Geographic Connections
Mountains: Pingshan, Wushan, Yushan (The Three Mountains), North Ling Mountain Range. Water Systems: Min River, Jin’an River, Baima River, Antai River (Hongqiao River), Xima River, Dongxi River. Lakes: West Lake (Xihu Tang), East Lake (now reclaimed). Landmarks: Sanfang Qixiang (Three Lanes and Seven Alleys), Tongji Bridge, Wumen Sluice, Wanzao Canal, Daqiaotou, Wuyi Square.
I. City Built on Water: The Foundation of Drainage in Jin and Tang Dynasties
The drainage logic of ancient Fuzhou began with its unique “basin” geography. Located in the lower reaches of the Min River, Fuzhou is flanked by the North Ling Mountains and the Min River to the south. According to the Fuzhou City Gazetteer, the foundation of Fuzhou’s urban planning lies in the deep coupling of “Mountains, City, and Water”.
In 282 AD (3rd year of Taikang, Jin Dynasty), Prefect Yan Xuan constructed the “Zi City” and excavated West Lake (then known as “Xihu Tang”). This was not only for irrigation but served as Fuzhou’s first artificial “detention basin” to regulate floods. In its early days, West Lake’s surface area far exceeded its current size, playing a crucial role in peak shaving. By 901 AD (1st year of Tianfu, Tang Dynasty), Wang Shenzhi built the “Luo City,” utilizing the city’s natural low-lying areas to dig inner rivers. The construction of Luo City established Fuzhou’s fundamental form: “the city among mountains, mountains within the city, and a dense network of rivers”. During this period, the drainage system relied on natural slopes to discharge accumulated water into the Min River through the lower southeastern exits.
Historical records suggest that the total length of inner rivers had already begun to take shape by the late Tang, laying the groundwork for the later “Two Rivers and Three Ditches” system.
II. Song Dynasty’s “Two Rivers and Three Ditches”: The Pinnacle of Hydraulic Engineering
During the Song Dynasty, as a major hub in Southeast China, Fuzhou’s hydraulic drainage system reached the peak of ancient craftsmanship. In 1058 AD (3rd year of Jiayou, Northern Song), Cai Xiang, as the Prefect of Fuzhou, presided over numerous water conservancy projects, including dredging inner rivers to cope with the frequent “Min River Floods”.
In 1183 AD (10th year of Chunxi, Southern Song), Fuzhou’s water system was formally summarized as the “Two Rivers and Three Ditches” system. The “Two Rivers” refers to the Jin’an River and Baima River, located on the east and west sides of the ancient city, respectively. They served as both moats and primary flood discharge channels. The “Three Ditches” ran through the city, directing rainwater and mountain torrents to the main rivers. According to the Fuzhou Prefecture Gazetteer, Fuzhou’s urban area possessed 42 major inner rivers with a total length exceeding 30 kilometers at that time.
The brilliance of this system lay in the combination of “storage and discharge.” During heavy rains, mountain torrents from North Ling were collected in West Lake or low-lying urban areas through canals like the Wanzao Canal. When the Min River’s water level dropped, sluice gates like the Wumen Sluice were opened to rapidly discharge internal floods using the water level difference.
III. Mastery of Gates and Dams: Fine-tuned Regulation in Ming and Qing
Maintenance of Fuzhou’s inner rivers during the Ming and Qing dynasties moved beyond simple dredging to a more sophisticated dispatching of tides and internal waters through sluice gates (dams). In 1602 AD (30th year of Wanli, Ming Dynasty), Fuzhou underwent a large-scale renovation of its city walls and riverbeds, establishing the operational rule: “Close the gates when the tide rises to prevent backflow; open the gates when the tide recedes to drain floods”.
In 1754 AD (19th year of Qianlong, Qing Dynasty), local officials reinforced the Wumen Sluice (located near today’s Daqiaotou). According to the Qianlong Fuzhou Prefecture Gazetteer, there were 12 major and minor sluices distributed throughout the city. These gates precisely controlled inner river levels by monitoring the tidal changes of the Min River. If the Min River threatened backflow, the gates were quickly closed; as the tide ebbed, the accumulated rainwater in the inner rivers would pour out, creating a “scouring and silting” effect that helped keep the channels deep.
The drainage system also reflected “social participation.” Wealthy merchants and gentry in the Sanfang Qixiang area often self-funded the dredging of the Antai River (Hongqiao River) during the Jiaqing and Daoguang periods (c. 1796–1850 AD), ensuring this arterial drainage line through the city center remained unobstructed. Records show that the Antai River alone was served by 8 branch canals, forming a dense micro-circulation drainage network.
IV. West Lake Detention: The “Central Command” of Ancient Drainage
West Lake’s role in Fuzhou’s drainage system was akin to a modern “urban sponge.” In 1828 AD (8th year of Daoguang, Qing Dynasty), the national hero Lin Zexu presided over the dredging of West Lake. In his proposal Planning for Lake Dredging, he noted that West Lake “both irrigates farmland and aids in drainage,” serving as the hub of the entire city’s water system.
According to the West Lake Gazetteer, the dredging project led by Lin Zexu removed tens of thousands of cubic meters of silt, restoring much of the detention capacity West Lake held during the Jin and Tang dynasties. At that time, West Lake’s effective flood storage capacity could temporarily absorb high-intensity runoff from the northern foothills of Pingshan. West Lake was connected to the inner rivers via the Muxi and Xima rivers, creating a dynamic balance. During heavy storms, West Lake’s water level could rise by 3 to 5 feet without overflowing.
Furthermore, a modern hydraulic survey in the early 1950s showed that despite centuries of sedimentation, West Lake could still reduce instantaneous peak flood pressure for Fuzhou’s old city by approximately 15% under extreme rainfall conditions. This proves the foresight of ancient planners in using the lake as a drainage core.
V. Modern Insights from a Digital Humanities Perspective
By analyzing documents such as the Wanli Fuzhou Prefecture Gazetteer and the Fuzhou City Gazetteer, which span nearly 500 years, we find that the drainage of Fuzhou’s ancient city was not just an engineering problem but an early practice of “ecological civilization”.
In 1986, the Fuzhou municipal government began implementing a large-scale comprehensive treatment project for inner rivers, a move largely informed by the logic of the ancient “Two Rivers and Three Ditches”. According to modern surveying data, Fuzhou currently has 107 inner rivers with a total length of approximately 244 kilometers, most of whose backbone channels (such as the Jin’an and Baima rivers) still follow the framework established in the Song and Yuan dynasties.
Historical data tells us that the essence of drainage is “following the timing of nature.” Ancient Fuzhou solved the core survival challenges of a basin city through 42 inner rivers and more than 10 sluice gates without any electric pumping. This wisdom of “leveraging terrain for storage and precise gate control” remains highly valuable for building smart cities and solving urban flooding issues today.