The Longshou Canal and Ancient Luohe River Irrigation District of Shaanxi Province are located on the terraces of Weihe River and Luohe River. This area is plagued by frequent drought. Therefore, diverting water from the Luohe River for irrigation has been an essential means to tackle the water shortage challenge faced by local agricultural production.

Luohe River, as a secondary tributary of the Yellow River, originates from the southern slope of the Baiyun Mountain in Dingbian County. Flowing through three cities and eleven counties, it enters Weihe River at Sanhekou. The barrier of Tielian Mountain makes it very hard to develop and utilize the lower reaches of the Luohe River.

History

In 120 BC, Emperor Wu of Han Dynasty took the advice of the local governor and sent more than ten thousand soldiers to construct an irrigation canal at the Laozhuang Waterfall of the Luohe River in Chengcheng County. It took them more than 10 years to complete this oldest gravity irrigation project of the Luohe River Basin.

The construction of the canal was extremely difficult. For instance, a 3.5km-long tunnel had to be built in the Tielian Mountain for water diversion. The digging of the tunnel was divided into multiple sections. Shafts were dug at both ends of each section, and workers were sent to the bottom of the shafts to dig toward each other. And these sections would naturally join together upon completion to form the tunnel. The shafts could serve as exits and entrances for workers, pathways for muck disposal, and openings for ventilation and daylighting. In this way, the working efficiency was greatly improved. During the construction of the tunnel, dinosaur bones were unearthed, and the ancient Chinese mistook them for dragon bones, hence the name of Longshou Canal, or the canal of a dragon head. 

When constructing the 20km main canal, the ancient Chinese adopted the technology of intercept to cross rivers and streams. Also, the open canals at the two ends of the tunnel of the Tielian Mountain are of the proper gradient, which has been the result of excellent measuring techniques.

More than 2000 years ago, the famous Chinese historian Sima Qian commented in the Historical Records that the construction of the Longshou Canal was the earliest application of the shaft-tunnel method. This method, breaking new ground for the theory and practice of tunnel construction, has contributed greatly to the treasure trove of science and technology.

As loess subsided in water, the banks of the canal collapsed frequently, and the tunnel was often blocked due to the impact of quicksand and submerged springs. Besides, the area was plagued by frequent wars. Due to these factors, the project failed to achieve sustainability. However, later generations have never stopped reconstructing the canal and utilizing Ruohe River for irrigation.

In 227, the Kingdom of Wei started to expand the irrigation district. The Linjin Weir was built at the downstream of the Longshou Canal. The improvement of the irrigation infrastructure turned this area into a granary, laying the foundation for the expansion of the Kingdom of Wei.

In 561, Emperor Wu of Northern Zhou Dynasty ordered the reconstruction of the Longshou Canal, which had greatly improved the national strength.

In 712, the local governor diverted water from Luohe River through Tongling Weir for irrigation and the alleviation of soil salinization. As a result, crop yield surged, laying the economic foundation for the Kaiyuan Heyday of the Tang Dynasty.

During Yuan, Ming and Qing Dynasties, many small water diversion projects were built along the Luohe River. Most of these projects irrigated farmland by diverting spring water from wells.

The inscriptions of these two stone tablets of the Qing Dynasty describe the management system of the irrigation district, including the irrigation order, organizational structure, and the handling of disputes. The Taibai Temple, the Quli Temple, and the Pinglu Temple, where the water god was worshipped, had grown into major sites of water-related affairs management. Today, these temples still serve as the management stations of the irrigation district.

In the late Qing Dynasty, the Fengtu Granary was built on the site of the Chengyi Granary of the Han Dynasty. Known as the first granary of China, it now serves as one of the state-owned grain reserves, demonstrating the affluence and prosperity of the irrigation district.

In 1929, a famine broke out at the central Shaanxi Plain. Years of drought had led to severe crop failure. To prevent it from happening again, the society reached a consensus to restore and improve local irrigation projects.

In 1934, Li Yizhi, a famous Chinese hydraulic engineer, presided over the construction of the Luohui Canal based on the Longshou Canal and Ancient Luohe River Irrigation District. He also named the water-diverting dam of the new canal as Longshou Dam. The ancient Longshou Canal was, once again, reborn.

The Luohui Canal, integrating different ancient Luohe River irrigation projects, took 14 years to complete. It has expanded the area of irrigation. Its scientific and efficient layout and management system share many similarities with the ancient Longshou Canal, proving the wisdom and superior skills of the ancient Chinese people.

Irrigation System

As a fine combination of Chinese and western styles and technologies, the Luohui Canal has one dam, two aqueducts, and five tunnels. These hydraulic structures have added touches of modern technology to the ancient irrigation district which itself embodies the mixed culture of a dragon, Han and water.

Today, Luohui Canal has evolved into a large irrigation district with a complete irrigation and drainage system. The irrigation district, divided into two systems by the Luohe River, is composed of a dam, a canal network, and supporting facilities. Its 235km canal network, with 1 general main canal, 4 main canals, and 13 branch canals, irrigates 49500ha of farmland of Chengcheng, Pucheng and Dali Counties, nourishing 690000 people and generating remarkable biological, economic, and social benefits.

Water Heritage

Since the construction of the Longshou Canal by Emperor Wu of the Han Dynasty, locals have started to alleviate soil salinization using the water of the Luohe River which is high in sand concentration. This approach of soil desalinization, contributing greatly to the improvement of soil quality and crop yield, is a milestone in the development of irrigated agriculture.

The construction of the Longshou Canal was ahead of its times in terms of engineering design, construction techniques (measuring technique, the shaft-tunnel method, and the building materials), and dimensions (it took tens of thousands of soldiers more than ten years to complete this 20km-long canal, including a 3.5km-long tunnel). The layout of the Longshou Canal is the same as that of the Luohui Canal which was planned and built with modern technologies. And this fully proves the fact that the construction of the Longshou Canal was ahead of its times.

The Longshou Canal has made an outstanding contribution to enhancing food production, livelihood opportunities, rural prosperity, and poverty alleviation in the region. It is testimony to the highly developed agriculture and economic prosperity in the central Shaanxi plain. The Chengyi Granary for Grain Shipping, located in the irrigation district, while displaying the grain shipping culture of the Luohe River, serves as a proof to the high crop yield in the region. In the Tang Dynasty, the local governor Jiang Shidu, fully tapping the water sources of the Luohe River and the Yellow River, greatly expanded the irrigation district. As a result, grain output in the region surged, laying the foundation for the Kaiyuan Heyday of the Tang Dynasty. The Fengtu Granary, built in the late Qing Dynasty, shows the prosperity of the region and the foresight of the locals to always stay forearmed.

With the help of the Longshou Canal and the tunnel in the Tielian Mountain, locals diverted water from the Luohe River at the point where the altitude is relatively high and managed to achieve gravity irrigation for the vast land south of the Tielan Mountain. This was innovative in its ideas at the time of its construction.

Shafts were dug to facilitate the opening of the tunnel. With the shafts, it was easier to measure the direction and the elevation of the tunnel, and they were also used for ventilation and muck disposal. In this way, the working efficiency was improved. This shaft-tunnel construction approach was innovative at its times, contributing to the evolution of contemporary engineering theories and practices.

It is an example of attention to environmental aspects in its design and construction. Since the construction of the Longshou Canal, the irrigation district has been using local materials for repairs, renovations and expansions. Meanwhile, water with high sand concentration has been employed for soil desalinization. These practices have improved the local ecosystem.

The Longshou Canal, perfectly combining the shafts, the 3.5km-long tunnel and the open canal, and achieving smooth gravity irrigation, was an example of engineering marvel at the time of its construction (more than 2000 years ago).

The Longshou Canal bears the stamp of the cultural tradition of the past. In the past two millennia, the Canal, having witnessed rises and falls, vividly reflects the unyielding national spirit of the Chinese--their belief in hard work and dogged perseverance. The culture of the Longshou Canal is the perfect combination of the cultures of a dragon, Han and water, and local customs, religions, and architectural style. For instance, the name of Longshou means dragon head, reflecting the worship of the totem of a dragon; several villages in the irrigation district were formed in the Han Dynasty when the Canal was built, so they are called Zhong Han Village, Dong Han Village, and Zhong Han Village.

Present State of Conservation

Within the Ancient Luohe River Irrigation District, the ruins of the shaft-tunnel construction and the Longshou Canal have been listed as officially protected cultural heritage sites. In 2018, the Implementation Plan of the Maintenance and Protection of Luohui Canal Heritages, with a budget of 12.17 million RMB, was approved by the Department of Water Resources of Shaanxi Province. In 2019, the irrigation district spent 2.88 million RMB on improving the surrounding environment of key heritages such as the ruins of Longshou Canal, the ruins of the shaft-tunnel construction, the Longshou Dam, the five tunnels, etc. The key parts of the heritages have been guarded with a protective mesh. And the responsibilities of management and maintenance have been clarified and distributed.