Southeast Asia & the Pacific: Water surpluses will shrink

Southeast Asia & the Pacific: Water surpluses will shrink

28 June 2021

THE BIG PICTURE
The 12-month forecast through February 2022 indicates intense water surpluses in the Lesser Sunda Islands, particularly Timor. Surpluses will also be intense in Banda Aceh in Sumatra’s northern tip and in Palawan, Philippines. Moderate to extreme surpluses are forecast for Sulawesi’s northern arm and for Samar in eastern Philippines.

Surpluses will be generally moderate in eastern Java, northern Borneo, the Maluku Islands, the Bird’s Head Peninsula (Doberai Peninsula) in New Guinea, central Papua New Guinea, and a few other regions of the island. Moderate surpluses are also expected throughout Mindanao, Philippines.

Moderate to severe deficits are forecast around the metropolis of Medan in Sumatra’s northern half.

In Southeast Asia, moderate surpluses are forecast in a pocket of Peninsular Malaysia, coastal Cambodia, and the Central Highlands of Vietnam. Some moderate deficits are forecast near the city of Chiang Mai in northwestern Thailand. Myanmar can expect surpluses in the center of the nation and in the Lower Irrawaddy region, and moderate deficits and transitional conditions west of Mandalay.

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

The forecast through August indicates that surpluses will shrink and downgrade considerably. In the Pacific region, extreme to exceptional anomalies will persist in the Lesser Sunda Islands along with transitional conditions (pink/purple). Surpluses will be extreme in Borneo’s northeastern tip and in Palawan, Philippines, and severe in Samar, Philippines. Surpluses of generally lesser intensity are forecast in several other regions including New Guinea’s northern coast and other pockets on the island, Sulawesi’s northern arm, southwest Sumatra and the island’s northern tip, and Mindanao, Philippines. Deficits will intensify around Medan in northern Sumatra, becoming extreme to exceptional. Severe deficits will persist along the western shore of the Gulf of Papua and will emerge in a pocket of northern Luzon, Philippines.

In Southeast Asia, pockets of surplus are expected in Peninsular Malaysia near Kuala Lumpur; Peninsular Thailand and Myanmar; coastal Cambodia and spanning Cambodia’s central border with Thailand; northeastern Laos; and a few areas in Vietnam. Moderate deficits are forecast for northwestern Thailand reaching into Myanmar, and mixed conditions in central Myanmar.

From September through November, water conditions in Southeast Asia will be relatively normal though moderate deficits will linger northwest of Mandalay and moderate surpluses are forecast in the Central Highlands of Vietnam. Intense surpluses are expected in the Lesser Sunda Islands and generally moderate surpluses in Palawan, southern Mindanao, northern Borneo, Sulawesi’s northern arm and southeastern leg, and scattered regions in New Guinea. Deficits will shrink near the Gulf of Papua, but a small, exceptional pocket is forecast south of the Fly River Delta.

The forecast for the final months – December 2021 through February 2022 – indicates the emergence of moderate to exceptional deficits in Myanmar and moderate deficits in Sumatra and Peninsular Malaysia. Moderate surpluses are forecast in Vietnam’s Central Highlands, the central Philippines, the small islands of eastern Indonesia, and pockets in New Guinea.

Please note that WSIM forecast skill declines with longer lead times.

IMPACTS
A tropical storm hit the central and southern Philippines in early June, triggering flooding and landslides that left three people dead and thousands displaced. The coast guard suspended sea travel in the region due to treacherous conditions, stranding cargo and 3,000 travelers in local seaports.

By late June, rainfall in the Mekong region was 60 percent greater than during the same period in 2019 and 2020, according to the Mekong River Commission. The increased precipitation brought flooding to Phnom Penh, Cambodia’s largest city, turning roads into rivers.

After several years of drought, Thailand’s rice production is expected to rebound. Sugar cane output, however, has not recovered, leaving millers to compete for cane by offering higher prices in order to keep mills operating.

In Cambodia, successive droughts have reduced hydroelectricity production, leading the government to invest in rapid construction of thermal plants.

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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