Weekly Wet Season Situation Report in the Lower Mekong River Basin – 17-23 August 2021

Key Messages

Key messages for this weekly report are presented below.

Rainfall and its forecast

Rainfall focused in the areas from Chiang Saen in Thailand to Pakse in Lao PDR, including the lower part in Cambodia and Viet Nam, varying from 3.60 millimetres (mm) to 169.90 mm.

There will be some rainfalls for the next 5 days over the Mekong region from 24 to 29 August 2021 due to low-pressure dominating the Mekong region.

Water level and its forecast

According to MRC’s observed water level data, the outflows at Jinghong hydrological station showed slightly increase over the monitoring period from 17 to 23 August 2021. It was rising about 0.26 metres (m) from 535.26 m on August 17 to 535.52 m on August 23. The outflows increased from 825 cubic metres per second (m³/s) on August 17 to 997 m³/s on August 23.

Amid the significantly low outflow from Jinghong upstream, water levels across most monitoring stations from Chiang Saen in Thailand to Paksane in Lao PDR increased during August 17-23 due to average rainfall in some parts of the LMB. However, water levels from Nakhon Phanom in Thailand to Pakse were even lower than their historical minimum level. Like Chiang Saen and Paksane, water levels from the stretches of the river from Stung Treng to Kratie and at Kampong Cham in Cambodia went up following the same trend of the upstream ones and stayed close to their minimum level.

The water volume of the Tonle Sap Lake during this reporting period wasslightly higher than that in 2019 and 2020 of the same period but was still lower than its LTA.

Over the next few days, the water levels across most monitoring stations are expected to continue rising but still staying below their long-term value in most stations.

Drought condition and its forecast

Drought situation was getting better in the monitoring week during August 14-20. The combined drought indicator shows no significant threat in the region amid some meteorological droughts in the middle part of the LMB.

For the upcoming thee-month forecast, the LMB is likely to receive much below average rainfall in August mainly in the central and southern parts of the region; September is forecasted to be extremely wet in the north, moderately wet and normal in the middle, and normal and moderately dry in southern areas of the region. Like 2020, the forecast shows that October is likely the wettest month of the year. November is forecasted to receive from average to above average rainfall throughout the LMB.

Source: Agency Kampuchea Press