Southeast Asia & the Pacific: Extreme water deficits forecast Sumatra & Java

Southeast Asia & the Pacific: Extreme water deficits forecast Sumatra & Java

16 October 2019

THE BIG PICTURE
The 12-month forecast through June 2020 indicates intense water deficits around Tonlé Sap in western Cambodia and in Java, Indonesia. Moderate to severe deficits are forecast for Sumatra and paths along Papua New Guinea’s northern and southern shores. Moderate deficits are expected in pockets of Thailand and Indonesian Borneo.

Widespread surpluses are forecast for Myanmar, Laos, Vietnam, and eastern Cambodia; surpluses will be exceptional in western Myanmar and southern Laos.

Intense surpluses are also forecast in central Philippines around Cebu, and surpluses of lesser intensity are expected in northern Luzon.

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

The forecast through December indicates surpluses in parts of Southeast Asia and deficits in Malaysia and Indonesia. Surpluses of varying intensity will persist in much of Myanmar, shrinking somewhat, and will remain intense in the west. Surpluses will downgrade in Laos, eastern Cambodia, and Vietnam, becoming generally moderate to severe, though exceptional anomalies will persist in southwestern Laos. Nearly normal conditions will return to Thailand from prior deficit, but moderate deficits will emerge in peninsular Thailand and deficits will persist in western Cambodia around Tonlé Sap. Deficits of varying intensity are expected in pockets of Malaysia, and extreme deficits are forecast for Sumatra and Java. Some moderate deficits are expected in pockets of Indonesian Borneo and along the northern shore of the island of New Guinea. Deficits are also forecast for the eastern Philippines, though Cebu in the center of the country can expect surplus.

From January through March 2020, moderate surpluses will persist in Laos, Vietnam, and eastern Cambodia, with exceptional anomalies in southwestern Laos. Deficits will persist around Tonlé Sap in western Cambodia. Conditions of both deficit and surplus (pink/purple) are forecast in Myanmar as transitions occur. Malaysia will normalize and nearly normal conditions are forecast for the Philippines. Deficits are expected to shrink in Indonesia but intensify in southern Sumatra and throughout Java, becoming exceptional in some regions. Moderate to severe deficits will increase in Papua New Guinea.

The forecast for the final months – April through June 2020 – indicates nearly normal conditions in most of the region with some areas of surplus in western Myanmar and spanning the border between Cambodia and Vietnam. Deficits will persist north of Tonlé Sap, Cambodia.

(It should be noted that forecast skill declines with longer lead times.)

IMPACTS
[added 30 October 2019]
Much of Cần Thơ City in Vietnam’s Mekong Delta was under water in early October due to rising river levels and high tides. The Hau River, a tributary of the Mekong, reached its highest level in 30 years. Around 30,000 people were affected by flooding in the city of over a million inhabitants as floodwaters submerged many roads and caused a dike to collapse.

Dry weather in Thailand and parts of Cambodia has taken a toll on the rice crop and will likely result in significantly lower yields. In mid-September, paddies in northern Thailand were cracked and speckled with brown plants on the verge of collapse. In Nakhon Ratchasima Province four dams had run dry and dams in other regions of the nation were around 20 to 30 percent of capacity. Projected economic damages are estimated at around USD $477 million. The Thai government will approve a 5.4-billion-baht (USD $178.6 million) budget to aid farmers affected by drought and by recent flooding.

Drought-stricken farmers in Siem Reap Province, Cambodia received rice seeds, fertilizer, and training from the International Rice Research Institute.

Cambodia’s Tonlé Sap, the largest freshwater lake in Southeast Asia and a primary source of protein for Cambodians via its fish stock, is experiencing a decline in fish production. Causes include changes in the lake’s seasonal rise and fall, growing population, dam construction, and illegal fishing activities. During the monsoon season earlier this year, the lake swelled for only six weeks instead of the usual four months, portending a diminished fish stock. Experts predict that the lake may not reach its normal annual catch of 500,000 tons this year, which could spike a food crisis during the major fishing months of December and January.

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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Many analyses reported in ISciences-authored blog posts are based on data generated by the ISciences Water Security Indicator Model (WSIM). Other sources, if used, are referenced in footnotes accompanying individual posts. WSIM is a validated capability that produces monthly reports on current and forecast global freshwater surpluses and deficits with lead times of 1-9 months at 0.25°x0.25° resolution. This capability has been in continuous operation since April 2011 and has proven to provide reliable forecasts of emerging water security concerns in that time-frame. WSIM has the ability to assess the impacts of water anomalies on people, agriculture, and electricity generation. Detailed data, customized visualizations, and reports are available for purchase.

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