After a record heatwave parched large areas of the Yangtze basin, Chinese provinces are planning to spend billions of dollars on new water infrastructure as they try to fend off the growing impact of extreme weather on agriculture and hydropower.

The prolonged drought in southwest China has exposed the vulnerability of hydropower-dependent regions such as Sichuan to falling water levels and disrupted electricity transmission to other parts of the country.

With per capita water supplies already only a quarter of the global average, authorities are also concerned about the impact of low rainfall on the upcoming autumn harvest, with some suggesting 20% of China's crop could be affected.

Drought-hit regions have been digging emergency wells and deploying firefighters and cloud-seeding rockets to irrigate crops, but governments are also turning to larger, long-term water infrastructure.

"Because of the strong extremes, and the worsening of both floods and droughts, the ability to store and transfer water becomes very important," Mao Liuxi, an expert with the China Meteorological Administration, told a recent teleconference.

The Ministry of Water Resources has already approved 25 big projects this year, with total investment of 1.7 trillion yuan ($246 billion).

Central China's Hubei province, hit hard by the Yangtze drought, began construction of 18 giant water projects on Wednesday, and plans to spend 176 billion yuan over 2021-2025.

Last month, southwest China's Yunnan also began work on four big water storage projects with a combined investment of 211.8 billion yuan.

China has long relied on large-scale infrastructure projects to control its rivers. The giant Three Gorges Dam was designed not only to generate electricity but also to regulate the flow of the Yangtze, on which around a third of the population depends.

China has also been building the ambitious South-North Water Diversion Project, with channels now in place in eastern and central China to use Yangtze waters to replenish the arid north.

"There's a mentality that there's always an engineering, infrastructure solution," said David Shankman, a geographer with the University of Alabama who studies China's water system.

"They are trying to plan for the exceptional, but you can't predict the future."

DAMMING THE YANGTZE

With around 80% of Sichuan's energy supplies coming from hydropower, the drought forced authorities to shut down industries and ration power for households.

In response, China's energy bureau said it would build more grid infrastructure and develop alternative energy sources. It also vowed to speed up the construction of more dams on the Yangtze's upper reaches.

In theory, the construction of more upstream hydropower plants, particularly in parts of Tibet where melting ice in spring and summer could be diverted into reservoirs, could help even out seasonal water flow changes.

China already stores huge amounts of water in its giant reservoirs, and says they serve an important function in limiting flood damage during rainy seasons.

But critics say the projects are costly, environmentally damaging and remain at the mercy of unpredictable weather.

"If you're anticipating droughts, you want to have the highest water capacity, but in anticipation of severe floods, you want to have the lowest water level you can have," said Shankman, adding the situation is further complicated by the need to retain enough water to generate electricity.

Zhou Jinfeng, Secretary General of the China Biodiversity Conservation and Green Development Foundation (CBCGF), an environmental group, says the construction of giant water projects has already severely disrupted the Yangtze's natural habitats and hydrological functions.

"Water engineering projects are neither the best solution, nor the only solution," he said.

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