Southeast Asia & the Pacific: Intense water deficits forecast for Cambodia & Java

Southeast Asia & the Pacific: Intense water deficits forecast for Cambodia & Java

18 November 2019

THE BIG PICTURE
The 12-month forecast through July 2020 indicates exceptional water deficits around Tonlé Sap in western Cambodia and deficits of varying intensity throughout most of Thailand.

Deficits are also forecast for small pockets of Malaysia and more extensive regions of Indonesia and Papua New Guinea. Deficits will reach extreme to exceptional intensity in Java, southern Sulawesi, Lombok Island, Timor-Leste, and around the western shore of the Gulf of Papua. Moderate to severe deficits are forecast for Sumatra, western and southern Borneo, and along Papua New Guinea’s northern and southern coasts.

Widespread surpluses are forecast for Myanmar, Laos, Vietnam, and eastern Cambodia. Surpluses will be exceptional in western Myanmar, southwestern Laos, and Vietnam’s North Central Coast.

Intense surpluses are also forecast in central Philippines around Cebu, and surpluses of lesser intensity are expected in northern Luzon.

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

The forecast through January 2020 indicates that surpluses will persist in Laos, Vietnam, and eastern Cambodia but will generally downgrade in intensity. In Myanmar, surplus anomalies will remain fairly widespread, and will be exceptional in the west. Surpluses around Cebu in central Philippines will moderate. Intense deficits will persist in northwestern Cambodia, and deficits of lesser intensity in much of Thailand.

Deficits are expected to nearly disappear from Malaysia and northern Sumatra but will intensify in southern Sumatra, becoming severe to extreme. Moderate surpluses are forecast for a pocket in northernmost Sumatra. Deficits ranging from severe to exceptional are forecast for Java, Sulawesi’s extremities, and along Papua New Guinea’s north-central coast and the western shore of the Gulf of Papua. Severe deficits are expected in southern Borneo and generally milder deficits scattered throughout the smaller islands in the region.

From February through April 2020, moderate surpluses will persist in Laos, Vietnam, and eastern Cambodia, with exceptional anomalies in southwestern Laos and Vietnam’s North Central Coast. Surpluses will shrink in southern Myanmar, with conditions of both deficit and surplus (pink/purple) forecast as transition occur, but intense surpluses will persist in the west. Extreme deficits will persist west and north of Tonlé Sap in western Cambodia. Some small pockets of intense deficit will persist in a few locations in Thailand including the far north and along the coast southeast of Bangkok, and surpluses will re-emerge in eastern Thailand. Deficits will shrink and downgrade in Indonesia, with some anomalies forecast for Sumatra, Java, and pockets of Sulawesi. In Papua New Guinea, deficits along the northern coast will nearly disappear but deficits along the southern coast will increase and intensify.

The forecast for the final months – May through July 2020 – indicates nearly normal conditions in most of the region with some surpluses in Vietnam’s South Central Coast and western Myanmar, and some moderate deficits in Sumatra and Papua New Guinea.

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

IMPACTS
Water levels in Thailand’s four main reservoirs have dropped so low due to drought that the federal government is asking farmers in 22 provinces not to grow off-season rice. Off-season planting usually begins in November during the dry season and is dependent on irrigation, but conditions have been so dry even prior to the dry season that water in the depleted reservoirs must now be reserved for household consumption. In the northeastern province of Khon Kaen the situtation is being described as the worst in 50 years. Thailand is a major rice exporter, second only to India, but exports have fallen 28 percent year-on-year during the first nine months of 2019, a projected loss of 30 to 40 million baht (~USD $1 million).

In mid-summer the Mekong River fell to its lowest level in nearly 100 years affecting not only Thailand but Cambodia whose Tonlé Sap Lake provides much of the country’s protein through fishing. Normally, monsoon season swells the lake to five times its dry season size over several months. This year, however, drought and upstream damming significantly reduced the water level, reducing fish stock.

Tropical storms in late October and mid-November brought flooding and landslides to central Vietnam. Authorities evacuated 20,000 people from the path of Tropical Storm Matmo which damaged over 2,000 homes and 35 school buildings, left roads blocked, and rivers swollen. Two people died during Tropical Cyclone Nakri and 70,000 were evacuated.

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.

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