East Asia: Water surpluses forecast to persist in Shanghai, Jiangsu; deficits near Seoul

November 23, 2016

The Big Picture
The 12-month forecast map for East Asia ending July 2017 (below) shows a complex patchwork of water anomalies throughout the region. Water surpluses are forecast for Hebei, Shanxi, Shanghai, Jiangsu, Anhui, Fujian, and Hainan Provinces, China; southern Taiwan; and eastern Hokkaido, Japan. Deficits are forecast for central and northeast regions of the Korean Peninsula; China’s Liaodong Peninsula on the Bohai Sea; the Shandong Peninsula on the Yellow Sea; eastern Sichuan; and eastern Yunnan. Both deficits and surpluses are forecast in Mongolia and northwestern regions of China.

Impacts
Water levels along the Huaihe River, China's third longest waterway, reached record levels after 177 millimeters (7 inches) of rain fell in October, 289 percent more than in prior years, prompting flood concerns. The 1,000-km (621 miles) long river originates in Henan Province and traverses Hubei, Anhui, Shandong and Jiangsu provinces. The Huiahe water conservation commission has directed local authorities to monitor the situation and be prepared to use hydropower stations and irrigation facilities to control potential flooding.

In part due to what one weather wonk has referred to as the "sneaky drought" in northeast China, this season's corn harvest is expected to fall by 7.3 percent, the largest drop since 2000. Production dropped 17 percent in Heilongjiang, and more than 10 percent in Hebei, Inner Mongolia, and Henan provinces.

China's deserts appear to be expanding and drought across northern China is getting worse. According to a recent estimate, 54,400 square kilometers more desert exists now than in 1975. As China's deserts begin to merge the government has instituted relocation programs for "ecological migrants," many of whom are ethnic herders.

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

Deficits are forecast to diminish in severity November through January in Northeast China, the Korean Peninsula, and the Shandong Peninsula. Deficits will continue to emerge on Liaodong Peninsula. The extent of exceptional deficits in eastern Sichuan Province will diminish somewhat; moderate deficits are expected to emerge to the south in Guizhou and northeast Guangxi; and exceptional deficits will persist in eastern Yunnan. Pockets of deficits are forecast to emerge in Tokyo, Saitama, Ibaraki, and Fukushima Prefectures, Japan.

Exceptional surpluses are forecast to persist in Shanghai, Jiangsu, Anhui, Fujian, and southern Taiwan. Surpluses will persist in Hebei, Shanxi, and Hainan. Both deficits and surpluses are forecast for a vast area from central Inner Mongolia to the western Tibetan Plateau.

Though the distribution of water anomalies in East Asia remains complex in the February through April forecast, in general the severity of anomalies is expected to diminish. Most noticeable is the absence of widespread and exceptional water surpluses in Fujian, and the diminished severity of surpluses to the north in Shanghai, Jiangsu, and Anhui. Hainan and southern Taiwan are expected to transition from surplus to both deficits and surplus (shown in purple). Surpluses will persist in Shanxi but surpluses in nearby Hebei will transition to both deficits and surpluses. Deficits will persist, though with somewhat reduced severity in Liaodong Peninsula, eastern Sichuan, Guizhou, northeast Guangxi, and eastern Yunnan. Deficits will persist near Seoul, South Korea, and moderate deficits will emerge in much of North Korea. Deficits will also emerge in eastern and northern Honshu, Japan.

After April, moderate to severe deficits are forecast for central Mongolia and surpluses are forecast for the Tibetan Plateau.

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