Strange as it may sound, Chen Chaoxiang, a man in his early 60s, goes fishing these days on an ancient rampart instead of going to a stream or a pond.

Under Chen's feet is the vast body of water outside the wall protecting Shouxian County of east China's Anhui Province, which has been created by the Huaihe River flood. Chen also fished from the wall in 1991 when another major flood ravaged the region.

The Huaihe River, which runs through the provinces of Henan, in central China, and Anhui and Jiangsu provinces, both in east China, has been one of the most difficult rivers to control since ancient times.

However, its floods have never burst into Shouxian County proper, thanks to the wall where 63-year-old Chen now fishes.

The designers and builders of the wall in the imperial Tang Dynasty (618-907), Chen said, probably never anticipated that the wall they had built could endure repeated devastating floods in the ensuing thousand years and remain standing.

The bricks of the 7,147-meter wall were solidified by a mixture of glutinous rice gruel and lime. The water-proof and weather-resistant mixture was also employed in the construction of some sections of the world famous ancient Great Wall in northern China.

The wall, originally built with tamped earth, was coated with stones and large bricks in the Southern Song Dynasty (1127-1279), when the untamable Huaihe River would inundate the areas it passed.

Shi Hongping, a county official, acknowledged that the design of the rampart gateways give scope to an essential role in safeguarding the county from floods. The ramparts have two gates, which form a right angle instead of standing on a straight line.

The design helps alleviate the pressure against the inner gates caused by an onrushing flood even if a flood breaks into the gateways, Shi said.

In the Ming Dynasty (1368-1644), a drainage system was added to the rampart, to help drain water outside of the county proper when there was too much rainfall.

As a key project in the flood control of the Huaihe River, the ancient rampart has been receiving maintenance since new China was founded in 1949. Zhou Zunli, a former county water control chief, said that the wall was reinforced in 1991 and 1998, when two fierce floods hit eastern and central China areas, with a total investment of 9.8 million yuan (about US$1.2 million).

A major threat to the ancient wall comes from white ants, Zhou said. The most serious dangers caused by the ants occurred in 1993 and 1994, when some ant nests were large enough for seven or eight people to stand in.

Experts worked out a solution in which pesticides were grouted into the nests and after the ants were killed, the nests were filled with earth, Zhou added.

The gates of the rampart have been closed 16 times to ward off floods over half a century ever since 1949. Unlike gates in other ancient towns or cities, the gates of Shouxian County were inscribed with water-level marks. When a flood hits, local people usually know how deep the water outside the wall is by checking the marks on the gates.

(Xinhua News Agency July 29, 2003)