Southeast Asia & the Pacific: Water surplus will persist in SE Asia

23 March 2022

THE BIG PICTURE
The 12-month forecast through November indicates water surpluses of varying intensity in several regions in Southeast Asia and much of the Pacific.

Widespread surpluses are expected in most of Vietnam, moderate in the north but more intense in the narrows and from the Highlands to the coast. Mild to moderate surpluses are forecast in Cambodia, eastern Thailand, and parts of Laos, but anomalies will be more intense in Peninsular Thailand. In Myanmar, small pockets of surplus are forecast, and surpluses will trail through the southernmost tip. Peninsular Malaysia can expect exceptional surpluses.

Surpluses will be moderate to severe in the central and southern Philippines. Surpluses of varying intensity are forecast for many regions of Indonesia and western Papua New Guinea. Areas with a forecast of exceptional surplus include Banda Aceh (Sumatra’s northern tip); eastern Java; Flores Island; Sulawesi’s northern arm; and the Bird’s Head Peninsula on New Guinea. Deficits are forecast in central Sumatra and the western shore of the Gulf of Papua.

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

The forecast through May indicates that widespread, intense surpluses will persist in Southeast Asia, but surpluses in Indonesia and Pacific regions will shrink and downgrade. Severe to exceptional surpluses are forecast throughout Vietnam, Laos, Cambodia, Thailand, and Peninsular Malaysia. Exceptional surpluses will be especially widespread in northwestern Thailand and anomalies will follow the Chao Phraya and Tha Chin Rivers in the south. In Myanmar, severe to extreme surpluses will persist in the western coastal and near-coastal states, and surpluses of varying intensity are forecast in the east and through the nation’s narrow southern extreme. Deficits are forecast in the north. In the Philippines and northeastern Borneo, moderate to severe surpluses are expected, but more intense anomalies are forecast intense in eastern Sumatra and Banda Aceh. Surpluses, generally moderate, are also forecast for eastern Java, Flores and Timor Islands, Sulawesi’s northern arm, the northern Maluku Islands, and pockets of New Guinea. Deficits on the Gulf of Papua will moderate, and severe deficits are forecast on the island of New Britain.

From June through August, surpluses will shrink considerably and moderate in Southeast Asia but increase in Indonesia and New Guinea. Primarily moderate surpluses will linger in northern regions of Vietnam and Laos, Vietnam’s central coast, eastern Thailand into Cambodia, and along the shared southern border of Thailand and Myanmar. Conditions in the rest of Myanmar will normalize overall with some moderate deficits in Sagaing State in the northwest. In Indonesia and the Pacific, surpluses of varying intensity will emerge throughout most of New Guinea and deficits around the Gulf of Papua will retreat. Moderate surpluses are forecast for pockets of Malaysia and the central Philippines, many regions in Indonesian Borneo, much of Sulawesi and Flores Island, and parts of Java, southern Sumatra and Aceh, and Timor. Surpluses will be more intense in the southern Maluku Islands. Moderate deficits are forecast in northeastern Sumatra.

The forecast for the final months – September through November – indicates that surpluses will linger in central Vietnam, retreating elsewhere in Southeast Asia. Deficits are expected in northern regions of Southeast Asia and in Peninsular Malaysia and central Sumatra. Widespread surpluses are forecast in remaining areas of Indonesia and New Guinea as anomalies increase and intensify.

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

IMPACTS
Flooding and landslides in Indonesia have claimed 9 lives this month and affected 50,000 people. Flood regions include Java, Borneo, Sumatra, and Sulawesi. Serang City on Java received 180.4 millimeters (7 inches) of rain in just 24 hours at the beginning of March.

Four people died after torrential rain triggered a landslide outside of Malaysia’s capital, Kuala Lumpur, on 10 March. Earlier in the month, four deaths were reported in Kelantan State, also in Peninsular Malaysia, after floodwaters rose to 2 meters (over 6.5 feet) and 17,000 people were evacuated. Spring flooding has followed several months of some of the worst flooding the country has seen in decades, resulting in 50 deaths from mid-December to early January, 125,000 displaced people, and US $1.45 billion in damages.

In southern Thailand, flooding at the end of February caused a bridge to collapse, killing six people. The country’s medical authorities are warning that Dengue fever is on the rise, citing stagnant waters that encourage the mosquito-borne illness.

The sewers in Phnom Penh, Cambodia’s capital, overflowed into the streets after heavy rainfall in late March, forcing city sanitation crews armed with pumps into the muck.

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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