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China is bracing for climate uncertainties after a persistent drought hit the entire Yangtze River Basin, with experts warning of shocks to come

By Yu Xiaodong Updated Nov.1

Seen from a high-resolution satellite, the water level in Dongting Lake in Yueyang, Hunan Province is high, August 31, 2021

Seen from another high-resolution satellite, the water level in Dongting Lake in Yueyang, Hunan Province is much reduced, exposing the lakebed due to the prolonged summer drought, August 6, 2022

Since China reported its first heat wave this year on June 13, unusually high temperatures ravaged much of the country throughout the summer for more than 70 days until the end of August. In the first month, heat waves swept half of China’s land area, affecting over 900 million people. 

The figures are daunting. According to the National Meteorological Center (NMC), by August 17, 1,426 of China’s 2,424 meteorological monitoring stations (59 percent) reported temperatures of over 37 C. In a press briefing on September 6, Xiao Chan, vice-director of the NMC told the media that by the end of August, 267 weather stations have reported record-breaking temperatures, a record high since China started collecting meteorological data in 1961.

Hottest Summer
As temperatures stayed above 40 C in a massive area along the river for several weeks, it has been the hottest summer in China’s recent history. The duration, intensity, extent and impact of the more than 70-day heat wave have been the biggest since 1961, Xiao said, adding that the average national temperature in August was 22.4 C, 1.2 C temperatures higher than the seasonal norm. According to statistics from the Ministry of Emergency Management of China, in August, high temperatures in the southwest, central and south of China lasted five to 10 days more than the same month in previous years. 

The persistent heat waves, along with a lack of precipitation, brought unprecedented drought, with the Yangtze River Basin the worst-affected area. China’s longest and the world’s third-longest river, the Yangtze runs for over 6,300 kilometers through 11 provinces and municipalities, and it is the most vital waterway to China’s economy, providing water to more than 400 million people. 

The long-lasting drought caused water flows on the Yangtze’s main channel to decline by 50 percent. Pictures of people sitting in dried up river beds in the middle of cities have gone viral. According to China’s Ministry of Emergency Management, precipitation on the Yangtze River Basin in July and August totaled just 160 millimeters, 49.6 percent of a normal year and the lowest since 1961. 

In August, average national rainfall fell by 23.1 percent to 82.4 millimeters. This is the third-lowest since records began, Xiao said at the NMC briefing. 

In Sichuan Province in the upper reaches of the river, where 80 percent of power comes from hydropower, the drought forced the provincial government to impose electricity rationing on industry, as water flow to Sichuan’s hydropower reservoirs dropped by half compared to the previous summer while electricity demand increased by a quarter. 

Downstream in Jiangxi Province on August 6, the water level of Poyang Lake, China’s largest freshwater lake, declined below 12 meters, technically the dry season line, 69 days earlier than the average date between 2003 and 2021. 

“In the past, the water level in Poyang Lake dropped under the dry season line only in October, rarely in September, and never in August,” Wu Guocai, director of the bureau of water resources in Chudu County in Jiangxi told NewsChina. By August 29, the surface area of Poyang shrank to 465 square kilometers, just one-sixth of its normal size in summer. 

Elsewhere in Jiangxi, 1,734 reservoirs reached “dead pool status,” meaning that water can no longer flow downstream. Over 40,000 ponds completely dried up, according to provincial authorities. 

In Chongqing along the upper reaches of the Yangtze, home to 31 million people, 66 rivers and 25 reservoirs had dried up by August 16. In Beibei District, the temperature reached 45 C on August 17, an all-time high ever recorded in China’s recent history. The searing heat set off wildfires in the hills and forests on Chongqing’s outskirts, where tens of thousands of firefighters and volunteers worked to put out blazes. There were 62 forest wildfires in August, mainly in Chongqing, Sichuan, Hunan and Jiangxi, much more than the last year. The drought in July and August affected more than 38 million people and nearly 41 square kilometers of crops, with direct damages of 328 million yuan (US$47m) according to the statistics that was published by Ministry of Emergency Management. 

Lü Juan, director of the Research Center on Flood and Drought Disaster Reduction under the Ministry of Water Resources, told NewsChina that although summer is more associated with flooding in the Yangtze River Basin, summer drought is not new.

Unprecedented Severity
In fact, summer drought has become noticeably more frequent in recent years. Major droughts struck the Yangtze River Basin in 2006, 2013, 2017 and 2019. 

But the drought this summer was unprecedented, as the severity of its scale and duration was far beyond previous ones. In 2006, a severe drought that lasted more than four months hit Sichuan and Chongqing, but the rest of the Yangtze River Basin was not affected. In 2013 and 2019, the downstream suffered severe droughts. Never has a severe drought struck the entire Yangtze River region during this summer. 

Typically, if there were summer droughts in the Yangtze region, they hit in late July and early August. But this year, the drought started in early June and lasted for at least three months, and looks like it is continuing into autumn. According to the NMC’s forecasts, the drought could last well into the autumn in the middle and lower reaches. 

Lü told NewsChina that what makes it difficult to deal with a drought is that unlike floods, which develop quickly and prompt authorities to take swift action, drought has an accumulating effect and it takes time before it develops into a severe disaster. 

This is the case this year, as the drought became more severe each day. Data released by the NMC showed that precipitation along the Yangtze River in June and July was about 20 percent and 40 percent less than in previous years. In August, average rainfall in the Yangtze River Basin dropped to less than 50 millimeters, only one-fifth of a normal year, with rainfall in the upstream region less than 1 millimeter for the entire month. 

Lü said the unexpected drought caught many officials off guard, as they are more familiar with fighting floods. “Many adopt the mentality that rain will come soon and everything will be fine,” Lü said. “This has to change in the future.”

Reservoir Dilemma
As the drought posed a major threat to the autumn harvest in the Yangtze region, central authorities mobilized a cross-provincial action to release water from major reservoirs to ease water shortages. 

Between August 1 and 15, the Changjiang Water Resources Commission which manages water resources of the Yangtze River Basin ordered major reservoirs along the Yangtze to release 5.3 billion cubic meters of water, including 1.09 billion cubic meters from the Three Gorges Reservoir, the world’s biggest reservoir. In the latter half of the month, an additional 3.17 billion cubic meters of water was released. This involved 51 large reservoirs, including 27 major reservoirs in the upper Yangtze and 24 in the middle reaches. 

“Such extensive cross-regional coordination involving dozens of reservoirs along the entire Yangtze River region is rare, and reflects the severity and scale of the drought,” Lü said. 

But while the volume of the released water may sound huge, its impact is rather limited given the scale of the drought. According to Wu Daoxi, deputy director of the Yangtze River Water Resources Commission of the Ministry of Water Resources, the large water release helped elevate the water level in the middle and lower reaches, but only by 40 centimeters to 1 meter. 

An expert with the Ministry of Water Resources who asked not to be named told NewsChina that water released from reservoirs can help ease drought along the main trunk of the Yangtze, but offers little help to the Yangtze’s tributaries and the vast areas around them. “Water released from reservoirs differs from rainfall, as its impact follows a single line, not an area,” said the expert. “Nor does it help the areas along the tributaries of the Yangtze.” 

What further limits the reservoir system’s capability to combat the drought is that the summer months are usually the monsoon season, when the primary concern is flood prevention, not drought mitigation. 

According to the ministry expert, in meetings to prepare for the summer held in March and April, most meteorologists believed there would be more precipitation in the Yangtze. “Nobody predicted that there would be a drought like this.” 

As a result, the water level in most reservoirs in the Yangtze River Basin was maintained at a relatively low level, known as the flood limit level to prepare for increased rainfall. For the Three Gorges Reservoir, the flood limit level is 145 meters. Alarmed by early signs of drought in June, authorities kept the water level of the Three Gorges Reservoir five meters higher than the flood limit level, said the expert. But it was far from enough. 

“It’s a tough choice,” said the expert. “If you keep the water level too high, what if there are floods? And if you keep the water level too low, there is a risk of being hit by drought, like this year.” Given the increasing uncertainty and unpredictability of climate in both China and the world, authorities will have to face the same dilemma repeatedly in the future.

Drought-Flood Transition
In late August, rain finally arrived in Sichuan and Chongqing in the upstream Yangtze, though it may not be good news. The heat, which has caused crusting and compaction of the surface soil, means heavy rain can cause flash floods and mudslides. 

On August 24, Sichuan’s meteorological station issued a blue rainstorm warning – the highest level under China’s four-tier warning system – meaning that over 50 millimeters of rain would fall within 12 hours. In certain parts of Sichuan, more than 165 millimeters of rain eventually fell within 24 hours the following day. 

As it continued to rain in the upper Yangtze, the Ministry of Emergency Management launched a national level IV emergency response for floods (the lowest in the four-tier system) for Sichuan, Chongqing, and neighboring Gansu and Shaanxi provinces in northwestern China on August 28, urging local authorities to brace for “an abrupt drought-flood transition.” 

As the heat wave finally subsided, the NMC announced on August 30 that it would stop issuing high-temperature alerts, the first time since the NMC issued its first yellow high-temperature alert on July 21. But the NMC maintained its orange drought alert, saying it is likely to continue in the middle and lower reaches of the Yangtze in September. 

In a briefing published on its website, the Water Resources Ministry estimated rainfall in the upper Yangtze in September would be 10 percent more than previous years, which will help alleviate the drought. But in the middle and lower reaches, it estimated precipitation in September to be 20 percent to 50 percent less than in past years, and forecast the drought in these regions may continue well into the autumn. 

According to Lü Juan, as frequent extreme weather events become the new norm against the backdrop of global warming, authorities along the Yangtze River, a region long known for its abundance of water resources, can no longer consider drought as a temporary and short-term problem. 

“People must be aware that droughts will become as frequent as floods in the region, and it is now the time to establish a systematic and long-term anti-drought mechanism for the entire region,” Lü said. 

On September 13, the Ministry of Water Resources declared that more than 1.78 billion cubic meters of water had been released from the upper and middle reaches to the lower reaches of the Yangtze since September 12, as there still had not been sufficient rain. However, the next day, from September 14-18, rainstorms brought by a typhoon swept across the downstream of the Yangtze and the northeast of the country, then torrential rain hit Sichuan, Chongqing and Hubei from 18 to 19.

The bed of Poyang Lake in Jiujiang, Jiangxi Province is cracked and fissured, August 19, 2022

Looking down from the head of Leshan Giant Buddha in Sichuan Province, the flow of water at the junction of the Dadu River, Qingyi River and the Minjiang River has significantly reduced, August 20, 2022