Three Gorges Probe

China turns floodwater into new source for irrigation


December 8, 2000

 Floods become friends rather than foes in China, since the country has succeeded in making terrible summer floodwater useful in drought resistance.

Some water-deficient regions in China have began diverting floodwater from major rivers for storage in flood season and make use of these valuable sources of water for irrigation in dry season to ensure stable yields.

Major rivers, often referred to as "mother rivers", serve as the principal source of irrigation in China. However, raging floods on these rivers in high-water seasons pose a great threat to people living on both banks, just like a sword of Damocles.

According to the State Floods Prevention and Drought Relief Headquarters, floods killed 1,231 people, left 331 others missing and caused direct economic losses of 136 billion yuan (about 16.9 billion U.S. dollars) in the first three quarters of 2005.

The traditional way to curb floods is to reinforce river embankments and open reservoir sluices to discharge floodwater. But, in dry season, people in riverside areas often face water shortage.

Encouraged by a government-initiated concept of scientific development, Baicheng city, which lies on Nenjiang River, a tributary of Songhua River in northeast China, has made original and unprecedented experiment in 2003.

"The city often suffers from severe drought as it uses less than 2 percent of Nanjing River’s average yearly water flux, or 21.6 billion cubic meters," said Xu Kai, an official with the local water resources bureau.

After realizing the value of floodwater, the city began to channel floodwater into reservoirs and ponds for storage for use in dry seasons.

"During the past three years, we have utilized 3 million cubic meters of floodwaters, which have helped to improve 50 square kilometers of wetlands, and raised the underground water level by one meter," Xu said.

The city’s five reservoirs and 18 ponds are now filled with Floodwater.

To date, people live in areas adjacent to large rivers, such as the Yangtze River and Yellow River, have followed the example of Baicheng City.

The move is important for China, as nearly two thirds of the 660 cities in China lack water supply. The per capita share of water resource in China is only a quarter of the world’s average, according to the Ministry of Water Resources.

Water shortages cause 200 billion yuan (24.9 billion U.S. dollars) in losses of industrial output value and 150 billion yuan (about 18.6 billion U.S. dollars) in losses of agricultural output value each year.

"To solve severe shortages, China should store floodwater for utilization in dry seasons instead of simply discharging it during the flood season," said Wang Shucheng, Minister of Water Resources.

China stored 11.7 billion cubic meters of floodwater from the Yellow River, the second longest in China, during the flood season in 2003. Floodwater greatly relieved water shortage in the following dry season.

A dam, at a cost of 282 million U.S. dollars, is being built on Huaihe River. It would be able to store 10 billion cubic meters of floodwater for agricultural use after it is completed by the end of this year.

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