East Asia: Water surpluses to persist on Yellow River & lower Yangtze River (August 23, 2016)

The Big Picture
The water anomaly index for the 12-month period ending April 2017 (below) shows widespread moderate (5 to 10 years) to exceptional (greater than 40 years) water surpluses along the Yellow River and along the middle and lower reaches of the Yangtze River in China. Deficits are forecast for Shandong, eastern Yunnan and western Guangxi, South Korea, and Honshu, Japan. Both deficits and surpluses are forecast in western regions of China including the Tibetan Plateau.

Impacts
Global reinsurance company Aon Benfield estimates that recent flooding in China resulted in economic losses of US$33 billion, with at least US$28 billion in the Yangtze River Basin. Less than 2 percent of the total was paid out in insurance claims, cites China Insurance Regulatory Commission, with most of the claims from lost agriculture.

Drought in northern China's Inner Mongolia Autonomous Region has damaged almost 70,000 square kilometers of pastures, caused a shortage of drinking water for nearly 10,000 people and 3.5 million head of livestock, and cost 46 million yuan (US $7 million). The temperature reached 111F (44.1C) in one city, Hulun Buir, the highest ever recorded in its history.

Water levels in Tokyo, Japan's dams and reservoirs have fallen, with little replenishment from a recent typhoon. On August 12, the Yagisawa dam -the largest of eight dams in the Tonegawa system - had declined to 43%.

Forecast Breakdown
The 3-month maps (below) show the evolving conditions in more detail. Evident in the August through October map, water surpluses are expected to persist along the Yellow River and along lower reaches of the Yangtze River. Deficits will continue to emerge in Shandong, eastern Yunnan, and western Guangxi, but will diminish in extent on Honshu, Japan. Beginning in August, deficits will begin to emerge in North Korea and will persist on much of the Korean Peninsula through April, with greatest extent from September through January.

While Mongolia has been dotted with both deficit and surpluses for the last three months - a pattern that will basically continue through July – the areas of surplus will begin to disappear, giving way to widespread, mostly moderate deficits through April.

Looking at the November through January map, surpluses in southeast China will continue to diminish and moderate deficits will emerge. Moderate deficits will continue to emerge in Northeast China. In November deficits may re-emerge in Honshu, Japan and may spread in December in Honshu, and to Shikoku and Kyushu.

The map depicting the forecast for the end of the 12-month period (February through April) shows considerable contrast to the beginning months of the period (May through July), with a predominance of yellow and orange hues indicating water deficits.

(It should be noted that forecast skill declines with longer lead times.)