CHINA'S national economy grew by 12.8 per cent last year over the previous year - the highest rate in the world - and its Gross Domestic Product is expected to grow at a similar rate this year. To maintain sustainable high economic growth, China is carrying out massive infrastructure works. ''The country is a vast construction site,'' a Western economist said. Ten projects rate as the most important. The Three Gorges hydroelectric power station: after more than 40 years, the Three Gorges project was finally approved by the Chinese legislature last year and construction has begun. The project, the largest of its kind in the world, is located at the Three Gorges, or middle section of the Yangtze River. A planned dam will be 1,983 metres long and 185 m high and will create a vast reservoir. The project will cost 60 billion yuan (HK$81 billion), and construction will take about 18 years. With 26 generators, the hydroelectric power station will produce 85 billion kilowatts per hour of electricity a year. The reservoir to be created by the super station will dislocate more than one million people in Hubei and Sichuan provinces. Relocation of these people began late last year. Pudong Development Zone: Pudong, an area the size of Singapore, is wedged between Shanghai and the East China Sea. In 1990, the government declared Pudong a development zone open to foreign investment. Pudong's development is intended to revive Shanghai as the business centre of the Far East. Major projects completed, or under construction, include two bridges across the Huangpu, highways, ports, a railway, an airport, a bonded area, and facilities for gas and power supplies. Total investment for Pudong is estimated at more than 100 billion yuan. Yangpu Economic Development Zone: in August, last year, Japanese-controlled Kumagai Gumi (Hong Kong) Ltd won the right to use, for 70 years, a 30-square-kilometre area at Yangpu, a small peninsula on the western shore of Hainan island. The company has promised to invest over HK$100 billion to build Yangpu into an industrial area with a concentration of foreign business using advanced technology. Beijing-Kowloon Railway: the 2,370-km-long railway will run parallel to the Beijing-Guangzhou line, which cuts through nine provinces and municipalities. Construction has started and is scheduled for completion by the end of 1995. Tuman River development area: the 459 km Tuman River empties into the Sea of Japan in northeast Asia. It originates in Jilin province and runs across the borders of China, Russia and North Korea. Development of the zone will take 20 years and will require a total investment of US$30 billion. Water diversion from the Yangtze to the North China Plain: to quench the thirsty North China Plain, water will be diverted north from the Yangtze River in Jiangsu province, via an ancient canal built more than 600 years ago. About 30 billion cubic metres of water will be diverted every year. It will irrigate more than 400,000 hectares of farm land in six north China provinces and make up for water deficiencies in major cities in these areas. Double tracking of Northwest China Railway: the 1,600-km railway from Lanzhou, capital of Gansu province, to Urumqi, capital of the central Asian region of Xinjiang, is being double tracked, and will be completed in 1995. Beijing-Dandong Expressway: the 850-km expressway, running from the Chinese capital to Dandong on the Sino-Korean border in the northeast, is a section of a proposed international expressway that links Tokyo, Seoul, Pyongyang, Beijing, Moscow and London. Construction began last year and is expected to be completed before 2000. Beijing-Guangzhou Expressway: the 2,300-km expressway runs via major cities in Hebei, Henan, Hubei and Hunan provinces. It will run parallel to the Beijing-Guangzhou Railway. Harbin-Ningbo Expressway: this 3,500-km thoroughfare starts from Harbin, capital of Heilongjiang province in the northeast, and ends at the port city of Ningbo in the eastern province of Zhejiang. This road, which is part of a nationwide expressway network under construction, will be completed in the last years of the decade.