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Weekly Wet Season Situation Report in the Lower Mekong River Basin - 24-30 August 2021

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Situation Report
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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 16.20 millimetres (mm) to 186.70 mm.

  • There will be some rainfallsfor the next 5 days over the Mekong region from 31 August to 05 September 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 decrease over the monitoring period from 24 to 30 August 2021. It was down about 0.09 m from 535.68 metres (m) on August 24 to 535.59 m on August 30. The outflows increased from 1106 cubic metres per second (m³/s) on August 24 to 1,043 m³/s on August 30.

  • Along with significant low outflow from Jinghong upstream, water levels across most monitoring stations from Chiang Saen in Thailand to Thakhek in Lao PDR decreased during August 24-30 due to below average rainfall in the upper parts of the LMB. Moreover, water levels from Khong Chiam in Thailand to Pakse were even lower than their historical minimum level. Water levels from the stretches of the river from Stung Treng to Kratie and at Kampong Cham in Cambodia, moreover, followed the same trend of the upstream ones and stayed lower than 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 periods but was still lower than its LTA.

  • Over the next few days, the water levels across most monitoring stations are expected to slightly rise but remain lower than their long-term value in most stations.

Drought condition and its forecast

  • The drought situation from August 21 to 27 was similar to last week (August 14 to 20). The combined drought indicator shows no significant threat in the region except some moderate and severe hot spots in Savannakhet and Khammuan of Lao PDR which was caused by meteorological indicator.

  • For the upcoming thee-month forecast, the LMB is likely to receive above average rainfall in September and October mainly in the central and southern parts 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.