The Timeless Genius of Dujiangyan: Taming a River Without a Dam

Today, we’ll talk about the Dujiangyan irrigation system, a 2,200-year-old Chinese marvel of engineering that tamed a violent river using nature’s own forces, transforming a flood-ravaged plain into a prosperous “Land of Abundance”.

Transcript

The Timeless Genius of Dujiangyan: Taming a River Without a Dam

Today, we’ll talk about the Dujiangyan irrigation system, a 2,200-year-old Chinese marvel of engineering that tamed a violent river using nature’s own forces, transforming a flood-ravaged plain into a prosperous “Land of Abundance”.

The 2025 Tianfu Forum on Chinese Culture was held from October 30 to 31 in Chengdu, capital city of Sichuan Province. Global participants engaged in intellectual exchanges and academic discussions on topics including the conservation and management of archaeological sites from the Bronze Age, the protection and utilization of cultural heritage in urban development, digital preservation and living inheritance of cultural heritage, as well as the transmission of cultural heritage values and dialogue. They reflected on the distinctive features of Chinese civilization and experienced the unique charm of Sichuan culture. 

Attending experts and scholars visited the UNESCO World Heritage sites of Mount Qingcheng and the Dujiangyan irrigation system for on-site investigation. Today, we will discuss the history of Dujiangyan.

In the western reaches of China’s Sichuan Basin, where the vast Chengdu Plain meets the foothills of mountains, the Min River thunders out of the highlands, its powerful currents surging toward the fertile land below. Today, this scene is one of serene productivity. But over 2,200 years ago, during the Warring States period, this very river was not a source of life, but a bringer of despair for the ancient Sichuan people. 

Each summer, torrential rains in the mountains would transform the Min River into a raging, coffee-colored monster. It would burst its banks with terrifying ferocity, swallowing farmland, washing away homes, and leaving destruction in its wake. When the rains ceased and the dry season arrived, the river would shrink dramatically, sometimes to a trickle, leaving the vast plain parched, cracked, and barren. 

The fate of this land and its people hung precariously on the mood of this capricious river. This chronic instability also posed a significant problem for the ambitious Qin state, which sought to unify China under its rule. A starving, unstable Sichuan was a strategic liability; by contrast, a prosperous one could serve as the grain-filled breadbasket to fuel its military campaigns.

The man who stepped forward to challenge this aquatic tyrant was Li Bing, the Qin-appointed governor of the Sichuan Commandery around 256 BCE. He was not merely some bureaucrat who happen to be in charge of the region, but rather a visionary hydrologist and engineer. Assisted by his son, whom folklore remembers as Li Erlang, Li Bing embarked on a mission that would alter the course of history. 

Rejecting the simplistic, and often futile, approach of simply building dams to block the water, Li Bing chose a method that demonstrated profound wisdom. To better understand his opponent, he led his team on extensive surveys up and down the Min River, meticulously studying its flow, its sediment, and the lay of the land. He observed that the Chengdu Plain sloped naturally from northwest to southeast. 

Instead of fighting nature, he conceived a plan to work with it – a comprehensive water management system designed to harness the river’s own power to tame itself. This masterpiece of engineering would later be known as Dujiangyan. 

To accurately gauge the river’s fluctuations, Li Bing had three stone figures carved and placed in the inner river channel. These “water gauges” were inscribed with the rule: (quote) “Dry season should not submerge their feet; flood season should not surpass their shoulders.” That is, if the water level fell to the stone men’s feet, it signaled an impending drought; if it rose above their shoulders, a flood was likely. 

This is considered one of the earliest water-level measuring systems in the world. It is said he crafted white jade horses and oxen as offerings to the river god. In a more dramatic legend, Li Bing transformed into a grey bull to engage in an epic, watery battle with the dragon-like river deity who caused the floods. These stories, whether grounded in fact or fantasy, speak volumes about the immense difficulty of the task and the deep reverence people had for the man who dared to confront the mighty Min River.

The heart of the Dujiangyan system is located at a critical point where the Min River exits the mountains, where three brilliantly conceived components work in perfect, self-regulating harmony. The first is the Fish Mouth Levee, a man-made peninsula shaped like the head of a giant fish, pointing upstream. Built strategically on a mid-river shoal, it masterfully splits the Min River into two channels: the Outer River and the Inner River. 

The genius lies in its application of the “Curve Flow” principle. During the dry season, the river level is low. About 60 percent of the water is naturally directed into the Inner River, which lies on the concave side of the curve, ensuring a steady supply for irrigation. In the wet season, when the water level rises and the current speeds up, the flow dynamics change. The majority of the torrent, laden with silt, is now forced toward the convex bank – the Outer River – which acts as the main floodway. 

The Inner River’s intake is automatically reduced to about 40 percent. This is the “Four-Six Split,” a natural, dynamic, and automatic regulation of water volume. The water channeled into the Inner River then meets the second marvel: the Flying Sand Spillway. This is a low, weir-like embankment adjacent to the final channel. Its height is a product of incredibly precise calculation, making it the system’s “safety valve”. 

When the water level in the Inner River becomes dangerously high, the excess water simply spills over the top of this low barrier, draining back into the Outer River and thus, protecting the downstream plains from flooding. But its magic doesn’t stop there. It also performs a critical “sand-flying” function. The same swirling currents that bring water down the Inner River also carry sediment. 

As the water curves and spills over the weir, vortexes are created that literally “fling” the heavier sand and pebbles over the spillway and into the Outer River. This “front water intake, side sand discharge” mechanism elegantly solved the universal problem of canal siltation centuries before modern engineering. 

Finally, for the third and final act of Li Bing’s masterpiece, the now-tamed and relatively clear water from the Inner River arrives at the system’s throat: the Precious Bottle Neck. This is a 20-meter-wide channel cut directly through a towering mountain of extremely hard rock called Mount Yulei. Legend has it that Li Bing’s team used a method of “fire and water” – heating the rock with fire and then rapidly cooling it with water to cause it to crack – a painstaking process that took eight years to complete. 

This narrow inlet, named for its bottle-like shape, acts as the final and ultimate regulator, strictly controlling the amount of water that enters the intricate network of irrigation canals. From here, life-giving water flows like blood through veins onto the Chengdu Plain. 

The three components – Fish Mouth, Flying Sand Spillway, and Precious Bottle Neck – are not separate structures but parts of an integrated, interdependent whole. Together, they achieve the magnificent goal of “dam-less water diversion” and automatic flow regulation.

The impact on the region was immediate and profound. The great historian Sima Qian, writing a century later, praised the project in his Records of the Grand Historian saying, “These canals were all made navigable, while the surplus water was used for irrigation... the people enjoyed great benefits. The canals made for irrigating the fields were countless.” 

The once-volatile Chengdu Plain had been transformed into (quote) “a land where drought and flood are controlled by man, and the people know not famine” – or as I mentioned in today’s intro, it become the legendary “Land of Abundance.” 

Over the centuries, subsequent dynasties – Han, Tang, Song, Yuan, Ming, and Qing – maintained and expanded the irrigation network, creating a systematic web of canals that remains vital today. 

Dujiangyan’s fame eventually reached the Western world through the accounts of travelers. The Venetian merchant Marco Polo, who visited Chengdu during the Yuan Dynasty in the 13th century, did not explicitly mention Dujiangyan in his travelogues, but he was deeply impressed by the region’s waterborne commerce, a direct benefit of the managed rivers. He wrote of “a great river... on which a great volume of shipping is borne, carrying much merchandise.” 

It was the German geologist and geographer Baron Ferdinand von Richthofen who, during his extensive travels in China in the 1870s, truly introduced Dujiangyan to the international scientific community. With an expert eye, he recognized its unparalleled sophistication. In his letters published in 1872, he dedicated a full chapter to Dujiangyan, stating unequivocally: “The perfection of the irrigation system of Dujiangyan is unrivalled anywhere in the world.” His endorsement cemented Dujiangyan’s status as a global marvel of hydraulic engineering.

A project of stone and earth cannot last 2,200 years without meticulous care. The secret to Dujiangyan’s longevity lies in a set of simple, yet profound, maintenance rules passed down through generations, and believed to originate from Li Bing himself. At its core is the Six-Character Maxim: “Deep Dredging, Low Weir.” Deep Dredging mandates that, during the annual dry season, the Inner River channel must be dredged deeply to remove silt to ensure that its water-carrying capacity remains consistent from season to season. And the standard for how deep to dig was marked by a buried “Recumbent Iron” bar.

“Low Weir” insisted that the Flying Sand Spillway must never be built higher during repairs. Its low profile was essential for its spillover and sand-flying functions. Another phrase to guide maintenance, this one with eight characters, said to “Cut the corner at the bends, dredge the center in the straights,” thus providing guidance for managing the river’s course, ensuring the main channel remained clear and swift. This practical wisdom, born from centuries of observation, is what has kept Dujiangyan alive and vibrant for more than two millennia.

After the founding of the People’s Republic of China, Dujiangyan entered a new era of development. Modern sluice gates, including the Outer River Gate built in the 1970s, were integrated, enhancing control while preserving the original, dam-less philosophy. Its irrigated area has exploded from under 300,000 acres in the mid-20th century to over 1.6 million acres today, serving dozens of counties. 

In the year 2000, Dujiangyan was inscribed on the UNESCO World Heritage List, jointly with the nearby Taoist Mount Qingcheng. UNESCO recognized it as “a major landmark in the development of water management technology” and “the only surviving dam-less diversion irrigation project of its time in the world.” 

Dujiangyan stands not merely as a relic, but as a living testament to a philosophy of “working with nature,” not against it. In an age of colossal concrete dams, it offers a quieter, more sustainable alternative. Its message of “Taoist Naturalism” and “Harmony between Man and Water” resonates powerfully today, providing timeless wisdom for global challenges in water resource management and sustainable development. It is a story of how human ingenuity, humility, and perseverance can partner with nature to create a legacy that endures for millennia.

Well, that’s the end of our podcast. Our theme music is by the famous film score composer Roc Chen. We want to thank our writer Lü Weitao, translator Liu Junhuan, and copy editor Pu Ren. And thank you for listening. We hope you enjoyed it, and if you did, please tell a friend so they, too, can understand The Context.