Biao)
* Identity: A native of Songyang County, Chuzhou, and the ancestor of the Lishui Zhan clan.
* Contribution: In the fourth year of Emperor Liang's Tianjian reign (505 AD), Sima Zhan was sent to Songyang County, Chuzhou, to inspect military preparedness. He discovered that the water resources of Songyin Creek and the Bihu Plain were not fully utilized, so he proposed to the court to build the Tongjiyan canal. With the support of Emperor Wu of Liang, he and Sima Nan were responsible for the construction of the canal. They built the world's first arched dam, inspired by the image of a white snake crossing the water.
* He Dan
* Identity: A politician, writer, and calligrapher of the Southern Song Dynasty.
* Contribution: After retiring in the first year of Emperor Kaixi's reign in the Southern Song Dynasty (1205 AD), He Dan presided over the reconstruction of the Tongjiyan canal. He replaced the wooden dam with a stone dam and adopted the techniques of iron-water grouting and pinewood foundation filling, making the dam last for a thousand years. He Dan also built the "Wanxiang Tower" on the highest mountain in Lishui City and was the chief editor of the "Longquan County Chronicle," which recorded the cultivation method of shiitake mushrooms. Therefore, he is known as the "Father of Chinese Shiitake Mushroom Culture."
* Fan Chengda
* Identity: A poet and official of the Southern Song Dynasty.
* Contribution: In the fourth year of Emperor Gaozong's reign in the Southern Song Dynasty (1168 AD), Fan Chengda was appointed governor of Chuzhou Prefecture, responsible for repairing the Tongjiyan canal. He formulated the "Tongjiyan Regulations," which is the first canal regulation in Chinese water conservancy history. It covers twenty aspects, with comprehensive, specific, and scientific content. Fan Chengda's efforts made the management of Tongjiyan more standardized, and it was used by local people until the Ming Dynasty.
* Tang Xianzu
* Identity: A writer of the Ming Dynasty.
* Contribution: In the thirty-fifth year of Emperor Wanli's reign (1607 AD), Fan Liangshu, a native of Jiangxi and Tang Xianzu's fellow villager, repaired the Tongjiyan canal during his tenure as magistrate of Lishui. He built the Temple of the Two Sima beside the canal and completed the renovation work in the thirty-sixth year of Emperor Wanli's reign (1608 AD). Based on Fan Chengda's "Tongjiyan Regulations," Fan Liangshu formulated the "Eight New Regulations for Tongjiyan in Lishui County," further improving the management of the canal.