Southeast Asia & the Pacific: Water surpluses in Laos, Vietnam, & Malay Peninsula

31 January 2017

The Big Picture
As seen in the 12-month map (below), exceptional water deficits are forecast for Cambodia and moderate to extreme deficits are forecast for Borneo and Papua New Guinea. Surpluses are forecast for western Myanmar, Laos, and Vietnam, with greatest extent and severity in Vietnam.

Impacts
Flooding in southern Thailand claimed the lives of 91 people and affected 1.8 million across 12 provinces, damaging 4,314 roads, 348 bridges, and 2,336 schools.

The Rubber Authority of Thailand expects the country's rubber output to fall by 7.6 percent this year due to flood damage. Thailand produces nearly 40 percent of the world's rubber, two-thirds of which is grown in the country's southern province plantations, where in early January rubber growers boated past trees poking through 2 meters (6.5 feet) of water.

The flooding destroyed livestock farms as well and 897,000 farm animals were rescued and relocated.

After floodwaters washed out a bridge in Thailand's main north-south highway, traffic was backed up for 125 miles (200km).

Mid-December flooding in the south-central Vietnam beach resort city of Nha Trang caused VND100 billion (US$4.4 million) in damages, killing two people, washing rocks down a mountainside onto rail tracks, and causing a mudslide that blocked a section of the National Highway 1 in Khanh Hoa.

Forecast Breakdown
The 3-month maps (below) show the evolving conditions in more detail. Noting the predominance of blue/green through March and yellow/orange in the months that follow, the map progression clearly indicates a transition to water deficits in the latter six months of the forecast.

For the next three months – January through March – exceptional surpluses are forecast for Laos, central Vietnam, and eastern Gorontalo (Sulawesi, Indonesia). Surpluses are also expected in the Malay Peninsula, particularly southern Thailand, and eastern Borneo and parts of the Philippines. The extent of water deficits in Cambodia will shrink slightly during this period but exceptional deficits will persist near Tonlé Sap Lake. Deficits of lesser severity are forecast in northern Myanmar, central Thailand, and Gulf and Madang Provinces, Papua New Guinea.

Both deficits and surpluses are expected in Vietnam from April through June. Near-normal water conditions are forecast for much of the rest of Southeast Asia, though a small pocket of exceptional deficit is forecast in Cambodia northeast of Tonlé Sap Lake.

A transition to water deficit in parts of Malaysia, Indonesia, and Papua New Guinea can be seen in the April through June map. Moderate to extreme deficits are forecast to emerge in western Borneo and on the island of New Guinea, particularly in Papua New Guinea, along with deficits of lesser severity north of Kuala Lumpur on the Malaysian Peninsula and in southern Sumatra.

The forecast for the latter three months – July through September – indicates that moderate to severe deficits will continue to emerge in Malaysia, Indonesia, and Papua New Guinea.

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