Southeast Asia & the Pacific: Water deficits to persist in W Cambodia, increase in Thailand

26 November 2018

NOTE: The WSIM model makes use of seasonal temperature and precipitation forecasts produced by the U.S. National Oceanic and Atmospheric Administration (NOAA) Climate Forecast System Version 2 (CFSv2). These forecasts predict broad temperature and precipitation patterns, but do not effectively predict singular events such as tropical storms. Detailed outlooks and analyses of tropical storms are available from the NOAA National Hurricane Center.

The 12-month forecast through July 2019 indicates exceptional water deficits in much of western Cambodia, and severe to exceptional deficits throughout Thailand. Deficits of varying intensity are expected in Malaysia, pockets of Indonesia, the Philippines, and Papua New Guinea.

Water surpluses are forecast for Myanmar, northern Vietnam and Dak Lak Province in southern Vietnam. Surpluses are expected to be exceptional in western Myanmar and the Irrawaddy Delta.

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

The near-term forecast through January indicates that intense surpluses in Southeast Asia will shrink and downgrade, but exceptional conditions remain in the forecast for western Myanmar and northern Laos. Severe to extreme surpluses are expected in eastern Myanmar along the Sittong and Salween Rivers and in northern Vietnam. Deficits will emerge in central Myanmar, central Laos, and central Vietnam. Exceptional deficits are forecast to persist in the bulk of western Cambodia and severe to exceptional deficits will increase in Thailand, encompassing much of the county. Conditions in the Philippines will transition from surplus to deficit. Moderate surpluses are forecast for Sumatra, peninsular Malaysia, and West Kalimantan in Indonesian Borneo. Deficits are forecast in Papua New Guinea and in pockets throughout Indonesia.

From February through April, many regions of prior surplus will exhibit both surpluses and deficits (purple) as conditions continue to transition, including Myanmar, Laos, and eastern Cambodia into southern Vietnam. Exceptional deficits will shrink slightly in western Cambodia. Deficits will downgrade somewhat in Thailand but remain widespread; will increase in central and southern Vietnam; and will intensify in the Philippines. Aforementioned surpluses in peninsular Malaysia and Sumatra will transition to deficits, while some surpluses are expected to emerge in central Java. Deficits remain in the forecast for Papua New Guinea and scattered pockets in Indonesia.

The forecast for the final months – May through July – indicates fairly intense deficit conditions throughout much of the region

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

Flooding triggered massive mudslides that killed 27 people and devastated part of an elementary school in Indonesia’s North Sumatra last month. The disaster comes less than a month after a powerful earthquake and tsunami hit the Indonesian island of Sulawesi, killing nearly 2,000 people.

Super Typhoon Yutu pummeled the Northern Mariana Islands late last month, prompting President Trump to declare a major disaster in the US commonweath. Tied for the most powerful storm on Earth this year, Yutu killed at least one person and injured others, and caused extensive damages to neighborhoods, schools, businesses, and airports.

Flash floods in the Keerom regency of Papua New Guinea swept away several homes in the middle of the night and caused serious damage to almost every house in the district.

A heavy downpour lasting over 90 minutes flooded Penang International Airport in Malaysia late last month.

Floods damaged over 2,000 hectares (4,942 acres) of rice paddy in the Mekong Delta last month. Early-season flooding reportedly peaked early this year, catching forecasters and farmers off-guard.

Looking ahead though, Vietnam’s Department of Cultivation under the Ministry of Agriculture and Rural development is advising regional localities to reserve water for this year’s winter-spring rice crop, as an El Niño event threatens to cause drought and salt water intrusion.

Thailand’s Office of National Water Resources declared 32 districts of the northeastern Nakhon Ratchasima province as drought-hit areas. Dry conditions have damaged over 112,000 hectares (277,000 acres) of farmland in the province this season. Production of popular rice variety hom mali is expected to drop 10 percent due to drought damage.

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 0.5°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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