Dujiangyan Things to Do

2 more images

The main dyke was partially built by Li Bing's men, using boulders in bamboo baskets, and then the inner channel excavated. The key to the whole system is the point at the northern end which splits the river into two channels. The point is very carefull shaped and works with the contours of the Yuzui dyke to split the river water. The second element is that the dyke is shaped like the wing of an aircraft, with the water on convex side flowing faster, so carrying less silt which stays in the slower water on the convex side in the main channel. Furthermore, the inner channel that feeds into the irrigation canal takes the upper part of the water that has less boulders and silt anyway. All very clever. The dyke is planted up with trees and is a pleasant place, overlooked by the cliffs and wooded slopes of Yuleishan.
At the northern end of the dyke is the famed Altan bridge, a very early cable bridge which stretches across the two parts of the river. As is often the case in China, the bridge was moved at some stage, but the bridge is still presented as if it was the original.
It is easy enough to walk down the dyle, but there are also electric buses for RMB10 each way or RMB15 return. Even if you only buy the single at first, you can return by just paying the extra RMB5 if you show the outward ticket.
Up at the fishmouth, the point looks very low-tech, but don't be deceived by what just looks like a concrete slope; this is one of the most signficant engineering works in China. A few hudred metres ahead of this place is another short mid-stream dyke that also helps to split the water.
One of the least-known features of the system, but one of the most important, is also visible from the Yuzui dyke. Below the cliffs of the Yuleishan, the river widens at a place called Fengqiwo. This momentary widening of the channel slows the water and most of the remaining silt and boulders are dropped to the bed of the river.

In front of the Baopingkou lies the Feisha or Flying Sands Spillway which is an essential part of the whole system and allows much of the silt and boulders to be swept away from the irrigation works and back into the Minjiang River. Now the spillway is covered in boulders, much of it cemented in, which is not altogether surprising as this is what flows over it during the flood season. However, in the early days the bed of the spillway was lower and the entrance was formed of stones in bamboo baskets. Despite having worked fine for a couple of thousand years, it was felt necessary to infill it with concrete to the correct level in recent years. The spillway is now a little spoilt by a huge sluice facility alongside the bridge.

4 more images

Sitting on the rocky promontory overlooking the Botleneck - or Baopingkou - the Fulong Temple was built to celebrate the taming of a vicious dragon. The creation of Chinese legends by means of his genius and engineering skills seems somewhat undermined when Li Bing needs that bit more to prove that he was truly great: so he is portrayed as slayinhg a dragon. An awful lot of Chinese culture seems to involve dragons. It's all a little spooky; like the heritage has to be reinforced by stuff out of a child's cartoon book.

It is better presented also as Ligong Temple (or Engineer Li Temple) and it is the perfect place to view the engineering works at Dujiangyan, although much of the main elements cannot be seen from here. A huge flight of steps leads up to the first of three halls, in which Li Bing and his sons are all honoured.In between the temple halls are some old trees and several attractive contemporary mosaic calligraphic works. Behind the halls, a small network of paths leads around a pavilion to various vantage points above the fast-flowing green water in the Baopingkou. You can see all the way down to the Nanqiao or Southern Bridge spanning the main irrigation canal. Steps lead down to a walkway which is suggested as being a plank road, used for pulling unpowered boats. However, this would not have been possible with the present Qing balustrade, but the balustrade does at least make it safe to walk here.

4 more images

Most visitors make a beeline for the spectacular views of the Dujiangyan Irrigation Works, but it is worth prolonging the suspense a little longer and taking time to see the gardens at Lidui Park.

The main avenue from the entrance goes stright to the Fulong Temple and the Duyiangyan Museum. Statues of all the great men involved with this engineering masterpiece line the path, with water channels appropriately edgeing the path. At the start of this avenue is a fountain, with the iron dredging bars in the middle and some bamboo baskets of boulders around the edge. These simple gadgets are the key to the entire project and take rightful centre-stage here. The stone baskets were used to build the Yizui dyke and the iorn dredging bars were laid in the river (although stone ones were originally used) to set the level for annual dredging activities at key points in the system.

To the left of the Contributors Avenue are the pools, ponds and lakes and, especially, the stunning bonsai gardens.

There are several crape myrtle trees and trellises that are over 1000 years old and the whole area has been delicately landscaped.

1 more image

In fact, Li Bing was not even the first to recognise the advantages of managing the Minjiang at this point. There is some evidence to suggest that 4000 years ago (!), the local Caocang tribe of the Yu people were already harnessing the water for irrigation, although there are no remaining groundworks at all.

The museum by Fulong Temple has a working model of the system and an excellent video documentary (in Chinese with English subtitles)

A similar principle applies right next to the bottleneck by the Fulong Temple, where a churning "bowl" of water can be seen. In the flood season, any silt and boulders here are swept over the much newer spillway. The water entering the irrigation system next to the Fulong Temple has had 99% of the silt removed by harnessing the natural actions of the river itself.

Other than the very last spillway, all this was designed in 256BC!

The present sluice-gates are a modern feature intended simply to divert more than 60% of the river into the irrigation system during the dry season, with no risk to the irrigation system. However, it would appear to have had an effect on the enviornment of the main river which is almost dry for much of the year. No idea whether any Environmental Impact Assessment was done!

But how does this all prevent flooding? Well although not well explained on site...the interpretative panels are full of nonsens and non-sequiturs...it is a simple process. The floods are ironically prevented by filling the irrigation system to its maximum. In effect, the irrigation canals, channels and ditches of the Chengdu Plain fil and fill and fill, so storing the floodwater until the floodwaters have receded (flooding rivers never actually flood for more than a few days at a time). By "storing the water" in the irrigation system, it dramatically increases the ability of the river system to hold water. On many rivers in the world there are natural versions of this 'storage' system, most notably in Dongting Lake in Hunan Province which soaks up the excess of the Yangtze River until the floodwater pass, and the water then flows back out of Dongtinghu into the Yangtze. Li Bing, 2250 years ago, created a man-made storage system for the floodwaters of the Minjiang River. He did it with no moving parts. His system is more technically sound than any modern day irrigation system.

1 more image

The Dujiangyan Irrigation System is both simple in concept but also very cunning. It is a combination of genius and location.
The Minjiang River pours out onto the plain from the Minshan Mountains here, but just as it does it is forced to turn south because of a low ridge, the Yulei Shan. The river curves further just at the southern tip of this ridge, which is precisely where the irrigation works are located.
Li Bing and his engineers used the river's natural hydraulic action (to flow faster around the outside of a curve) to split the river into two channels by building a dyke along the centre of the river. In addition a similar, much shorter, dyke was built just a few hundred metres upstream of the top end of the first dyke. By cleverly designing the tip of the dykes (now faced with concrete set with large boulders for protection), 60% of the water flows into the "inner" (western) channel and 40% continues down the main river. Because the water at the top is taken, most of the silt stays in the flow of the main river. During the flood season, the main river takes 60% of the flow and the inner channel just 40%. By the same principle, most of the silt stays in the main river and does not enter the irrigation system.
The silt that does get through (around 20% of the total) into the inner channel is then sucked into a clever notch on the east bank, about 200 metres around the corner from the Fulong Temple (but not visible from it). This notch widens the river, so slowing the speed, so the silt and boulders quickly sink. Then during the next flood season, when the river level rises such that the water overflows the 'Flying Sands Spillway', the rush of water takes the silt back into the main river.

Duyiangyan lies on the east bank of the Minjiang river, at the very western edge of the great Sichuan bowl. The Qingcheng mountains rise up steeply on the western bank, and this is where the Minjiang river flows out into the plain.

The main entrance to the Dujiangyan Irrigation Works is at a square outside the Lidui Park, although there is another entrance across the southern bridge (you can see it from the square - it was covered by scaffolding and netting in October 2006).

Access to the whole irrigation works is from this park, which costs RMB60 (RMB30 concessions) to enter.

The islands forming the irrigation system are across the park about 200 metres and accessed by a suspension bridge. Before that point there is the Fulong Temple that overlooks the bottleneck entrance to the irrigation system, and the river beyond.

Before going to the Fulong Temple - up the stairs - it is worth looking through the museum which is just to the south of the temple.

But before that it is worth exploring the beautiful gardens to the left of the main thoroughfare. They are always peaceful and are filled with bonsai, some amazingly old crape myrtle trees and wonderful ponds teeming with goldfish. There is also a nice teahouse.

To the north of Fulong Temple is a small ridge which is covered with old pavilions and temples. If you have time - and many visitors don't - take the time to explore these woods and buildings. The entrance is either through the separate access from across the Southern Bridge (i.e. outside the park) or via the second suspension bridge by the point known as the Fishmouth.

Please see the safety warning tip! There is a real risk to life here!