Mekong River Commission Regional Flood Management and Mitigation Centre

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U Mekong River Commission Regional Flood Management and Mitigation Centre Weekly Flood Situation Report for the Mekong River Basin Prepared at: /7/, covering the week from the th June to nd July

usually, abundant rainfall occurs during this month due to the influential southwest monsoon prevailing over Lower Mekong Basin together with low-pressure air mass cells.

1 U Mekong River Commission Regional Flood Management and Mitigation Centre Weekly Flood Situation Report for the Mekong River Basin Prepared at: /7/, covering the week from the th June to nd July Weather Patterns, General Behaviour of the Mekong River and Flood Situation General weather patterns During the week of th June to nd July, the weather bulletins were issued by the Department of Meteorology (DOM) of Cambodia. The weather maps of the th June st July are presented in the Figures & below: Figure : Weather map for th June Figure : Weather map for st July Moderate South-West (SW) Monsoon From June to July, usually, abundant rainfall occurs during this month due to the influential southwest monsoon prevailing over Lower Mekong Basin together with low-pressure air mass cells. The weather maps from Thai Meteorological Department on th June and st July, see Figure and. Tropical depressions (TD), tropical storms (TS) or typhoons (TY) No TD, TS or TY was presented in LMB during last week. Other weather phenomena that affect the discharge According to the Thai Meteorological Department (TMD), there will influence the prevailing southwest monsoon over Mekong region, including the Gulf of Thailand to become more rainfall. No low pressure was hit the Mekong region, during that time. Over weather situation During the last week, the weather was scattered thundershowers with isolated heavy rain of the Southwest monsoon. Consequently, on th there was heavy rainfall over Chiang Sean and Luang Prabang catchment areas which caused of water raised up to. m on 9 th June at Chiang Sean and at Luang Prabang water level raised up to. 7 m on th June. The weekly rainfall distribution from th June to nd July is shown in Figure. MRC Weekly Flood Situation Report Week th June nd July Page

2 Tuesday, rd July Figure : Weekly Rainfall Distribution over the LMB from th June - nd July MRC Weekly Flood Situation Report Week th June nd July Page

3 Tuesday, rd July General behaviour of the Mekong River During the last week, the water levels at stations from upper to middle part of LMB has been decreasing due to inflow operation upstream part, while at downstream part has been slightly rising. For stations from Chiang Saen and Luang Prabang Compared to the long-term average (LTA), water levels from h June to nd July at Chiang Sean station were rapidly raised up to. m on 9 th June which over the LTA, while at Luang Prabang station also water level were jumped up to.7 on th June,. For stations from Chiang Khan, Vientiane and Nong Khai and Paksane Compared to the long-term average (LTA), water levels at these stations were increasing above their LTAs due to the upstream effected rainfall. For stations from Nakon Phanom/ Thakhet to Pakse Compared to their long-term averages (LTAs), water levels at Thakhet to Pakse stations were slightly increased due to upstream influent. For stations from Stung Treng to Kompong Cham Compared to their long-term averages (LTAs), water levels at these stations were slightly decreasing below their LTAs. For stations from Phnom Penh to Koh Khel/Neak Luong Compared to the long-term average (LTA), water levels at these stations were slightly decreasing below their LTAs. Tan Chau and Chau Doc Compared to the long-term average (LTA), water levels at these two tidal stations were fluctuated around their LTAs. Note: For areas between forecast stations, please refer to the nearest forecast station. Flood Situation Flood stage or alarm stage: No alarm stage (where the forecast is expected to reach flood level within three days) was reported anywhere on the mainstream of the Mekong River during the last week. Water levels were still significantly below flood levels (as defined by the national agency) at all forecast stations. Damage or victims: No damage or loss of life due to river flooding was recorded anywhere along the Mekong River during the last week. For more details see the following annexes: - tables and graphs for water level and rainfall for the last week in Annex A - a graph for accuracy in Annex B - a table of forecast achievement in Annex B - tables and graphs for performance in Annex B - the water level graphs showing the observed water level for the season in Annex C MRC Weekly Flood Situation Report Week th June nd July Page

4 Jinghong Chiang Saen Luang Prabang Chiang Khan Vientiane Nongkhai Paksane Nakhon Phanom Thakhek Mukdahan Savannakhet Khong Chiam Pakse Stung Treng Kratie Kompong Cham Phnom Penh (Bassac) Phnom Penh Port Koh Khel Neak Luong Prek Kdam Tan Chau Chau Doc Jinghong Chiang Saen Luang Prabang Chiang Khan Vientiane Nongkhai Paksane Nakhon Phanom Thakhek Mukdahan Savannakhet Khong Chiam Pakse Stung Treng Kratie Kompong Cham Phnom Penh (Bassac) Phnom Penh Port Koh Khel Neak Luong Prek Kdam Tan Chau Chau Doc Tuesday, rd July Annex A: Graphs and Tables Table A: observed water levels Unit in m // // // // // // /7/ /7/ Table A: observed rainfall Unit in mm // nr nr nr nr nr...9 // nr nr nr nr..9. nr. 7// nr.9 nr // nr nr... nr nr nr.7. 9// nr nr nr nr 7. nr. nr nr nr.7 nr nr 7..7 // nr nr nr nr nr nr nr - /7/. nr..7.. nr nr 7. nr nr nr nr nr nr. nr nr /7/ nr nr. nr nr.. nr nr nr nr nr nr nr nr MRC Weekly Flood Situation Report Week th June nd July Page

5 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 hour rainfall at 7am (mm) hour rainfall at 7am (mm) hour rainfall at 7am (mm) / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 / / / /7 Tuesday, rd July Figure A: Observed water level and rainfall for Jinghong, Chiang Saen, and Luang Prabang Jinghong Cheang Sean Luang Prabang 7 7 Chau Doc observed water level Flood level Alarm Level Jinghong Chiang Saen Luang Prabang Average level: 9-7 Average level: (Jinghong) MRC Weekly Flood Situation Report Week th June nd July Page

6 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 hour rainfall at 7am (mm) hour rainfall at 7am (mm) hour rainfall at 7am (mm) hour rainfall at 7am (mm) / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 Tuesday, rd July Figure A: Observed water level and rainfall for Chiang Khan, Vientiane, Nongkhai, and Paksane Chiang Khan Vientiane Nongkhai Paksane Chiang Khan Vientiane Nongkhai Paksane 7 MRC Weekly Flood Situation Report Week th June nd July Page

7 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 hour rainfall at 7am (mm) hour rainfall at 7am (mm) hour rainfall at 7am (mm) hour rainfall at 7am (mm) / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 Tuesday, rd July Figure A: Observed water level and rainfall for Nakhon Phanom, Thakhek, Mukdahan and Savannakhet Nakhon Phanom Thakhek Mukdahan Savannakhet 7 Nakhon Phanom Thakhek Mukdahan Savannakhet MRC Weekly Flood Situation Report Week th June nd July Page 7

8 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 hour rainfall at 7am (mm) hour rainfall at 7am (mm) hour rainfall at 7am (mm) hour rainfall at 7am (mm) / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 Tuesday, rd July Figure A: Observed water level and rainfall for Khong Chiam, Pakse, Stung Treng, and Kratie Khong Chiam Pakse Stung Treng Kratie Khong Chiam Pakse Stung Treng Kratie MRC Weekly Flood Situation Report Week th June nd July Page

9 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 hour rainfall at 7am (mm) hour rainfall at 7am (mm) hour rainfall at 7am (mm) hour rainfall at 7am (mm) / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 Tuesday, rd July Figure A: Water level and rainfall for Kompong Cham, Phnom Penh (Bassac and Port), and Koh Khel Kompong Cham Pnom Penh (Bassac) Phnom Penh Port Koh Khel Kompong Cham 9 Phnom Penh (Bassac) Phnom Penh Port Koh Khel 7 MRC Weekly Flood Situation Report Week th June nd July Page 9

10 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 hour rainfall at 7am (mm) hour rainfall at 7am (mm) hour rainfall at 7am (mm) hour rainfall at 7am (mm) / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 / / 7/ / 9/ / /7 /7 Tuesday, rd July Figure A: Water level and rainfall for Neak Luong, Prek Kdam, Tan Chau and Chau Doc Neak Luong Prek Kdam Tan Chau Chau Doc 9 7 Neak Luong Prek Kdam Tan Chau 9 Chau Doc 7 MRC Weekly Flood Situation Report Week th June nd July Page

Tuesday, rd July Annex B: Accuracy and performance Accuracy Accuracy describes the accuracy of the adjusted and published forecast, based on the results of the MRC Mekong Flood Forecasting System,

11 Tuesday, rd July Annex B: Accuracy and performance Accuracy Accuracy describes the accuracy of the adjusted and published forecast, based on the results of the MRC Mekong Flood Forecasting System, which are then adjusted by the Flood Forecaster in Charge taking into consideration known biases in input data and his/her knowledge of the response of the model system and the hydrology of the Mekong River Basin. The information is presented as a graph below, showing the average flood forecasting accuracy along the Mekong mainstream. In general, the overall accuracy is fair for -day to -day forecast lead time at stations in the upper and lower parts of the LMB. However, the accuracies at upper and middle reaches of the LMB stations from Chaing Sean to Paksane stations for -day to -day forecast were considered large. The above differences due to three main factors: () internal model functionality in forecasting; for which the parameter adjustment in the model is not possible especially at stations in the upper part and in the Mekong delta where are affected by tidal; () the adjustment by utilizing the practical knowledge and experience of flood forecaster-in-charge; and () the forecasted accumulated rainfall was not well represented. Figure B: Average flood forecast accuracy along the Mekong mainstream MRC Weekly Flood Situation Report Week th June nd July Page

Tuesday, rd July Forecast Achievement The forecast

particular station for a lead-time is successful against a

Table B: Evaluation performance forecasting (from June- July

12 Tuesday, rd July Forecast Achievement The forecast achievement indicates the % of days that the forecast at a particular station for a lead-time is successful against a respective benchmark (Table B). Table B: Evaluation performance forecasting (from June- July ) base on New Benchmark (%). Unit in % Unit in cm MRC Weekly Flood Situation Report Week th June nd July Page

13 Tuesday, rd July Table B: Evaluation performance forecasting (from June- July ) base on Old Benchmark (%). Unit in % Unit in cm Note: An indication of the accuracy given in the Table B is based on the performance of the forecast made in from the new flood forecasting system and the configuration for the 9 flood season and is published on the website of MRC ( A new set of performance indicators that is established by combining international standards and the specific circumstances in the Mekong River Basin, is applied officially for the flood season of onward. MRC Weekly Flood Situation Report Week th June nd July Page

14 Time FF completed and sent (time) Stations without forecast FF completed and sent (time) Weather data available (time) NOAA data China Cambodia - DHRW Cambodia - DOM Lao PDR - DMH Thailand - DWR Viet Nam - SRHMC Viet Nam - HMS NOAA data/dataset China/ Cambodia - DHRW/ Cambodia - DOM/ Lao PDR - DMH/ Thailand - DWR/ Viet Nam - SRHMC/ Viet Nam - HMS/9 Tuesday, rd July Performance Performance is assessed by evaluating a number of performance indicators, see table and graphs below: Table B: Overview of performance indicators for the past days including the current report date FF time sent Arrival time of input data Missing data (number-mainstream and trib.st.) week : : - - : 7: 7: 7: : :9 7: : 77 month : : - - : 7: 7: 7: : : 7: : 7 Week is the week for which this report is made; Month is actually the last days (or less if the flood season has just begun); Season is the current flood season up to the date of this report. 9: 9: : : 7: 7:9 7: Data Delivery - Delivery Times / / 7/ / 9/ / /7 /7 Date Figure B: Data delivery times for the past days including the current report date NOAA data/dataset China/ Cambodia - DHRW/ Cambodia - DOM/ Lao PDR - DMH/ Thailand - DWR/ Viet Nam - SRHMC/ Viet Nam - HMS/9 MRC Weekly Flood Situation Report Week th June nd July Page

15 Number Tuesday, rd July Data Delivery - Missing Data / / 7/ / 9/ / /7 /7 Date NOAA data/dataset China/ Cambodia - DHRW/ Cambodia - DOM/ Lao PDR - DMH/ Thailand - DWR/ Viet Nam - SRHMC/ Viet Nam - HMS/9 Figure B: Missing data for the past days including the current report date Time Flood Forecast - Completion Time Flood Forecast - Stations without Forecast Time Flood Forecast - Second Forecast Needed : : : : : : : : 9: Date / / 7/ / 9/ / /7 /7 Date / / 7/ / 9/ / /7 /7 9: Date / / 7/ / 9/ / /7 /7 Figure B: Flood forecast completion time Figure B: Flood forecast stations without forecast Figure B: Second forecast needed MRC Weekly Flood Situation Report Week th June nd July Page

16 Tuesday, rd July Annex C: Season Water Level Graphs This Annex has the water level graphs of the report date. These graphs are distributed daily by together with the Flood Bulletins. HYDROGRAPHS OF THE MEKONG AT MAINSTREAM STATIONS IN FLOOD SEASON FROM JUNE TO OCTOBER Water Level at 7am of Mekong at Chiang Saen -Jun -Jun -Jul -Jul -Jul -Aug -Aug -Sep 9-Sep -Oct 9-Oct -Nov Alarm Flood Av Time in days Water Level at 7am of Mekong at Luang Prabang -Jun -Jun -Jul -Jul -Jul -Aug -Aug -Sep 9-Sep -Oct 9-Oct -Nov Alarm Flood Av Time in days MRC Weekly Flood Situation Report Week th June nd July Page

17 Tuesday, rd July Water Level at 7am of Mekong at Paksane -Jun -Jun -Jul -Jul -Jul -Aug -Aug -Sep 9-Sep -Oct 9-Oct -Nov Alarm Flood Av Water Level at 7am of Mekong at Nakhon Phanom -Jun -Jun -Jul -Jul -Jul -Aug -Aug -Sep 9-Sep -Oct 9-Oct -Nov Time in days Alarm Flood Av Water Level at 7am of Mekong at Thakhek -Jun -Jun -Jul -Jul -Jul -Aug -Aug -Sep 9-Sep -Oct 9-Oct -Nov Alarm Flood Av MRC Weekly Flood Situation Report Week th June nd July Page 7

18 Tuesday, rd July Water Level at 7am of Mekong at Savannakhet -Jun -Jun -Jul -Jul -Jul -Aug -Aug -Sep 9-Sep -Oct 9-Oct -Nov Alarm Flood Av Water Level at 7am of Mekong at Mukdahan -Jun -Jun -Jul -Jul -Jul -Aug -Aug -Sep 9-Sep -Oct 9-Oct -Nov Alarm Flood Av Water Level at 7am of Mekong at Khong Chiam -Jun -Jun -Jul -Jul -Jul -Aug -Aug -Sep 9-Sep -Oct 9-Oct -Nov Alarm Flood Av MRC Weekly Flood Situation Report Week th June nd July Page

19 Tuesday, rd July Water Level at 7am of Mekong at Pakse -Jun -Jun -Jul -Jul -Jul -Aug -Aug -Sep 9-Sep -Oct 9-Oct -Nov Alarm Flood Av Water Level at 7am of Mekong at Stung Treng -Jun -Jun -Jul -Jul -Jul -Aug -Aug -Sep 9-Sep -Oct 9-Oct -Nov Alarm Flood Av Water Level at 7am of Mekong at Kratie -Jun -Jun -Jul -Jul -Jul -Aug -Aug -Sep 9-Sep -Oct 9-Oct -Nov Alarm Flood Av MRC Weekly Flood Situation Report Week th June nd July Page 9

20 Tuesday, rd July Water Level at 7am of Mekong at Kampong Cham -Jun -Jun -Jul -Jul -Jul -Aug -Aug -Sep 9-Sep -Oct 9-Oct -Nov Alarm Flood Av Water Level at 7am of Mekong at Phnom Penh Chaktomuk -Jun -Jun -Jul -Jul -Jul -Aug -Aug -Sep 9-Sep -Oct 9-Oct -Nov Alarm Flood Av Water Level at 7am of Tonle Sap at Phnom Penh Port -Jun -Jun -Jul -Jul -Jul -Aug -Aug -Sep 9-Sep -Oct 9-Oct -Nov Alarm Flood Av MRC Weekly Flood Situation Report Week th June nd July Page

21 Tuesday, rd July 9 Water Level at 7am of Bassac at Koh Khel 7 -Jun -Jun -Jul -Jul -Jul -Aug -Aug -Sep 9-Sep -Oct 9-Oct -Nov Alarm Flood Av Water Level at 7am of Mekong at Neak Luong 7 -Jun -Jun -Jul -Jul -Jul -Aug -Aug -Sep 9-Sep -Oct 9-Oct -Nov Alarm Flood Av Water Level at 7am of Tonle Sap at Prek Kdam -Jun -Jun -Jul -Jul -Jul -Aug -Aug -Sep 9-Sep -Oct 9-Oct -Nov Alarm Flood Av MRC Weekly Flood Situation Report Week th June nd July Page

22 Tuesday, rd July Water Level at 7am of Mekong at Tan Chau - -Jun -Jun -Jul -Jul -Jul -Aug -Aug -Sep 9-Sep -Oct 9-Oct -Nov Alarm Flood Av Water Level at 7am of Bassac at Chau Doc - -Jun -Jun -Jul -Jul -Jul -Aug -Aug -Sep 9-Sep -Oct 9-Oct -Nov Alarm Flood Av MRC Weekly Flood Situation Report Week th June nd July Page

Mekong River Commission Regional Flood Management and Mitigation Centre

U Mekong River Commission Regional Flood Management and Mitigation Centre Weekly Flood Situation Report for the Mekong River Basin Prepared at: /7/, covering the week from the th to th July Weather Patterns,