U Mekong River Commission Regional Flood Management and Mitigation Centre Weekly Flood Situation Report for the Mekong River Basin Prepared on: //9, covering the week from 19 to October 9 Weather Patterns, General Behaviour of the Mekong River and Flood Situation General weather patterns During the week of 19 October 9, seven weather bulletins were issued by the Department of Meteorology (DOM) of Cambodia. The weather charts of 19 and 5 October bulletins are presented in the figures below: Figure 1: Weather map for 19 October 9 Figure : Weather map for 5 October 9 Weak South-West (SW) Monsoon Week SW monsoon prevailed over the Bay of Bengal, Gulf of Thailand and Indochina Peninsula (Figure 1 and figure ). Inter Tropical Convergence Zone (ITCZ) On 1 October, Inter Tropical Convergence Zone (ITCZ) laid across Myanmar, Thailand, Northern Cambodia, Southern Lao PDR, and Southern Viet Nam and across the Bay of Bengal, Thailand, Cambodia and Southern Viet Nam during 3 October 9. Tropical depressions (TD), tropical storms (TS) or typhoons (TY) Severe Tropical Storm (STS) with a central pressure 9 hpa, located at latitude o N, longitude 131 o 7 E, which was over Philippine Sea on 5 October 9, was moving to NE with a speed of km/h with maximum wind speed in the central of STS is km/h (Figure ). Other weather phenomena that affect the discharge No other weather phenomena affecting the discharge were observed. Overall weather situation A normal weather situation lasted during last week. The SW monsoon prevailed over the Bay of Bengal, Gulf of Thailand and Indochina Peninsula. From October 9, scattered Cc, Cu and Cb cloud caps were observed over Myanmar, Thailand, Lao PDR, Cambodia and Viet Nam. The slight colder temperature occurred in Northern Thailand, Northern Viet Nam, and Northern Lao PDR from 3 rd October. The big thunderstorms and isolated very heavy rain occurred in MRC Weekly Flood Situation Report Week 19 th th October 9 Page 1
U Cambodia, Southern Thailand and Southern Viet Nam between 19 and 1 October 9 as the result of these phenomena. U General behaviour of the Mekong River Water levels along the Mekong River were more-or-less stable during the monitored period. Between Chaing Saen and Pakse water levels were slightly falling and most stations were recording levels that are somewhat below the long-term average. Between Stung Treng and Tan Koh Khel/Neak Luong water level were slightly rising and most stations were recording levels that are somewhat slightly above the long-term average. Water levels at Tan Chau and Chau Doc monitoring stations were above alarm levels during the past week. For stations from Chiang Saen to Vientiane/Nong Khai Water levels were more-or-less stable, slightly falling towards the end of the week. Most stations were recording levels that are somewhat below the long-term average for this time of the year. For stations from Paksane to Pakse Water levels were more-or-less stable, slightly falling towards the end of the week. Most stations were recording levels that are somewhat below the long-term average for this time of the year. For stations from Stung Treng to Kompong Cham Water levels were more-or-less stable, slightly rising towards the end of the week. Most stations were recording levels that are somewhat slightly above the long-term average for this time of the year. For stations from Phnom Penh to Koh Khel/Neak Luong Water levels were more-or-less stable, slightly rising towards the end of the week. Most stations were recording levels that are somewhat slightly above the long-term average for this time of the year. Tan Chau and Chau Doc Water levels were falling towards the end of the week. Both stations were recording levels that are somewhat slightly below the long-term average for this time of the year. The water levels at both stations were above the alarm levels as defined by the national agency. Note: for areas between forecast stations, please refer to the nearest forecast station. Flood Situation Flood stage or alarm stage: During the last week, the water levels at Tan Chau and Chau Doc were above alarm levels as defined by the national agency. No alarm stage (where the forecast is expected to reach flood level within three days) was reported anywhere on the mainstream Mekong River during the past week. Water levels are still below flood levels (as defined by the national agencies) 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 past week. 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 Page MRC Weekly Flood Situation Report Week 19 th th October 9
Annex A: Graphs and Tables Table A1: observed water levels unit in m Jinghong Chiang Saen Luang Prabang Chiang Khan Vientiane Nongkhai Paksane Nakhon Phanom Thakhek Mukdahan Savannakhet 9 19/ 3.35 7. 7.5.33 5.1.3. 5..15 3.13 5.9.7 5..5 11. 9..3 7.1.7. 3. 3.3 / 3.53 7. 7.37.1...15 5.39.9 3. 5.93.3..7.93.99.3 7.17.5.57 3.79 3.3 1/ 3.5.9 7.7..7.7.7 5.3.5 3. 5... 15.5 11..99.3 7..55.5 3.7 3.3 / 3..9 7..1.5 5.99 3.9 5. 3.9. 5.9.5 5.5.7 11.1.97.9 7.13.5.55 3.7 3. 3/ 3.5.95 7...3 5.9 3.7 5. 3..77 5.9.1 5.7.5.7.9. 7...51 3.1 3. / 3.77. 7. 3.95. 5.9 3. 5.7 3.77.7 5.7. 5.75..71..1 7.9..9 3.57 3. 5/ 3.7. 7. 3.9.5 5. 3.79 5.5 3.7.5 5..37..9.7.7.13 7..3.5 3.53 3.13 / 3.1 7. 7.1 3..5 5.7 3. 5.5 3.7.3 5..33.1 15.35.9..19 7..37.3 3.5 3. Flood level 11. 1. 17..5..5.7.. 13.... 3... 11. 7.9... 3.5 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 9 19/ 3.......... 3.5 1.3.3. 7... 9.5..3.. /. 19..........3 11... 5.1.. 1.5 1.... 1/. 3..... 3. 1............... /.. 9. 1......... 1....... 9.5.. 3/ 9........... 1... 7.9.3.... 1.. / 3.............. 1..5. 13. 55. 53... 5/.7............. 1. 3.7.. 3.. 19.. /..... 5............ 5.5 1.... 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 19 th th October 9 Page 3
Figure A1: Water level and rainfall for Jinghong, Chiang Saen, and Luang Prabang Jinghong Chiang Saen Luang Prabang 5 1 1 Jinghong Chiang Saen Luang Prabang 3 Rainfall data is not available from // until 15// 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / hour rainfall at 7am (mm) 19/ / 1/ / 3/ / 5/ 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / 3 hour rainfall at 7am (mm) Water level data is not available from // until 15// 3 hour rainfall at 7am (mm) Page MRC Weekly Flood Situation Report Week 19 th th October 9
Figure A: Water level and rainfall for Chiang Khan, Vientiane, Nongkhai, and Paksane Chiang Khan Vientiane Nongkhai Paksane 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / Chiang Khan Vientiane Nongkhai Paksane 7 7 5 3 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / hour rainfall at 7am (mm) hour rainfall at 7am (mm) 5 3 hour rainfall at 7am (mm) hour rainfall at 7am (mm) 1 1 MRC Weekly Flood Situation Report Week 19 th th October 9 Page 5
Figure A3: Water level and rainfall for Nakhon Phanom, Thakhek, Mukdahan and Savannakhet Nakhon Phanom Thakhek Mukdahan Savannakhet 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / Nakhon Phanom Thakhek Mukdahan Savannakhet 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / hour rainfall at 7am (mm) hour rainfall at 7am (mm) hour rainfall at 7am (mm) hour rainfall at 7am (mm) Page MRC Weekly Flood Situation Report Week 19 th th October 9
Figure A: Water level and rainfall for Khong Chiam, Pakse, Stung Treng, and Kratie Khong Chiam Pakse Stung Treng Kratie 1 1 1 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / Khong Chiam Pakse Stung Treng Kratie 3 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / hour rainfall at 7am (mm) hour rainfall at 7am (mm) hour rainfall at 7am (mm) hour rainfall at 7am (mm) MRC Weekly Flood Situation Report Week 19 th th October 9 Page 7 1
Figure A5: Water level and rainfall for Kampong Cham, Phnom Penh (Bassac and Port), and Koh Khel Kompong Cham Phnom Penh (Bassac) Phnom Penh Port Koh Khel 1 1 9 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / Kompong Cham Phnom Penh (Bassac) Phnom Penh Port Koh Khel 7 7 5 3 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / hour rainfall at 7am (mm) hour rainfall at 7am (mm) hour rainfall at 7am (mm) 7 5 3 1 Page MRC Weekly Flood Situation Report Week 19 th th October 9 9 7 5 3 1 5 3 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 Chau Doc 9 9 5 5 5 7 7 5 3 5 3 3 1 1 1 1 1 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / Neak Luong Prek Kdam Tan Chau Chau Doc 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / 19/ / 1/ / 3/ / 5/ / hour rainfall at 7am (mm) hour rainfall at 7am (mm) 3 3 hour rainfall at 7am (mm) MRC Weekly Flood Situation Report Week 19 th th October 9 Page 9 5 3 1 hour rainfall at 7am (mm)
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. The graph of average difference between forecast and actual water levels for the past week shows that the overall accuracy is fairly good for 1-day to -day forecasts. The poor accuracy for 5-day lead times at many locations perhaps caused by poor satellite forecast rainfall. Figure B1: Average flood forecast accuracy along the Mekong mainstream Page MRC Weekly Flood Situation Report Week 19 th th October 9
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 B1: Achievement of daily forecast against benchmarks unit in % Chiang Saen Luang Prabang Chiang Khan Vientiane Nongkhai Paksane Nakhon Phanom Thakhek Mukdahan Savannakhet Khong Chiam 1-day.............9.9 71. 5.7...... 9.9 -day... 3.3 3.3....... 33.3 33.3.7....... 9.9 3-day...................... 7.3 -day.. 75. 75. 75.. 5. 5... 75. 75. 5. 5. 75.... 75.... 1. 5-day...7 33.3.7. 33.3 33.3.7.7 33.3 33.3.......7..7.7 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 1-day 5 5 5 5 5 5 5 5 5 5 5 5 -day 75 75 5 5 5 5 5 5 5 5 5 5 5 5 5 3-day 75 5 5 5 5 5 5 5 5 75 75 5 5 5 -day 5 75 5 5 5 5 5 75 75 75 75 5 5 5 5 5 5 5 5-day 15 75 75 75 75 75 75 75 75 75 75 5 5 5 5 5 5 5 Khong Chiam 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). In the future these indicators will be adjusted against a set of performance indicators that is established by combining international standards and the specific circumstances in the Mekong River Basin. An expert mission to establish these performance indicators is planned for the fourth quarter of 9. MRC Weekly Flood Situation Report Week 19 th th October 9 Page 11
Performance Performance is assessed by evaluating a number of performance indicators, see table and graphs below: Table B3: 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 9 week :19 - : - : : :3 : :15 1 3 7 month : - 3 : :19 : 7:57 :7 : 7:5 33 5 5 5 season : 33 : 1 : :3 :3 :1 : :1 7:55 77 3 1599 91 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 3 days (or less if the flood season has just begun); Season is the current flood season up to the date of this report. Time 13: : 11: : 9: : 7: Data Delivery - Delivery Times 19/ / 1/ / 3/ / 5/ / Date NOAA China CAM DHRW CAM DOM LAO DMH THAI DWR VN NCHMF Figure B: Data delivery times for the past days including the current report date Page MRC Weekly Flood Situation Report Week 19 th th October 9
Number 3 5 15 5 Data Delivery - Missing Data 19/ / 1/ / 3/ / 5/ / Date NOAA China CAM DHRW CAM DOM LAO DMH THAI DWR VN NCHMF Figure B3: Missing data for the past days including the current report date Time 11: Flood Forecast - Completion Time Flood Forecast - Stations without Forecast Time 15: Flood Forecast - Second Forecast Needed : : 13: : 11: : 9: Date 19/ / 1/ / 3/ / 5/ / Date 19/ / 1/ / 3/ / 5/ / 9: Date 19/ / 1/ / 3/ / 5/ / Figure B: Flood forecast completion time Figure B5: Flood forecast stations without forecast Figure B: Second forecast needed MRC Weekly Flood Situation Report Week 19 th th October 9 Page 13
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 WET SEASON FROM 1 JUNE TO 31 OCTOBER 59. Water level at 7am of Mekong at Jinghong 57. 55. 53. 51. 539. 537. 535. 15/Jun 3/Jun 15/Jul 3/Jul /Aug 9/Aug 13/Sep /Sep 13/Oct 3 Av- 9. Water level at 7am of Mekong at Chiang Saen....... 1/Jun /Jun 1/Jul /Jul 31/Jul 15/Aug 3/Aug /Sep 9/Sep /Oct 9/Oct Alarm Flood 199 199 Av- 9 Page MRC Weekly Flood Situation Report Week 19 th th October 9
Water level at 7am of Mekong at Luang Prabang. 15.. 5.. 1/Jun /Jun 1/Jul /Jul 31/Jul 15/Aug 3/Aug /Sep 9/Sep /Oct 9/Oct Alarm Flood 199 199 Av- 9. Water level at 7am of Mekong at Chiang Khan 1.......... 1/Jun /Jun 1/Jul /Jul 31/Jul 15/Aug 3/Aug /Sep 9/Sep /Oct 9/Oct Alarm Flood 199 199 Av- 9. Water level at 7am of Mekong at Vientiane........ 1/Jun /Jun 1/Jul /Jul 31/Jul 15/Aug 3/Aug /Sep 9/Sep /Oct 9/Oct Alarm Flood 199 199 Av- 9 MRC Weekly Flood Situation Report Week 19 th th October 9
. Water level at 7am of Mekong at Nong Khai........ 1/Jun /Jun 1/Jul /Jul 31/Jul 15/Aug 3/Aug /Sep 9/Sep /Oct 9/Oct Alarm Flood 199 199 Av- 9. Water level at 7am of Mekong at Paksane........ 1/Jun /Jun 1/Jul /Jul 31/Jul 15/Aug 3/Aug /Sep 9/Sep /Oct 9/Oct Alarm Flood 199 199 Av- 9. Water level at 7am of Mekong at Nakhon Phanom....... 1/Jun /Jun 1/Jul /Jul 31/Jul 15/Aug 3/Aug /Sep 9/Sep /Oct 9/Oct Alarm Flood 199 199 Av- 9 Page MRC Weekly Flood Situation Report Week 19 th th October 9
. Water level at 7am of Mekong at Thakhek........ 1/Jun /Jun 1/Jul /Jul 31/Jul 15/Aug 3/Aug /Sep 9/Sep /Oct 9/Oct Alarm Flood 199 199 Av- 9. Water level at 7am of Mekong at Savannakhet....... 1/Jun /Jun 1/Jul /Jul 31/Jul 15/Aug 3/Aug /Sep 9/Sep /Oct 9/Oct Alarm Flood 199 199 Av- 9. Water level at 7am of Mekong at Mukdahan....... 1/Jun /Jun 1/Jul /Jul 31/Jul 15/Aug 3/Aug /Sep 9/Sep /Oct 9/Oct Alarm Flood 199 199 Av- 9 MRC Weekly Flood Situation Report Week 19 th th October 9
. Water level at 7am of Mekong at Paksé....... 1/Jun /Jun 1/Jul /Jul 31/Jul 15/Aug 3/Aug /Sep 9/Sep /Oct 9/Oct Alarm Flood 199 199 Av- 9. Water level at 7am of Mekong at Stung Treng...... 1/Jun /Jun 1/Jul /Jul 31/Jul 15/Aug 3/Aug /Sep 9/Sep /Oct 9/Oct Alarm Flood 199 199 Av- 9 Water level at 7am of Mekong at Kratie.... 1.......... 1/Jun /Jun 1/Jul /Jul 31/Jul 15/Aug 3/Aug /Sep 9/Sep /Oct 9/Oct Alarm Flood 199 199 Av- 9 Page 1 MRC Weekly Flood Situation Report Week 19 th th October 9
1. Water level at 7am of Mekong at Kompong Cham......... 1/Jun /Jun 1/Jul /Jul 31/Jul 15/Aug 3/Aug /Sep 9/Sep /Oct 9/Oct Alarm Flood 199 199 Av- 9 1. Water level at 7am of Bassac at Phnom Penh......... 1/Jun /Jun 1/Jul /Jul 31/Jul 15/Aug 3/Aug /Sep 9/Sep /Oct 9/Oct Alarm Flood 199 199 Av- 9 1. Water level at 7am of Tonle Sap at Phnom Penh Port......... 1/Jun /Jun 1/Jul /Jul 31/Jul 15/Aug 3/Aug /Sep 9/Sep /Oct 9/Oct Alarm Flood 199 199 Av- 9 MRC Weekly Flood Situation Report Week 19 th th October 9
9. Water level at 7am of Bassac at Koh Khel. 7.. 5.. 3.. 1.. 1/Jun /Jun 1/Jul /Jul 31/Jul 15/Aug 3/Aug /Sep 9/Sep /Oct 9/Oct Alarm Flood 199 199 Av- 9 9. Water level at 7am of Mekong at Neak Luong. 7.. 5.. 3.. 1.. 1/Jun /Jun 1/Jul /Jul 31/Jul 15/Aug 3/Aug /Sep 9/Sep /Oct 9/Oct Alarm Flood 199 199 Av- 9. Water level at 7am of Tonle Sap at Prek Kdam...... 1/Jun /Jun 1/Jul /Jul 31/Jul 15/Aug 3/Aug /Sep 9/Sep /Oct 9/Oct Alarm Flood 199 199 Av- 9 Page MRC Weekly Flood Situation Report Week 19 th th October 9
. Water level at 7am of Mekong at Tan Chau 5.. 3.. 1.. 1/Jun /Jun 1/Jul /Jul 31/Jul 15/Aug 3/Aug /Sep 9/Sep /Oct 9/Oct Alarm Flood 199 199 Av- 9. Water level at 7am of Bassac at Chau Doc 5.. 3.. 1.. 1/Jun /Jun 1/Jul /Jul 31/Jul 15/Aug 3/Aug /Sep 9/Sep /Oct 9/Oct Alarm Flood 199 199 Av- 9 MRC Weekly Flood Situation Report Week 19 th th October 9