The Qingming Festival, or the Pure Brightness Festival, which falls April 5 every year, is a time-honored tradition for every Chinese family to visit the tombs of their ancestors to show respect and offer sacrifices.

Some 2,000 people from different parts of the country gathered last week in Dujiangyan in Sichuang Province's Chengdu City to take part in the Qingming Water-releasing Festival to commemorate Li Bing, who built the project 2,262 years ago. Dujiangyan, 55 kilometers west of Chengdu, is the world's oldest irrigation scheme still in operation.

The festival started around 11 am with the firing of three cannons. Next, 20 men began to play bugles, while 100 men wearing coir raincoats and ancient masks danced.

Led by a baldachin, two male hosts of the sacrificial rite unfolded a piece of brocade and handed it to a person who read the elegiac address written on the brocade.

In the wake of the reading, a man riding on a white horse rode along the river bank with a flag in hand, the horse rider kept shouting: "Release water!" while galloping to the sacrificial altar.

Receiving the flag, which symbolized authority, the official waved it and shouted: "Release water!" to the audience. His call was echoed by people from the sacrificial altar.

Then eight people carried a pig and a sheep to the altar. Following instructions from the official, they threw the pig and sheep as sacrifices into the river.

Next, several workers jumped onto the rafts that blocked the water from the river. They cut the ropes made of three big trunks and tied big ropes onto the top of the rafts. Holding the ropes, a dozen men on the bank of the river pulled them.

With the falling of the rafts, the torrent from Minjiang River burst into the fertile West Sichuan Plain, to irrigate an area of 670,000 hectares of farmland in 34 counties.

The water-releasing ceremony, which lasted about 50 minutes, was officially named a festival in AD 978 to commemorate Li Bing. But the ceremony existed long before that, said Yi Zhongtian, a professor with the Institute of Humanities at Xiamen University in East China's Fujian Province.

In ancient times, the West Sichuan Plain, now one of China's most populous and important agricultural regions, used to suffer from regular flooding of Minjiang River in the summer, while it was stricken with drought in the winter.

The Sichuan governor, Li Bing, decided to harness the Minjiang River and launched the construction of the Dujiangyan Irrigation Project in about 256 BC.

He divided the river into two by building a midstream weir; from there, at Fish Mouth, the Minjiang splits into the Outer River which runs in its old bed, and the Inner River, which Li Bing diverted to a new course to the east.

The Inner River was in turn divided at Lidui Hill, a man-made embankment, where the right-hand (west) stream was linked to the Outer River through the Flying Sands Spillway, and the left-hand stream squeezes through the Precious Bottleneck Channel to feed a grid of irrigation canals now watering 670,000 hectares of the West Sichuan Plain.

Thanks to the project, the plain has been more or less spared from flood and drought for more than 2,000 years, winning the name the "land of abundance" in ancient times.

"Dig the beds deep; keep the dikes low," Li Bing warned. This principle has been observed ever since and the spillway and channels are kept in good order to this day.

Since ancient times, workers have used rafts to block water from Minjiang River each winter to maintain the river-beds and reinforce the dykes in the dry season. They would tear down the rafts in spring to release water to irrigate farmland in the West Sichuan Plain.

With the construction of an electrical strobe in 1957, Dujiangyan no longer used rafts to block the water to engage in its annual maintenance and the ceremony was no longer held.

In 1991, the Qingming Water-releasing Festival resumed. The festival in 2004 attracted numerous visitors from home and abroad, said Deng Ying, deputy chief of the Dujiangyan Irrigation Project Administration.

(China Daily April 14, 2006)