Southeast Asia & the Pacific: Retreat of water surpluses forecast

23 August 2017

The Big Picture
The 12-month map (below) indicates exceptional water deficits in a large block of western Cambodia and a small pocket in northern Sumatra near Medan. Deficits of lesser severity are forecast for Malaysia and central Papua New Guinea.

Exceptional surpluses are forecast for western Myanmar and parts of the northern stretch of the Salween River; north-central and southwestern Laos; central and eastern Thailand; and southeastern Sulawesi. Surpluses of varying severity are forecast for: eastern Cambodia into Vietnam; northern Vietnam; Laos; southern Philippines; and western Papua, Indonesia.

Impacts
Recent flooding in north and northeastern Thailand has killed 29 people, affected over 721 million, and caused damages estimated at US$300 million. The federal government has approved 1.6 billion baht (US$48 million) in relief for farmers in the region, and insurance compensation is projected at around 1 billion baht (US$30 million), according to Thai General Insurance Associated.

In northern Vietnam 26 people have died in flooding that caused damages estimated at more than 940 billion dong (US$41 million) to roads, farmland, homes, and water infrastructure. Vietnam's Ministry of Rural Development and the Japan International Co-operation Agency recently signed a grant agreement worth US$18.2 million to improve Vietnam's flood management capability through additional hydrological observation facilities and water-related disaster management systems in the Hương River Basin in central Vietnam.

The normally measured voices typical of scientific conferences were replaced by more somber inflections as water and food security experts gathered recently to discuss the fate of Cambodia's Tonlé Sap Lake, whose fisheries have traditionally provided 75 percent of the country's protein. Experts at the International Symposium on Flood Pulse Ecosystems described pressures on the vast wetland from climate change, over-fishing, upstream dams, and drought that, said some, give it no more than a three-year window of time before collapse.

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

The August through October map indicates a significant retreat of exceptional water surplus in the region. However, exceptional surpluses are forecast for western Myanmar; eastern Thailand into southern Laos; and, southeastern Sulawesi and Sumbawa and Flores Islands in Indonesia. Moderate to extreme surpluses are forecast for: the Salween River and extreme south of Myanmar; much of Laos; central and northern Vietnam; Papua, Indonesia; and pockets in Papua New Guinea. Exceptional deficits are forecast for a large block of western Cambodia. Deficits are also forecast for: the Mekong Delta; southern Thailand trailing south into Malaysia; Singapore; Malaysian Borneo; southern Sumatra; and pockets in central Papua New Guinea.

The map for November 2017 through January 2018 shows a forecast of near-normal conditions for Vietnam, the Philippines, much of Indonesia, and Papua New Guinea. Deficits in western Cambodia are forecast to moderate. Both deficit and surplus conditions are forecast for western Myanmar and northern Laos as deficits emerge in areas of prior surplus.

After January deficits are expected to emerge throughout much of the region.

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

Note on Administrative Boundaries
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