Southeast Asia & the Pacific: Exceptional water deficits to persist in Cambodia, surpluses in Laos

October 25, 2016

The Big Picture
As seen in the 12-month map (below), exceptional water deficits are forecast for Cambodia and the Malay Peninsula, along with moderate deficits in Malaysian Borneo, Brunei, and pockets of Sumatra and eastern Papua New Guinea. Greatest severity and extent is expected to be in Cambodia. Water surpluses are forecast for Java. Both surpluses and deficits are forecast for Laos and Vietnam.

Impacts
In Cambodia, according to a new UN report, the recent El Niño-induced drought affected not only the poorest, but also forced more than 50 percent of middle and upper income families to take out loans, pushing them into lower income brackets.

Torrential rains in central Vietnam produced flooding that killed 31 people, inundated 125,000 homes and 14,500 hectares of cropland (paywall), drowned livestock, and disrupted services on the North-South Highway and railway links. Provincial officials say that discharges from hydropower reservoirs made the situation worse.

To the south in the Mekong Delta - Vietnam’s “rice bowl” - it is the lack of water that is causing hardship. The rainy season brought about half the average amount of water this year, leaving rice paddies parched. The Delta has not seen major flooding in recent years, forcing rice farmers to switch crops. Fisherman have been impacted as well. A day's catch this year might yield 5-7 kg a day compared to 100 kg in prior years, and lower catches are driving prices up. Many fisherman are leaving the area to seek employment elsewhere.

Forecast Breakdown
The 3-month maps (below) show the evolving conditions in more detail. At a glance, what is most evident in the map series is the predominance of blues and greens from July to December and more oranges and reds from January through June. With some notable exceptions this indicates a transition away from surplus water conditions to deficit.

Clearly, from October through December Cambodia is forecast to remain in primarily exceptional deficit, as is southern Thailand along the Gulf of Thailand. Primarily moderate deficits are forecast in pockets of Thailand, in southeast Papua New Guinea, and along the Tayabas Bay in Quezon, Philippines. Exceptional surpluses are forecast in northern and southern Laos; Java; Gorontalo Province in central Sulawesi Island, Indonesia; and western Flores Island. Surpluses of lesser severity are expected in Indonesian Borneo, southern Sumatra, Sulawesi, and central New Guinea.

From January through March much of Southeast Asia, Malaysia, and parts of Indonesia are forecast to transition to conditions of water deficit. Exceptional deficits will persist in much of Cambodia. Moderate to severe deficits are expected to emerge throughout much of Thailand; moderate to extreme deficits in Malaysia; and moderate to exceptional deficits in much of Sumatra. Surpluses forecast in prior months for Laos and Vietnam are expected to transition to both deficits and surpluses, while conditions should return to normal or near normal in most of Indonesian Borneo, Java, Sulawesi, and central New Guinea.

The forecast for the latter three months – April through June – indicates that deficits of varying severity will continue to emerge throughout the region.

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