The Chinese Ministry of Water Resources predicts that beginning from 2010, a serious water shortage will lie ahead of the country. By 2030, when the shortage peaks, the nation will have 40-50 billion cubic meters of water in short supply. What's more, Shanghai -- the biggest Chinese metropolis situated in the estuary of the Yangtze River, by the East China Sea -- has been added to the United Nations' list as one of the six cities predicted to experience severe drinking-water problems in this century. Shanghai Water Affairs Bureau has foreseen that during this summer, when the city uses up to 9.64 million cubic meters of water per day, there will be a possible daily water shortage of 1.5 million tons.
"Unlike north China, which is often afflicted with severe drought, what Shanghai lacks is quality water suitable for both drinking and industrial production," says 73-year-old Zhang Jiacheng, an expert of water affairs.
Although Shanghai abounds with water resources, its usable fresh water is very limited, with the total amount standing at 11.88 billion cubic meters, only 20 percent of the city's surface water. Shanghai's per capita water availability is 1,049 cubic meters, 40 percent of the country's average and 10 percent of the world's average.
"Pollution either occurs in the upper reaches of the Yangtze, or is caused by local plants," said Zhang Jiayi, director of Shanghai Water Affairs Bureau.
The Huangpu River, a tributary of the Yangtze flowing through Shanghai, has supplied 80 percent of drinkable water for the local residents. Nonetheless, in recent years, the river has been seriously defiled by industrial wastes, pointed out Zhang Jiatuan, a senior engineer of the Ministry of Water Resources.
Furthermore, contamination in the neighboring Taihu Lake remains a direct menace to the Huangpu River. Due to discharge of domestic and industrial sewage, high content of phosphorus in the lake has led to the occurrence of potentially toxic blue-green alga over large areas, bringing severe drinking-water problems to Wuxi City at the lakeside. According to Zhang Jiatuan, as a result, in the upper reaches of the Huangpu, dense aquatic plants have been seen floating on the water surface several times since the middle of June. On severe occasions, they covered up almost one-third of the river.
Experts from the Ministry of Water Resources pointed out that along with sharp population growth and rapid economic development, the imbalance between supply and demand of water has become a bottleneck in the nation's industrial and agricultural production and urban development. A scarcity of drinking water in Shanghai will greatly hinder its developing into an international metropolis.
However, most local residents have not yet come to realize the seriousness of the situation. Many people are in the habit of keeping the tap running while brushing teeth and washing up. Old-fashioned toilet tank, with 13 liters of water released in each flush, is still used in many households. At car-washers, tapped water is used to wash vehicles with very low charges. In fact, besides water contamination, wasteful consumption of clean water is also to blame for the water shortage.
"Few water-saving devices are used in Shanghai households," says Yu Longxiang, a water-saving expert. "According to statistics, each of the city's nearly 900,000 old flush toilets leaks 0.5-1 liters of water on average per day, letting millions of tons of clean water flow away for nothing each year!"
Meanwhile, there are quite a few loopholes in the city's management of water resources.
The water subsidy policy originating in the old planned economy era has not yet been completely abandoned today, though reforms have been carried out in the tap water industry. Exploiting this advantage, some street restaurants and car washers use subsidized water to do business. To wash a car, which charges from five to 10 yuan (US$0.625-1.25), 0.2 ton of water is needed, equal to the amount a resident's daily use in the summer, but the cost is only 32 cents. Cheap water charges have encouraged people to use water lavishly.
In a city like Shanghai, which has abundant rainfall throughout the year, rain water could have been collected and used to irrigate fields, wash down vehicles, flush toilets, fight fire, and so on, to reduce the reliance on rivers. However, so far the city is not prepared for rain water collection.
After making an inspection tour to Shanghai, 19 members of the Chinese Academy of Sciences and Chinese Academy of Engineering, including 81-year-old Qian Zhengying, suggested the city to promote water-saving devices, while tapping new water sources and reducing water pollution to the greatest extent.
According to Zhang Jiayi, the city is carrying out a program to remake old water closets used in as many as 600,000 households, aiming at saving an estimated 9.84 million cubic meters of water a year.
"A direct effect of economization on water is to reduce the release of waste water," says Yu Longxiang. "Consequently, the city's burden of sewage treatment will be lessened. This is an act to serve two purposes at the same time."
In terms of tapping new water sources, Gu Yuliang, chief engineer of Shanghai Municipal Raw Water Co Ltd, suggested to establish a water source preservation zone at the mouth of the Yangtze River. "The water flow of the Yangtze reaches 0.93 trillion cubic meters in Shanghai and its environs. Along with harnessing the Yangtze, constructions of mid-stream and riverside reservoirs should also be considered," Gu said.
Currently, Shanghai's waterworks take water mostly from the Huangpu River. Qian Zhengying proposed to shift water intakes from the Huangpu to the Yangtze, which has better-quality water. In addition, related institutions must pay enough attention to preventing salt water from intruding into the Yangtze mouth area, Qian warned.
Currently, the city is considering different ways to tackle the water shortage crisis, including desalination of sea water, full exploitation of rain water, and rational use of groundwater resources, according to Zhang Yijia.
(China.org.cn by Shao Da, July 2, 2004)