• Dujiangyan

• General Overview

  

  Dujiangyan is a very improbable tourist attraction. Often hailed as the Dujiangyan Irrigation Project it sounds functional, dull and something that only farmers could find even moderately interesting. The surprise is that the site is actually more a demonstration that wisdom is precious and long-lasting. Some very clever construction work was very successful on two fronts - flood control and irrigation - and remains so more than 2000 years later.

  The wise old man that is credited with the Irrigation Project at Dujiangyan is Li Bing a magistrate in the Kingdom of Qin during the Warring States Period (475-221BC).

  The project at Dujinagyan is actually very well known across the Orient. For domestic and overseas Chinese the site is an absolute must-see for any visit to Chengdu, Sichuan Province. The site is beginning to get more interest from discerning western groups who realise that it offers a much more authentic way to experience China. The site offers a rich cultural experience as well as some real-China experiences through interaction with locals.

  Attractions For Visitors

  Dujiangyan is a county within the Chengdu Prefecture. It suffered considerable damage during the Wenchuan Earthquake of 2008 but the Dujiangyan site is open again and ready to receive visitors from home and abroad. Some of the outlying features (temples and viewing towers) were damaged during the earthquake but are expected to be restored within a couple of years.

  Dujiangyan can be visited as a day excursion from Chengdu. Those wishing to visit nearby Mt Qingcheng, a mountain associated with Daoism and longevity, could consider staying overnight locally.

  The site at Dujiangyan is fairly extensive. Walking gives the best impression of scale - but there are electric cars along the island for those who prefer.

  The first section is a walk through gardens. These are fairly pleasant with water features and statues. Most characters will have little meaning to non-Chinese. One will, perhaps; the creator of the dish Gong Bao Ji Ding a favourite across China and one you are very likely to get to try. Essentially it is spicy chicken cubes with peanuts and vegetables. Since this has no bones it is considered a good one for foreigners.

  Next comes the temple overlooking the irrigation channel. This has a model (see below) which is helpful for any explanation of the project, its components and their functions.

  Continue over a swaying bridge (which spans one of the overspills) before heading along the island to its upstream end. This end is known as the Fish Mouth. It is now a concrete pier of no beauty but it still serves the same purpose - dividing the river flow into water destined for the fields and water for the original Min River. A new concrete barrier has been placed across the Min River here so as to be able to add to the amount of water going into the irrigation channel. In winter this is often closed entirely and the riverbed is left dry.

  

  What the above lacks is an explanation of what these features are all for.

  An Explanation

  Look at this model from the temple above the irrigation channel. This represents the project under construction with a coffer dam keeping water out of the irrigation channel whilst the soon-to-be island is constructed and the path for the irrigation channel cleared. Please note the following features:

  • The Fish Mouth: the head of the island;
  • the irrigation channel: shown as a stony river bed;
  • the temple: overlooking the irrigation channel. This is the orange/pink building at the back of the model just above a small pool of blue;
  • the ridge: running down from the left to this temple; and
  • the overspill: heading off to the right just in front of the temple;
  

  The Fish Mouth plays a vital role for the project; it divides the River Min into two flows. Its position was determined by Li Bing very cleverly. It is positioned such that 40% of the river flow heads into the irrigation channel. Not so difficult: assuming an even depth of water that just requires the head to be positioned four tenths of the way across the river. Li Bing was cleverer than that and chose a position downstream from a bend in the river. Why?

  Li Bing must have been a good student of nature. By choosing to site the island downstream from a bend he was taking advantage of two characteristics of a river:

  1. the sediment in a river tends towards the oustide of the current. Since the irrigation channel was placed on this side it received more nutrients for the fields and, conversely, the water remaining in the Min River was cleansed and more suitable as drinking water; and
  2. during a flood the current is stronger and more is directed to the outside of the bend; more than 40% entered the irrigation channel without requiring any moving parts - truly a magnificent achievement.

  In practice it was found that too much water was diverted during a flood and an overspill was created allowing some of the excess back to the main stream. Another was added later. The capacity and height of these was determined so as to cause the least damage whatever the level reached.

  The Construction

  The diagram gives an overview of the contruction near the end of the project but does not explain how the coffer dam was built, nor how the irrigation channel managed to take water away on a different course than the original river.

  The Coffer Dam

  The coffer dam was created by extending the shoreline and deflecting the flow of the river until a dry bed was created behind. This was no easy task as the Min is a powerful river. Giant wooden caltrops were built and dropped into place so as to create a hold on the river bed. These were secured by long woven-bamboo baskets filled with rocks; the weave preventing those rocks from being washed away.

  

  The Irrigation Channel

  The irrigation channel had to divert water away from the river and to the land where crops could be grown. This required a canal that would remain higher than the original river course but still with a downward gradient. Li Bing recognised that the route that he wanted lay on the other side of the ridge; all he needed was a way to cut a way through that ridge and let the water head off on a course to the farmland bypassed by the Min River's original course.

  We must remember that this was in the days before the widespread use of steel, and only steel tools would have been strong enough to cut through the rock. Another natural phenomenon was put to use. The workers were instructed to heat the rocks with fire and, when very hot, douse them with cold water. The rock shattered and was then easily removed. Even then, the process must have been a very time-and-wood-consuming one.

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  Outside the venue

  

  Visitors should allow time to explore the area immediately outside the Dujiangyan tourist site. There is generally plenty of local flavour to enjoy especially on the characteristic covered bridge over the irrigation channel, and on the far side where there is a small street of local cafes and shops.

  The Significance Of Dujiangyan ...

  The Dujiangyan Irrigation Project had a vast impact on Sichuan Province, particularly Chengdu. Once the project was complete, a vast area of land was irrigated and became incredibly more productive. Chengdu became less prone to devastating floods and developed at a fast pace, fuelled by the agricultural surpluses. Given that the area we now know as Sichuan Province is relatively remote, being cut off from much of the rest of the Chinese mainland by mountain ranges, this allowed for a powerful and independent state to develop. This kingdom of Shu> later became one of the contenders in the period glorified in the novel The Romance of the Three Kingdoms.

  ... and the mystery

  Given the success of the Dujiangyan project, and the fact that it is well known across the sphere of Chinese influence, it is hard to understand why the project has not been repeated elsewhere. The exact circumstances that Li Bing took advantage of are not so very special that they are not to be found elsewhere; his techniques were not so special or demanding that others could not muster the same forces. Why then has this elegant solution not become the standard, or at least a common feature? Modern technology allows massive dams to be built almost anywhere but they block the river flow completely causing issues in the natural world - blocking fish migration for one thing - and have a relatively short lifespan, being subject to blockage by sedimentation. Dujiangyan is hailed as a great example of Daoism and will, perhaps, one day become recognised as a very early example of sustainable development in the field of river control.

  Visit Dujiangyan with China Journeys

  The following China holidays include a visit to Dujiangyan:

  • China Showtime
  • Yangtse River Explorer
  
  
  
• 
  
  

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