East Asia: Water surpluses will retreat from southern China

22 July 2020

THE BIG PICTURE
The 12-month forecast for East Asia through March 2021 indicates widespread surpluses in the Yellow River Basin (Huang He River), primarily moderate in the lower and middle regions but more intense in the upper portion of the watershed.

In the Yangtze River Basin, surpluses will be moderate to severe in the lower and middle watershed, but more intense in the upper reaches.

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Surpluses are also expected in the Pearl River Basin (Zhujiang River) in southern China and will be extreme in Guizhou, though conditions of both surplus and deficit are expected in surrounding regions as transitions occur. Farther south in peninsular Guangdong, severe deficits are forecast and moderate deficits in nearby Hainan. Deficits are also expected in southern Yunnan. Surpluses are forecast for western Tibet (Xizang) and anomalies will be exceptional including along much of the Yarlung (Brahmaputra) River.

Western Inner Mongolia will see severe to exceptional deficits, conditions that will reach west into Xinjiang through the center of the Taklimakan Desert. Some conditions of both deficit and surplus (pink/purple) are also expected in Xinjiang as transitions occur. Deficits of varying intensity are forecast for central Mongolia, and pockets of surplus in the west and far east. Northeast China can expect widespread surpluses of varying intensity.

On the Korean Peninsula, moderate surpluses are forecast in the north and moderate deficits in the south. Nearly normal conditions are expected in Japan.

FORECAST BREAKDOWN
The 3-month time series maps below show the evolving conditions in more detail.

The forecast through September indicates that surpluses in China will shrink and downgrade overall but remain widespread. In the Yellow River Watershed, surpluses will moderate in the lower region, will downgrade but be severe along the Ordos Loop and in much of the upper region, and will be exceptional in southern Gansu. Surpluses will emerge on the Shandong Peninsula. In the lower and middle regions of the Yangtze River Watershed, surpluses are expected to moderate overall though severe anomalies will persist in Shanghai. Along the Upper Yangtze River (Tongtian River) and in much of Qinghai, surpluses will be intense. Surpluses will retreat from the Pearl River Basin and shrink and downgrade in Tibet and Northeast China though remain widespread.

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Deficits will shrink in western Inner Mongolia, Mongolia, and Xinjiang, but in southern China deficits will intensify in southern Yunnan and southern Guangdong.

Conditions will normalize in South Korea, surpluses will increase in North Korea, and nearly normal water conditions are forecast for Taiwan and Japan.

From October through December, near-normal conditions are forecast for many regions in East Asia. Surpluses will shrink and downgrade in China, persisting from northern Anhui into Shandong in the east; in Shaanxi, southern Gansu, and Qinghai; central Tibet; and large pockets of Northeast China. Deficits will nearly disappear in Mongolia, western Inner Mongolia, and Xinjiang, but widespread moderate deficits will emerge in southern China. Nearly normal conditions are forecast for Taiwan, some surpluses in coastal North Korea and some mild deficits in the south and in Japan.

The forecast for the final three months – January through March 2021 – includes widespread deficits in northwestern China, the Lower and Middle Yangtze River Basin, and South Korea. Surpluses will persist in Northeast China and parts of the Yellow River Basin and Tibet.

Please note that WSIM forecast skill declines with longer lead times.

IMPACTS
Intense rainfall has battered central and southern China for weeks creating flood conditions on both the Yellow and Yangtze Rivers, displacing millions of people, and challenging the nation’s Three Gorges Dam whose floodgates were opened in mid-July. The worst flooding in decades brought the dam to its highest water level since 2009. More than 150 people have died and around 1.8 million have been evacuated. Direct economic losses are estimated at more than 49 billion yuan (US $7 billion).

In Anhui Province, authorities blew up a portion of a dam on the Chu River, a tributary of the Yangtze, to release excess water. In eastern Anhui, 10,000 people in the town of Guzhen were trapped when floodwaters breached the levees. And in Jiangxi Province, China’s largest freshwater lake, Poyang, rose to a record level.

The epicenter of the coronovirus outbreak, Wuhan in Hubei Province, has been inundated, threatening the global supply of PPE, personal protective equipment, primarily face masks, produced in nearby factories.

Nearly 20 percent of China’s productive farmland has been impacted and African swine fever has emerged in hog farms in several southern provinces, threatening restocking efforts after last year’s outbreak reduced national stock by 40 percent.

NOTE ON ADMINISTRATIVE BOUNDARIES
There are numerous regions around the world where country borders are contested. ISciences depicts country boundaries on these maps solely to provide some geographic context. The boundaries are nominal, not legal, descriptions of each entity. The use of these boundaries does not imply any judgement on the legal status of any territory, or any endorsement or acceptance of disputed boundaries on the part of ISciences or our data providers.

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