Southeast Asia & the Pacific: Intense surplus persists in Malaysia, Philippines

1 March 2023

THE BIG PICTURE

The 12-month forecast ending in October 2023 indicates widespread surpluses of varying intensity throughout Southeast Asia and the Pacific.

Areas that can expect exceptional surplus include:

Northern Vietnam, near the city of Dong Hoi.
Eastern islands of the Philippines, specifically Eastern Samar and northern Surigao, near Surigao City.
Southern Thailand, along eastern coastal regions of Pattani and Narathiwat, which spread further south into central Malaysia.
Far southern Myanmar, near the city of Kadin.
Northern coastal areas of Aceh, on Indonesia’s island of Sumatra. Eastern coastal regions of Jawa Timur and western regions of Nusa Tenggara Timur can expect surpluses of similar intensity.

Severe to extreme surplus are expected in:

Central Vietnam, in regions along the Ba River.
Northern and southern islands of the Philippines, throughout the regions of Zamboanga, Samar, and Leyte.
Indonesia, appearing in northern Sulawesi and eastern Java.
Southern Papua, appearing in southern coastal regions below the Digul River.

Moderate to severe deficits are forecast in:

Central Papua New Guinea, in the northern regions of Sanduan and East Sepik as well as coastal regions of Middle Fly.
Western Malaysia, in the southern regions of Perak.

FORECAST BREAKDOWN
The forecast through April 2023 indicates that exceptional surpluses along the border of Thailand and Cambodia will reemerge, with severe to extreme surpluses persisting throughout the rest of Thailand, Vietnam, Singapore, and Malaysia. Exceptional transitional conditions are expected to emerge in southwest Myanmar. Exceptional surpluses are expected to continue in the Zamboanga, Samar, and Leyte regions of the Philippines, with mostly moderate surpluses occurring in the northern regions of Sulawesi and Kalimantran, Indonesia and Sabah, Malaysia. Surpluses of similar intensity continue through the majority of the Greater Sunda Islands. In Papua New Guinea, exceptional deficits are expected to occur in regions along and south of the Ramu River.

From May through July 2023, near-normal conditions will return to much of Indonesia and Pacific regions, with surpluses persisting in central Vietnam and the central Philippines. Moderate deficits are expected to occur in western Malaysia, near Perak.

The forecast for the final months – August through October 2023 – indicates continued near-normal conditions throughout the area, with small instances of moderate to severe deficits occurring in western Malaysia, central Philippines, and areas along the shared border of Papua and Papua New Guinea.

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

IMPACTS
Over 13 million people living in the city of Manila, Philippines are facing constant intense flooding caused by aggressive deforestation practices. Locals experience constant inundation of their towns and homes, with one resident blaming development in the Upper Marikina River Basin—a nearby catchment spanning roughly 64,500 acres flow in the southern foothills of the Sierra Madre. This development, such as public roads, parking lots, private resorts, and residential subdivisions, has hindered the catchment’s ability to absorb a sufficient amount of water, which also causes shortages in the dry season. Runoff from the nearby mountains drains into the Upper Marikina River Basin, which is critical for regulating water flow into Manila. However, according to a World Bank report, only 2.1 percent of the watershed was covered by dense "closed forest" in 2015.

Heavy rain on February 1st triggered intense flooding in the Indonesian city of Parepare on the island of Sulawesi, impacting the districts of Ujung, Bacukiki, West Bacukiki and Soreng. Water levels in areas near the river amounted to 1 meter deep, affecting over 5,000 residents. One of the hardest hit areas was the village of Lappadde in Ujung District, which reported damage to 350 homes and two deaths. Additionally, flooding struck the district of Mallusetasi in the South Sulawesi province on February 2nd, flooding 215 homes and affecting over 700 people.

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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