Seasonal Flood Situation Report 2015
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Mekong River Commission Flood Management and Mitigation Programme Seasonal Flood Situation Report for the Lower Mekong River Basin Covering the period from 1st June to 31rd October 2015 (Final) Prepared by: Regional Flood Management and Mitigation Centre April 2016 Certification of Approval of Internal FMMP Technical Document Seasonal Flood Situation Report for the Lower Mekong River Basin st Cover the period from 1 June to 31 st October 2015 No Name of Person Position Date Signature Mr. Nguyen Quoc Operational l. Anh MeteorologistIForecaster Dr. Pichaid River Flood Forecasting 2. Varoonchotikul Expert 3. Mr. Hourt Khieu Operations Manager International Technical 4. Ir. Nicolaas Bakker Advisor Mr. Oudomsack 5. FMMP Coordinator Philavong Dir. Truong Hong 6. TSD Director Tien Seasonal Flood Situation Report for the Lower Mekong River Basin, 1st June - 31st October 2015 Table of Contents Table of Contents ...................................................................................................................... i List of Figures ........................................................................................................................... i List of Tables ........................................................................................................................... ii 1. INTRODUCTION .......................................................................................................... 1 2. FLOOD SEASON 2015 ................................................................................................. 3 2.1 Rainfall situation ............................................................................................................... 3 2.2 General Behaviour of the Mekong River and Seasonal Flood Situation ........................ 15 3. FLOOD FORECAST IN 2015 ..................................................................................... 29 3.1 Data collection for models and flood forecast bulletin dissemination ............................ 29 3.2 Accuracy and limitations in forecasting ......................................................................... 30 3.3 Lesson learned and actions to be taken ........................................................................... 32 Annex A Graphs and Tables .............................................................................................. 35 Annex B Accuracy and performance ................................................................................. 43 Annex C Season Water Level Graphs ............................................................................... 47 List of Figures Figure 2-1 Rainfall Distribution from 01 June to 31 October 2015 in the Lower Mekong Basin. ................................................................................................... 5 Figure 2-2 Weather map for TLP and ITCZ on 31 July 2015 .............................................. 6 Figure 2-3 Typhoons, Tropical Storms and Tropical Depressions entering the Pacific Ocean area in 2015 ................................................................................. 8 Figure 2-4 Tropical Depressions, Storms and Typhoons that directly affected the LMB in 2015 from East Sea ............................................................................... 9 Figure 2-5 Tropical Cyclone KOMEN from North India Ocean affected the LMB. ........... 9 Figure 2-6 KUJIRA tropical storm track. .......................................................................... 11 Figure 2-7 LINFA tropical storm track .............................................................................. 12 Figure 2-8 VAMCO tropical storm track ........................................................................... 13 Figure 2-9 MUJIGAE tropical storm track ........................................................................ 15 Figure 2-10 Rapidly rising of water levels at stations: Chiang Saen, Luang Prabang, Chiang Khan, Vientiane, Nong Khai and Paksane. .......................................... 19 Figure 2-11 Hydrograph of Flood event 1 at Luang Prabang. ............................................. 19 Figure 2-12 Rainfall – runoff graph at Paksane (25 July – 16 August 2015). ..................... 20 Figure 2-13 Rapidly rising of water levels at stations: Nakhon Phanom, Thakhek, Mukdahan, Savannakhet, Khong Chiam and Pakse. ........................................ 21 Page i Seasonal Flood Situation Report for the Lower Mekong River Basin, 1st June - 31st October 2015 Figure 2-14 Rainfall – runoff graph at Nakhon Phanom (25 July – 16 August 2015). ....... 22 Figure 2-15 Rapidly rising of water levels from Stung Treng to Kampong Cham. ............ 25 Figure 2-16 Hydrographic at stations Phnom Penh Bassac Chactomuk / Phnom Penh Port to Koh Khel / Neak Luong / Prek Kdam. ................................................. 26 Figure 2-17 Hydrographic at stations at Tan Chau and at Chau Doc. ................................. 27 Figure 3-1 Forecast performance based on original results by URBS and Regression........................................................................................................ 31 Figure 3-2 Forecast performance based on original results by URBS and ISIS................ 31 Figure A1 Monthly rainfall distribution for Jinghong, Chiang Saen, Luang Prabang and Chiang Khan. ............................................................................................ 35 Figure A2 Monthly rainfall distribution for Chiang Khan, Vientiane, Nong Khai, Paksane and Nakon Phanom. ........................................................................... 35 Figure A3 Monthly rainfall distribution for Thakhek, Mukdahan, Savannakhet and Khong Chiam. .................................................................................................. 36 Figure A4 Monthly rainfall distribution for Pakse, Stung Treng, Kratie and Kampong Cham. .............................................................................................. 36 Figure A5 Monthly rainfall distribution for Phnom Penh (Bassac and Port), Koh Khel and Neak Luong. ..................................................................................... 36 Figure A6 Monthly rainfall distribution for Prek Kdam, Tan Chau and Chau Doc. ......... 36 Figure A7 Monthly rainfall in June for main stations along the Mekong River. .............. 37 Figure A8 Monthly rainfall in July for main stations along the Mekong River. ............... 38 Figure A9 Monthly rainfall in August for main stations along the Mekong River. .......... 39 Figure A10 Monthly rainfall in September for main stations along the Mekong River ..... 40 Figure A 11 Monthly rainfall in October for main stations along the Mekong River. ....... 41 Figure B1 Average flood forecast accuracy along the Mekong mainstream. ................... 43 Figure B2 Data delivery times for flood season 2015 from June to October. .................. 45 Figure B3 Missing data for flood season 2015 from June to October .............................. 45 Figure B4 Flood forecast completion time. ...................................................................... 45 Figure B5 Flood forecast stations without forecast .......................................................... 45 Figure B6 Second forecast needed .................................................................................... 46 List of Tables Table 2-1 The average monthly rainfall in the flood seasons 2000-2015. ......................... 4 Table 2-2 Average total rainfall in Upper, Middle and Downstream part in flood season 2015. ....................................................................................................... 4 Table 2-3 List of tropical depressions, storms and typhoons in 2015 ................................ 7 Table 2-5 KUJIRA Track History. ................................................................................... 10 Table 2-6 LINFA track history. ...................................................................................... 12 Table 2-7 VAMCO track history. .................................................................................... 13 Table 2-8 MUJIGAE track history. .................................................................................. 14 Table 2-9 The flood peaks of the Mekong mainstream stations during the 2015 flood season. .................................................................................................... 16 Table 2-10 Flood event characteristics from Chiang Saen to Paksane. ............................. 17 Page ii Seasonal Flood Situation Report for the Lower Mekong River Basin, 1st June - 31st October 2015 Table 2-11 Precipitation observed in the mainstream stations during the flood event 25 July – 16 August 2015 in the LMB ............................................................. 18 Table 2-12 Flood event characteristics from Nakhon Phanom to Pakse. .......................... 21 Table 2-13 Precipitation observed in the mainstream stations during the 2015 flood season. .............................................................................................................. 23 Table 2-14 Flood event characteristics from Stung Treng to Kampong Cham. ................. 24 Table 2-15 Flood event characteristics from Phnom Penh Bassac Chaktomuk / Phnom Penh Port to Koh Khel / Neak Luong / Prek Kdam. ............................ 26 Table A1 Monthly observed rainfall in flood season 2015. ............................................. 35 Table B1 Achievement of daily forecast against