Southeast Asia & the Pacific: Water deficits will downgrade but persist in Thailand & Cambodia

25 March 2019

THE BIG PICTURE
The 12-month forecast through November 2019 indicates severe to exceptional water deficits in much of western Cambodia, Thailand, and peninsular Malaysia. Moderate deficits are expected in western and southern Laos and southern Vietnam centered around Ho Chi Minh City.

Deficits of varying intensity are forecast for the Philippines, pockets in eastern and southern Sumatra, eastern and southern Borneo, and Sulawesi. Deficits are also forecast for much of New Guinea and will be exceptional in Papua New Guinea around the western shore of the Gulf of Papua.

Surpluses are forecast for Flores Island; pockets of western Myanmar and Java; and the eastern region of Bird’s Head Peninsula on New Guinea.

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

The forecast through May indicates that, while the extent of exceptional deficits will shrink in Cambodia and Thailand, intense deficits will remain widespread in both nations and severe deficits will emerge in northern Thailand. Severe deficits are also expected to emerge in Myanmar’s narrow, southern Tanintharyi Region, becoming extreme to exceptional on the Malay Peninsula and into northern Sumatra. Severe deficits are forecast in central Laos and southern Vietnam as conditions in those two nations transition from surplus. Intense surpluses will persist in western Myanmar and both deficits and surpluses (purple) are forecast for the Irawaddy Delta as transitions occur.

Severe to exceptional deficits are forecast for the Philippines, particularly Mindanao, and a pocket of surplus is forecast around Cebu City. Moderate to exceptional deficits are forecast for northeastern Borneo, northern Sulawesi, Ternate Island, and central Papua New Guinea. Surpluses are forecast for western Indonesian Borneo, Java, and Flores Island.

From June through August, surpluses in the region will nearly disappear and deficits will downgrade somewhat overall but increase in extent. Deficits in Thailand and Cambodia will be severe with pockets of extreme intensity. Primarily moderate deficits are expected in eastern Myanmar and Laos, and severe deficits in Vietnam’s narrow central region and in the south around Ho Chi Minh City. Deficit anomalies on the Malay Peninsula will shrink slightly but will reach extreme to exceptional intensity. Moderate deficits are expected in the southern Philippines, and deficits of varying severity in Borneo, eastern Sumatra, and Sulawesi. Exceptional deficits are forecast for the Lesser Sunda Islands. Deficits will emerge in western New Guinea but downgrade in Papua New Guinea. Some moderate surpluses are forecast for Java.

The forecast for the final months – September through November – indicates deficits of varying intensity throughout much of the region, mild to moderate in Southeast Asia but more intense elsewhere.

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

IMPACTS
Floods and landslides killed at least four people in Indonesia’s East Nusa Tenggara province early this month. Mere weeks later, disaster struck again when heavy rain caused flash flooding and landslides ravaged Papua province, killing over 100 people. The disaster in Papua destroyed hundreds of buildings and tore down bridges. The two floods came months after 68 people were killed by floods and landslides in January on the island of Sulawesi.

Typhoon Wutip formed near Guam last month and grew to a Category 5 storm, making it the first Category 5 storm recorded in the Northern Hemisphere in the month of February. The storm skirted Guam, causing flash flooding on the southeastern part of the island, providing relief – albeit dramatic relief – to dry conditions that were preparing local officials last month to issue fire watches and drought warnings.

The prime minister of Cambodia urged rice farmers to reduce cultivation of the dry-season rice crop, echoing a warning from the Ministry of Water Resources and Meteorology that the country will not have enough water to plant multiple crops this year.

The largest of the irrigation projects built under the Khmer Rouge Regime in the 1970’s is running dry, in one of Cambodia’s worst droughts in history. The Trapaing Thmar reservoir serves thousands of rice farmers in northwestern Cambodia and provides habitat to some endangered species. The drought has affected over 20,000 hectares (49,421 acres) of rice fields in 13 provinces. In some villages, local chiefs estimate that paddy rice production will be merely ten percent of normal production this year, adding that people are in debt and often migrate to Thailand for work, putting their children to work as well.

Amid the current dry season, coffee farmers in Vietnam are running low on water for their trees as a drought threatens the Central Highlands – Vietnam’s main coffee-growing region.

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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