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

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

30 March 2021

THE BIG PICTURE
The 12-month forecast through November 2021 indicates widespread surpluses of varying intensity throughout the Philippines, including exceptional surpluses in Negros.

Normal water conditions are expected in much of Southeast Asia. However, surpluses reaching exceptional intensity are forecast in Vietnam’s narrow neck with moderate anomalies bleeding into Laos. Moderate anomalies are also forecast in the Central Highlands. Rakhine State in western Myanmar can expect surpluses as can Peninsular Thailand, Malaysia’s peninsular tip, and nearby Singapore. Moderate deficits are forecast for Kuala Lumpur.

Deficits will reach across the Malacca Strait into Sumatra, Indonesia, but surpluses are forecast for Banda Aceh in the island’s northern tip and in the southwest. Surpluses will be intense in eastern Java and the Lesser Sunda Islands. Moderate surpluses are forecast for Borneo’s northern reaches, but anomalies will be more intense in the delta area of the south around the city of Banjarmasin. Elsewhere in the region surpluses are forecast for Sulawesi’s northern arm, the Maluku Islands, and pockets in New Guinea.

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

The forecast through May indicates widespread surpluses throughout the Philippines with extreme anomalies in the central islands. Widespread surpluses are also forecast in Vietnam, Cambodia, Laos, and Thailand. Anomalies will be exceptional in Vietnam’s narrow neck, central Cambodia, and the Mekong Delta. A patchwork of water conditions is forecast in Myanmar including deficits and transitional conditions in the north, and surpluses in its narrow southern extent, west of the Irrawaddy River and in the delta, and near the Salween River in the east.

Deficits are forecast in Kuala Lumpur and across the Malacca Strait into Sumatra. Moderate surpluses are expected in Banda Aceh in Sumatra’s northern tip, and moderate deficits in the south. Deficits are also forecast for southwestern Borneo, and surpluses in the island’s northern region and a pocket of the south around Bandjarmasin. Surpluses will stretch from Java through the Lesser Sunda Islands, and other areas of surplus include northern Sulawesi, the Maluku Islands, and small pockets in New Guinea.

From June through August, surpluses will shrink considerably returning many areas to near-normal water conditions. Severe surpluses will persist in the central Philippines, and moderate surpluses in central Vietnam, peninsular Myanmar, and a few small pockets in Thailand. Surpluses will shrink and moderate in northern Sulawesi, eastern Java and the Lesser Sunda Islands. Some areas of deficit, primarily small and moderate, will persist in Kuala Lumpur and Sumatra and will emerge in northern Indonesian Borneo.

The forecast for the final months – September through November – indicates nearly normal water conditions in Southeast Asia and the Philippines. Surpluses will persist in Java and the Lesser Sunda Islands and northern Sulawesi, and will emerge in northern Borneo, the Maluka Islands, and the Bird’s Head and Fakfak Peninsulas of western New Guinea and in the island’s Central Highlands.

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

IMPACTS
Mid-March downpours in the central Philippines left several towns in Aklan Province flooded as many rivers breached their banks.

Intense rainfall in West Java, Indonesia at the end of March triggered flooding that left over 60,000 people affected, and 10,000 homes damaged as well as schools, roads, and businesses.

An official at Thailand’s Office of National Resources warns of impending drought in northern provinces. The region’s water-intensive rice industry, heavily reliant on irrigation, is especially at risk. Water storage in most of Thailand’s reservoirs is about half that needed to sustain agricultural production in the next few months.

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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