Southeast Asia & the Pacific: Water surplus will persist in SE Asia

21 November 2021

THE BIG PICTURE
The 12-month forecast through July 2022 indicates water surpluses of varying intensity in many regions of Southeast Asia. Anomalies will be extreme to exceptional in the Mekong River Watershed through southern Laos, Cambodia, and Vietnam, and widespread though generally less intense elsewhere in those nations.

Surpluses will also be widespread in Thailand and Myanmar, extreme in Myanmar’s southwestern states and extreme to exceptional in the southeast leading into Thailand. Transitional conditions (pink/purple) are expected in central Myanmar around Mandalay.

Surpluses are also forecast in the Philippines, primarily in central and southern regions. Many areas of Indonesia and its neighbors can expect surpluses of varying intensity. In Borneo, surpluses will be intense in the southwest but primarily moderate in the southeast and northeast, while a pocket of moderate deficit is expected in Sarawak in Malaysian Borneo in the Upper Rajang River region. Some pockets of surplus are forecast in Sumatra at its northern tip in Banda Aceh and along its central east coast. Extreme to exceptional surpluses are forecast for Sulawesi’s northern arm, and moderate to extreme surpluses in the Lesser Sunda Islands. Surpluses will be severe in the Maluku Islands reaching into the Bird’s Head Peninsula (Doberai) of New Guinea. Widespread surpluses are forecast throughout southern Papua, Indonesia, and surpluses are also forecast in the Highlands region of Papua New Guinea and scattered pockets along the coast of the Papuan Peninsula.

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

The forecast through January 2022 indicates that widespread surpluses will persist in Southeast Asia, increasing in northern regions of Thailand and Vietnam. Anomalies will be exceptional in much of Cambodia from Tonlé Sap past the Mekong River into southern Laos and Thailand. In Myanmar, severe surpluses will persist in the coastal west reaching inland, and in the Sittaung and Salween River regions in the east, but transitional conditions are expected in the center of the nation surrounding Mandalay and deficits will emerge in the north.

In the Philippines, moderate surpluses are forecast in central and southern regions. Surpluses will nearly disappear in Malaysia and Sumatra and, while shrinking in Indonesian Borneo, will remain intense in the west. A few small pockets of deficit will emerge Borneo, particularly in the northwestern tip near Kuching. Moderate to extreme surpluses are forecast for Sulawesi, the Lesser Sunda Islands, and the Maluku Islands. Surpluses will persist in western and southern Papua, Indonesia, and a few pockets are forecast in Papua New Guinea.

From February through April 2022, surpluses will remain widespread in Thailand, Laos, Cambodia, and Vietnam with exceptional anomalies persisting from central Cambodia into Laos and Thailand. Surpluses will persist in eastern Myanmar, transitional conditions are expected in the west, and deficits will emerge in the Irrawaddy Delta while normalizing northeast of Mandalay. Surpluses will downgrade in the Philippines and shrink considerably in Indonesia and Papua New Guinea. Mild to moderate deficits will emerge in central Malaysian Borneo including the Upper Rajang River region, western Indonesian Borneo, and a pocket in west-central Sulawesi.

The forecast for the final months – May through July 2022 – indicates moderate surpluses in northern and central Vietnam, pockets of Laos and Thailand, the central Philippines, northern Sulawesi, the Lesser Sunda Islands, and southern and eastern New Guinea. A few pockets of moderate deficit will emerge in Peninsular Malaysia.

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

IMPACTS
More than 343,000 hectares of cropland in Cambodia has been affected during this year’s rainy season, damages incurred from flooding but also from drought.

Five districts in the nation’s capital, Phnom Penh, flooded in late October after heavy rainfall collapsed a floodgate on the Praek Tnout stream, forcing 1,000 families to set up temporary shelters on a nearby dam. Floodwaters also destroyed rice fields in the region. The local electricity company cut off service to the area, citing dangerous conditions due to rising waters.

This year’s monsoon swamped Bangkok, Thailand. The Chao Phraya River overflowed in the capital and several train routes north of the city were suspended. Thailand’s popular resort island, Koh Samui, suffered damages after heavy rainfall and a landslide caused eight villas to collapse. Road construction in the area may have contributed to the landslide.

Vegetable prices in Thailand are spiking due to widespread flooding in agricultural regions.

Eleven people remain missing after torrential rainfall swelled rivers in East Java, Indonesia, inundating the Kota Batu region. A late-November landslide triggered by heavy rainfall left four dead in Central Java. Flooding in West Kalimantan submerged dozens of districts when the Melawi and Kapuas Rivers overflowed. Over 230,000 people were affected, 4 deaths were reported, and 5 bridges and 77 power stations damaged.

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