East Asia: Widespread, exceptional water surpluses continue to emerge on Yangtze

29 November 2017

THE BIG PICTURE
The 12-month forecast map for East Asia (below) indicates widespread surpluses reaching exceptional intensity in the Han River (Hanjiang) watershed, an eastern tributary of the Yangtze; the Middle and Upper Yellow River; Qinghai Lake; western Tibet; and north of the Bohai Sea in far eastern Inner Mongolia.

Surpluses of varying severity are forecast for the Lower Yangtze, Qinghai, the western Pearl River (Zhujiang) watershed, and around the Gulf of Tonkin.

Extreme to exceptional water deficit conditions are forecast for southern Mongolia; Inner Mongolia, China; and northern Gansu. Deficits reaching exceptional severity are forecast for a large block of southeastern China including Zhejiang, Fujian, Taiwan, and northern Guangdong.

Primarily moderate deficits are forecast in South Korea but may be more intense near Seoul.

IMPACTS
The Danjiangkou reservoir on the Hanjiang River, a tributary of the Yangtze in China's Hubei province, reached record levels at the end of October, insuring water supply to the middle route of the north-south water diversion project serving Beijing and Tianjin.

Heavy downpours forced the evacuation of 11,000 people in South China's Hainan province.

In the 13th annual joint collaboration, Chinese and US military forces met in Oregon to practice international relief missions whose focus this year was on flood disasters. Participants included representatives of the US Army and China's People’s Liberation Army, as well as the US Center for Excellence in Disaster Management and Humanitarian Assistance, US Army Corps of Engineers, National Oceanic and Atmospheric Administration, US Geological Survey, and China's State Drought Control and Flood Relief Headquarters.

By April of next year, two pilot districts in the city of Wuhan, China are to be transformed into the first of 30 planned “sponge cities,” designed to help mitigate flood impacts through the use of features like permeable concrete, rooftop green spaces, and wetland water storage areas. Heavy rain events have strained the nation's drainage systems and "sponge cities" could help China achieve its 2020 goal of having 80 percent of its cities absorb 70 percent of rainwater. The initiative is not without problems, including funding in the midst of a growing municipal debt crisis.

The head of the UN World Food Programme (WFP) plans to visit North Korea, which is in the middle of a drought and reportedly facing famine. The WFP is struggling to raise the $52 million it seeks in aid to North Korea, and cites international mistrust of North Korean authorities to properly disseminate funds.

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

The near-term forecast through January indicates that surpluses in the Lower Yangtze reaches are expected to become widespread and exceptional in Jiangsu, Anhui, Henan, Hubei, and Chongqing. Exceptional surpluses are forecast for the Middle and Upper Yellow River, will emerge in greater extent in northern Sichuan, and will continue to emerge in Qinghai and western Tibet. Surpluses in the western Pearl River watershed will downgrade slightly becoming primarily moderate, but will remain exceptional near the Gulf of Tonkin. Moderate surpluses will emerge in Hainan, China, and will continue to emerge in southern Honshu, Japan.

Severe to exceptional deficits will continue to emerge in Mongolia and Inner Mongolia during this period, and deficits in South Korea are forecast to increase in both extent and intensity. Deficits in southeastern China will diminish and moderate, except in Fujian where severe deficits will persist. Both deficits and surpluses are expected in Xinjiang with primarily deficits in the east.

From February through April exceptional deficits will continue to emerge across much of Mongolia and into China, creating a massive stretch from Xinjiang through southern Mongolia and Inner Mongolia. Deficits reaching exceptional severity will emerge around the Bohai Sea in Shandong, Hebei, Tianjin, and into Beijing. Deficits are expected to retreat in South Korea but will remain intense near Seoul. Deficits in southeastern China will continue to moderate. Moderate deficits will begin to emerge in Japan.

The distribution of water surplus conditions will remain much the same during this period as in the prior three months’ forecast but the extent of exceptional surpluses will diminish in the Lower Yangtze, and surpluses along the Yellow River in Inner Mongolia will begin to transition to deficits.

The forecast for the final months, May through July, indicates diminished severity of water conditions overall.

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

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.