Southeast Asia & the Pacific: Intense deficits to persist in W Cambodia

27 October 2017

The Big Picture
The 12-month map (below) indicates exceptional surpluses in western Myanmar, eastern Thailand, Laos into Vietnam, and Negros Island, Philippines. Surpluses of lesser intensity are forecast for much of Vietnam, other parts of the Philippines, and in scattered pockets from northwestern Indonesian Borneo through western Papua.

A large block of exceptional water deficit is forecast for western Cambodia. Moderate to exceptional deficits are expected in the Highlands of central Papua New Guinea, and deficits of lesser severity are forecast for Malaysia and north and south regions of Sumatra.

Mid-October rains triggered flooding and landslides in northern and central Vietnam, killing 72 people, in what the country's agricultural minister described as the worst flooding in a decade. Impacts include 34,000 homes submerged, 40,000 animals killed or washed away, and 22,000 hectares (54,300 acres) of rice damaged. A state of emergency was declared in Ho Bin province and officials ordered the discharge of water from Hoa Binh dam, Vietnam’s largest hydroelectric dam, for the first time in years. Water levels on the Hoang Long river were the highest since 1985. 

Flooding has affected at least 22 provinces in Thailand, resulting in 9 deaths, according to the Department of Disaster Prevention and Mitigation. Flash flooding and discharge from the Chao Phraya dam swamped 76 districts, and authorities in Bangkok advised residents to stay home after overnight flooding inundated at least 55 major roads with knee-deep water. Thailand's Ministry of Public Health has issued a warning about flood-related diseases, particularly leptospirosis, which has killed 47 people this year.

The Philippines will receive loans totaling US$415.2 million split evenly between co-financers World Bank and Asian Infrastructure Investment Bank to support a phase of the US$500 million Metro Manila Flood Management Project to upgrade pumping stations in the mega-city.

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

Clearly indicated in the map progression is a gradual transition in the region from predominantly surplus conditions to deficit. Note, however, that Cambodia and eastern Papua New Guinea show deficit conditions throughout the 12-month forecast period.

The October through December map shows a significant downgrade in the intensity of water surpluses. However, exceptional surpluses are forecast for western Myanmar, northern and southern Laos, and along the west side of the Mekong River in Cambodia down to Phnom Penh. Extreme surpluses are forecast for Vietnam’s Central Highlands in the south, and surpluses of varying severity are forecast for the remainder of Vietnam and for eastern Myanmar, mainland Thailand, Laos, central Sumatra, Indonesian Borneo, southern Philippines, and from Sulawesi through western Papua New Guinea.

Exceptional deficits remain in the forecast for a large block of western Cambodia, and moderate deficits are forecast surrounding Ho Chi Minh City in southern Vietnam. Intense deficits in Papua New Guinea are expected to disappear, leaving scattered mild deficits. Moderate deficits will emerge in southern Thailand and the Lesser Sunda Islands.

From January through March surpluses in western Myanmar, Thailand, Laos, and much of Vietnam will transition to conditions of both deficit and surplus as deficits emerge. The block of exceptional deficits in western Cambodia will diminish somewhat in extent but intense deficits will persist. Severe to occasionally exceptional deficits are expected to emerge in Malaysia, Brunei, western Indonesian Borneo, Sumatra, and southern Sulawesi. Surpluses on Papua will nearly disappear as deficits continue to emerge in the eastern half of the island and begin to emerge in the west.

After March the forecast indicates the continued presence of deficits in the region, particularly in Cambodia, Malaysia, Indonesia, and Papua.

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

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.


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 0.5°x0.5° 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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