As the world's third largest country by territorial area, China covers 9.6 million square kilometers of land – that's more than 6 percent of the Earth's total.

Similar to other large countries like the U.S. and Australia, China's north and south have different climates. In general, the north is cold and dry, while the south is hot and wet.

As the world's weather slowly goes to the extreme, this south-north difference is scaling up. The difference is so big that China on Sunday issued a cold wave alert and a heat alert at the same time.

Such a complicated situation resulted in some of the most serious droughts in the north and some of the most serious floods in the south.

Basically, there's too little water in the north and too much in the south.

The Chinese have been dealing with this problem for thousands of years. According to an ancient Chinese myth, Yu the Great, who led China's flood control more than 4,000 years ago, eventually created China's first dynasty, the Xia Dynasty.

In modern times, the Chinese utilize new technology to keep water under control. One of the most significant projects is the South-to-North Water Diversion Project, which transfers water from the south to the north.

The government started planning the project back in the 1950s, not long after the People's Republic was founded.

It took half a century to finalize the plan, and construction started in late 2002.

Three routes were planned in China's east, middle and west. The first phase of the east route was put into operation in 2013 and the middle route in 2014.

The construction of all 155 units on the east and middle routes was finished in August 2022.

Data from the Ministry of Water Resources showed that the project has transferred over 56.5 billion cubic meters of water as of September, benefiting 150 million people.

Many dried rivers and lakes were restored thanks to the project, with people in 42 cities replacing low-quality local water with high-quality southern water.