East Asia: Water deficits will persist in SE China

31 March 2021

THE BIG PICTURE
The 12-month forecast for East Asia through November 2021 indicates widespread surpluses in Northeast China that will reach exceptional intensity in some areas including western Jilin. Surpluses of varying intensity are expected in the Yellow (Huang He) River Basin, moderate to extreme in the river’s lower reaches but reaching exceptional intensity in Shanxi, Shaanxi, and Gansu at the base of the Ordos Loop.

Water conditions are expected to be relatively normal in much of the Yangtze River Basin. Moderate to severe deficits are forecast for a vast region of Southeast China from just south of Shanghai to Hong Kong and reaching through southern Taiwan. Farther south, moderate surpluses are forecast in Guangdong’s Leizhou Peninsula and nearby in Hainan.

East_Asia_Composite_Adjusted_202012-202111_12mo_twitter.png

In the northwest, deficits will be extreme to exceptional from western Inner Mongolia well into the Tarim Basin in Xinjiang where transitional conditions are also forecast.

Tibet (Xizang) can expect a complicated patchwork of water conditions including mixed and transitional conditions in the west, surpluses in the center, and deficits in the east. Deficits will reach into northwestern Yunnan, but some isolated pockets of moderate surplus are forecast elsewhere in the province.

In Mongolia, moderate to exceptional deficits are forecast in the nation’s south-central region, and deficits of lesser intensity will trail from there through the Hangayn (Khangai) Mountains leading to intense deficits in the northwest around Lake Uvs. Surpluses are forecast along the northern border near Lake Khövsgöl and a pocket in the northeast in the Upper Kherlen River region.

On the Korean Peninsula, moderate surpluses are expected on the coast west of Pyongyang, and deficits in coastal South Korea on the Sea of Japan. In Japan, moderate deficits are forecast for Honshu’s southern half and into Shikoku and Kyushu.

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

The forecast through May 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 southern portion of the Yangtze Basin. In the south, surpluses in Guizhou, Guangdong’s Leizhou Peninsula, and Hainan will moderate.

Widespread deficits will persist in Southeast China, shrinking and moderating in Guangdong but intensifying in Fujian, Jiangxi, and Zhejiang. Deficits in Taiwan will moderate. In western Inner Mongolia, deficits will increase, and intense deficits and transitional conditions will persist in central Xinjiang. Mixed conditions are forecast in Tibet. In Yunnan, deficits will recede in the east while intense deficits emerge in the northwest.

East_Asia_Composite_Adjusted_202012-202111_3mo_twitter.png

From June through August, surpluses will shrink in Northeast China and the Yellow River Watershed and disappear from the Yangtze region. Deficits in the southeast and Taiwan will disappear as well. Deficits will persist in northwestern Yunnan, but moderate surpluses will emerge in central and eastern regions. Anomalies elsewhere in China and Mongolia will shrink as well, but deficits will persist in western Inner Mongolia and central Xinjiang. Normal water conditions are forecast for North Korea while the south transitions from moderate deficit to mild surplus. In Japan, some moderate deficits are expected on Honshu east of Kyoto.

The forecast for the final three months – September through November – indicates that surpluses will continue to shrink in Northeast China but remain intense in western Jilin. Moderate to severe surpluses will persist north of Beijing. Pockets of surplus will persist in the Yellow River Watershed and western Tibet. Deficits will recede in Yunnan, emerge in eastern Sichuan, and increase in southern Japan.

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

IMPACTS
As the drought in Taiwan continues, authorities will begin rationing water to one million households on 4 April and offering supplementary supplies via tankers. Two large industrial parks in Taichung can expect reductions of 15 percent, though semiconductor manufacturers in the area say that the water cuts will not affect production. Government responses to the drought include activating a desalination plant and cloud-seeding.

Around $12 million (80 million yuan) in federal drought-relief has been allocated to eastern and southern regions of China recently affected by precipitation shortfalls, including Yunnan, Zhejiang, Fujian, Jiangxi, Hunan, Guangdong, and Guangxi.

In mid-March, a massive sandstorm swept into northern China from Mongolia, blanketing Beijing and reaching from Xinjiang in the west to the Bohai Sea. The storm created hazardous air quality in the capital, grounded hundreds of flights across the nation, and forced many schools to close. A snowstorm in Mongolia helped stir up the dust, leaving nine people dead in that nation and knocking out power. Though the two countries have been cooperating for decades on desertification control, the March storm brought renewed interest in monitoring via remote sensing technologies.

The Chinese government is initiating efforts to crack down on illegal sand-mining in the Yangtze River and to invigorate regulations on condoned activities in an attempt to prevent drought and control flooding. The mining operations are a lucrative business, supplying sand to the country’s voracious construction business, but are cited as the cause of a 20m drop in the bed of Poyang Lake, a Yangtze River flood outlet.

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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