Southeast Asia & the Pacific: Water deficits to shrink in Thailand

22 June 2020

THE BIG PICTURE
The 12-month forecast through February 2021 indicates moderate to extreme deficits in western Thailand, becoming exceptional across the border in a pocket of southern Myanmar. Surpluses of varying intensity are forecast in pockets of central, western, and southern Myanmar, and will reach exceptional intensity on the Irrawaddy as it approaches the Delta. Moderate surpluses are expected in the Central Highlands of Vietnam and small pockets along the eastern coast of the Gulf of Thailand.

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Surpluses are also forecast in many regions of Indonesia. Anomalies will be intense in Aceh Province in northern Sumatra, Java, Flores Island, southeastern Sulawesi, and the Bird’s Head Peninsula (Doberai Peninsula) of New Guinea. Moderate anomalies are forecast for western Borneo, Sumatra’s western shore, many small islands in Indonesia, and pockets of Papua, Indonesia.

Pockets of deficit are expected in Peninsular Malaysia, northeastern Sumatra, and in Papua New Guinea along its northern coast and around the Gulf of Papua where anomalies will be exceptional. Nearly normal conditions are forecast for the Philippines.

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

The forecast through August indicates that deficits will shrink and downgrade in the region, leaving surpluses as the predominant anomaly, particularly in Indonesia. In Southeast Asia, deficits in Thailand and Cambodia will nearly disappear, leaving primarily mild anomalies in western Thailand. However, a pocket of extreme deficits will emerge nearby in Myanmar’s Kayin State. Surpluses will emerge in the Mun River Watershed in eastern Thailand. In Cambodia, surpluses will shrink in the east, along with those in the Central Highlands of Vietnam, and emerge in the west. Moderate surpluses will increase somewhat in the Mekong Delta and intense surpluses will re-emerge along the Lower Irrawaddy River in Myanmar.

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Surpluses of varying intensity are forecast throughout much of Malaysia and Indonesia with extreme to exceptional anomalies forecast for Aceh Province in Sumatra’s northern tip, eastern Java, Malaysian Borneo, and Flores Island. Deficits will emerge in the western half of Timor Island but will shrink and downgrade in Papua New Guinea, persisting mainly along the western shore of the Gulf of Papua. In the Philippines, surpluses will retreat from most of Luzon but emerge in eastern Mindanao.

From September through November, water conditions in many parts of Southeast Asia will normalize though generally mild deficits are expected in western Myanmar and northwestern Thailand, and moderate surpluses will increase in Vietnam’s Central Highlands. Surpluses will shrink and downgrade in Malaysia and Indonesia leaving normal conditions in mainland Malaysia and Sumatra. Extreme surplus anomalies are forecast for many of the Lesser Sunda Islands and Sulawesi’s northern peninsula, and surpluses will increase in western New Guinea. Deficits will shrink along the western shore of the Gulf of Papua but will be exceptional.

The forecast for the final months – December through February – indicates that deficits, generally mild to moderate, will increase and surpluses will decrease.

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

IMPACTS
Floodwaters reaching 1.5 meters (nearly 5 feet) forced around 13,000 people to abandon their homes in the Indonesian province of Gorontalo on the island of Sulawesi after heavy rainfall caused the Taludaa River to breach its banks. Two bridges were damaged and one was completely destroyed.

At the end of May, 25 Thai provinces remained in a classification of drought-disaster as designated by the Interior Ministry’s Department of Disaster Prevention and Mitigation.

Thailand’s sugarcane industry can expect 10 billion baht (US $319 million) in relief from the federal government to help compensate for drought loss that pushed December-April production down by 40 percent from last year. Around 300,000 farmers will benefit from the distribution. Analysts predict that, due to persistent drought during the spring months, crops planted in April and May will also yield losses, estimated at 20 percent.

Tourism has suffered in drought-ravaged Nakhon Ratchasima province in northeastern Thailand. Wetlands in the Lahan Luk Nok Reservoir, a favorite attraction renowned for the beauty of its lotus blossoms, have dried up after two years.

In Non Sang district, however, tourists are flocking to see a 200-year old temple that has revealed itself from the depths of the Ubolratana Dam after the water level dropped to its lowest in half a century.

Shortage of water from the Upper Mekong River is cited as a cause of significant salt-water intrusion in the Mekong Delta during the 2019-2020 dry season, which arrived several months earlier than average. Conditions were the most severe in history, according to the Minister of Agriculture and Rural Development.

Erosion on the Hau River, a branch of the Mekong in Vietnam, nibbled away at a major highway until 40 meters simply collapsed into the river. Nearby residents were evacuated. The provincial government of An Giang has allocated VND70 billion (US $3 million) to address erosion on the Hau.

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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