In the mid-nineties, I came to know about the Three Gorges Dam (TGD) in China. At that time, Narmada Bachao Andolan against Sardar Sarovar Project and protests against Tehri Hydro Electric Project were at their peak. Critics of large dams proposed watershed schemes, small tanks, contour bunds, and check-dams as alternatives to large dams stating that these would not cause submergence, displacement, environmental degradation, apart from costing less.
Presenting a counterview, T Hanumantha Rao, then advisor to the UN, argued that watershed schemes and small tanks cannot be alternatives to large dams. Citing the severe drought of 1986, he said that large dams like Bhakra Nangal, Damodar Valley Project and Nagarjuna Sagar helped sustain food production and overcome severe drought.
He also cited the example of the Aswan High Dam on the Nile in Egypt that eradicated recurrent droughts and floods, and made Egypt self-reliant in food and power. Referring to the TGD, which was being constructed then, he said it would bring in huge economic benefits to China in power generation, irrigation, inland navigation, tourism, fish food processing and employment generation.
Recently, I had the opportunity to visit the Three Gorges Dam in Hubei province of Western China. We were accompanied by Chinese engineers, with whom we discussed the TGD and its contribution to China’s economic growth. TGD is built across the Yangtze, the third longest river in the world, and its main objective was to generate power and mitigate losses due to severe floods. The planners selected the dam site to utilise the deep gorges of the Yangtze river that had the potential of generating huge power and absorb as much water as possible to mitigate flood losses to almost zero level.
TGD has an installed capacity of 22,500 Mw with 32 turbines of 700 Mw capacity each and two power plant generators of 50 Mw capacity. The annual electricity generation is estimated to be 100 trillion kilowatts. The TGD produces 50% more power than Itaipu Dam in Brazil that was the largest hydropower project in the world.
Before TGD came into being, flood frequency on the Yangtze was once in 10 years but after the TGD started impounding water to its full depth of over 175 m above MSL, the flood frequency fell to once in 100 years, because the dam can store 39.30 cubic km of water, in its reservoir of 600 km length. China also constructed three smaller dams below the TGD to facilitate inland navigation from Shanghai port city in Eastern China to Chongqing city in western China, covering a length of about 2,250 km.
Cargo ships of 10,000 mt can navigate through the two-way five-stage shiplocks while tourist cruises of 3,000 mt can navigate through the ship lifts. The maximum height of the dam is +185 m and the length is 2,335 m. Its full reservoir level is +175 above MSL. At FRL, the reservoir submerged about 1,600 villages, 140 towns and two cities, displaced 1.3 million population and submerged about 1,000 sqkm.
The maximum average actual flow of the Yangtze river at the TGD site is estimated as 10,59,450 cusecs and powerhouses have the capacity to take 10,19,350 cusecs for power generation when all the 32 turbines are on. Twenty-six turbines can take discharge of 8,47,560 cusecs. It is estimated that $37 billion was invested in the project. In terms of storage capacity, there are bigger reservoirs than the TGD and Aswan Dam. Kariba Dam in Zimbabwe has a storage capacity of 6,325 tmc, Bratsk dam in Russia has 6,000 tmc), Akosombo Dam in Ghana (5,000 tmc), Johnson dam in Canada (5,000 tmc) and Guri Dam in Venezuela has 4,767 tmc. Still, the TGD is the biggest hydroelectric project in the world.
The TGD was originally envisaged in 1919 but the actual work took off in 1993 when Premier Li Peng convinced the National People’s Congress. To administer the dam construction, the Chinese government established China Three Gorges University in Yichang city in 2000 and in June 2003, authorities began filling the dam while construction was still on up to the level of + 35 m. Second filling began in September 2006 up to +143 m level and the dam attained full water depth of +175 m in 2009.
Model for Us
The huge Kaleshwaram lift irrigation project can be compared with the TGD. There were apprehensions that the TGD would displace a large number of people, relocating them would be a big problem, it would affect the biodiversity of the Yangtze catchment area, will be detrimental to wildlife, pose a threat to potential riverbank slides and adversely impact local culture as 1,300 archaeological and historical sites would be lost.
It was also said that 40 million tonnes of sediments would deposit annually in the reservoir affecting the fertility of Yangtze delta and reduce the capacity of the reservoir. Many felt that the dam would be a potential target for enemies, raising security concerns for the cities downstream, especially Shanghai — the financial capital of China — apart from the possibility of the huge water storage inducing tremors and earthquakes or causing dam breaks, thereby risking millions of people and properties.
However, after a decade of TGD, there have been no major tremor or earthquakes except some landslides. China built several cities along the Yangtze at higher elevations and relocated all people, who were given employment in the industries that came up in the area. The R&R activities were completed along with the dam construction.
We visited one of the relocated cities, and it has all the civic amenities. In fact, the positive contribution of TGD can be distinctly seen across China.
The dam reduced coal consumption by 31 million tonnes and emission of 100 million tonnes of greenhouse gases as well as a significant amount of sulphur dioxide, nitric acid, carbon monoxide, dust particles and mercury into the atmosphere annually. The authorities installed 50 wastewater plants along the Yangtze river and bank protection works were completed at vulnerable reaches.
At the same time, river shipping capacity increased from 10 million to 100 million tonnes, reducing the transportation costs by 30% and the freight capacity of the river increased six times, cutting shipping cost by 25%. The dam supplies irrigation water to 30 lakh acres of farmlands downstream
Industries and employment opportunities have grown manifold along the river bank from Shanghai to Chongqing. The dam is now a national tourist attraction and tourists from all over the world flock to see it. All these have contributed to rejuvenating the Chinese economy in a big way.
In the recent TRS plenary, Chief Minister KCR pointed out how China’s growth zoomed in the last 40 years. The TGD has a distinctive role in it.
(The author is Officer on Special Duty to Irrigation Minister)