East Asia: Water surpluses from Jiangsu to Guangdong

19 December 2016

The Big Picture
The 12-month forecast map for East Asia ending August 2017 (below) shows a complex patchwork of water anomalies throughout the region. Water surpluses are forecast for Shanghai, Jiangsu, Anhui, Fujian, and Hainan Provinces, China; and southern Taiwan. Deficits are forecast for central and northeast regions of the Korean Peninsula; northern Honshu, Japan; China’s Liaodong Peninsula on the Bohai Sea; eastern Sichuan into Shaanxi; and eastern Yunnan.

Impacts
Flooding in China was one of the most expensive natural disasters of 2016, according to reinsurer Munich Re, along with earthquakes in Japan. Yet only 2 percent of losses from those events were insured. China’s summer floods caused $20 billion in damage, only $300 million of which was insured.

Poyang Lake – China’s largest freshwater lake and home to several endangered species – has been shrinking over the last decade. And though the lake’s size has always fluctuated, reaching 1,700 square miles at times, in November drought dried parts of the lake completely allowing cattle to graze near stranded ships.

Mongolian officials have declared a high “dzud” risk in 13 northern and eastern provinces – a weather phenomenon unique to Mongolia in which massive livestock die-off occurs due to starvation and cold. Dry summer conditions followed by heavy snowstorms with ice crust make it difficult for livestock to reach grass. Around 153,000 herders in 16,000 households are at risk of losing their animals – seven million livestock – and their livelihoods.

Forecast Breakdown
The 3-month maps (below) show the evolving conditions in more detail.

As seen in the December through February map above, a large block of water surplus is forecast to persist along China’s coast from Jiangsu south through Guangdong and in Hainan, including exceptional surpluses in Shanghai, Jiangsu, Anhui, Fujian, Guangdong, and southern Taiwan. Small pockets of exceptional surpluses are forecast in northern Henan and northeastern Shaanxi.

A vast expanse of exceptional deficit (dark red) intermingled with conditions of both deficit and surplus (purple) is expected across northern China from central Inner Mongolia west to Central Asia and bleeding north into Mongolia.

Moderate to extreme deficits will continue to emerge on the Liaodong Peninsula in Northeast China December through February reaching into North Korea, and deficits of similar severity will persist in northeast North Korea. Exceptional deficits remain in the forecast near Incheon, South Korea. Deficits will continue to emerge in eastern Sichuan Province though the extent of exceptional deficits will shrink. Deficits will also emerge nearby in southern Shaanxi and eastern Gansu Provinces. Though deficits will persist in Yunnan the extent of exceptional deficits will shrink.

The distribution of water anomalies in East Asia remains complex in the March through May forecast, but the severity and extent of anomalies is expected to diminish. Most noticeable on the map is the expanse of white in Southeast China, indicating a transition to normal water conditions, and the diminished severity of surpluses to the north in Shanghai, Jiangsu, and Anhui. Surpluses will continue to emerge in northeast Shaanxi, western Shanxi, and Hebei; and small pockets of exceptional surplus are forecast to emerge in Northeast China near Changchun and Yanbian, Jilin.

Exceptional deficits will continue to emerge in eastern Yunnan, and the extent of moderate deficits in eastern Guizhou will increase. Severe deficits are forecast to emerge along the Han River in southern Shaanxi. Deficits will persist near Incheon, South Korea, and will emerge in northern Honshu, Japan. Moderate to severe deficits are forecast for Inner Mongolia, China and southern Mongolia.

The forecast for June through August is similar to the prior three months.

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