Mekong River Commission Regional Flood Management and Mitigation Centre

Transcription

1 U Mekong River Commission Regional Flood Management and Mitigation Centre Weekly Flood Situation Report for the Mekong River Basin Prepared on: 9/9/, covering the week from the th to the th September, Weather Patterns, General Behaviour of the Mekong River and Flood Situation General weather patterns During the week of the th to the th September, four weather bulletins were issued by the Department of Meteorology (DOM) of Cambodia. The weather charts of the th and the 9 th August bulletins are presented in the figures below: Figure : Weather map for th September Figure : Weather map for th September Strong to week South-West (SW) Monsoon Strong SW monsoon prevailed over Andaman Sea, the Gulf of Thailand, Thailand and Cambodia the beginning to the mid of the week and became weakening in the rest of the week (Figure and ). Inter Tropical Convergence Zone (ITCZ) ITCZ laid across the Myanmar, Thailand, Lao PDR and Viet Nam during last week (Figure and ). Tropical depressions (TD), tropical storms (TS) or typhoons (TY) No Tropical Depression, Tropical Storm or Typhoon has significant affected to the LMB in last week. Other weather phenomena that affect the discharge No other weather phenomena affecting the discharge were observed. Over weather situation A severe weather situation was occurred during the first half of the week. As the result of strong SW monsoon activity, appearances of ITCZ in the whole week and low pressure trough laid across Thailand, Lao PDR, Cambodia and Viet Nam at the height.5 km (5 hpa), heavy rain occurred in the North and central of Myanmar, Thailand, the North of Lao PDR and Viet Nam during the mid of the week. Figure illustrates rainfall amount distribution over the LMB, covering last week. During MRC Weekly Flood Situation Report Week th September th September Page

2 Monday, 9 th September last week, heavy rain occurred in the upper and middle parts of LMB from Luang Prabang to Savannkhet/Mukdahan and the amounts of rainfall covering last week, which is over mm, were recorded at Paksane (mm); at Nong Khai (5.7mm); at Thakhek (mm); at Nakon Phanom (57.mm); at Ban Tha Kok Daeng (9.5mm); at Ban Phone Si (7. mm); at Muong Mai (5. mm). Figure : Rainfall distribution over the LMB, covering the week September, General behaviour of the Mekong River Water levels at most stations along the Mekong river were above the long-term average except Chiang Saen and Luang Prabang. While water level in the Mekong showed a falling and rising trend at stations in the upper reach, water levels at stations in the middle and lower reaches were rising during reporting period. Regarding to two stations in downstream at Tan Chau and Chau Doc, water levels at those two stations were fluctuated by tidal with increasing trend in the monitoring period. MRC Weekly Flood Situation Report Week th September th September Page

3 Monday, 9 th September For stations from Chiang Saen to Vientiane/ Nong Khai Water level showed a decreasing trend in the first half of the week then was increasing till the end of the week and these stations were recording levels that are somewhat over the long-term average except Chiang Saen and Luang Prabang where were recording levels that somewhat are below and around the long-term average for this time of the year. For stations Paksane to Pakse Water levels were rapidly rising with average intensity of.. m/day as the result of inter tropical convergence zone and strong Southwest monsoon influences during last week. These stations were recording levels that are above the long-term average for this time of the year. Figure and 5 show rapidly rising of water levels at stations from Nakon Phanom/Thakhek to Khong Chiam in last week..5 H (m).5.5 R_Nakon Phanom R_Thakhek H_Nakon Phanom H_Thakhek H Nakon Phanom =.7m H Thakhek =.9m R (mm) Sep -Sep -Sep 5-Sep -Sep 7-Sep -Sep Time (day) 5 Figure : Rapidly increasing of water level on mainstream at stations Nakon Phanom, Thakhek H (m) 5 R_Nakon Phanom R_Thakhek R_Khong Chiam H_Mukdahan H_Savannakhet H_Khong Chiam H Mukdahan =.5m H Khong Chiam =.m R (mm) 9 H Savannakhet =.m -Sep -Sep -Sep 5-Sep -Sep 7-Sep -Sep Time (day) 5 Figure 5: Rapidly increasing of water level on mainstream at stations Savannakhet, Mukdahan and Khong Chiam MRC Weekly Flood Situation Report Week th September th September Page

4 UU U U Monday, 9 th September Water levels at stations on the left bank tributaries of Lao PDR such as at Ban Phone Si of Nam Ca Dinh river, at Mahaxai of Se Bang Fai and at Ban Pak Kanhoung of Nam Ngun river rose up quickly in last week (Figure ). H (m) 5 R_Ban Pak Kanhoung R_Ban Phone Si R_Mahaxai H_Ban Pak Kanhoung H_Ban Phone Si H_Mahaxai H Ban Phone Si =.m H Mahaxai =.55m R (mm) 9 H Ban Pak Kanhoung =.m 5 7 -Sep -Sep -Sep 5-Sep -Sep 7-Sep -Sep Time (day) 7 Figure : Rapidly increasing of water levels at stations on tributaries: Nam Ca Dinh river at Ban Phone Si, Se Bang Fai river at Mahaxai and Nam Ngun river at Ban Pak Kanhoung For stations Strung Treng to Kompong Cham Water levels were falling in the first half of the week and then rising till the end of the week. These stations were recording levels are above the long-term average for this time of the year. For stations from Phnom Penh Port/ Phnom Penh Bassac to Prek Dam Water levels at these stations showed a slightly rising trend during last week and were above the longterm average for this time of the year. Tan Chau and Chau Doc Water levels were rising till the end of the week. Both stations were recording levels that are above the long-term average for this time of the year and significantly affected by tidal. Note: for areas between forecast stations, please refer to the nearest forecast station. MRC Weekly Flood Situation Report Week th September th September Page

5 Monday, 9 th September Flood Situation Flood stage or alarm stage: - The Mekong has reached flood stage at Pakse since th September,. - The Mekong has reached alarm situation at 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 September th September Page 5

6 Monday, 9 th September 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 / / / / / / / / Flood level 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 7.. nr nr. -.. nr. - / nr nr nr - / nr. nr -.7 nr 5. nr - 5/ nr nr -. nr nr.5 - / nr / nr nr nr.... nr / nr. nr - nr nr 7. nr - 9/ nr nr - nr nr nr nr 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 Page MRC Weekly Flood Situation Report Week th September th September

7 Monday, 9 th September Figure A: Water level and rainfall for Jinghong, Chiang Saen, and Luang Prabang Chiang Saen Luang Prabang Jinghong /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 hour rainfall at 7am (mm) /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 Chiang Saen hour rainfall at 7am (mm) 7/9 /9 9/9 Luang Prabang MRC Weekly Flood Situation Report Week th September th September Page 7 hour rainfall at 7am (mm) 7/9 /9 9/9 Jinghong 5 5 5

8 Monday, 9 th September Figure A: Water level and rainfall for Chiang Khan, Vientiane, Nongkhai, and Paksane Chiang Khan Vientiane Nongkhai Paksane /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 /9 9/9 Chiang Khan Vientiane Nongkhai Paksane /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 /9 9/9 hour rainfall at 7am (mm) hour rainfall at 7am (mm) 9 hour rainfall at 7am (mm) hour rainfall at 7am (mm) Page MRC Weekly Flood Situation Report Week th September th September

9 Monday, 9 th September Figure A: Water level and rainfall for Nakhon Phanom, Thakhek, Mukdahan and Savannakhet Thakhek Mukdahan /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 Thakhek 5 9 /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 hour rainfall at 7am (mm) 7/9 /9 9/9 Mukdahan MRC Weekly Flood Situation Report Week th September th September Page 9 Savannakhet hour rainfall at 7am (mm) 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 /9 9/9 5 Savannakhet /9 /9 /9 5/9 /9 7/9 /9 9/9 hour rainfall at 7am (mm) Nakhon Phanom Nakhon Phanom 5 9 hour rainfall at 7am (mm)

10 Monday, 9 th September Figure A: Water level and rainfall for Khong Chiam, Pakse, Stung Treng, and Kratie Khong Chiam Pakse Stung Treng Kratie /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 /9 9/9 Khong Chiam Pakse Stung Treng Kratie /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 /9 9/9 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 th September th September

11 Monday, 9 th September Figure A5: Water level and rainfall for Kompong Cham, Phnom Penh (Bassac and Port), and Koh Khel Kompong Cham Phnom Penh (Bassac) Phnom Penh Port /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 Phnom Penh (Bassac) /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 hour rainfall at 7am (mm) /9 9/9 Phnom Penh Port MRC Weekly Flood Situation Report Week th September th September Page Koh Khel hour rainfall at 7am (mm) /9 9/9 /9 /9 /9 5/9 /9 7/9 /9 9/9 5 Koh Khel /9 /9 /9 5/9 /9 7/9 /9 9/9 hour rainfall at 7am (mm) Kompong Cham hour rainfall at 7am (mm)

12 Monday, 9 th September 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 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 /9 9/9 Neak Luong Prek Kdam Tan Chau Chau Doc 5 /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 /9 9/9 /9 /9 /9 5/9 /9 7/9 /9 9/9 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 th September th September

13 Monday, 9 th September 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 good for -day and -day forecast lead time at most stations; however accuracies at stations Luang Prabang and Khong Chiam for -day to 5-day forecast were less than expected. The above differences due to main factors: () high variability of the SRE and NWP when appearance of critical weather pattern as ITCZ; () internal model functionality in forecasting for middle reach of the LMB in taking into account flow contribution from tributaries, for which the parameter adjustment in the model is not possible; () the adjustment by flood forecaster-in-charge at those stations. Figure B: Average flood forecast accuracy along the Mekong mainstream MRC Weekly Flood Situation Report Week th September th September Page

14 Monday, 9 th September 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 day day day day 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 -day day day day day 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. Khong Chiam Pakse Stung Treng Kratie Kompong Cham Phnom Penh (Bassac) Phnom Penh Port Koh Khel Neak Luong Prek Kdam Tan Chau Chau Doc Page MRC Weekly Flood Situation Report Week th September th September

15 Monday, 9 th September 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 5 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 :7-5 : :9 7: :7 9:7 7: :5 month : - :9 : 7: :5 9: 7: 7: season :9 : : :9 7:5 : :5 7:5 7: 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 /9 /9 /9 5/9 /9 7/9 /9 9/9 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 MRC Weekly Flood Situation Report Week th September th September Page 5

16 Monday, 9 th September Number 5 Data Delivery - Missing Data /9 /9 /9 5/9 /9 7/9 /9 9/9 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 5: Flood Forecast - Second Forecast Needed : : : : : : 9: Date /9 /9 /9 5/9 /9 7/9 /9 9/9 Date /9 /9 /9 5/9 /9 7/9 /9 9/9 9: Date /9 /9 /9 5/9 /9 7/9 /9 9/9 Figure B: Flood forecast completion time Figure B5: Flood forecast stations without forecast Figure B: Second forecast needed Page MRC Weekly Flood Situation Report Week th September th September

17 Monday, 9 th September 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 5 Water level at 7am of Mekong at Jing Hong Jun -Jun 5-Jul -Jul -Aug 9-Aug -Sep -Sep -Oct -Oct Av9-99 Water level at 7am of Mekong at Chiang Saen -Jun -Jun -Jul -Jul -Jul 5-Aug -Aug -Sep 9-Sep -Oct 9-Oct Alarm Flood Av Water level at 7am of Mekong at Luang Prabang -Jun -Jun -Jul -Jul -Jul 5-Aug -Aug -Sep 9-Sep -Oct 9-Oct Alarm Flood Av MRC Weekly Flood Situation Report Week th September th September Page 7

18 Monday, 9 th September Water level at 7am of Mekong at Chiang Khan -Jun -Jun -Jul -Jul -Jul 5-Aug -Aug -Sep 9-Sep -Oct 9-Oct Alarm Flood Av Water level at 7am of Mekong at Vientiane Km -Jun -Jun -Jul -Jul -Jul 5-Aug -Aug -Sep 9-Sep -Oct 9-Oct Alarm Flood Av Water level at 7am of Mekong at Nong Khai -Jun -Jun -Jul -Jul -Jul 5-Aug -Aug -Sep 9-Sep -Oct 9-Oct Alarm Flood Av Page MRC Weekly Flood Situation Report Week th September th September

19 Monday, 9 th September Water level at 7am of Mekong at Paksane -Jun -Jun -Jul -Jul -Jul 5-Aug -Aug -Sep 9-Sep -Oct 9-Oct Alarm Flood Av Water level at 7am of Mekong at Nakhon Phanom -Jun -Jun -Jul -Jul -Jul 5-Aug -Aug -Sep 9-Sep -Oct 9-Oct Alarm Flood Av Water level at 7am of Mekong at Thakhek -Jun -Jun -Jul -Jul -Jul 5-Aug -Aug -Sep 9-Sep -Oct 9-Oct Alarm Flood Av MRC Weekly Flood Situation Report Week th September th September Page 9

20 Monday, 9 th September Water level at 7am of Mekong at Savannakhet -Jun -Jun -Jul -Jul -Jul 5-Aug -Aug -Sep 9-Sep -Oct 9-Oct Alarm Flood Av Water level at 7am of Mekong at Mukdahan -Jun -Jun -Jul -Jul -Jul 5-Aug -Aug -Sep 9-Sep -Oct 9-Oct Alarm Flood Av Water level at 7am of Mekong at Paksé -Jun -Jun -Jul -Jul -Jul 5-Aug -Aug -Sep 9-Sep -Oct 9-Oct Alarm Flood Av Page MRC Weekly Flood Situation Report Week th September th September

21 Monday, 9 th September Water level at 7am of Mekong at Stung Treng -Jun -Jun -Jul -Jul -Jul 5-Aug -Aug -Sep 9-Sep -Oct 9-Oct Alarm Flood Av Water level at 7am of Mekong at Kratie -Jun -Jun -Jul -Jul -Jul 5-Aug -Aug -Sep 9-Sep -Oct 9-Oct Alarm Flood Av Water level at 7am of Mekong at Kompong cham -Jun -Jun -Jul -Jul -Jul 5-Aug -Aug -Sep 9-Sep -Oct 9-Oct Alarm Flood Av MRC Weekly Flood Situation Report Week th September th September Page

22 Monday, 9 th September Water level at 7am at Phnom Penh Chaktomuk -Jun -Jun -Jul -Jul -Jul 5-Aug -Aug -Sep 9-Sep -Oct 9-Oct Alarm Flood Av Water level at 7am of Tonle Sap at Phnom Penh Port -Jun -Jun -Jul -Jul -Jul 5-Aug -Aug -Sep 9-Sep -Oct 9-Oct Alarm Flood Av Water level at 7am of Bassac at Koh Khel 7 5 -Jun -Jun -Jul -Jul -Jul 5-Aug -Aug -Sep 9-Sep -Oct 9-Oct Alarm Flood Av Page MRC Weekly Flood Situation Report Week th September th September

23 Monday, 9 th September 9 Water level at 7am of Mekong at Neak Luong 7 5 -Jun -Jun -Jul -Jul -Jul 5-Aug -Aug -Sep 9-Sep -Oct 9-Oct Alarm Flood Av Water level at 7am of Tonle Sap at Prek Kdam -Jun -Jun -Jul -Jul -Jul 5-Aug -Aug -Sep 9-Sep -Oct 9-Oct Alarm Flood Av Water level at 7am of Mekong at Tan Chau 5 - -Jun -Jun -Jul -Jul -Jul 5-Aug -Aug -Sep 9-Sep -Oct 9-Oct Alarm Flood Av Water level at 7am of Bassac at Chau Doc 5 - -Jun -Jun -Jul -Jul -Jul 5-Aug -Aug -Sep 9-Sep -Oct 9-Oct Alarm Flood Av MRC Weekly Flood Situation Report Week th September th September Page