Southeast Asia & the Pacific: Exceptional water surpluses forecast on Mekong River

23 August 2018

The 12-month forecast through April 2019 (below) indicates intense water surpluses in Myanmar, Laos, eastern Cambodia into Vietnam, and northern Vietnam.

Intense deficits are forecast for Papua New Guinea, especially widespread in the center of the country. Deficits of varying severity are forecast for southern Thailand, western Cambodia, eastern peninsular Malaysia, western Indonesian Borneo, northeast Sumatra, Java, West Nusa Tenggara, Timor-Leste, and Mindanao.

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

The near-term forecast through October indicates that surpluses will persist in much of Myanmar, retreat from northwestern Thailand, downgrade in Laos and Vietnam but remain widespread, shrink considerably in the Philippines, and nearly disappear in Malaysia and Indonesia. Exceptional surpluses are forecast during this period in western and southern Myanmar, pockets in northern Laos and northwestern Vietnam, and along the Mekong River.

Some pockets of deficit in southern mainland Thailand will intensify, becoming extreme to exceptional, as will deficits nearby in Cambodia north of Tonle Sap. Deficits of varying intensity will emerge in southern peninsular Thailand and peninsular Malaysia, transitioning from surplus in some areas. Moderate deficits will emerge in western Indonesian Borneo, southern Sumatra, and much of Sulawesi. Intense deficits will moderate in Java and downgrade in Papua New Guinea, but spread in Timor-Leste.

From November through January, surpluses in the region will continue to shrink, persisting in northern Vietnam, northern Laos, and along the Salween River in eastern Myanmar. Conditions of both surplus and deficit are forecast for western Myanmar and central Laos as transitions occur. Moderate deficits will spread in Thailand and Cambodia, and will emerge in central Vietnam and the Philippines. Mild to moderate deficit conditions are forecast for many parts of Indonesia, including widespread emergence in Indonesian Papua.

The forecast for the final months – February through April – indicates that deficits will intensify in Southeast Asia and the Philippines, but recede somewhat in Indonesia.

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

A dam under construction on a tributary of the Mekong River in Laos failed last month amid heavy rainfall, sweeping away hundreds of people in a horrific flood and forcing thousands to flee their homes. As of mid-August 39 people were confirmed dead, and survivors were still being found. The dam was one of 140 dams comprising a large effort to boost Laos’ presence as an energy generator in the region.

Monsoon flooding in Myanmar killed at least 11 people and forced over 100,000 others to evacuate last month. The heavy rains washed away a section of a concrete bridge in the northern Shan state, and damaged rice paddies and roads in central Kayin state. Flooding this year has destroyed 100,000 acres of rice paddy in the country, and the ministry of agriculture is distributing paddy seeds to flood-affected farmers.

Flooding in a suburb of Hanoi, Vietnam killed three people in late-July monsoon rains.  Among the destruction, roads to a remote community of ethnic-Hmong Catholics were destroyed, cutting off access to resources and other communities. In Thailand, eight people were killed in a deadly mudslide after heavy rainfall, which triggered flood warnings along the Mekong River, and submerged several rice and rubber plantations.

The government of the regency of Wonogiri in central Java has been unable to afford permanent solutions to months-long water shortages, such as a new system for pumping groundwater. At least 50,000 people living in the regency have been affected by drought since July, and effects are expected to last until October.

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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