Southeast Asia & the Pacific: Intense water surpluses to persist in Vietnam

19 December 2017

THE BIG PICTURE

The 12-month map (above) indicates surpluses of varying intensity in western and eastern Myanmar and the southern portion of the Irrawaddy River, Laos, eastern Cambodia, much of Vietnam, central Philippines and scattered pockets from northwestern Indonesian Borneo through western Papua. Surpluses are expected to be exceptional in western and eastern Myanmar, north-central Laos, and north-central Vietnam.

A large block of exceptional water deficit is forecast for western Cambodia. Moderate to extreme deficits are expected in central Malaysian Borneo and the Highlands of central Papua New Guinea.

IMPACTS
Vietnam is requesting support from the international community as it recovers from tropical storm Damrey and associated flooding events. Immediate support for food and housing relief, in addition to aid to restore local livelihoods over the longer term, is requested. Korea, Russia, New Zealand, and the United States have committed US$7.3 million in aid funds. Damrey hit central Vietnam in early November and resulted in 123 deaths or missing persons, 3,550 collapsed homes, and US$2.6 billion in damages.

The Malaysian state of Penang has paid out 33.4 Malaysian Ringgit (US$8.2 million), the highest amount ever paid by state flood aid to victims in Malaysian history, for damages resulting from the Penang floods in November. Some 52,000 families applied for relief, documenting damage to property or vehicles. The heavy rainstorm forced the evacuation of 6,000 residents and killed at least seven in the worst flood to hit the state.

Monsoon season continues to strain Malaysia this month. Flooding in the East Malaysian state of Sabah, just two months after the worst in the state's history, displaced over 1,800 residents in the Kota Belud district, and the Kadamaian River overflowed its banks in 26 villages.

Monsoon flooding has similarly ravaged several districts in Thailand over the last several weeks. Collapse of a Trang River embankment resulted in 70 million baht (US$2 million) in damages. Over 760,000 people were affected by flooding in six southern provinces including the Songkhla, in which prolonged flooding kept 21 of the 62 closed schools from re-opening after almost two weeks. The flooding is expected to decrease shrimp production by up to 56 percent.

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

Clearly indicated in the map progression is a gradual transition in the region from predominantly surplus conditions to deficit. Notably, western Cambodia - and to a lesser extent Papua New Guinea – stand in contrast with deficit conditions throughout much of the forecast period.

The December through February forecast shows a retreat of surplus conditions in Malaysia, Indonesia, Philippines, and Papua, leaving some scattered pockets of primarily moderate surplus. Conditions in Southeast Asia, however, are expected to be similar to the prior three months though deficits will begin to emerge. In Myanmar exceptional surpluses will persist in the west and east, but the center of the country will transition to deficit or both deficit and surplus as deficits emerge. Some areas of surplus in Thailand, Laos, and Vietnam will begin to transition as well. Severe deficits will persist in Papua New Guinea but with diminished extent.

From March through May surpluses will retreat almost entirely from Malaysia, Indonesia, and Papua and deficits will emerge. Emerging deficits may be extreme in Malaysian Borneo, western Indonesian Borneo, and southern Sumatra into western Java. In contrast, the extent of deficits in western Cambodia will diminish, though exceptional deficits will continue to emerge, and deficits in Papua New Guinea will moderate. Surpluses will diminish in both extent and severity in eastern Myanmar, Laos, Vietnam and central Philippines, but will remain severe in north-central Vietnam.

After May the forecast indicates primarily mild to moderate deficit conditions throughout the region with more intense deficits in the Lesser Sunda Islands.

(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.