Mekong River Commission Regional Flood Management and Mitigation Centre Weekly Flood Situation Report for the Mekong River Basin Prepared at: //, covering the week from the th October to the st October Weather Patterns, General Behaviour of the Mekong River and Flood Situation General weather patterns During the week of th October to st October six weather bulletins were issued by the Department of Meteorology (DOM) of Cambodia. The weather charts of the th October and th October are presented in the figures below: Figure : Weather map for th October Figure : Weather map for th October Moderate South-West (SW) Monsoon No active monsoon was reported during last week. Inter Tropical Convergence Zone (ITCZ) No ITCZ was reported during last week. Tropical depressions (TD), tropical storms (TS) or typhoons (TY) On the th October, Typhoon (TY) NARI moved from middle of South China Sea to middle of Viet Nam and finally landfall over Da Nang, Viet Nam before downgrade as Tropical Depression (TD) over Lao PDR on th October. This took about - days from the beginning of last week. See Figure for Forecasting track of Tropical Cyclone issued at : AM on October (Japan meteorology Agency). Other weather phenomena that affect the discharge Low pressure area was formed after TY-NARI downgrade and move westward from Southern part of Lao PDR and North-east of Thailand to the West of Myanmar for the rest of the week. Over weather situation The TY-NARI happened at beginning of last week followed by the low pressure area that move westward from Southern part of Lao PDR and North-east of Thailand to the West of Myanmar for the rest of last week. As a result, scattered isolated heavy rainfall occurred in many areas in upper, middle and lower reaches of LMB. The amount of rainfall from th October to st October was recorded at Chiang Khan mm (with a one day maximum of. mm), Khong Chiam.7 mm (with a one day maximum of 7. mm), Pakse. mm (with a one day maximum of 9.7 mm), Neak Luong. mm (with a one day maximum of 7. mm) and Chau Doc mm (with a one day maximum of mm). See Figure for Weekly Rainfall Distribution of LMB covering the week th October to st October. MRC Weekly Flood Situation Report Week th October to st October Page
Figure : Forecasting track of Tropical Cyclone issued at : AM on October Source: Japan meteorology Agency MRC Weekly Flood Situation Report Week th October to st October Page
Figure : Weekly Rainfall Distribution of LMB covering the week th October to st October MRC Weekly Flood Situation Report Week th October to st October Page
General behaviour of the Mekong River During last week water levels at most stations in the upper and middle reaches of LMB, started below the long-term average water level (LTA), recessed at the beginning of the week then rose up at middle of last week before recessed at the end of last week below LTA except in Savannakhet, Mukdahan, Khong Chiam and Pakse which were above LTA. The water levels of the lower reach of LMB were rising above LTA. For stations from Chiang Saen and Luang Prabang Water levels of these stations were recessing at the beginning then rose up during last week lower than the LTA. For stations from Chiang Khan, Vientiane and Nong Khai and Paksane Water levels of these stations recessed at the beginning of the week then rose up at middle of last week before recessed at the end of last week below LTA. For stations from Thakhet/Nakhon Phanom to Pakse Water levels of these stations recessed at the beginning of the week then rose up at middle of last week before recessed at the end of last week below LTA except in Savannakhet, Mukdahan, Khong Chiam and Pakse which were above LTA. For stations from Stung Treng to Kompong Cham Water levels of these stations recessed at the beginning of the week then rose up at middle of last week before recessed at the end of last week above LTA. For stations from Phnom Penh to Koh Khel/Neak Luong Water levels at these stations were slowly recessing above the LTA at first half of last week then rose up for the rest of last week. Tan Chau and Chau Doc Water levels at these stations recessed at the first half of last week then rose up for the rest of last week above LTA. Note: For areas between forecast stations, please refer to the nearest forecast station. Flood Situation Flood stage or alarm stage: During the last week, water levels of some station along the Mekong have risen up to and above the alarm level, at Koh Khel, Tan Chau and Chau Doc monitoring stations. For more details see the following annex: - 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 October to st October Page
Annex A: Graphs and Tables Table A: observed water levels Unit in m Jinghong Chiang Saen Luang Prabang Chiang Khan Vientiane Nongkhai Paksane Nakhon Phanom Thakhek Mukdahan Savannakhet /...9 7...9..9....9...9. 9..7 7. 7. 9... /...79 7.9.9..9......7... 9.. 7. 7. 9..99. /...7.97.7......7..7... 9..7 7..9 9..9.7 7/.9.9..9.7.....9..9. 7.7..9 9.. 7...9.9. /...7 7....7.7...9 7.7.9 7. 7.. 9.. 7...99.9. 9/......9.. 7... 7.77. 7. 7.. 9..7 7..9 9.9.9. /... 7.9..7.. 7..9... 7. 7.7. 9..7 7..97 9..9. / 7..9 7. 7..7..7.9...9.. 7. 7.. 9..7 7..97 9..97. Khong Chiam Pakse Stung Treng Kratie Kompong Cham Phnom Penh (Bassac) Phnom Penh Port Koh Khel Neak Luong Prek Kdam Tan Chau Chau Doc Table A: observed rainfall Unit in mm Jinghong Chiang Saen Luang Prabang Chiang Khan Vientiane Nongkhai Paksane Nakhon Phanom Thakhek Mukdahan Savannakhet /.. nr... nr. nr. nr. nr nr nr nr nr - nr nr nr nr - /.. nr. nr. nr. nr. nr.. nr nr nr nr - nr nr nr nr - /.. nr. nr...... 7. 9.7 7.. nr. - nr.. nr - 7/.. nr...7..7.... nr 9.. nr nr -.. nr nr. /.. nr..... nr... nr. 9. nr. -... nr 7. 9/. 7.7 nr. nr. nr. nr. nr.. nr nr.7. -.. 7. 7.7. /. 7... nr. nr. -. nr. nr nr nr nr nr - nr. nr.. /.. nr. nr. nr. nr. nr. nr. nr nr nr - 7. 7. nr.. Khong Chiam Pakse Stung Treng Kratie Kompong Cham Phnom Penh (Bassac) Phnom Penh Port Koh Khel Neak Luong Prek Kdam Tan Chau Chau Doc MRC Weekly Flood Situation Report Week th October to st October Page
Figure A: Water level and rainfall for Jinghong, Chiang Saen, and Luang Prabang Chiang Saen Luang Prabang Jinghong / / / 7/ / 9/ / / / / / 7/ / 9/ / / / / / 7/ / hour rainfall at 7am (mm) / / / 7/ / 9/ / / / / / 7/ / 9/ / / / / / 7/ / Chiang Saen.... hour rainfall at 7am (mm) 9/ / / Luang Prabang. Page MRC Weekly Flood Situation Report Week th October to st October hour rainfall at 7am (mm) 9/ / / Jinghong
Figure A: Water level and rainfall for Chiang Khan, Vientiane, Nongkhai, and Paksane Vientiane Nongkhai / / / 7/ / 9/ / / / / / 7/ / 9/ / / / / / 7/ / Vientiane...... / / / 7/ / 9/ / / / / / 7/ / 9/ / / / / / 7/ / hour rainfall at 7am (mm) / / 9/ Nongkhai...... MRC Weekly Flood Situation Report Week th October to st October Page 7 Paksane hour rainfall at 7am (mm) 9/ / / / / / 7/ / 9/ / /..... Paksane hour rainfall at 7am (mm) / / / 7/ / 9/ / / Chiang Khan Chiang Khan..... hour rainfall at 7am (mm)
Figure A: Water level and rainfall for Nakhon Phanom, Thakhek, Mukdahan and Savannakhet Thakhek / / / 7/ / 9/ / / / / / 7/ / 9/ / / / / / Thakhek...... / / / 7/ / 9/ / / / / / 7/ / 9/ / / / / hour rainfall at 7am (mm) Page MRC Weekly Flood Situation Report Week th October to st October Mukdahan 7/ / 9/ / /..... Mukdahan Savannakhet hour rainfall at 7am (mm) / 7/ / 9/ / / / / / 7/ / 9/ / /..... Savannakhet hour rainfall at 7am (mm) / / / 7/ / 9/ / / Nakhon Phanom Nakhon Phanom..... hour rainfall at 7am (mm).
Figure A: Water level and rainfall for Khong Chiam, Pakse, Stung Treng, and Kratie Khong Chiam Pakse Stung Treng / / / 7/ / 9/ / / / / / 7/ / 9/ / / / / / 7/ / Pakse / / / 7/ / 9/ / / / / / 7/ / 9/ / / / / / 7/ / hour rainfall at 7am (mm) 9/ / / Stung Treng..... MRC Weekly Flood Situation Report Week th October to st October Page 9 Kratie hour rainfall at 7am (mm) 9/ / / / / / 7/ / 9/ / / Kratie hour rainfall at 7am (mm) / / / 7/ / 9/ / / Khong Chiam..... hour rainfall at 7am (mm)
Figure A: Water level and rainfall for Kompong Cham, Phnom Penh (Bassac and Port), and Koh Khel Kompong Cham Phnom Penh (Bassac) Phnom Penh Port / / / 7/ / 9/ / / / / / 7/ / 9/ / / / / / 7/ / 9/ Phnom Penh (Bassac) / / / 7/ / 9/ / / / / / 7/ / 9/ / / / / / 7/ / 9/ / / Phnom Penh Port Page MRC Weekly Flood Situation Report Week th October to st October 9 7 Koh Khel 9 7 / / / / 7/ / / 9/ / / Koh Khel hour rainfall at 7am (mm) / / 7/ / / 9/ / / Kompong Cham hour rainfall at 7am (mm) hour rainfall at 7am (mm) hour rainfall at 7am (mm)
Figure A: Water level and rainfall for Neak Luong, Prek Kdam, Tan Chau and Chau Doc Neak Luong Prek Kdam Tan Chau 9 9 7 7 - / / / 7/ / 9/ / / / / / 7/ / 9/ / / Neak Luong Prek Kdam / / / 7/ / 9/ / / / / / 7/ / 9/ / / / / / 7/ / hour rainfall at 7am (mm) hour rainfall at 7am (mm) / / / 7/ / 9/ / / Tan Chau MRC Weekly Flood Situation Report Week th October to st October Page - - Chau Doc hour rainfall at 7am (mm) 9/ / / / / / 7/ / 9/ / / Chau Doc - hour rainfall at 7am (mm) / / / 7/ / 9/ / /
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 all stations in LMB. However, the accuracies at Nakhon Phanom to Kratie for -day to -day forecast were less than expected. The above differences due to three main factors: () internal model functionality in forecasting; for which the parameter adjustment in the model is not possible; () the adjustment by utilizing the practical knowledge and experience of flood forecaster-in-charge; () Vital data from NOAA was not received during the week. Figure B: Average flood forecast accuracy along the Mekong mainstream Page MRC Weekly Flood Situation Report Week th October to st October
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: Achievement of daily forecast against benchmarks Unit in % Chiang Saen Luang Prabang Chiang Khan Vientiane Nongkhai Paksane Nakhon Phanom Thakhek Mukdahan Savannakhet Khong Chiam -day..7 7..9.9.9.9. 7..9.....9.7 7....... -day...7.7.......7.7..7..7.....7.. -day....................... -day 7. 7................. 7.... 7. -day.7.7................7...7. 9.7 Pakse Stung Treng Kratie Kompong Cham Phnom Penh (Bassac) Phnom Penh Port Koh Khel Neak Luong Prek Kdam Tan Chau Chau Doc Average Table B: Benchmarks of success (Indicator of accuracy in mean absolute error) Unit in cm Chiang Saen Luang Prabang Chiang Khan Vientiane Nongkhai Paksane Nakhon Phanom Thakhek Mukdahan Savannakhet Khong Chiam -day -day -day -day 7 7 -day 7 7 Pakse Stung Treng Kratie Kompong Cham Phnom Penh (Bassac) Phnom Penh Port Koh Khel Neak Luong Prek Kdam Tan Chau Chau Doc 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 (http://ffw.mrcmekong.org/accuracy.htm). 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 October to st October Page
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 Flood Forecast: time sent Arrival time of input data (average) Missing data (number) FF completed and sent (time) stations without forecast FF completed and sent (time) Weather informaition available (number) NOAA data China Cambodia - DHRW Cambodia - DOM week : - : :7 7: : : 7: 7: 9 month : - : : 7: : : 7: 7: 7 7 season : - : : 7: : :9 7: 7:9 99 7 77 Lao PDR - DMH Thailand - DWR Viet Nam - NCHMF NOAA data China Cambodia - DHRW Cambodia - DOM Lao PDR - DMH Thailand - DWR Viet Nam - NCHMF 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. Time : 9: : 7: Data Delivery - Delivery Times / / / 7/ / 9/ / / Date NOAA China CAM DHRW CAM DOM LAO DMH THAI DWR VN NCHMF Page MRC Weekly Flood Situation Report Week th October to st October
Figure B: Data delivery times for the past days including the current report date Number Data De live ry - Miss ing Data / / / 7/ / 9/ / / Date NOAA China CAM DHRW CAM DOM LAO DMH THAI DWR VN NCHMF 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/ / / Date / / / 7/ / 9/ / / 9: Date / / / 7/ / 9/ / / 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 October to st October Page
Annex C: Season Water Level Graphs This Annex has the water level graphs of the report date. These graphs are distributed daily by email 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 Jing Hong -Jun -Jul -Aug -Sep -Oct -Nov Av9-99 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- 99 99 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- 99 99 Page MRC Weekly Flood Situation Report Week th October to st October
Water Level at 7am of Mekong at Chiang Khan -Jun -Jun -Jul -Jul -Jul -Aug -Aug -Sep 9-Sep -Oct 9-Oct -Nov Alarm Flood Av- 99 99 Water Level at 7am of Mekong at Vientiane -Jun -Jun -Jul -Jul -Jul -Aug -Aug -Sep 9-Sep -Oct 9-Oct -Nov Alarm Flood Av- 99 99 Water Level at 7am of Mekong at Nong Khai -Jun -Jun -Jul -Jul -Jul -Aug -Aug -Sep 9-Sep -Oct 9-Oct -Nov Alarm Flood Av- 99 99 MRC Weekly Flood Situation Report Week th October to st October Page 7
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- 99 99 Water Level at 7am of Mekong at Nakhon Phanom -Jun -Jun -Jul -Jul -Jul -Aug -Aug -Sep 9-Sep -Oct 9-Oct -Nov Alarm Flood Av- 99 99 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- 99 99 Page MRC Weekly Flood Situation Report Week th October to st October
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- 99 99 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- 99 99 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- 99 99 MRC Weekly Flood Situation Report Week th October to st October Page 9
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- 99 99 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- 99 99 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- 99 99 Page MRC Weekly Flood Situation Report Week th October to st October
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- 99 99 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- 99 99 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- 99 99 MRC Weekly Flood Situation Report Week th October to st October Page
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- 99 99 9 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- 99 99 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- 99 99 Page MRC Weekly Flood Situation Report Week th October to st October
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- 99 99 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- 99 99 MRC Weekly Flood Situation Report Week th October to st October Page