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Weekly Wet Season Situation Report in the Lower Mekong River Basin - 10-16 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 took place from Chiang Sean in Thailand to Pakse in Lao PDR, including the lower part in Cambodia and Viet Nam, varying from 10.20 millimetres (mm) to 261.00 mm.

  • There will be some rainfalls for the next 5 days over the Mekong region from 17 to 23 August 2021 due to low-pressure dominating the Mekong region.

Water level and its forecast

  • The outflows at Jinghong hydrological station slightly increased over the monitoring period from 10 to 16 August 2021. It was up about 0.02 m from 535.25 metres (m) on August 10 to 535.27 m on August 16. The outflows increased from 818.00 cubic metres per second (m³/s) on August 10 to 832.00 m³/s on August 16.

  • Amid the significantly low outflow from Jinghong upstream, water levels across most monitoring stations from Chiang Saen in Thailand to Pakse in Lao PDR increased during August 10-16 but were still lower than their long-term averages. Similarly, water levels from the stretches of the river from Stung Treng to Kratie and at Kampong Cham in Cambodia also went up following the same trend of the upstream ones.

  • 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

  • From August 7 to 13, the LMB was still experiencing some moderate and severe droughts in overall conditions mainly in the central part of the region covering Roi Et, Maha Sarakham, Surin, Yasothon, and Amrat Charoen. In the lower part of the LMB, some areas of Dak Lak and Gia Lai were also experiencing some moderate and severe droughts.

  • 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.