East Asia: Water deficits will shrink in SE China

22 April 2021

THE BIG PICTURE
The 12-month forecast for East Asia through December 2021 indicates widespread water surpluses in Northeast China’s Manchurian Plain with exceptional anomalies from northwest Jilin into Heilongjiang. Surpluses of varying intensity are expected in the Yellow (Huang He) River Watershed, primarily moderate to severe in the river’s lower reaches and reaching exceptional intensity in Shanxi, Shaanxi, and Gansu. Conditions will be relatively normal in the Yangtze Watershed.

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Deficits of varying intensity are forecast for Southeast China from south of Shanghai to Hong Kong and in southern Taiwan. Moderate surpluses are forecast in western Hainan. In northwestern China, deficits will be severe to exceptional from western Inner Mongolia well into the Tarim Basin in Xinjiang where transitional conditions are also forecast. Intense deficits are forecast for the Qaidam Basin in Qinghai. Mixed conditions are forecast for western Tibet (Xizang) and deficits in the east, which will reach into northwestern Yunnan. Some isolated pockets of moderate surplus are forecast elsewhere in Yunnan.

In Mongolia, moderate to exceptional deficits are forecast in the south-central region with deficits of lesser intensity trailing through the Hangayn (Khangai) Mountains leading to intense deficits in the lakes region of the northwest. Surpluses are forecast along the northern border near Lake Khövsgöl and in a pocket of the northeast in the Upper Kherlen River region. Nearly normal conditions are forecast for the Korean Peninsula with some moderate 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 June indicates that widespread surpluses of varying intensity will persist in the Yellow River Watershed but will shrink and downgrade in the Yangtze. Surpluses will persist in Northeast China, and while shrinking and downgrading overall will remain exceptional in northwestern Jilin and in Heilongjiang. Moderate surpluses are expected in the region west and north of Beijing.

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Deficits in Southeast China and Taiwan will shrink and downgrade, but anomalies will be extreme in Fujian and moderate to severe in Taiwan. In the south, surpluses will retreat from Guangdong’s Leizhou Peninsula and shrink and moderate in Hainan. Surpluses will emerge in eastern Yunnan, transitioning from former deficit. Intense deficits will persist in northwestern Yunnan and into Tibet; surpluses are forecast for western Tibet.

In northwest China, deficits of varying intensity are expected from western Inner Mongolia into the Taklimakan Desert in Xinjiang, but surpluses are forecast surrounding the region’s capital city of Ürümqi.

Intense deficits are forecast for southern Mongolia, and surpluses are expected in the northwest between Khyargas Lake and Khovsgol Lake and in the northeast in the Onon River region. Near-normal conditions are expected on the Korean Peninsula. In Japan, deficits are expected in Hokkaido and in a pocket of northern Honshu’s Yamagata Prefecture.

From July through September, anomalies will shrink and downgrade considerably overall. While many areas of Northeast China will return to normal, intense surpluses will persist in northwestern Jilin and nearby regions. Moderate surpluses will persist north of Beijing, and some pockets of surplus will linger in the Yellow River Watershed and Yunnan. Surpluses and transitional conditions are forecast for western Tibet. Deficits will persist in western Inner Mongolia and eastern and central Xinjiang and will emerge in eastern Sichuan.

The forecast for the final three months – October through December – indicates primarily mild to moderate deficits in the Korean Peninsula and the Liaodong nearby, southern Japan, central and Southeast China, and from western Inner Mongolia into Xinjiang. Surpluses are forecast in Northeast China and eastern Qinghai.

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

IMPACTS
Drought in South China has impacted drinking water supplies in Guangdong Province prompting water rationing. March runoff from the Hanjiang River watershed was down 76 percent and precipitation in the province since October is down 58 percent. In addition to rationing, officials have instituted cloud-seeding, laid new water pipes, and installed water pumps, and the provincial government has allocated 330 million yuan ($50.4 million) in drought relief funding.

Reservoirs in Taiwan remain low as of mid-April and diminished water supplies are threatening the island’s water-intensive semiconductor industry. Farmers are feeling the pinch too as water allocations are cut leaving croplands fallow, and residents are filling bathtubs as rationing spreads. Agricultural losses could total over 400 million new Taiwan dollars (USD $14 million). In early March, the Irrigation Agency held a rain worshipping ceremony.

The drought fits into a longer climate change pattern according to one climatologist who notes that the number of rainy days has decreased in some parts of the island by 50 days since the 1960s.

In Japan, the cherry blossoms peaked on 26 March, the earliest date in over a thousand years, as warmer temperatures coaxed the buds open. Long-term cherry blossom records establish a pattern of earlier spring flowering, particularly over the last 150 years.

A flash flood in Hutubi county in China’s Xinjiang Uyghur Autonomous Region in the northwest trapped 21 workers in a coal mine on 11 April. Successful rescue operations unfolded over the next week but the shutdown disrupted the fuel supply to power plants feeding the voracious Bitcoin “mining” industry, leading to a 14 percent drop in the cryptocurrency’s price.

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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