Southeast Asia & the Pacific: Water deficits will retreat

23 September 2020

THE BIG PICTURE
The 12-month forecast through May 2021 indicates moderate to exceptional deficits in western Thailand, and moderate to severe deficits in the northeast crossing the Mekong River into central Laos. Deficits are also forecast in western Cambodia from Tonlé Sap Lake to the coast, and in a few pockets of northeastern Vietnam and peninsular Malaysia.

ISciences_Southeast_Asia_Composite_Adjusted_202006-202105_12mo_twitter.png

Surpluses of varying intensity are forecast for many regions in Myanmar and will be particularly intense along much of the Salween River and west of the Irrawaddy River. Surpluses, primarily severe, are expected in north central Laos reaching into Vietnam. In southern Laos anomalies could reach greater intensity reaching through Cambodia’s eastern half well into Vietnam and south to Ho Chi Minh City.

In Indonesia, surpluses are forecast for Sumatra’s northern tip, western Borneo and coastal regions in the south and southeast, northern and eastern Sulawesi, Flores Island, many small Indonesian islands, the Bird’s Head Peninsula (Doberai Peninsula), and other pockets in Papua, Indonesia. In Papua New Guinea, some deficits are expected along the western shore of the Gulf of Papua and on the nation’s north central coast. Moderate surpluses are forecast for the central Highlands. In the Philippines, surpluses are forecast in the central region and western Mindanao.

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

The forecast through November indicates that surpluses will shrink and downgrade overall but persist in many areas, particularly Indonesia. Surpluses are forecast in Myanmar west of the Irrawaddy River, where anomalies will be extreme, and in the north and east, with conditions of both deficit and surplus (pink/purple) in the center of the nation as transitions occur. Moderate surpluses are expected in northern Laos and severe surpluses in the south leading through Cambodia’s eastern half and well into Vietnam to Ho Chi Min City. Deficits will nearly disappear, with some moderate pockets lingering in northeastern Vietnam and northeastern and western Thailand.

ISciences_Southeast_Asia_Composite_Adjusted_202006-202105_3mo_twitter.png

Surpluses are forecast for many regions of Borneo, some coastal pockets in Sumatra, eastern Java, Sulawesi, Flores and Sumba Islands, the Maluka Islands, and several regions of Papua Indonesia, including the Bird’s Head Peninsula. Anomalies will be extreme in northern Sulawesi, and Flores and Sumba Islands. In Papua New Guinea, exceptional deficits are forecast on the western shore of the Gulf of Papua, some moderate deficits on the nation’s northern coast, and a few pockets of moderate surplus in the center and far east of the country. In the Philippines, surpluses are expected in the central islands and into Mindanao.

From December 2020 through February 2021, surpluses will shrink considerably, persisting primarily from southern Laos through eastern Cambodia into southern Vietnam. Former areas of surplus in Myanmar will become transitional, though moderate surpluses are forecast near the northern path of the Salween River. Some deficits will persist in northeastern Vietnam and a few pockets in mainland Thailand. Deficits will emerge in the Malay Peninsula and pockets of northern Borneo and Sumatra. Surpluses are forecast for many small Indonesian islands and pockets of Sulawesi and New Guinea. Surpluses in the Philippines will shrink.

The forecast for the final months – March through May 2021 – indicates surpluses in north central Laos and from eastern Cambodia into Vietnam. In Myanmar, surpluses are expected in the far west, in the north, and near the northern Salween River. Intense deficits will emerge in northeastern Thailand. Moderate deficits are forecast for the Malay Peninsula and pockets in Sumatra, Java, and Sulawesi. A few small areas of surplus will persist in Indonesia’s small islands and in New Guinea.

Please note that WSIM forecast skill declines with longer lead times.

IMPACTS
In mid-September, the Thai government announced that it will allocate 6.17 billion baht (US $192.8 million) to prepare for and mitigate impacts of flooding and drought in the nation. Projects where funds will be directed include water diversion systems, irrigation, aquifer development, and flood pumps.

Drought and salt water intrusion have damaged 25,000 hectares of fruit trees in Vietnam’s Mekong Delta with over 40 percent of that declared a total loss. Though still in the planning stages, in 2021 the region will begin construction of the Delta’s largest freshwater reservoir with a capacity of 1.3 million cubic meters, part of a larger development that will include residential units. The complex is expected to cost VND352 billion (US $15 million). The World Bank estimates that the Mekong Delta, the nation’s agricultural center, will need US $4.7 to $6.7 billion over the next five years to address climate change.

Flooding in West Java, Indonesia left three dead and inundated 49 neighborhoods in the capital, Jakarta, 100 kilometers (62 miles) to the north.

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.

Subscribe to our monthly Water Watch List

Search blog categories

Search blog tags