Attachments
Key Messages
Key messages for this weekly report are presented below:
Rainfall and its forecast
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Rainfall focused in the areas from Chiang Saen in Thailand to Tan Chau and Chau Doc in Viet Nam, including the upper, middle and lower parts of the LMB covering Lao PDR and Cambodia, varying from 2.30 millimetres (mm) to 162.00 mm.
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There will be moderate and heavy rainfall for the next 5 days over the Mekong region from 25 to 31 July 2023 although there is no any movement of tropical storm moving towards the Mekong region.
Water level and its forecast
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According to MRC’s observed water level at Jinghong, it showed fluctuated water levels from 535.79 m and 538.11 m during 18-24 July 2023. The current level is staying about 0.79 m higher than its LTA value. The outflow at Jinghong station varied between 1,210.00 m3/s and 3,1420.00 m3/s during 18-24 July 2023.
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With the fluctuated outflow from Jinghong upstream and rainfall at catchment inflow, water levels of monitoring stations at Chiang Saen in Thailand increased about 0.59 m from 18 to 24 July 2023, staying about 2.08 m lower than its LTA level. WLs at Xieng Kok upstream of Chiang Saen increased about 2.08 m.
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Water level at Chiang Khan in Thailand from 18 to 24 July 2023 decreased about 1.30 m and stayed about 3.62 m lower than its LTA value, while water level at Vientiane decreased about 0.56 m staying about 2.65 m lower than its LTA level. Water levels at Nong Khai decreased 0.30 m and stayed about 4.06 m lower than its LTA, while at Paksane it increased about 0.17 m, staying about 4.08 m lower than its LTA value. Water levels at these stations are still considered low.
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Water levels from Nakhon Phanom to Pakse increased from 0.54 m to 0.85 m, due to the contribution of high rainfalls and inflows from upstream. The current WLs at these stations are staying lower than their LTA value, considering low levels.
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From the stretches of the river from Stung Treng, Kratie to Kompong Cham, water level increased and still stayed lower than their LTA value, which was also considered low.
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The water volume of the Tonle Sap Lake was lower than its LTA (about 40%) during the same period from 18 to 24 July 2023, which is considered low.
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Water levels from downstream at Chaktomuk, Koh Khel on the Bassac and Phnom Penh Port to Prek Kdam in Cambodia increased and still staying lower than their LTA level.
The current water levels for stations are lower than their LTA value. WLs at the 2 tidal stations at Tan Chau and Chau Doc were fluctuating and lower than their LTA value, due to tidal effect during this monitoring period, considered critical. -
Over the next five days, the water levels at the upper, middle and lower parts from Chiang Saen to Pakse and those in downstream from Stung Treng down to the Mekong floodplain area are expected to go up due to moderate rainfall and dam operation upstream.
Drought condition and its forecast
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During July 17-23, moderate and severe droughts took place over some areas from the eastern part to the southern part covering Banteay Meanchey, Phrea Vihear, Kampong Chhang, Kampong Thom, Oudomxay, Bokeo, Borikhamxay, Phongsaly, Khammuane, Savannakhet, Chiang Rai, Nong Khai, Nakhon Phanom, Ubon Ratchathani, Sakon Nakhon, Burirum, Surin, and Si Saket.
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The three-month forecast shows that July is likely to be moderately and severely dry over the northern and some southern parts of the LMB. They specifically cover Chiang Mai, Chiang Rai, Phongsaly, Vientiane, Xaysomboun, Borikhamxay, Nong Khai, Chanthaburi, Pailin, Battambang, Pursat, Kampong Speu, Kom Tum, Gia Lai, Dak Lak, Kien Giang, and Ca Mau. August is likely to be moderately and severely dry over some area of the north and south-eastern LMB. They cover Vientiane, Khammuane, Savannakhet, Saravane, Sekong, Champasack, Attapeu, Kon Tum, Gia Lai, Ratana Kiri, Stung Treng, Kratie, Kampong Cham, Mondul Kiri, Dak Lak, and Lam Dong. While in September, drought is forecasted to be from moderate to exceptional drought covering eastern and southeastern LMB including Chaiyaphum, Nakhon Ratchasima, Burirum, Surin, Sa Kaeo, Ordar Meanchey, Banteay Meanchey, Siem Reap, Preah Vihear, Kampong Thom, Chantaburi, Pailin, Battambang, Pursat, Kampong Chhnang, Kampot, Kampong Spue, Takeo, Kandal, Prey Veng, Kampong Cham, Kratie, Prey Veng, Svay Rieng, Tay Ninh, Kien Giang, Ca Mau, Bac Lieu, and Soc Trang.