By staff reporter HUO JIANYING

IN August 2002, the Changpu River east of the Tian'anmen Rostrum saw daylight once more after 40 years concealment underground. In the late 1960s the river was boarded over and warehouses in which to store adornments for Tian'anmen Square pageants were built on it. Increasing concern for the Beijing eco-environment and preservation of its historic features in recent years has resulted in the municipal government's launching of a series of measures, and that of renewing the city's river network carries high priority.

The Imperial River Network

Despite measuring only 510 meters in length, during the 14th to 20th century the Changpu was one of Beijing's two most important rivers, the other being the Golden Water River by the Hall of Supreme Harmony in the Forbidden City. As the Changpu runs outside the imperial compound, it is also known as the Outer Golden Water River. In the Ming Dynasty, the city of Beijing was divided into three concentric rings, with the downtown area at the periphery, the Forbidden City at the center, and the imperial city between the two. As domicile to the royal family, the Forbidden City was surrounded by water, with the Golden Water River to the south and the Tongzi River to the east, west and north. Both still exist. The downtown area was also encircled by moats. Moats extant in Beijing were constructed during the Ming Dynasty, when they performed the multiple functions of water supply, sewage treatment, transportation, and defense.

The Inner Golden Water River inside the Forbidden City.

Originating as they did in south China, the Ming emperors had a strong affinity for water. Emperor Zhu Yuanzhang, founder of the dynasty, selected Nanjing, on the Yangtze River, as capital of his empire, but after a coup by his son Zhu Di and his subsequent ascension to the throne, the capital was moved to Beijing. The reasons for this were that Beijing had long been Zhu Di's sphere of influence, and that it had mighty economic and military strength. Its location was also strategically significant as regards defense against the enemy states in the north. After Zhu Di died in 1424, his son Zhu Gaochi succeeded the throne, and soon took the decision to move the capital back to Nanjing. He died, however, only two months later. Otherwise, the history of Beijing would have taken a completely different course.

Since ruling Beijing as Prince Yan, Zhu Di had stressed the need for the construction of its water works. In 1371 he gave the order to shift the Yuan (previous dynasty) city wall to the south, and make the Broomcorn River and Jishuitan its northern moats. In 1419 a new moat, Qiansanmen, was dug south of the imperial city, and the eastern and western Yuan moats were dredged and expanded to link with it. Later the external city moat was also excavated after a city wall had been built, and all these moats were channeled into the Tonghui River. Beijing was thereafter circumfused with rings of green waters.

Ancient Water Works

The Kunyu River was the imperial watercourse during the Qing Dynasty.

In ancient times Beijing was a busy port. After the city was made capital of the Yuan Dynasty in the 13th century, its population underwent a sharp increase. At that time Beijing ruled 16 counties, and its local residents exceeded 400,000. Taking into account government employees, garrisons, and itinerants, the real population in Beijing approached one million. Feeding a population of this magnitude entailed regular shipments of grains to Beijing from south China, the "state granary," via the Beijing-Hangzhou Canal. Freights were unloaded at Zhangjiawan Dock.

Located south of today's Tongzhou District, Beijing, Zhangjiawan Dock handled all shipments of grain to Beijing throughout the Yuan, Ming and Qing dynasties. Zhangjiawan city housed the Administration of Water Transportation of Grain to Beijing office, as well as large numbers of granaries, and was therefore heavily guarded. Cargo boats formed long queues along the canal a few kilometers away from the city.

In its capacity of political, economic and cultural hub of the Yuan Dynasty, Beijing faced two pressing tasks: to explore new sources of water, and to build a waterway linking Beijing to the Zhangjiawan Dock, so that grains could be shipped directly into the city.

The two projects were masterminded by Guo Shoujing (1231-1316), a renowned astronomer and hydraulic engineer. After careful hydrological and geographic reconnaissance Guo discovered Baifu spring in the Shenshan Mountain. He built the 30-km-long Baifu Weir in northwest Beijing to divert the spring water to the city, and then channeled it, via the existing river course, into the Grand Canal.

To solve the problem of the riverbed gradient, Guo built dozens of sluices along the canal to control the water level and runoff. The 80-km canal was built by 20,000 laborers in just over one year. On its completion, Yuan Emperor Kublai Khan was delighted at the sight of Jishuitan Lake crowded with boats from Tongzhou, and named the canal the Tonghui River. Today the river has been renovated, and a boat tour is in operation.

Spates of Disaster

The Lotus Pool in Beijing was formerly a reservoir.

Although Beijing now faces increasing water shortages, it nevertheless practices flood-fighting drills every year. This is due to the city having suffered serious floods in past centuries, when the main culprit was the Yongding River. According to historical documents, during the 834 years from 1115 to 1949 the Yongding River burst its banks 140 times, the time lapse between each occurrence ever shorter. During the 268-year reign of the Qing Dynasty it was breached 68 times, on average causing floods every four years.

In 1626, torrents from the Yongding River swept across the city from west to east, bringing a high death toll. In the 1890 flood, the eastern, western and southern regions outside Beijing were all immersed. Within the city, flood water could not be drained away, as all trenches and ditches were blocked up. All its residences were consequently inundated, and many collapsed.

Despite all the calamities it has caused, the Yongding River is nevertheless Beijing's lifeline. Without it, Beijing could not have grown from a desolate settlement into a metropolis. The sweet and refreshing springs of Yuquan Hill were actually Yongding River water filtered through limestone. It was a source of irrigation for the farmland in rural Beijing, and the rivulets and lakes throughout the city were generally its tributaries. Centuries ago, there were vast waters in the west flank of the imperial city teeming with fish, lotus, and waterfowl, and temples, pavilions, gardens and villas were scattered over its banks.

Rescuing Beijing's Rivers

Jishuitan was the main deport for grain transported by canal from southern China to Beijing.

Over the past century, owing to climatic and other reasons the waters in Beijing have shrunk. In the 1960s the Forbidden City western moat was transformed into an underground river, and in ardent urban construction drives of the 1970s more moats followed suit. Today only the southern moat and part of the northern moat are extant, and are half their original length. Cement-enforced banks present a further blemish on Beijing's ancient rivers.

This situation is, however, to be changed with the drawing up by the government this year of the Plan to Protect the Historic and Cultural City of Beijing. This plan is specifically to protect Beijing's water system, and according to it, special efforts will be made to harness and protect waters relevant to the city's history and eco-environment. It also includes restoration of rivers and lakes of historic significance to Beijing.

Since 1998 the municipal government has invested one billion yuan in water system projects. So far the Beihai and Shichahai lakes and the Tongzi River have been dredged, and their banks and bounding walls repaired. Work on Qingshui, Bahe and Liangshui rivers is also underway. By the year 2005 the government will invest another 5.45 billion yuan in cleaning up 20 more rivers, with the aim of restoring Beijing's former aquatic splendor .