East Asia: Widespread water deficits will emerge in SE China

25 February 2021

THE BIG PICTURE
The 12-month forecast for East Asia through October 2021 indicates moderate to extreme deficits in a vast region of Southeast China from just south of Shanghai to Hong Kong and in Taiwan. Deficits will be intense in coastal Zhejiang and southern Taiwan. Farther south, surpluses are forecast in Guangdong’s Leizhou Peninsula and also in Hainan where anomalies will be exceptional.

Widespread surpluses are expected in Northeast China and will be exceptional in some areas including from western Jilin into western Heilongjiang trailing south into Liaoning. Surpluses of varying intensity are expected in the Yellow (Huang He) River Basin, moderate to severe in the river’s lower reaches but reaching exceptional intensity in Shanxi, Shaanxi, and Gansu at the base of the Ordos Loop.

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In the northwest, deficits are forecast from western Inner Mongolia well into Xinjiang. Anomalies will be severe to exceptional in Inner Mongolia, the Qaidam Basin in Qinghai, and the Tarim Basin in Xinjiang.

Tibet (Xizang) can expect a complicated patchwork of water conditions including surpluses in the center, deficits in the east, and mixed and transitional conditions in the west. Extreme deficits are forecast in western Yunnan.

In Mongolia, moderate to extreme deficits are forecast in the nation’s south-central region and deficits of lesser intensity will trail through the Hangayn (Khangai) Mountains leading to severe deficits in the northwest. Surpluses are forecast southwest of Lake Baikal in the region of the Selenga River’s headwater tributaries, and in a pocket in northeastern Mongolia in the Upper Kherlen River region.

On the Korean Peninsula, moderate surpluses are expected in the region north of Pyongyang, and deficits in coastal South Korea on the Sea of Japan. In Japan, normal conditions will prevail though a pocket of moderate deficit is forecast north of Tokyo in the Tone River Watershed.

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

The forecast through April 2021 indicates that surpluses will remain widespread and intense in Northeast China from the Russian border to the Bohai Sea. Surpluses will also be widespread in the Yellow River Watershed but will shrink and downgrade in the Yangtze’s, with moderate anomalies north of Wuhan and more intense surpluses around Chongqing. Surpluses are also forecast reaching south into Guizhou and in Guangdong’s Leizhou Peninsula and Hainan where anomalies will be exceptional.

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Widespread deficits will emerge in Southeast China and will be extreme to exceptional in Zhejiang, Fujian, and Jiangxi. Intense deficits will persist in Taiwan. Deficits will increase in Yunnan; mixed conditions are forecast in Tibet. Deficits will also increase in Xinjiang in northwestern China and in central Mongolia. Surpluses will moderate in North Korea but remain widespread and deficits will emerge in South Korea, intense on the Sea of Japan. In Japan, deficits in eastern Honshu will shrink, persisting from Sendai to Tokyo. Surpluses are forecast around Nagano in the west and in western Hokkaido including Sapporo.

From May through July 2021, surpluses will shrink in Northeast China and the Yellow River Watershed and disappear from the Yangtze region. Deficits in the southeast will shrink considerably but will be extreme in Fujian and severe on the Gan River in Jiangxi. Deficits in Taiwan will shrink and moderate. Anomalies elsewhere in China and Mongolia will shrink as well, but deficits will persist from eastern Tibet into Yunnan and will intensify in western Inner Mongolia. Nearly normal water conditions are forecast for the Korean Peninsula and Japan.

The forecast for the final three months – August through October 2021 – indicates normal conditions in many areas of East Asia. Surpluses will shrink in Northeast China, persist in scattered small pockets in the Yellow River Watershed, and persist in western Tibet. Deficits will emerge in southern Yunnan, central Sichuan, and Xinjiang.

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

IMPACTS
Drought in China’s southeastern provinces threatens the drinking water supply for 330,000 people, particularly in Zhejiang, Guangdong, and Fujian. The Ministry of Water Resources reports that rainfall in regions south of the Yangtze River has been 50 to 80 percent below normal since October. In response, authorities have initiated limits on water for industrial production and agricultural irrigation in Wenzhou and Ningbo, Zhejiang. At the end of January, an estimated 475,333 hectares of arable land were affected. Water levels dropped so low at the Jiaokou Reservoir in Ningbo that a 40-year old village site was revealed.

In Taiwan, drought conditions have forced the largest semi-conductor maker in the world to truck in water for production of chips destined for the global auto industry and for Apple. Water levels in several regional reservoirs are below 20 percent and recent rainfall has not improved the situation.

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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