East Asia: Water surplus will persist in the Yangtze Basin, NE China, & DPRK

East Asia: Water surplus will persist in the Yangtze Basin, NE China, and DPRK

22 December 2020

THE BIG PICTURE
The 12-month forecast for East Asia through August 2021 indicates widespread, intense surpluses in the Yellow (Huang He) and Yangtze River Basins. Conditions in the Yellow River Basin will include exceptional anomalies in southern Gansu and northern Shaanxi.

In the Yangtze region, moderate to severe surpluses are expected along the river’s lower path, but exceptional surpluses will dominate the middle path of and many pockets in the river’s upper basin, dipping south into the Pearl River Basin between the Hongshui and Rong tributaries. Between the Yellow and the Yangtze, moderate to severe surpluses are expected.

Northeast China can expect widespread extreme to exceptional surpluses, and surpluses are expected on the Liaodong Peninsula in the northern Bohai Sea reaching well into Liaoning Province.

Nearly normal conditions are forecast for much of southeastern China, but moderate deficits are expected in central Guangdong and more intense deficits in coastal Fujian and Taiwan. Southern Guangdong can expect intense surpluses as can nearby Hainan.

In Tibet (Xizang), intense deficits are forecast in the west, surpluses or transitional conditions in the center, and deficits skirting its southern border. In China’s vast northwest, surpluses are expected in northern and western Xinjiang Province, intense deficits and transitional conditions in the Taklimakan Desert, and moderate to severe deficits in the northeastern region of the province leading to exceptional deficits in northern Gansu and northern Qinghai.

In Mongolia, moderate deficits are forecast in the south-central region, reaching greater intensity in the center of the nation. Surpluses are forecast in the east and far north. On the Korean Peninsula, exceptional surpluses are expected in North Korea and much milder surpluses in South Korea.

In Japan, deficits are predicted for Hokkaido and much of central Honshu.

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

The forecast through February 2021 indicates that surpluses will remain widespread in the Yellow and Yangtze River Watersheds, though the extent south of the Yangtze will shrink. Exceptional surpluses are forecast between the Hongshui and Rong Rivers, tributaries of the Pearl River, and in Hainan, with surpluses of varying intensity between. In southeastern China, surpluses will shrink and moderate and deficits will emerge along the coast. Deficits will persist in Taiwan, downgrading slightly. Deficits in Yunnan will increase somewhat as surpluses retreat. Deficits will also increase along the Yarlung (Brahmaputra) River in Tibet. On the Korean Peninsula, exceptional surpluses will persist in the north, while the south transitions to mild deficit. In Japan, surpluses will retreat from Shikoku, and deficits will intensify in eastern Honshu.

From March through May 2021, surpluses will persist in the Yellow River Basin though shrinking and downgrading. Surpluses will retreat from much of the Yangtze Basin and the Pearl River region to the south and will moderate in Hainan and the Leizhou Peninsula nearby. In China’s Northeast, surpluses will shrink and downgrade, but a vast extent will persist, including exceptional surpluses. Deficits in Taiwan will shrink and moderate and deficits on the mainland through coastal Zhejiang and Fujian will persist, with a slight uptick in intensity in Fujian, becoming severe. Western Inner Mongolia will transition from surplus to deficit; deficits in northeastern Xinjiang will become severe; and deficits in central Mongolia will increase. On the Korean Peninsula, surpluses in the north will shrink and moderate considerably and mild deficits are forecast in the south. Deficits in Honshu, Japan, will increase as intense anomalies emerge in the northern half of the island.

The forecast for the final three months – June through August 2021 – indicates normal conditions overall, with surpluses in the Northeast, the Upper Reaches of the Yellow River, central Tibet, and Yunnan. Deficits are forecast for Xinjiang, Western Inner Mongolia, and southeastern Tibet.

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

IMPACTS
After China’s devastating summer of floods, the Ministry of Water Resources has announced a 100 billion yuan (US $15.2 billion) investment in reinforcing the country’s 98,000 reservoirs.

Reservoirs in central and southern Taiwan remained at extremely low levels in mid-December, with many below levels experienced in the 2015 drought. Reservoirs in trouble include Taichung Deji Reservoir which is at 35.95 percent; Wushe Reservoir at 13.42 percent; and Zengwen Reservoir at 22.18 percent.

Over the past few decades, heatwaves and droughts on the Mongolian Plateau have increased. Researchers report that the combination of soil moisture deficits and higher temperatures is accelerating in the region, indicating that the Plateau may be approaching a tipping point into permanent drought.

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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Many analyses reported in ISciences-authored blog posts are based on data generated by the ISciences Water Security Indicator Model (WSIM). Other sources, if used, are referenced in footnotes accompanying individual posts. WSIM is a validated capability that produces monthly reports on current and forecast global freshwater surpluses and deficits with lead times of 1-9 months at 0.25°x0.25° resolution. This capability has been in continuous operation since April 2011 and has proven to provide reliable forecasts of emerging water security concerns in that time-frame. WSIM has the ability to assess the impacts of water anomalies on people, agriculture, and electricity generation. Detailed data, customized visualizations, and reports are available for purchase.

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