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GDO Analytical Report: Drought in mainland Southeast Asia – March 2020

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Executive summary

  • Most of the Mekong river basin and neighboring regions in Southeast Asia are experiencing relatively dry conditions, involving most of mainland Thailand and parts of Cambodia, Laos and Vietnam. Despite a wet climate, underperforming precipitation since at least mid-2019 has hampered the yearly water balance, both in terms of precipitation per se and downstream river flows.

  • Impacts on crops and water supply have been reported, mostly in the lower Mekong basin and in relation to saline intrusion from the river delta. Reservoirs are lower than average for the period, but generally not critically low. Substantial support is being provided by local governments.

  • With the month of March marking the end of the short dry season, the precipitation outlook from March to May 2020 is overall neutral, suggesting normal rainfall for the months of transition to the wetter half of the year. If the forecasts prove correct, the affected areas may endure a couple of more months of drought before recovery.

Risk of drought impact for agriculture (RDrI-Agri)

The GDO indicator RDrI-Agri shows the risk of having impacts from a drought, by taking into account the exposure and socio-economic vulnerability of the area, with particular focus on the agricultural impacts.

The months from December to March are generally the driest in an otherwise wet climate. However, seasonality is quite marked, with about 50% of the annual total precipitation falling in just three or four months. In case of prolonged below-average precipitation, the agricultural areas that are not strategically equipped with reservoirs and irrigation systems are vulnerable. In the entire lower Mekong basin, the river plays a fundamental role in water supply, as well as in keeping salty waters out of the Mekong delta. Agriculture is the major source of income and subsistence for the population, and rice is the main staple crop in the whole peninsula, requiring a significant amount of water. The total population living in the area under drought is in the order of millions.

Compared to the situation of mid-2019, the drought has moved southwards, mainly over Thailand, while also reaching Cambodia and the Mekong delta in Vietnam. The RDrI-Agri indicator for the first dekad of March 2020 (Figure 1) shows a wide region under moderate risk, with Thailand as the most exposed country, as well as central and western Cambodia.