East Asia: Water deficits in Yangtze, SE China, Taiwan

19 October 2022

THE BIG PICTURE
The 12-month forecast for East Asia through June 2023 indicates widespread water deficits in the Yangtze Watershed, Southeast China, and Taiwan, with exceptional deficits near the Danjiangkou Reservoir in Central China; at the intersection of Chongqing and Hunan; and in Jiangxi, Fujian, and Taiwan. In the south, surpluses are forecast from southern Guangdong through Hainan.

In the Yellow River Basin (Huang He) and much of the North China Plain surpluses will be widespread. Anomalies will be intense in Shandong, the Lower Yangtze region and North China Plain, and Ordos Loop. Northeast China, too, can expect surpluses in a vast area from Liaoning to the Chinese border. Intense deficits are forecast in central Inner Mongolia and a vast belt from western Inner Mongolia into Xinjiang Uygur. Surpluses will trace the Tongtian River in Qinghai. In Tibet (Xizang), surpluses are forecast for many areas in the west and exceptional surpluses along parts of the Yarlung (Brahmaputra) River. Central Tibet can expect moderate deficits.

Intense surpluses are forecast in North Korea and a pocket south of Seoul, but deficits are predicted for the southern half of South Korea. Japan can expect moderate deficits in southern Honshu and Shikoku, and surpluses on Honshu’s central east coast and from the island’s northern tip into coastal Hokkaido. In Mongolia, deficits will be widespread in the south and west, exceptional in many areas. Transitional conditions are forecast in the east and surpluses in the Hentiyn Mountains in the northeast.

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

The forecast through December indicates widespread deficits in the Yangtze Watershed, Southeast China, and Taiwan. Anomalies will be exceptional in Guizhou and southern Taiwan. Deficits in northeastern Yunnan will downgrade but will be severe. Deficits and transitional conditions (pink/purple) are forecast in the Pearl River Watershed, and surpluses will continue in southern Guangdong and southern Hainan. Intense surpluses will persist in the Yellow River Watershed and North China Plain, and along the Bohai Sea into Northeast China where anomalies will downgrade somewhat. Deficits in northern Hebei will become exceptional. Deficits in northern Gansu will modify and intense deficits in Xinjiang Uygur will shrink somewhat. Mixed conditions are forecast in Tibet including deficits in central Tibet and intense surpluses in the central west and along the Upper Yarlung Tsangpo (Brahmaputra) River. Moderate surpluses are forecast in eastern Tibet and central Yunnan.

In North Korea, widespread surpluses will persist, severe overall. Surpluses in a pocket near Seoul will moderate, and generally moderate deficits are expected in southern South Korea. Japan can expect near-normal conditions with some small pockets of deficit from southeastern Honshu into Shikoku, and moderate surpluses in Honshu’s northern tip. In Mongolia, deficits and transitional conditions are expected in the west in the Hangayn Mountains and central Altay Mountains. Mixed conditions are forecast in the nation’s east including surpluses in the Hentiyn Mountains.

From January to March 2023, widespread deficits will continue in the Yangtze Watershed, but will downgrade somewhat, and deficits will shrink considerably in Southeast China. Intense anomalies will persist, however, from southwestern Hubei into Guizhou and in Taiwan. Moderate surpluses will continue in the Leizhou Peninsula, Hainan, and central Yunnan. Surpluses will persist in much of the Yellow River Watershed, and in Shandong, the northern region of the North China Plain, Northeast China, and North Korea. Intense deficits will persist in northern Hebei, and moderate deficits will emerge to the north in Inner Mongolia. Deficits from western Inner Mongolia into Xinjiang will moderate. Deficits will continue in South Korea and will increase in southern and eastern Japan, with extreme deficits in Kyushu. Surpluses will emerge in western Hokkaido.

The forecast for the final three months – April through June 2023 – indicates that deficits will shrink considerably in the Yangtze Basin and Southeast and emerge in northern Japan as they retreat from the south. Surpluses will persist in Shandong and the Yellow River Basin, shrink in Northeast China, and retreat from Korea.

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

IMPACTS
As drought and high temperatures in China persist into the fall, over 900 million people and 2.2 million hectares of agricultural land have been affected. Drought in the Yangtze River Basin, where about half of the nation’s grain is produced, is threatening the autumn harvest.

Water levels in Sichuan’s reservoirs are at just 50 percent of normal, resulting in hydropower shortages that are likely to last into the winter as the province looks elsewhere for energy supplies.

In early October, Poyang Lake in Jiangxi Province, China’s largest lake, dropped to its lowest level on record, 6.68 meters, but by mid-month had risen to 8 meters. By comparison, in June, the lake level stood at 19.43 meters.

The drought sparked panic buying in Shanghai as residents crowded markets in search of bottled water, ignoring assurances from authorities that water supplies were secure. Shanghai sits at the mouth of the Yangtze River, where dry conditions invite saltwater intrusion in the river’s estuary and the region’s reservoirs.

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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