Its largest lake is so dry that China is digging deep to water crops

BEIJING

As China’s largest freshwater lake has been reduced to just 25% of its usual size by a severe drought, work crews are digging trenches to keep water flowing to one of the main rice-growing regions from the country.

The dramatic decline of Poyang Lake in the landlocked southeastern province of Jiangxi had also cut off irrigation channels to nearby farmlands. The teams, using excavators to dig trenches, only work after dark due to the extreme heat of the day, the official Xinhua news agency reported.

A severe heat wave is wreaking havoc across much of southern China. High temperatures have sparked mountain fires that have forced the evacuation of 1,500 people in the southwest, and factories have been ordered to cut output as hydroelectric plants cut output amid drought conditions. Extreme heat and drought have withered crops and narrowed rivers, including the giant Yangtze, disrupting cargo traffic.

Fed by major rivers in China, Lake Poyang averages about 3,500 square kilometers (1,400 square miles) in peak season, but contracted to just 737 square kilometers (285 square miles) during the recent drought.

As determined by water level, the lake officially entered this year’s dry season on August 6, earlier than at any time since records began in 1951. Hydrological records prior to this date are incomplete, although it looks like the lake is at or around its lowest level. level in recent history.

In addition to providing water for agriculture and other uses, the lake is a major stopover for migratory birds heading south for the winter.

China is more accustomed to dealing with the opposite problem: seasonal rains that trigger landslides and floods every summer. Two years ago, villages and fields of rice, cotton, maize and beans around Poyang Lake were flooded after torrential rains.

This year, a wide swath of western and central China experienced days of temperatures exceeding 40 degrees Celsius (104 Fahrenheit) in heat waves that started earlier and lasted longer than usual.

The heat is likely linked to human-caused climate change, although scientists have yet to do the complex calculations and computer simulations to say for sure.

“The heat is certainly breaking records and is certainly aggravated by human-induced climate change,” said Maarten van Aalst, director of the Red Cross Red Crescent Climate Center in the Netherlands. “Drought is always a bit more complex.”

The “truly breathtaking temperatures scorching China” are linked to a blocked jet stream – the river of air that moves weather systems around the world – said Jennifer Francis, a climatologist at the Woodwell Climate Research Center in Falmouth, Massachusetts.

She said an elongated area of ​​relatively high atmospheric pressure hovering over western Russia is responsible for heat waves in China and Europe this year. In the case of China, the high pressure prevents cool air masses and precipitation from entering the region.

“When hot, dry conditions stay locked in, the ground dries out and warms up more easily, further strengthening the overhead heating dome,” Francis said.

In the hard-hit city of Chongqing, some malls have been told to only open from 4 p.m. to 9 p.m. to save energy. Residents sought respite in the cool air-raid shelters dating back to World War II.

This mirrors the situation in Europe and elsewhere in the northern hemisphere, with high temperatures harming public health, food production and the environment.

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Associated Press science writer Seth Borenstein in Washington, DC, contributed to this report.

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