Among the four countries examined, Thailand and Cambodia would be hit harder than Laos and Vietnam, it said Tuesday.

The MRC said dry conditions created by insufficient rainfall during the wet season, coupled with the El Nino weather phenomenon, may cause a meteorological drought – a situation when dry season dominates certain areas for a period of time – and abnormal high temperatures and evapotranspiration (evaporation of water from soil and other surfaces and by transpiration from plants).

This year's shortage of rainfall was caused by the late arrival and early departure of monsoon rains. The rains arrived nearly two weeks late and stopped three weeks earlier than usual.

In Vietnam's Mekong Delta, there has been no strong indicator of drought, but saline intrusion can significantly affect local agriculture, MRC said.

The dry conditions in the region are forecast to improve from the second week of January 2020 after an expected increase in rainfall.

"This year's prolonged dry weather conditions can adversely impact agricultural production. The issue of water shortage could also come up if the drought persists," said Dr Lam Hung Son, MRC Secretariat's Head of Regional Flood and Drought Management Center.

The severe drought in 2019 has caused water levels in the region to drop to its lowest point in more than 60 years. Most parts of the basin have been experiencing an exceptionally low flow since June.

The MRC Council – the highest ministerial body of the organization – will discuss the drought issue while a Drought Management Strategy is expected to get approved at the council's annual meeting in Phnom Penh, Cambodia.

MRC will also work with the Lancang Water Resources Cooperation Center on joint research, enhanced data exchange, better communication and coordination.

This year, saltwater intrusion in Vietnam's Mekong Delta arrived at least four months earlier than usual to an extreme extent. According to the Southern Institute of Irrigation Science, from the end of 2019 to March 2020, saline intrusion in the Mekong Delta could inflitrate 10-15 kilometers further inland than the average of previous years, adversely affecting the lives of about 50,000 families in the region.

The Mekong Delta has struggled with the late arrival of annual flooding in recent years, keeping water levels much lower than usual. The annual flooding not only replenishes the region’s supply of fish and other aquatic species but also carries and deposits large amounts of fertile alluvium that has nourished it for centuries.