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

22 February 2022

THE BIG PICTURE
The 12-month forecast through October indicates water surpluses of varying intensity in several regions in Southeast Asia and much of the Pacific.

Widespread surpluses are expected in Vietnam, moderate overall but exceptional in the narrows and extreme to exceptional from the Highlands to the coast. Generally moderate surpluses are forecast in Cambodia and eastern and Peninsular Thailand. In Myanmar, pockets of surplus are expected in the center of the nation, the Irrawaddy Delta, the southwest, and trailing through the southernmost tip.

The central and southern Philippines can expect moderate to extreme surpluses. Surpluses of varying intensity are forecast in Malaysia, many regions of Indonesia, and western Papua New Guinea. Areas with a forecast of exceptional surplus include Banda Aceh (Sumatra’s northern tip); the Mahakam River watershed in East Kalimantan on Borneo; eastern Java; Flores Island; Sulawesi’s northern arm; and the Bird’s Head Peninsula on New Guinea. A pocket of moderate deficit is expected in central Sumatra.

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

The forecast through April indicates that surpluses will remain widespread and intense in much of Southeast Asia but will shrink and downgrade in Indonesia and Pacific regions. Anomalies will be extreme to exceptional in the Lower Mekong River Basin through southern Laos, Cambodia, and Vietnam, and in the Hong (Red) River Basin in northern Vietnam. Widespread surpluses of varying intensity are forecast in Thailand. Surpluses are forecast in eastern Myanmar and its states bordering Bangladesh, but transitional conditions (pink/purple) are expected in the center of the nation. In the central and southern Philippines, moderate to severe surpluses are predicted. Surpluses are also expected in Malaysia, Brunei, northeastern Indonesian Borneo, Banda Aceh and eastern Sumatra, from eastern Java through Flores Island, Sulawesi’s northern arm, the Maluku Islands, and the Bird’s Head Peninsula and Pulau Dolok Island of Papua, Indonesia. Intense deficits are forecast around the Gulf of Papua and the island of New Britain, and moderate surpluses in the Highlands of Papua New Guinea.

From May through July, surpluses will shrink and downgrade considerably. Moderate surpluses will linger in northern and central Vietnam and pockets of Cambodia, Thailand, and southern Myanmar. Generally moderate surpluses are also forecast in pockets of the central Philippines and pockets of Malaysia and Indonesia including Banda Aceh, northeastern Indonesian Borneo, Sulawesi, the Malukus, and many of the Lesser Sunda Islands. Surpluses will downgrade to mild in the Bird’s Head Peninsula, but widespread moderate surpluses will emerge in Papua Indonesia and surpluses will increase in Papua New Guinea as deficits retreat.

The forecast for the final months – August through October – indicates surpluses in central Vietnam and widespread surpluses in many regions of Indonesia and Papua New Guinea. Deficits are forecast for central Sumatra.

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

IMPACTS
Damage assessment from widespread flooding in Malaysia over the past few months now totals USD $1.46 billion. Much of that impact - damage to public assets and infrastructure, homes, and manufacturing - was in the wealthy and populous Selangor state that includes the nation’s capital of Kuala Lumpur. Intense rainfall triggered the flooding that displaced over 120,000 people.

Heavy rainfall in Vietnam and Cambodia has left many cashew plantations under water. Cambodia will likely lose 30 percent of its crop and the quality of the remaining harvest in both nations has suffered, consequences that will reverberate through the global market translating to higher cashew prices.

In southern Thailand’s Prachuap Kiri Khan province, a backhoe was carried 300 meters by floodwaters from torrential rain in mid-February, floating down a river until it eventually became lodged next to a bridge. Many rice paddies in the region were inundated in the deluge. Bridges and roads were damaged in Nakhon Si Thammarat province in the south.

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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