U
Mekong River Commission Flood Management and Mitigation Programme
Final
Seasonal Flood Situation Report for the Lower Mekong River Basin
Covering period from 1st June to 31st December 2012
Prepared by Regional Flood Management and Mitigation Centre December 2012
Certification of Approval of Internal FMMP Technical Document
Seasonal Flood Situation Report for the Lower Mekong River Basin Covering period from 1st June to 31st December 2012
Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Table of Contents
Table of Contents ...... i
List of Figures ...... i
List of Tables ...... ii
1. Flood season 2012 ...... 1 1.1 Rainfall situation ...... 1 1.2 General Behaviour of the Mekong River and Seasonal Flood Situation ...... 6
2. Flood Forecast in 2012...... 13 2.1 Data collection for models and flood forecast bulletin dissemination ...... 13 2.2 Accuracy and limitations in forecasting ...... 13 2.3 Lesson learned and actions to be taken ...... 15
Annex A Graphics and Tables ...... 19 Annex B Accuracy and performance ...... 41 Annex C Season Water Level Graphs ...... 49
List of Figures
Figure 1‐1 Total depth of rainfall in the flood season of the years 2000, 2002, 2008, 2009, 2010, 2011, 2012 and the long‐term average flood seasonal rainfall ...... 1 Figure 1‐2 Weather map for Southwest Monsoon in the end of July ...... 2 Figure 1‐3 Weather maps for ITCZ in the end of August and mid‐October...... 3 Figure 1‐4 VICENTE Storm Track...... 4 Figure 1‐5 Weather map for VICENTE Typhoon on 24th July 2012, before landing ...... 4 Figure 1‐6 Weather map for VICENTE Tropical Depression on 25th July 2012, after landing ...... 4 Figure 1‐7 TEMBIN and BOLAVEN Storm Tracks...... 5 Figure 1‐8 TEMBIN and BOLAVEN weather chart...... 5 Figure 1‐9 GAEMI Storm Track ...... 6 Figure 1‐10 Weather map for GAEMI in the afternoon 06th Oct, before landing...... 6 Figure 1‐11 Weather map for GAEMI in the evening 06th Oct, after landing...... 6 Figure 1‐12 Quick rising of water levels at stations: Xieng Kok and Chiang Saen during 26th – 29th July 2012 ...... 9 Figure 1‐13 Water level rising at stations: Pak Beng, Chiang Khong, Muong Ngoy and Luang Prabang during 26th – 29th July 2012...... 10 Figure 1‐14 Water levels rising at stations: Vientiane, Nong Khai and Paksane during 26th – 29th July 2012 ...... 11 Figure 2‐1 Forecast performance based on original results by URBS and Regression...... 14 Figure 2‐2 Forecast performance based on original results by URBS and ISIS ...... 15
Figure A1 Monthly rainfall distribution for Jinghong, Chiang Saen, Luang Prabang and Chiang Khan...... 20
Page i Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Figure A2 Monthly rainfall distribution for Chiang Khan, Vientiane, Nong Khai , Paksane and Nakhon Phanom...... 21 Figure A3 Monthly rainfall distribution for Thakhek, Mukdahan, Savannakhet and Khong Chiam...... 22 Figure A4 Monthly rainfall distribution for, Pakse, Stung Treng, Kratie and Kompong Chiam...... 23 Figure A5 Monthly rainfall distribution for Phnom Penh (Bassac and Port), Koh Khel and Neak Luong...... 24 Figure A6 Monthly rainfall distribution for Prek Kdam, Tan Chau and Chau Doc...... 25 Figure A7 Monthly rainfall in June for main stations along the Mekong River...... 26 Figure A8 Monthly rainfall in July for main stations along the Mekong River...... 28 Figure A9 Monthly rainfall in August for main stations along the Mekong River...... 30 Figure A10 Monthly rainfall in September for main stations along the Mekong River...... 32 Figure A11 Monthly rainfall in October for main stations along the Mekong River...... 34
Figure B1 Average flood forecast accuracy along the Mekong mainstream...... 41 Figure B2 Data delivery times for flood season 2012 from June to October...... 45 Figure B3 Missing data for flood season 2012 from June to October...... 46 Figure B4 Flood forecast completion time...... 47 Figure B5 Flood forecast stations without forecast...... 47 Figure B6 Second forecast needed...... 47
List of Tables Table 1‐1 The flood peaks of main locations along the Mekong mainstream during 2012 flood season ...... 8
Table A1 Monthly observed rainfall in flood season 2012 ...... 19 Table A2 The characteristics of flood events for station from Chiang Saen to Vientiane/Nong Khai ...... 36 Table A3 The characteristics of flood events for stations from Paksane to Pakse ...... 37 Table A4 The characteristics of flood events for stations from Stung Treng to Kompong Cham ...... 38 Table A5 The characteristics of flood events for stations from Phnom Penh Bassac/Phnom Penh Port, Koh Khel/Neak Luong to Prek Kdam ...... 39 Table A6 The characteristics of flood events for stations from Tan Chau and Chau Doc (**) ...... 40
Table B1 Achievement of daily forecast against benchmarks ...... 42 Table B2 Benchmarks of success (Indicator of accuracy in mean absolute error) ...... 43 Table B3 Overview of performance indicators for flood season 2012 from June to October ...... 44
Page ii Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
1. Flood season 2012
1.1 Rainfall situation
The critical rainfall situation in the Lower Mekong Basin, as previous year, was concentrated in July and August, a period of Southwest Monsoon activity, low pressure troughs, storm and typhoon’s appearances in the South China Sea. In terms of total seasonal rainfall, the general picture was one of the average years (see Figure 1‐1). It can be seen that the total rainfall in the flood season 2012 at all stations in LMB (except Luang Prabang, Chiang Khan, Kratie, Kompong Cham and Phnom Penh Bassac) is lower than the long‐term average and all is lower than those of the previous flood season 2011.
The spatial variation of rainfall is high indicating that the intensity of heavy rain situations along the Lower Mekong Basin from upstream to downstream took place as a function of time (Annex A: 1. Graphs and Tables for monthly observed rainfall distribution during flood season 2012): • The wet season started in early June; the heavy rain mostly occurred in upper reach of the LMB. • During July ‐ August, the intensive and continued rain covered the most of upper and middle reaches of LMB and appeared more frequently in August. • From September to October was the time of intensive rainfall in lower reach, especially from Kratie to Kompong Cham.
4000
3500
3000
2000 2500 2002 2008 2009 2000 2010 2011 2012 1500 Mean
1000 Total depth of rainfall in 2012 flood season (mm) flood season 2012 in depth of rainfall Total
500
0
g e k t g n ne ai n e an e m n m a h h ia a ia K sa kh a kh h re h uong Stations aB nt g k a a C Pakse T Kratie C L r e a hanom kd nn g g P Vi P Th P u a hBassac g Non M run n Tan ChauChau Doc ChiengSaenon ChiengKhan hong T gPon Neak u Sav K S n L Nakon Ko hnomPe P
Figure 1‐1 Total depth of rainfall in the flood season of the years 2000, 2002, 2008, 2009, 2010, 2011, 2012 and the long‐term average flood seasonal rainfall
Page 1 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
In 2012, three main weather patterns caused heavy rains, which are presented below: • Southwest monsoon: influenced the Mekong River basin from early June to mid‐ October; the critical activity mostly occurred from the end of July to the end of August and from the mid‐September to mid‐October. As a common phenomenon, there was after mid‐October that a moderate to weak SW monsoon prevailed over lower parts of Thailand, Myanmar, Cambodia and Viet Nam. Figure 1-2 shows an illustration of weather map for Southwest Monsoon in the end of July.
Figure 1‐2 Weather map for Southwest Monsoon in the end of July.
• Tropical Low Pressure (TLP) and Inter Tropical Convergence Zone (ITCZ): these periodically appeared from early June to the mid of October with on average 3 to 7 days duration. In the flood season 2012, the frequent appearances of TLP and ITCZ during almost the entire flood season were one of the main phenomena which caused continuous heavy rain and rising water along the Mekong River. In August, TLP and ITCZ were observed and had significant influence on the upper and middle reaches of the LMB while the influence on the lower reach took place mostly in October. Figure 1‐3 shows an illustration of the appearances and influences of TLP and ITCZ to the LMB in August and October. • Tropical depressions (TD), tropical storms (TS) or typhoons (TY): Same as previous year, there were about 8 tropical depressions, storms and typhoons which came to South China Sea and affected the Mekong River basin with different levels. Of these, the five storms DOKSURI, VICENTE, TEMBIN, BOLAVEN, and GAEMI were the most noticeable.
•
Page 2 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Figure 1‐3 Weather maps for ITCZ in the end of August and mid‐October.
1. DOKSURI was formed in the Philippines on 27th June, located in the South China Sea at latitude 22o N and longitude 112.8o E with maximum sustained wind about 65 kilometres per hour and moved West North‐ west ward and landed over China territory on 30th June. 2. VICENTE was formed in the South China Sea on the 22nd July, upgraded to the Typhoon on 23rd July afternoon when moving north‐west ward close to South China coastline and made landfall on 24th July. It was downgraded into a tropical depression on 25th July and became a low pressure after moving deep into the mainland of China. Figure 1‐4 presents the recorded track of Typhoon VICENTE and weather maps before and after landing were shown in Figure 1‐5 and Figure 1‐6, respectively. 3. TY‐TEMBIN and TY‐BOLAVEN were formed in the East of the Philippines on 19th and 20th August 2012, respectively. TEMBIN moved westward to the South of Taiwan while BOLAVEN moved northward to China, Korea and Japan. Figure 1‐7 and 8 show a Storm Track and weather chart of TAMBIN and BOLAVEN Typhoons, respectively. 4. GAEMI was formed on 30th September 2012 on the South China Sea, upgraded to severe Tropical Storm named GAEMI on 4th October and made landfall over Binh Dinh and Phu Yen provinces in the Central of Viet Nam in the afternoon 6th October. After moving deep into Viet Nam territory, the tropical storm GAEMI downgraded into tropical depression in the evening 06th October and became a low pressure later. Figure 1‐9 presents the recording storm track of GAEMI and weather maps of the GAEMI before and after landing over the northern part of Central Viet Nam are showed in Figure 1‐10 and Figure 1‐11, respectively.
Page 3 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Figure 1‐4 VICENTE Storm Track.
Figure 1‐5 Weather map for VICENTE Typhoon Figure 1‐6 Weather map for VICENTE Tropical on 24th July 2012, before landing. Depression on 25th July 2012, after landing.
Page 4 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Figure 1‐7 TEMBIN and BOLAVEN Storm Tracks.
Figure 1‐8 TEMBIN and BOLAVEN weather chart.
Page 5 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Figure 1‐9 GAEMI Storm Track.
Figure 1‐10 Weather map for GAEMI in the Figure 1‐11 Weather map for GAEMI in the afternoon 06th Oct, before landing. evening 06th Oct, after landing.
1.2 General Behaviour of the Mekong River and Seasonal Flood Situation
The terms “flood” and “flooding” may world‐wide have different meanings. Therefore the definitions as used in this report are basically adopted from the Mekong Annual Mekong Flood Forums: • Flood: natural abundance of water in response to storm, rainfall, snowmelt, etc ... ergo the flood season on the Mekong ...... however, this does not necessarily lead to flooding;
Page 6 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
• Flooding: the inundation of areas, which usually are not submerged.
The 2012 flood season started later than previous flood years. The first flood event occurred on the fourth‐week of July with the appearances and influences of South‐West Monsoon and two tropical storms: DOKSURI and VICENTE.
In general, the water levels at upper reach of LMB started below the long‐term average (LTA) while stations in middle and lower reaches of LMB were about or above the LTA. After the influences of VICENTE in July; TEMBIN and BOLAVEN in August, water levels of all stations rose up and were about or above the LTA except those in lower reach still below the LTA, in which only water level at Nong Khai was above alarm level of 11.4m (as defined by the national agencies) on 4th August (see Table 1‐1).
From September to the end of flood season, water levels recessed below LTA in many stations; except those in lower reach of LMB with the arrival flood water from the upper and middle reaches, water levels rose up steadily below LTA with average intensity of 0.10‐ 0.20m/day.
Regarding the downstream stations at Tan Chau and Chau Doc, the water levels were most of the time below the long‐term average. The water levels at Tan Chau was above alarm level of 3.0m on 3rd October, Chau Doc was above alarm level of 2.5m on 3rd October (see Table 1‐1 for detail and Annex C presents the hydrographs of 22 main hydrological stations along the Mekong River).
In 2012, although there were about the same numbers of tropical depressions, storms and typhoons, their influences were less than last flood season year.
Table 1‐1 shows the flood peaks of main locations along the Mekong mainstream during 2012 flood season.
Page 7 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Table 1‐1 The flood peaks of main locations along the Mekong mainstream during 2012 flood season
Alarm Flood Day/Month Hmax ID Station Comment level Level of Peak (m)
010501 Chiang Saen 11.50 11.80 29‐Jul 7.91 Below alarm level 011201 Luang Prabang 17.50 18.00 23‐Aug 15.25 Below alarm level 011903 Chiang Khan 17.32 17.40 02‐Aug 13.28 Below alarm level 011901 Vientiane 11.50 12.50 25‐Aug 10.28 Below alarm level Above alarm 012001 Nong Khai 11.40 12.20 04‐Aug 11.66 level 012703 Paksane 13.50 14.50 12‐Aug 12.42 Below alarm level 013101 Nakhon Phanom 12.60 12.70 13‐Aug 10.22 Below alarm level 013102 Thakhek 13.00 14.00 13‐Aug 11.31 Below alarm level 013402 Mukdahan 12.50 12.60 13‐Aug 9.99 Below alarm level 013401 Savanakhet 12.00 13.00 13‐Aug 8.85 Below alarm level 013801 Khong Chiam 16.00 16.20 04‐Sep 11.17 Below alarm level 013901 Pakse 11.00 12.00 04‐Sep 9.4 Below alarm level 014501 Stung Treng 10.70 12.00 05‐Sep 9 Below alarm level 014901 Kratie 22.00 23.00 06‐Sep 19.55 Below alarm level 019803 Kompong Cham 15.20 16.20 07‐Sep 13.46 Below alarm level 020101 Phnom Penh Port 9.50 11.00 29‐Sep 7.7 Below alarm level Phnom Penh 033401 10.50 12.00 Bassac 29‐Sep 8.56 Below alarm level 033402 Koh Khel 7.40 7.90 17‐Sep 6.94 Below alarm level 019806 Neak Luong 7.50 8.00 01‐Oct 6.12 Below alarm level 020102 Prek Dam 9.50 10.00 01‐Oct 7.76 Below alarm level 019803 Tan Chau 3.50 4.50 13‐Oct 3.19 Below alarm level 039801 Chau Doc 3.00 4.00 13‐Oct 2.86 Below alarm level (Alarm level, flood level are defined by the national line agency)
The main hydrological situations along the Mekong River are presented in more detail below:
For stations from Chiang Saen to Vientiane/Nong Khai During the 2012 flood season, water levels at stations Chiang Sean, Luang Prabang, Chiang Khan, Vientiane/Nong Khai were most of the time below the long‐term average (LTA), except for some periods in July and August that rose up above LTA. There were two flood events with amplitudes over 2 meters which occurred at those stations (see more detail in Annex A, Part 3, Table A2).
Influences of VICENTE in July and later TEMBIN and BOLAVEN in August, resulted in moderate to heavy rainfall in this upper reach of LMB. Some recorded of two‐month rainfalls (July and August) were over 300mm, such as at Cheang Saen (568.7mm), at Luang
Page 8 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012 prabang (498mm), at Vientiane (371.1mm) and Nong Khai (405.4mm). Therefore during mid‐July to August, the rising water level occurred at all stations from Chiang Saen to Vientiane/ Nong Khai and reached the 2012 flood peak during this period (see Table 1‐1 for details). It should be noted that flood amplitudes for the stations Chiang Sean to Vientiane/Nong Khai were over 4m (Annex A, Part 3, Table A2).
Figure 1‐12 shows quick rising of water levels at stations: Xieng Kok and Chiang Saen during 26th – 29th July 2012 with amplitudes of 4.67m and 7.38m, respectively. Xieng Kok is an upstream station of Chiang Saen, located on the mainstream of Mekong river at the border of Lao PDR and Myanmar.
12
11 H_Chiang Saen ΔH = 7.38m 10 Xieng Kok H_Xie ng Kok 9
8
7
H (m) 6
5 ΔHChiang Saen = 4.67m 4
3
2 22-Jul 23-Jul 24-Jul 25-Jul 26-Jul 27-Jul 28-Jul 29-Jul 30-Jul Time (days)
Figure 1‐12 Quick rising of water levels at stations: Xieng Kok and Chiang Saen during 26th – 29th July 2012.
Water levels at Luang Prabang rose 4.62m during 26th – 29th July 2012 and other upstream stations such as Chiang Khong, Pak Beng were also rose sharply; particularly at Pak Beng with the amplitude of 11.86m during 26th – 29th July 2012. The hydrograph at those stations was shown in Figure 1‐13.
From September to the end of season, influence of low pressures as well as ITCZ across upper Lao PDR, Northern Thailand, Viet Nam and Myanmar did not affect much in this region, no flood amplitudes over 2m had happened (Annex A, Part 3, Table A2).
Page 9 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
H_Luang Prabang 22 H_Chiang Khong H_Pak Be ng ΔHPak Beng = 11.36m H_Muong Ngoy 18
14
H (m) ΔHLuang Prabang = 4.62m 10
ΔHMuong Ngoy = 6.89m 6
ΔHChiang Khong = 5.82m
2 22-Jul 23-Jul 24-Jul 25-Jul 26-Jul 27-Jul 28-Jul 29-Jul 30-Jul Time (days)
Figure 1‐13 Water level rising at stations: Pak Beng, Chiang Khong, Muong Ngoy and Luang Prabang during 26th – 29th July 2012.
For stations from Paksane to Pakse During the 2012 flood season, water levels from Paksane to Pakse were most of the time below the long‐term average (LTA), except for some periods in July and August that rose up above or about LTA. There was one flood event with amplitudes over 2.5 meters which occurred at those stations (see more detail in Annex A, Part 3, Table A3).
The same influences of VICENTE in July and later TEMBIN and BOLAVEN in August, resulted in moderate to heavy rainfall in this middle reach of LMB. Some recorded of two‐month rainfalls were over 300mm, such as at Paksane (1109.7mm), at Nakhon Phnom (967.5mm), at Thakhek (856.2mm), at Mukdahan (342mm), at Savannakhet (418.2mm), at Khong Chiam (801.3mm) and at Pakse (505.7mm). Therefore during mid‐July to August, the rising water level occurred at all stations from Paksane to Savannakhet and reached the 2012 flood peak during August; only Khong Chiam and Pakse had reached flood peak a bit later at the beginning of September (see Table 1‐1). It should be noted that flood amplitudes for the stations Paksane to Pakse were over 2.5m (Annex A, Part 3, Table A3). Figure 1‐14 shown waters level rising at stations: Vientiane, Nong Khai and Paksane during 26th – 29th July 2012.
From September to the end of season, influence of low pressures as well as ITCZ across upper Lao PDR, Northern Thailand, Viet Nam and Myanmar did not affect much in this reach, no flood amplitudes over 2m had happened (Annex A, Part 3, Table A3).
Page 10 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
12 H_V ie ntiane 11 H_Nong Khai 10 H_Paksane 9 ΔHPaksane = 2.99m 8
7
H (m) 6 ΔHNong Khai = 4.66m
5 ΔHVientiane = 4.35m 4
3
2 22-Jul 23-Jul 24-Jul 25-Jul 26-Jul 27-Jul 28-Jul 29-Jul 30-Jul Time (days)
Figure 1‐14 Water levels rising at stations: Vientiane, Nong Khai and Paksane during 26th – 29th July 2012.
For stations from Stung Treng to Kompong Cham During the 2012 flood season, water levels from Stung Treng to Kompong Cham started above the long‐term average (LTA) and continue to rise up above LTA till end of September, then fall below LTA.
The same influences of VICENTE in July and later TEMBIN and BOLAVEN in August, resulted in moderate to heavy rainfall in this lower reach of LMB. Some recorded of two‐month rainfalls were over 500mm, such as at Stung treng (733mm), at Kratie (715.8mm) and at Kompong Cham (502.1mm).
As a result of flood water from the upper and middle reaches of LMB together with heavy rainfall, the rising water level occurred at all stations from Stung Treng to Kompong Cham and reached the 2012 flood peak in early September and their flood amplitudes were over 2 meters at Stung Treng and over 3 meters at Kratie and Kompong Cham (see more detail in Annex A, Part 3, Table A4). .
From September to the end of season, water levels were more or less stable and finally recessed at the end. No flood amplitudes over 2m had happened (Annex A, Part 3, Table A4).
For stations from Phnom Penh to Koh Khel/Neak Luong During the 2012 flood season, water levels from Phnom Penh to Koh Khel/Neak Luong were most of the time below the long‐term average (LTA), except for some periods in July and August that rose up about LTA.
The same influences of VICENTE in July and later TEMBIN and BOLAVEN in August, resulted in moderate rainfall in this reach of LMB. Some recorded of two‐month rainfalls were over 100mm, such as at Phnom Penh (Bassac Chaktomuk) (279.5mm), at Koh Khel (226.7mm), at Neak Luong (406.9mm) and at Prek Kdam (165.9mm). As a result of flood water from the
Page 11 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012 upper and middle reaches of LMB together with local rainfall, the rising water level occurred at all stations from Phnom Penh to Koh Khel/Neak Luong and reached the 2012 flood peak in end of September and early October (see Table 1‐1). It should be noted that flood amplitudes for the stations Phnom Penh to Koh Khel/Neak Luong were over 1m in August (Annex A, Part 3, Table A5).
From September to the end of season, water levels were more or less stable and finally recessed at the end. No flood amplitudes over 1m had happened (Annex A, Part 3, Table A5).
Tan Chau and Chau Doc During the flood season 2012 stations recorded water levels that most of the time remained below the long‐term average, except in the first half of July when flood water from the upper and middle reaches of LMB had arrived together with local rainfall that water levels of these two stations rose above LTA. From August to the end of flood season, water levels of these stations rose steadily with average intensity of 0.10 ‐ 0.15m/day levels and then recessed at the end. No flood amplitudes over 1m had happened (see more detail in Annex A, Part 3, Table A6).
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2. Flood Forecast in 2012
2.1 Data collection for models and flood forecast bulletin dissemination
Daily data collection consisted of hydrological and meteorological data (observed water level and rainfall) by HydMet from Line Agencies, Satellite Rainfall Estimate (SRE) and Numerical Weather Prediction (NWP) obtained from NOAA which served as inputs for the Mekong Flood Forecasting System (FFS). The performance indicators are shown in the Tables and graphs of the forecast achievement, Annex B (Table B3, Figure B2 to Figure B4).
The results of the evaluation show that the data from most of LAs normally arrived before 9 AM (Annex B, Table B3 and Figure B2). The manual data collected by HydMet was checked by LAs; hence, the quality of data is in general terms fairly good. However, there are a number of unavoidable problems in data transmission such as the late transfer of data, errors and especially missing data during five months of this flood season (see more detail in Table B3 and graphs in Performance, Annex B).
Satellite Rainfall Estimation and Numerical Weather Prediction inputs for the URBS/FEWS, were the most important factors to determine forecast results. Following the investigations and comments of the forecaster‐in‐charge in the weekly reports throughout the 2012 flood season, it is found that the high variability in both SRE and NWP was one of the main reasons which lead to large errors of forecast results, especially when the weather patterns caused heavy rain as tropical storms, south west monsoon and ITCZ.
Performance indicators of bulletin delivery (Annex B, Table B3 and Figure B4) shows that the flood bulletins containing flood situation information were disseminated timely to the registered national Line Agencies, MRC website, and other interested users around 10h30 AM, which is a prescribed time in the Operational Manual. It can be seen that the time of flood forecasting bulletin delivery in the first three months of the flood season was a bit later than 10h30. This was due to two main factors:
• The late transfer and incomplete of data from LA’s usually occurred during flood season. • The low water level together with significant tidal effect in the downstream of the LMB, which resulted in difficulties for forecaster‐in‐charge in analysing and adjusting forecast results and which consequently lead to the late bulletin dissemination.
During the 2012 flood season, the data of some stations was sometimes not updated by national Line Agency for 2 to 3 continuing days, and in case data were missing over 2‐3 days it was not possible to provide a forecast at those stations. Figure B5 in Annex B shows that during the 2012 flood season there was one station without forecasts in July.
2.2 Accuracy and limitations in forecasting
During the 2012 flood season, the degree of accuracy varies from station to station. The shorter the lead time, the more accurate of the forecast (see Annex B, Table B1). The
Page 13 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012 evaluation of forecast achievement is presented in Table B2 by indicating the % of days “successful” against a respective benchmark. In general, the forecast errors for all lead time show decreasing trend from upper to lower reaches, except Luang Prabang, those stations in middle reach and Kratie where the accuracy for 2‐3 day forecasts lead time was less than expected, if following the benchmarks of success. Based on the weekly flood situation reports, the large errors on 2‐3 day forecasts at three those stations mainly occur during the first two months of flood season when tropical storms were active in the areas.
Through forecast performances at other stations in the lower reach of Mekong River, it can be seen that the use of a regression model is quite promising. Downstream stations start from Phnom Penh Bassac to Chau Doc, show average errors for 1‐day and 2‐day forecasts smaller than 0.03m and 0.10m respectively; while average errors for 3‐day to 5‐day forecasts are smaller than 0.2m at stations from Koh Khel to Tan Chau.
Based on investigations and forecasting experiences of the RFMMC, the main factors that influenced forecast accuracy can be summarized as below:
1. Internal model functionality in forecasting at tidal affected stations in downstream: The forecast performances by mean absolute error in using original forecast results from both regression and ISIS models were presented in Figure 2‐1 and Figure 2‐2 respectively. It is easily realized that the average error results by URBS and Regression for 3‐day to 4‐day forecasts at Tan Chau and Chau Doc were over 0.1m; and for 5‐day were around 0.25m. It didn’t achieve the benchmarks of success at those two stations for 3‐day to 4‐day forecasts, as is shown in Table B2, Annex B.
Flood Forecasted Performance_Regression_SRE
180
cm 160 1‐day 2‐day 3‐day ‐ 140 120 4‐day 5‐day 100 Difference 80 60 40 Absolute
20
Mean 0 Doc Port Khel
Saen Chau Khan Treng
Kdam
Pakse Luang Luong Chiam Kratie
PP Nakhon (Bassac) Thakhek Paksane Koh Tan Chau Kompong Nongkhai Vientiane Mukdahan Prek PP Stung Neak Chiang Chiang Savannakhet Khong Figure 2‐1 Forecast performance based on original results by URBS and Regression.
Page 14 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Flood Forecasted Performance_ISIS_SRE
180
cm 160 1‐day 2‐day 3‐day ‐ 140 120 4‐day 5‐day 100 Difference 80 60 40 Absolute
20
Mean 0 Doc Port Khel
Saen
Khan Chau Treng
Kdam
Luang Pakse Luong Chiam Kratie
PP Nakhon (Bassac) Thakhek Paksane
Koh Tan Kompong Nongkhai Chau Vientiane Mukdahan Prek PP Stung Neak Chiang Chiang Savannakhet Khong Figure 2‐2 Forecast performance based on original results by URBS and ISIS.
2. The high variability of satellite rainfall estimate (SRE) and Numerical Weather Prediction (MWP): SRE rainfall is used, as the NWP model provided a 7‐day GFS rainfall forecast. Throughout the 2012 flood season, the output for the URBS model, as can be seen from the results of daily forecast, is really sensitive to both SRE and NWP. SRE can be either under‐ or overestimated if compared with the observed rainfall. NWP can provide high variable rainfall forecast leading to high variation of forecast results, especially at stations in the upper and middle reaches when critical weather patterns occur such as tropical storms DOKSURI and VICENTE. Based on weekly investigation of the forecasting team, the original forecast results calculated from the model caused relatively large errors compared with observations. This is a practical difficulty for forecaster‐in‐charge in forecast adjustment. 3. The quality and accuracy of forecast is also determined by the quality of forecast adjustment, which is usually performed by forecaster‐in‐charge so their knowledge, expertise and experiences are also the prominent determinant of the final forecast result.
2.3 Lesson learned and actions to be taken
The following lessons have been drawn from the 2012 flood season, which can serve as the main factors that need to be taken into account by the flood forecasting team of the RFMMC in improving the forecast results: 1. The availability and quality of both hydrological and meteorological (rainfall) data as inputs for models are always the highest priority because these are the deciding factors for forecast results and accuracy. The corrected SRE had been used in the forecast but its quality depended very much on observed rainfall data that contained lots of missing data (see Annex B; Table B3) 2. The data from stations in the upstream of the Mekong River system in China is very important for analysing and forecasting in the LMB, not only during the flood season but also during the dry season. Hydrological and meteorological data from
Page 15 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
stations belonging to China need as much and as often as possible to be shared during dry season of 2012‐2013. 3. Strengthening the relationship and cooperation with Line Agencies in exchanging and collecting observed water level and rainfall data at stations on the Mekong mainstream in order to collect daily data on time and to minimize the missing and incorrect data. 4. Improving model calibration by updating the rating curves and other parameters at stations in the MRC’s member countries to be supported by LAs. 5. The forecaster‐in‐charge needs to have more understanding of sub‐basin characteristics, flow regime of left bank tributaries in the middle part of the LMB where frequently intensive rainfall and flooding occurs as well as more understanding of influences of tidal regime to the downstream of the LMB.
Aside from above‐mentioned lessons in order to improve the accuracy of flood forecasting for next flood season 2012, a number of additional actions need to be undertaken as follows: 6. Performance of the ISIS model in the Cambodian Floodplain and the Mekong Delta should be compared with that of the Regression Model during the 2012 flood season. It is found that the discharges generated in ISIS are not consistent with the observed water levels. It is recommended to replace the old version in the MRC Mekong Flood Forecast System with the latest version of ISIS. 7. Continue to efficiently use water level and rainfall of the existing two stations: Jinhong and Manan of China. Analyse the impact of water release from dams to the water levels at Jinhong and to water level changes at stations in the upper part, such as at Chiang Saen and Luang Prabang, especially during transitional period between dry and wet season. 8. Watch closely situations of the sudden increasing water levels of left bank tributaries in the middle part of the LMB, such as Sre Pok River at Lumphat, Se Kong River at Vuen Khen, Se Bang Fai River at Mahaxai, when the weather patterns would inflict intensive rainfall such as Typhoon or Tropical Depression occurrences in South China Sea, the creations of low pressure trough line and Inter Tropical Convergence Zone (ITCZ) and sometimes the critical activity of South West monsoon. 9. Through the 2012 flood season, forecast results of water levels at stations in downstream of the LMB by using Regression model were evaluated as fairly good, however the error for 2‐day to 3‐day forecasts at hydrological stations affected by tidal from Neak Luong to Tan Chau/Chau Doc are quite high, based on benchmarks of success (Annex B, Table B2). Therefore, additional reference of tidal regime forecast documentation in 2012 provided by National Centre for Hydro‐ meteorology of Viet Nam can be referred to in improving the accuracy at those stations. 10. Learn more about the weather products of rainfall forecast published on the websites of the World Meteorological Organization and their practical applications. 11. Study the possibility of having 2nd run of daily flood forecast and medium‐term forecast (6‐10 days) – data availability and other requirements of the system by having further evaluation of the system’s performance by using historically similar rainfall patterns.
Page 16 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
For more details see the following Annex: Annex A; - Graphs and Tables for monthly observed rainfall distribution during flood season 2012 - Graphs for monthly rainfall in flood season from 2000 to 2012 and long‐term average along the Mekong River - Tables of flood event characteristics along the Mekong River during flood season 2012
Annex B: - Graph for accuracy - Table of forecast achievement - Tables and graphs for performance
Annex C: - Seasonal Water Level Graphs
Page 17
Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Annex A Graphics and Tables
1. Graphs and Tables for monthly observed rainfall distribution during flood season 2012
Table A1 Monthly observed rainfall in flood season 2012
Chau Doc Chau Tan Chau Tan
Unit in mm
Neak Luong Neak
ascCatmuk Chaktom Bassac
NoData D o N Phnom Penh Port Penh Phnom
Kompong Cham Kompong
Kratie 0 289.9 233.6 169.6 88.8 80.0 Stung Treng Stung 0.9 540.4 378.6 248.6 176.4 86.0 70.6
178.3 426.1241.5 265.9 534.5 358.1 157.4 106.5 216.2 41.4 150.3 33.5 64.5 50.0
Pakse
Khong Chiam Khong
Savannakhet Mukdahan 6 107.8 164.6 128.0 137.4 333.3 184.0 100.5 67.1 20.8 16.8
32.0 97.974.1 159.3 799.7 1,120.7 119.8 899.4 158.3 946.4 411. 2,245.2 1,476.5 956.3 669.9 301.6 250.9
Nakhon Phanom Nakhon Thakhek
67.0 233.2 226.0 193.2 274.2 225.9 23 Paksane
209.8 218.2359.4 181.0 328.8 183.5 295.5 150.0 287.0 207.5 250.8 166.4 315.2 259.3
Nong Khai Nong Vientiane
October October
th Chiang Khan Chiang
June to 15 June
th
Luang Prabang Luang
Chiang Saen Chiang Jinghong 194.0 142.8 304.9 299.8 210.7 240.6 292.2 2 r 2012 JulyAugust 318.0 265.8 115.3Septebe 182.6 238.0 398.8 223.9 367.2 120.1 272.4 141.4 308.7 June 17.0 64.9 147.5 157.6 69.8 87.7 164.4 173.7 136.3 145. October 4.0Season 798.8 124.7 630.2 249.8 1,338.9 248.6 1,297.2 819.5 146.5 946.2 167.9 1,233.4 207.6 1,162.7 983.7 175.0 9 137.7 1 (*) Observed data for Jinhong from 15 from Jinhong for data Observed (*)
Page 19
Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012 Oct.
213.9 Sep.
430.7 Aug.
455.0 July Chiang Khan
289.5 June 97.2
0
500 400 (mm) 300 Rainfall 200 Monthly 100 Oct.
55.0 Sep.
145.6 Aug.
401.6 July
Luang Prabang 278.4 June 154.4 0
500 400 300 200 100 Monthly Rainfall (mm) Rainfall Monthly Oct.
78.5 Sep.
293.1 Aug.
449.7 July
Chiang Saen Chiang
311.4 June 243.8 0
500 400 300 200 100 nhyRanal( ) m (m ainfall R onthly M Oct.
23.0 Sep.
124.0 Aug.
182.8 Jinghong July
360.0 June 58.0
0 500 400 (mm) 300 Rainfall 200 Monthly 100
Figure A1 Monthly rainfall distribution for Jinghong, Chiang Saen, Luang Prabang and Chiang Khan.
Page 20 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Oct.
189.7 Sep.
219.5 Aug.
513.0 July
411.2 Nakhon Phanom Nakhon June 175.1 0
800 600 400 200
1000 (mm) Rainfall Monthly Oct.
125.7 Sep.
613.9 Aug.
736.8 Paksane July
619.2 June 573.5 0
800 600 400 200
1000 (mm) Rainfall Monthly Oct.
45.4 Sep.
302.1 Aug.
659.0 July Nongkhai
213.5 June 201.4 0
800 600 400 200
1000 Monthly Rainfall (mm) Rainfall Monthly Oct.
71.6 Sep.
199.9 Aug.
669.7 July Vientiane
198.2 June 262.5 0
800 600 400 200 1000 (mm) Rainfall Monthly
Figure A2 Monthly rainfall distribution for Chiang Khan, Vientiane, Nong Khai , Paksane and Nakhon Phanom.
Page 21 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Oct.
179.6 Sep.
222.6 Aug.
380.2 July Khong Chiam Khong
229.6 June 211.6
0
500 400 (mm) 300 Rainfall 200 Monthly 100 Oct.
194.6 Sep.
166.7 Aug.
507.9 July
Savannakhet
158.0 June 215.6 0
800 600 400 200
1000 Monthly Rainfall (mm) Rainfall Monthly Oct.
215.7 Sep.
209.8 Aug.
641.9 July Mukdahan
113.5 June 197.9 0
800 600 400 200
1000 (mm) ainfall R Monthly Oct.
202.9 Sep.
230.2 Aug.
524.0 Thakhek July
386.3 June 167.5
0 800 ) m (m 600 Rainfall 400 onthly M 200 1000 `
Figure A3 Monthly rainfall distribution for Thakhek, Mukdahan, Savannakhet and Khong Chiam.
Page 22 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Oct.
288.5 Sep.
137.5 Aug.
236.5 July
Kompong Cham 159.3 June 316.2
0
500 400 (mm) 300 Rainfall 200 Monthly 100 Oct.
230.2 Sep.
214.0 Aug. 323.9
Kratie July
185.2 June 167.4 0
500 400 300 200 100 Monthly Rainfall (mm) Rainfall Monthly Oct.
250.4 Sep.
121.8 Aug.
233.4 July Stung Treng Stung
173.4 June 99.2
0
500 400 (mm) 300 Rainfall 200 Monthly 100 Oct.
167.4 Sep.
209.7 Aug. 458.2
Pakse July
182.8 June 164.7
0 500 400 (mm) 300 Rainfall 200 Monthly 100
Figure A4 Monthly rainfall distribution for, Pakse, Stung Treng, Kratie and Kompong Chiam.
Page 23
Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012 Oct.
357.8 Sep.
229.0 Aug.
230.1 July Neak Luong Neak
163.9 June 98.2
0
500 400 (mm) 300 Rainfall 200 Monthly 100 Oct.
552.5 Sep.
183.9 Aug.
135.5 July Koh Khel
109.1 June 191.1 0
800 600 400 200
1000 (mm) Rainfall Monthly
Oct.
Sep. Aug.
No measurement No July
Phnom Penh Port June
0
500 (mm) Rainfall Monthly Oct.
443.8 Sep.
165.6 Aug.
278.7 July 246.3
Phnom Penh(Bassac) June 172.1
0 500 400 (mm) 300 Rainfall 200 Monthly 100
Figure A5 Monthly rainfall distribution for Phnom Penh (Bassac and Port), Koh Khel and Neak Luong.
Page 24 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Oct.
163.5 Sep.
150.6 Aug.
88.6 Chau Doc Chau July
125.9 June 103.0 0
500 400 300 200 100
) Monthly Rainfall (mm Rainfall Monthly Oct.
332.8 Sep.
269.8 Aug.
178.0 Tan Chau Tan July
113.2 June 174.7 0
500 400 300 200 100
Monthly Rainfall (mm Rainfall Monthly ) Oct.
425.6 Sep.
122.5 Aug.
173.7 Prek KdamPrek July
73.1 June 176.7 0
500 400 300 200 100 ) Monthly Rainfall (mm Rainfall Monthly
Figure A6 Monthly rainfall distribution for Prek Kdam, Tan Chau and Chau Doc.
Page 25 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
2. Graphs for monthly rainfall in flood season from 2000 to 2012 and long‐term average along the Mekong River
Year Year Year n
16 7 . 4 ea 208.3
ean 646.6
M Mean M
2 2
1 14 5 . 6
164.4 157.6
201 20 2012
1
11 13 5 . 2
203.8 223.7
2011 201 20
0
97.2 10
19 7 . 9
573.5
2010 201 20
9 9
13 3 . 4 0 206.0
367.4 00
2 2009 20
8 8
89.0 0
272.0
119 9 . 3
200 20 2008
7 7
186.0 0
584.7
200 20 2007
6
29.0 06 114 . 0 117 . 0
514.8
2006 20 200 PakSane
Mukdahan Mukdahan 5
05 204.1
Chiang khan khan Chiang 263.5
10 8 6 . 6
2005 20 200
4 4
0 0 119 . 9
19 8 . 6
288.6
20 20 2004
3 3
0 152.2
699.9 275.4
200 20 2003
2 2
73.8 0 301.8
821.4
200 2002 20
1
62.5 01
714.5 387.8
2001 20 200
0 0
0 227.7 210.5
10 7 5 . 7 00 2 20 2000 0 0 0 800 600 400 200 800 600 400 200 500 X( mm) 1000 X( mm) X( mm) 1000 3000 2500 2000 1500 1000
Year
Year
Year
n
an 317.0
ean
243.2 e
18 0 . 1
M M Mea
87.7
14 7 . 5 12
2012 2012
20
1
1 11
1 139.2136.3 15 1. 3
1
215.3 0
2 20
20
0
10
1 17 5 . 1
10 201.4
154.4 0
0 2
20 2
9 9
13 4 . 0 0
73.3 09
266.7 00
20 2 20
638.0 307.4 188.0
2008
2008 2008
07 303.0
268.9 18 5 . 0
0
2007 2007 2
6
6
06 92.3 0 78.1
0
0
2 20 20 Data No
Nong Khai Nong
5
05
361.8 0 335.0
237.6 0
2 2005 LuangPrabang 20 Nakon PhanomNakon
4 4
0 04 226.1
268.8 208.4 0 00
20 2 2
3
0 18 0 . 7
374.1 315.4
2003 20 2003
754.0
265.7
2002 2002 2002
1
01 01
194.5 0 409.0 155.8155.6
0 0
2 2 20
0 0
0
0
269.1 0 373.0 287.3 00
20 20 2 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 X( mm) X( mm) 1000 1000 X(mm) 1000
Year Year Year n
an
17 8 . 1 an 414.3 255.2
ea
Me Me M
2 2
2
1 69.8 1 64.9
01
20 20 2
1
111. 5 11
12 3 . 5 17 3 . 8 17 3 . 7
2011 20 201 0
167.5
262.5
243.8
2010 2010 201
9
09 09
0 110 . 3 110 . 5
238.2
0 0
2 2 20
8
8
0
459.0 08 698.0 207.0 0 00
20 2 2
7 7
7
0
522.0 0
297.0 226.7 00
20 20 2
6
15 1. 3 06 118 . 0 258.6
ientiane 2006 20
200 Thakhet
V 5
Chiang Saen
338.0 556.3
262.4
2005 2005 200
4
04
0 319.2
189.9
286.9 0
2 20 2004
3
3
0
384.8 03 128.7 336.2 0 00
20 2 2
2 2
2
0
13 9 . 3 887.8 0
288.3 00
20 20 2
1
17 7 . 5 01 10 0 . 2 672.9
2001 200 20
0
00
318.2 0 482.5 346.6 0
2 20 2000 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 X( mm) 1000 X( mm) X( mm) 1000 1000 Figure A7 Monthly rainfall in June for main stations along the Mekong River.
Page 26 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Year Year Year n n
88.2
117 . 5
ea
259.8 ea ean
M M M
10 0 . 5
128.0 012 012
2 2 2012
18 . 4 16 . 8
10 6 . 4
110 . 7
2011 2011 2011
172.1
10 3 . 0
164.7
010
No No 010 2 2 2010 Data
14 . 4
129.9
348.1
2009 2009 2009
74.0
197.0
2008 2008 2008
24.9
90.3 279.6
2007 2007 2007 80.0 112 . 7
205.6
Pakse Pakse 2006 2006 2006 Chau Doc
28.0 117 . 1
212.1
2005 2005 2005
PhnomPenh Bassac 174.0 189.3
443.7
2004 2004 2004
37.4 117 . 6
240.2
2003 2003 2003
103.0
605.3
2002 2002 2002 91.9 92.4
12 5 . 0
475.8
2001 2001 2001 No Data
68.2
286.9
000 2000 2000 2 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 X(mm) X(mm) 1000 1000 X( mm) 1000 Year Year Year
77.9
254.1 206.8
ean
Mean Mean M
164.6 333.3
2012 2012 2012 21.8 20.8
13 9 . 8 335.7
2011 2011 2011
174.7
211.6 16 7 . 4
2010 2010 2010 6.4
15 0 . 2 196.9
2009 2009 2009
96.0 120.7
235.1
008
2008 2 2008
No Data
7 26.3 72.6
2007 2007 200
112 . 3
Kratie 006
2006 2 2006
Tan Chau
5 No 137.0133.2 77.0
333.1 Data
Khong ChiamKhong 2005 200 2005 4
110 . 2
362.5
200 2004 2004
45.3
294.2 348.4
2003
2003 2003
39.5 2
289.7 356.2
200 2002 2002 99.1
313.0 225.8
2001 2001 2001 No No No No Data
Data
339.8
2000 2000 2000 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 X( mm) 1000 X( mm) 1000 1000 X( mm)
Year Year
Year
12 4 . 2 an
169.7
216.1 e
ean
M Mean M 67.1
10 7 . 8
2012 2012
2012
1 68.8
92.9 135.6137.4
2011 201
2011
0 98.2 99.2
215.6
2010 2010
201 9 82.9
47.8
15 8 . 3
2009 200 2009
209.8 12 5 . 0
323.0
2008
2008
2008
33.2 7 158.0
292.0
2007 200 2007
90.0
122.0
12 1. 7
2006
2006
2006
5 Neak Luong 193.0
218.6
18 0 . 2
Savannakhet Savannakhet TrengStrung
2005 200 2005
128.7 12 8 . 1
305.8
2004
2004 2004
3 55.0 43.0 158.1
2003 2003 200
119 . 7
269.8
270.2
2002 2002 2002
18 7 . 0
251.8
447.5
2001 2001 2001
No Data 0
200.1 449.1
200 2000 2000 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 X(mm) 1000 X( mm) X( mm) 1000 1000 Figure A7 (cont.)
Page 27 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Year
Year Year n
675.9 a 15 1. 8 e 276.7
M Mean Mean
2
209.8 12 18 3 . 5
223.9 0 012
2 2 201
1
1
11 326.7
276.4 313.8
0
0
2011 2 2
0 0
619.2 113 . 5
289.5 10
0
201 201 2
9
93.6 09
159.8
1026.4 0
2 2009 200
8
08
0
84.0 08
1112 . 3
0 223.0
0
0
2 2 2
7
691.7 0 58.2 07 128.7
0
0
2007 2 2 6
116 . 0
1102.4 405.0 00
2 2006 2006 PakSane
Mukdahan Mukdahan 5
737.8 05 519.3
103.3
0
Chiang khan khan Chiang 005
2 2 200
4
0
04 677.9
583.7
234.8
0
0
2004 2 2 3
715.8
00 208.8 215.2
2 2003 2003
2
95.0 02
780.2
439.2
0 002
2 2 200
1
718.2 0 01 325.1
123.4
0
0
2001 2 2 0
110 . 3 633.4
225.9
200 2000 2000 0 0 0 500 800 600 400 200 800 600 400 200
X(mm) 3000 2500 2000 1500 1000 X(mm) 1000 X(mm) 1000
Year n Year
n Year n
223.5 a
445.4 259.7
Mea
Me Mea
2
2 14 1. 4
18 1. 0 1
1
238.0 012
0 0 2
2 2
1
1
255.7 1
0 280.6
320.8
2
2011 201 0
213.5
411.2
278.4 010 010 201
2 2
9
9
257.6 0
0 569.2 241.4
0 0
2009
2 2
8 250.1
585.0 200.2
2008 2008 200
7
150.2 0
0 233.7 140.2
2 2007 2007
6
6
6
0
0
0 253.5
756.0
306.9 0 0
0
2 2 2
Nong Khai
5 5
0
240.1 0 196.3
506.0
0 0
LuangPrabang 2005 2 Nakon Phanom 2
19 8 . 2
235.0
286.9 004
2 2004 2004
3 3 3
0
0
19 5 . 5 0
0 242.0 0 0
2 2 2
2
2 2
0 0 244.6244.6
766.0 384.4
0 0
200 2 2
301.8 393.1 482.0
2001 2001 2001
0 0 0
0 0
214.6 0
274.4 542.0 0 0 0
2 2 2 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 X(mm) X(mm) X(mm) 1000 1000 1000
Year
n Year n Year
a 470.6 299.5 e 250.4
M Mean Mea
2
2
12 1
115 . 3 1 12 0 . 1 218.2
0 0
0
2 2 2
1
11
218.9 1 313.8
14 8 . 8
0 0
2 2 2011
0 0
3 11. 4 198.2
386.3
201 201 2010
9
09
0 230.3 509.4
0 009
0
2 2 2
8
366.0 0
583.0
308.0308.8 0
2008 2 2008
7
108.1 7
16 1. 9 417.3 00
2
200 2007
6
439.9 06
311.0 0
0 747.6
006
0 2
ientiane ientiane 2
2 Thakhet
V
5
5
5 237.1 Chiang Saen
0
0 736.4
364.0
0 200
2 20
4
350.4 04
0 291.0 183.7
2
200 2004
3 130.1 03
0
0 319.4
309.8 0 2
2003 2
2
2
2 276.6
0
0 729.4
368.9 0
200 0
2 2
1
314.2 01
0
0 549.0
305.6 0 2
2 2001
2 11. 3
00 570.0 242.9 2000 0
2000 2 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 X(mm) 1000 X(mm) X(mm) 1000 1000 Figure A8 Monthly rainfall in July for main stations along the Mekong River.
Page 28 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Year Year Year n
12 0 . 5
379.8 ea
M
Mean Mean
33.5 2 1
12
12 157.4157.4 166.4
0 20
20 2
41.0 1 1
11
11 199.8
246.9
0 20
20 2
12 5 . 9 10 10
18 2 . 8 10
246.3
0
20
20 2
15 5 . 5 09 71.0
09
468.8 09
0 20
2 20
76.7 08
08
113 . 0 08 12 6 . 0
20
20 20
35.0 07
07 07
231.3 0
399.9
2 20 20
112 . 7 06
846.3 0 207.0
Pakse Pakse 2
2006 2006
Chau Doc
5
0
05 240.2
251.0
408.4
0
20 2005 2
61.0
04
04 PhnomPenh Bassac
398.7 14 2 . 0
0 0
2004 2 2
03 03 239.1
222.7
244.0
0 0
2003 2 2
2 67.0
02
02 32.0
623.8 0 0
20 2 20
1 98.1
13 . 0 01 01
352.4 0
0
20 2 20
0
00 00
0 10 9 . 3
728.7 12 5 . 0
20 20 20 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 X(mm) 1000 X(mm) 1000 X(mm) 1000 Year Year Year
103.5 330.0
242.7
Mean Mean Mean
41.4
12
207.5 12 12
0
0 426.1
0
2 2
2
1 55.3 11
301.5 1
515.7
20 20
2011
0 113.2
229.6
18 5 . 2
01
2010 2010
2
9 180.0
504.2
371.6
00 2009 2009
2
8 10.6
283.3 08
14 2 . 0
00
2008 20 No Data 2
41.2
07 07
18 2 . 5
007
20 20
2
73.5 6
0 06 Kratie
54.4
006 20 20 2
Tan Chau
05 05 215.1
358.6
375.0
Khong ChiamKhong No 20 20 Data 2005
27.0
454.1 04
20 2004
2004
185.6 03 366.9
14 7 . 5
20 2003 2003
71.1
02 02
558.9 02 0
208.3 0
0
2 2
2
1 46.4
01
301.8 0 01
10 3 . 6 0
0
2 20
2 No
Data
0
00
0
00
336.4 0
200.0
0 2 20 2 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 1000 X(mm) 1000 X(mm) X(mm) 1000
Year
Year Year n
14 0 . 7 a
e
an 229.2
271.9
e
M Mean
M
2
2 10 6 . 5
17 8 . 3
15 0 . 0 1
201
2012
20
1 13 4 . 9
1 228.4 251.2
2011 2011 20
16 3 . 9
17 3 . 4 10
15 8 . 0
2010
20
2010
9 88.8 149.1 0
15 6 . 1 009
2 20
2009
8 77.5
111. 0 0
08
211.0 008
2 20
20
68.1 7 15 8 . 1
07
219.1 07
200
20 20
6
06 12 6 . 0 517.9
372.9 06
200 20
20
5 Neak Luong 05 17 8 . 2
0 236.5
Savannakhet
Strung TrengStrung 0 595.4
2005 2 20
04 221.3
175.3
491.3 04 0
2004
2 20
03
03 240.0
294.0 15 5 . 6 0 003
2 2 20
2
0
02 273.7 481.9
002
2 20 20
1
96.0 97.0 1 0
01 304.8
271.5
200 20 20
No No
Data
00
00 269.0 204.6
2000 20 20 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 1000 1000 X(mm) X(mm) X(mm) 1000 Figure A8 (cont.)
Page 29 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012 Year Year Year
588.3 315.3 ean
248.7 ean
M M Mean
359.4
287.0
367.2
2012 2012 2012
388.9
365.6 352.0
2011 2011 2011
736.8 641.9
455.0
2010 2010 2010
268.6
13 0 . 5
2009 2009 2009
113 . 0
367.5 153.0150.2
2008 2008 2008 7
507.0 215.4
274.7
2007 2007 200
666.0
284.0 393.0
2006 2006 2006 PakSane
77.6 Mukdahan
856.1 Chiang khan
2005 2005 2005
671.3 166.4
309.3305.2
2004 2004 2004
119 . 4
771.8
279.6
2003 2003 2003
826.9 343.8
2002 2002 2002
521.1
695.4 414.9418.7
2001 2001 2001
14 5 . 7
669.2 205.8
2000 2000 2000 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 1000 X( mm) 1000 X( mm) 1000 X( mm) Year Year Year
327.3
316.3 494.6
ean
Mean
Mean M
295.5
398.8 2012
2012 2012
313.8308.7
355.9
362.7
2011 2011 2011
659.0 513.0 401.6
2010
2010 2010
267.7
414.0 629.0
2009 2009 2009
294.3
558.0 225.0
2008 2008 2008
283.9
377.8
337.5
2007 2007 2007
19 2 . 1
672.0
266.3
2006 2006 2006 Nong Khai Nong 5
308.9 601.0
322.4
200 2005 LuangPrabang 2005 Nakon PhanomNakon
253.1
759.0
233.0
2004 2004 2004
15 8 . 7
15 6 . 0
313.6
2003 2003 2003 2
484.5
523.0
258.9
2002 2002 200
472.0 476.3
395.7
2001 2001 2001
314.1
518.0
233.9
2000 2000 2000 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 1000 1000 X( mm) X( mm) 1000 X( mm) Year Year Year
349.7 362.9
ean 555.4
Mean M Mean
18 2 . 6
328.8
2012 2012 2012
271.8272.4
16 8 . 4
388.5
2011 2011 2011
669.7
449.7
524.0
2010 2010 2010
383.8 309.7 374.1
2009 2009 2009
340.0 510.0
2008 2008 2008
310.3
372.2368.0
623.6
2007 2007 2007
300.9 580.0
757.6
2006 2006 ientiane 2006
Thakhet
V 5
417.4 931.1 Chiang Saen
226.7
2005 2005 200
288.1 374.9 816.4
2004 2004 2004 3
217.0 235.8
720.4
2003 2003 200
411.2
455.3 481.6
2002 2002 2002
1 1
416.5 340.5 613.8
200 200 2001
268.5 245.8 492.4
2000 2000 2000 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 1000 1000 X( mm) X( mm) 1000 X( mm) Figure A9 Monthly rainfall in August for main stations along the Mekong River.
Page 30 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012 Year Year Year
15 1. 9 18 8 . 5 429.4
Mean Mean Mean
2 2
12 50.0
216.2 259.3
0
01 01
2 2 2
11 11 11 78.3
355.5
0 0 0
2 2 2
0
0 88.6
458.2
278.7278.5
01 01
2010 2 2
69.8 09 09 291.6 09 163.3
0 0 0
2 2 2
08
12 5 . 0 08 704.0 251.2
0 0
2008 2 2
56.7
07 07
278.8 07 240.6
0 0 0
2 2 2
06
239.0 06 250.6 234.7
0
Pakse Pakse 0 2006 2 2
Chau Doc
05 05 05 12 1. 8
404.0
0 0 0
2 2 2
86.4
211.0206.0 PhnomPenh Bassac 583.7
2004 2004 2004
18 1. 1
03 167.0
480.2 0
2003 2003 2
12 6 . 1 163.0 384.8
2002 2002 2002
01 210.3 13 4 . 0 665.1
0
2001 2001 2
84.0
507.8 307.4 000 000
2 2 2000 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 X(mm) X(mm) 1000 1000 X( mm) 1000
Year Year Year n n
12 8 . 1
328.2
426.2
Mea Mea Mean
64.5
12
12 534.5
315.2 012
0
0 2 2 2
10 1. 4 11
11 636.6
427.9 0
2011 2 20
0
1 178.0
323.9
380.2 010
2 2010 20
09 16 2 . 2 189.5
317.3
0
2009 2009 2
8
0 142.9 326.0 383.1
2008 2008 20 No Data
75.4
407.9 07
0
2007 2007 2
06 155.3 253.5
0
Kratie 2 2006 2006
Tan Chau
05 93.2 No
180.0 05
422.0 0
Data 0
Khong ChiamKhong 2 2005 2
04 103.6
457.6
0
2 2004 2004
03 512.9 03 13 1. 6
229.1
0 0
2 2003 2
303.8 02 126.7
20 2002 2002
1
0
01
843.0 01
262.8266.2 203.0
0 0
20 2 2 No Data
389.5 328.0
2000 2000 2000 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 1000 X( mm) X( mm) X( mm) 1000 1000
Year Year Year
n
a
an 162.9
302.2
302.5 e
Mean Me M
2 2
241.5 150.3
250.8 01
2 201 2012
1
11
11 198.9
299.4
329.9 0
0
2 201 2
0 0
10 230.1
233.4
507.9 01
2 201 20
9 94.8 09 09
0 120.5
102.3 0
2 20 20
8
08 208.1
12 9 . 0 328.0
2008 200 20
7
07 07
341.3 0 389.2 198.8
0
2 20 20
6 6
0 283.9 143.7
2006 20 200
69.0
05
Neak Luong 05
336.0
285.9289.8 Savannakhet TrengStrung 0
2005 2 20
4 4
0 437.0 102.8
323.5
2004 20 200
114.0 03
333.7 224.0
003
2 2003 20
02 219.8
447.7 134.0
0 002
2002 2 2
01
454.6 01 310.0
389.3 001
2 20 20
No
0
0 Data
284.3 0 360.9 00 000
20 2 2 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 X(mm) X(mm) 1000 1000 X( mm) 1000 Figure A9 (cont.)
Page 31 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012 Year Year Year
419.1 242.8 274.4 ean ean
M Mean M 2
292.2 226.0 299.8
201 2012 2012 1
318.9 351.3
372.5
201 2011 2011 0
613.9 209.8 430.7
201 2010 2010 9
97.7
307.9 322.0
200 2009 2009
8
0 08
284.6 08 265.0 233.0
20 20 20 7
17 3 . 0 533.6 234.0
200 2007 2007 6
68.0 221.1
13 2 . 0
00 006 006
2 2 2
PakSane PakSane 5 Mukdahan
376.4 290.8 323.2 Chiang khan
200 2005 2005 4
569.2 277.3 208.5
00 004 004
2 2 2 3
341.4
573.6 308.6
200 2003 2003 2
457.5 289.0 507.5
00 002 002
2 2 2 1
295.2 329.2 220.9
200 2001 2001 0
106.6
688.3 265.2
200 2000 2000 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 X( mm) X( mm) X( mm) 1000 1000 1000 Year Year Year
261.5
19 1. 0 287.1
ean
Mean Mean M
2 2
233.2
304.9 240.6
201 201 2012
1
321.1 1
314.8 11
363.8
2011 20 20
0 0
219.5
14 5 . 6 302.1
201 201 2010 9
214.5
12 2 . 8 243.3
00 009
2009 2 2
8
94.0 08
348.0
270.6
20 200 2008 7
10 9 . 0
17 9 . 0 260.5
00 007
2007
2 2
6 47.0 82.6
16 4 . 1
006
2 200 2006 5 Khai Nong
324.6
18 3 . 3 491.4
00 005
LuangPrabang 2005 2 2 Nakon Phanom 4
152.2 390.0 187.6
004
2 200 2004 3
233.0
222.6 528.7
2003 200 2003 2
16 1. 4
209.0 382.5
2002 200 2002 1
256.1
246.2 299.3
2001 200 2001 0
495.0
234.4 263.2
2000 200 2000 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 X( mm) 1000 1000 1000 X( mm) X( mm)
Year Year Year n
245.1
320.2
271.0
ea
Mean Mean
M
2 210.7
267.0
142.8
2012
2012 201
1 1 1
351.1 275.5
16 0 . 9
201 201 201
0
199.9
1 230.2
293.1
2010 2010 20
9
16 9 . 9 09 221.3
17 7 . 4
2009 20 200 8
285.0
480.0 275.0
00
2008 2008 2
7
214.0 07
257.0
496.3
2007
20 200 6 70.2 137.0
314.0
ientiane 2006 2006
200 Thakhet
V 5
372.0 406.1 Chiang Saen
321.8
00 005
2005 2 2 4
237.6 269.1 457.0
2004 2004 200 3
297.2
223.6 474.6
00
2003 2003 2 2
206.6 289.8
002
2 200 2002 1
277.0279.2 272.1 207.2
200 2001 2001 0
177.0 451.7
247.9 00 000 000
2 2 2 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 1000 1000 1000 X( mm) X( mm) X( mm) Figure A10 Monthly rainfall in September for main stations along the Mekong River.
Page 32 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012 Year Year Year
384.6 231.5 14 3 . 5 ean
ean
Mean M M 2
70.6 274.2
248.6
2012 2012 201 1
399.9
299.3 104.8
2011 2011 201 0
222.6 16 5 . 6 15 0 . 6
2010
2010 201 9
491.6 97.0
367.4
2009 2009 200 8
339.0 364.3
2008 2008 200
No Data 7
74.2
298.0
2007
2007 200 6
244.0 14 4 . 8
2006 2006 200
Chau Doc 419.6 413.4 5 No
256.3
209.2
Data Khong ChiamKhong
2005
2005 200 4
PhnomPenh Bassac
262.0
236.3
2004
2004 200
611.3 3 86.7
93.9
2003
2003 200
410.9 2 86.7
17 0 . 0
2002
2002 200 1
556.5
13 1. 6 001 230.6
2
2001 200 0
73.0
203.5
15 6 . 3
2000 2000 200 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 1000 X(mm) X(mm) 1000 X( mm) 1000
Year Year Year
an 322.8
18 0 . 1
292.5 ean e
M M Mean
2 2
86.0 540.4
225.9
01
2012 201 2
634.3
12 2 . 8
333.4 011
2011 2011 2
214.0
209.7 269.8
010
2010 2010 2
442.6
12 8 . 8
388.4
009
2009 2009 2
8 8
326.0
283.0 294.0 00
2008 200 2
7 7
90.8 241.0
16 8 . 0
00
2007 200 2
140.6
240.6 304.5
Kratie 006
Pakse Pakse 2006 2006 2 Tan Chau
No
319.0
203.4
Data 005
2005 2005 2
217.0
245.4250.6
004
2004 2004 2
3 3 3
270.9 13 2 . 3
498.7 00
2 200 200
2 2
402.0
17 5 . 7
235.2
00
2002 2 200
374.1 136.3 160.2
001
2 2001 2001 No Data
182.0
232.5 000
2000 2000 2 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 X(mm) X(mm) X(mm) 1000 1000 1000
Year Year Year
an 265.2 186.8
226.9 ean
Mean Me M
230.9
19 3 . 2 17 6 . 4
012
2012 2012 2
296.4
218.8
284.8 011
2011 2011 2
12 1. 8
16 6 . 7
229.0
010
2010 2010 2 9
13 2 . 1
140.3 308.8
009
200 2009 2
284.0
246.0
008 240.2 008
2 2008 2
19 1. 0 113 . 0
232.0
007
007
2007 2 2
327.9 13 0 . 8 16 2 . 0
006
2006 2006 2
320.9 Neak Luong
332.5
Savannakhet TrengStrung
005
2005 2005 2
204.4
207.0 238.8236.5 004
2004 2004 2
334.5
272.9 145.0 003 003 003
2 2 2
225.1
257.5 15 7 . 0
002
002
2002 2 2
315.2 247.1
18 5 . 0
001
2001 2001 2 No
Data
281.5
267.0 000
2000 2000 2 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 X( mm) X( mm) 1000 1000 X( mm) 1000 Figure A10 (cont.)
Page 33 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Year Year Year n
n
113 . 1 110 . 7 125.6
ea
ea
M Mean M
248.6 13 2 . 0 207.6
012
2012 2012 2 1
272.1
285.0
242.5
011
2011 201 2
0 0
213.9 125.7
215.7
01
2010 2 201
77.9 94.1 48.9
09
0
2009 2009 2
129.0 15 5 . 4
102.0
008
2008 2008 2
206.0 19 1. 9
272.0
007
2 2007 2007
6 6
237.0 16 8 . 0 12 2 . 3
006
200 200 2
PakSane PakSane
5 5 Mukdahan Mukdahan 5 7.8
10.8
29.5
Chiang khan
00
2 200 200
2.2 0.0
004
2 2004 2004
4.5
16 . 8 14 . 0
003
2 2003 2003
30.6 61.9
55.0
002
2 2002 2002
1 1
155.4 70.5
12 7 . 1
00
2 200 2001
61.0 0
71.9 40.4
000
2 2000 200 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 X( mm) X( mm) 1000 1000 X(mm) 1000
Year Year Year n n
93.7
112 . 8 12 2 . 9 ea ea
M Mean M
167.9 137.7 249.8
012
2 2012 2012
217.7 267.1
243.2 011
2 2011 2011
45.4 55.0
18 9 . 7
010
2 2010 2010
91.9
49.8 54.0 09 09 09
0
2 20 20
71.0 83.0
008
2 2008 2008
107.0 145.6146.4 202.0
007
2 2007 2007
15 7 . 1
12 2 . 5 227.0
006
2 2006 2006
Nong Khai Nong 18 . 6 17 . 7
49.5
005
2 2005 LuangPrabang 2005 Nakon PhanomNakon
0.0 4.0
16 5 . 5
004 004
2004 2 2
35.0 36.0
003
2 2003 2003
71.0
74.4
002
2 2002 2002
98.2
19 2 . 3
001
2 2001 2001
00 00 63.2 83.0 00
116 . 0
0
2 20 20 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 X( mm) X( mm) X( mm) 1000 1000 1000
Year Year n Year
111. 6
116 . 2 119 . 5 ea ean
M M Mean 2
14 6 . 5 17 5 . 0
12 4 . 7
012
01
2 2012 2
117 . 1
18 5 . 7
277.8
011
2011 2011 2
71.6
202.9
010
2010 2 2010
84.4
55.4 80.5 78.5
009
2009 2 2009
82.0
12 2 . 0
205.0 008
008
2 2008 2
13 8 . 0
150.0
328.0
007 007
2 2 2007
312.2
13 9 . 0
232.5
006 ientiane 2006 2 2006 Thakhet V
28.9
52.8
Chiang Saen 12 7 . 4
005
2 2005 2005
5.0
114 . 3
004
2004 2 2004
41.6 10 . 8
13 . 8
003 003
2 2 2003
10 . 0
13 3 . 6 10 6 . 0
002
2002 2 2002
80.9 27.9
198.1
001
2 2001 2001
60.1 59.0
59.7
000
2 2000 2000 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 X( mm) X( mm) 1000 1000 X( mm) 1000 Figure A11 Monthly rainfall in October for main stations along the Mekong River.
Page 34 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Year Year Year
n n
220.5 134.7 279.5
Mean Mea Mea
2
2 80.0
119 . 8 1
233.6
01
2 20 2012
1
11
1 129.5
328.3
268.6 0
2 2011 20
0 0
10 163.5
443.6 167.4
0 01
201 2 2
9
9 80.8
77.3 0 15 1. 6
00
0
2 2009 2
8
8
08 85.0 0
0 183.0 295.9
0
2 20 20 7
10 1. 7
385.1
289.0 00
2007 2 2007
6
06 272.0 239.2
257.5
006
Pakse Pakse 0 200 2 2
Chau Doc
5
18 . 2 5
05 0
0 354.0 340.9
0
2 20 20
0.3 4
04 PhnomPenh Bassac 0
164.0
375.0
0
2 20 2004 3
51.2
03 251.6
003
0
200 2 2
2
2 2
0 88.5
176.7 0
00
0
20 2 2
1
457.1 01
157.6 00
0
2
2 2001
165.8 00 249.9
0
2000 2000 2 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 1000 X(mm) 1000 X(mm) 1000 X(mm)
Year Year Year
an
114 . 6 an 251.7 262.0 e e
M M Mean
2
88.8 411.0 12 159.3
0
201 2012 2
1
11 14 4 . 6
326.5
597.5
0
2011 201 2
0 0
1 10
179.6 1
225.6 332.8 0 0
2 2 20
33.1 9
214.7 09
155.2
0
200 2 2009
8
207.0 08 153.0
267.0
0
200 2 2008
No Data
119 . 1 7
07
007 236.0 00
0
2 2 2
6
6 6
0
420.6 0 Kratie 233.4
0
00
2 20 2 5 Tan Chau
17 . 6
91.0
452.3 05
Khong Chiam Khong 0
200 2 2005 0.5 4
37.6
04 304.4
0
200 2 2004
17 . 3 3
69.9
03
003 269.9 00
0
2 2 2
2
2 2
79.2 0
13 3 . 3 0
0 292.7
00
2 2 20 1
152.7
432.4 01 424.0
0
200 2001 2 No
Data
139.8 00
000 309.0
0
2 2 2000 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 1000 1000 1000 X(mm) X(mm) X(mm)
Year
Year Year n n
16 1. 5 255.1
Mea Mea Mean
2
97.9 105.3 2 1 12 158.3 1 169.6
0 0
2 2 20
1 1
220.1
259.0 240.9 01
201 2011 2 0
194.6
250.4 357.8
2010 201 2010
78.2 9
14 0 . 8
323.7
009 00
2 2 2009
8 8
0 08 97.0 0
198.0
309.9 0 0
2 2 20 7
180.8
336.0 349.9 007
2 200 2007 6
19 4 . 4 15 7 . 5 17 2 . 0
00 006
2 2 2006
5
64.8 5
20.2 0 Savannakhet Savannakhet Neak Luong
317.0
Strung Treng Strung 00 005
20 2 2
4 4
04
0 130.3 177.5
00
0 0
2 2 2
5.2 3
158.0
2003 2003 200
57.9 2
27.4 14 0 . 0
00 002
2002 2 2
1
1
85.9 0
01 0 153.2
345.0
0 0
20 2 2
No
0 Data
28.5 150.0
000
2 200 2000 0 0 0 800 600 400 200 800 600 400 200 800 600 400 200 1000 X(mm) X(mm) 1000 1000 X(mm) Figure A11 (cont.)
Page 35 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
3. Tables of flood event characteristics along the Mekong River during flood season 2012
Table A2 The characteristics of flood events for station from Chiang Saen to Vientiane/Nong Khai Rising Flood Date (m) Hb Date (m) Hp Tp(day) (m) (Date) (m/day) (m/day) 19-Aug 5.5218-Aug 21-Aug 7.83 11.96 23-Aug 216-Aug 15.25 10.55 2.31 5 24-Aug 20-Aug - 21-Aug20-Aug 13.27 1.21 3.29 8.05 20-Aug - 21-Aug 8 1.1620-Aug 25-Aug 1.21 10.28 TY-TEMBIN, TY-BOLAVEN 2.72 9.14 0.66 20-Aug - 21-Aug 5 25-Aug 0.65 TY-TEMBIN, TY-BOLAVEN 11.24 2.23 0.34 20-Aug - 21-Aug 5 TY-TEMBIN, TY-BOLAVEN 0.81 2.10 0.45 20-Aug - 21-Aug 0.66 TY-TEMBIN, TY-BOLAVEN 0.42 TY-TEMBIN, TY-BOLAVEN Beginning of Flood Even of Flood Beginning of flood event Peak Flood of Rising Intensity ID Station Time Amplitude Imax of Interval Imax Iaverage Comment 010501 Chiang Saen 24-Jul011201 Luang Prabang 3.24 26-Jul011903 29-Jul 9.23 Chiang Khan 7.91 01-Aug 21-Jul011901 5 15.22 Vientiane 6.62 4.67 6 02-Aug012001 26-Jul - 27-Jul 28-Jul 5.99 13.28 Nong Khai 1.54 5.60 26-Jul - 27-Jul 12 0.93 28-Jul 03-Aug 1.54 6.66 9.97 6.52 1.00 28-Jul - 29-Jul TS-VICENTE 04-Aug 6 1.17 11.66 TS-VICENTE 4.37 0.56 7 28-Jul - 29-Jul 5.14 1.30 TS-VICENTE 29-Jul - 30-Jul 0.73 1.12 0.73 TS-VICENTE TS-VICENTE
Page 36 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Table A3 The characteristics of flood events for stations from Paksane to Pakse of Imax Imax Iaverage Comment Rising Flood Date (m) Hb Date (m) Hp (day) Tp (m) (Date) (m/day) (m/day) 21-Aug 11.1623-Aug 27-Aug 12.25 9.1824-Aug 28-Aug 6 10.23 9.8524-Aug 1.09 28-Aug 5 - 26-Aug 25-Aug 10.93 8.8224-Aug 0.30 0.67 28-Aug 4 0.18 7.72 - 27-Aug 26-Aug 9.5624-Aug 0.70 0.29 28-Aug TY-TEMBIN, TY-BOLAVEN 4 - 27-Aug 26-Aug 9.70 8.41 0.1325-Aug 0.26 0.74 30-Aug 4 TY-TEMBIN, TY-BOLAVEN 0.18 7.95 - 27-Aug 26-Aug 10.97 0.69 0.22 30-Aug TY-TEMBIN, TY-BOLAVEN 6 - 27-Aug 26-Aug 9.16 0.19 1.27 0.21 5 TY-TEMBIN, TY-BOLAVEN - 28-Aug 27-Aug 0.17 0.40 1.21 TY-TEMBIN, TY-BOLAVEN - 28-Aug 27-Aug 0.21 0.36 TY-TEMBIN, TY-BOLAVEN 0.24 TY-TEMBIN, TY-BOLAVEN Beginning of Flood Even Peak offlood event Intensity of Flood Rising ID Station Time Amplitude Interval 012703 Paksane013101 Nakhon Phanom 29-Jul 30-Jul013102 8.25 6.34 Thakhek 03-Aug013402 04-Aug 12.04 30-Jul Mukdahan 9.78 5013401 7.50 30-Jul 5 Savannakhet 3.79 04-Aug013801 6.19 01-Aug 3.44 30-Jul - 31-Jul 10.90 Khong Chiam 05-Aug 31-Jul - 1-Aug 5.60 1.25 5013901 31-Jul 9.68 1.87 05-Aug 0.76 3.40 Pakse 7.20 6 8.56 0.69 31-Jul - 01-Aug 05-Aug 3.49 4 01-Aug TS-VICENTE 1.59 10.85 TS-VICENTE 31-Jul - 01-Aug 2.96 6.21 0.68 5 1.45 - 02-Aug 01-Aug 05-Aug 3.65 0.58 2.30 9.01 TS-VICENTE - 02-Aug 01-Aug 0.74 4 1.41 TS-VICENTE 2.80 0.73 TS-VICENTE - 03-Aug 02-Aug 1.29 TS-VICENTE 0.70 TS-VICENTE
Page 37 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Table A4 The characteristics of flood events for stations from Stung Treng to Kompong Cham of Imax Imax Iaverage Comment Rising Flood Date (m) Hb Date (m) Hp (day) Tp (m) (Date) (m/day) (m/day) 02-Sep 8.0802-Sep 05-Sep 9.00 18.31 06-Sep 303-Sep 19.55 12.63 0.92 4 03-Sep - 04-Sep 07-Sep 13.46 0.38 1.24 03-Sep - 04-Sep 4 0.31 0.55 0.83 0.31 03-Sep - 04-Sep SW, ITCZ 0.30 0.21 SW, ITCZ SW, ITCZ Beginning of Flood Even Peak offlood event Intensity of Flood Rising ID Station Time Amplitude Interval 014501 StungTreng 02-Aug014901 6.53 Kratie 05-Aug019802 03-Aug Kompong Cham 8.90 02-Aug 15.27 3 9.43 06-Aug 2.37 18.64 06-Aug - 04-Aug 03-Aug 12.53 3 1.19 4 3.37 0.79 - 04-Aug 03-Aug 3.10 1.73 - 05-Aug 04-Aug TS-VICENTE 1.46 1.12 0.78 TS-VICENTE TS-VICENTE
Page 38 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Table A5 The characteristics of flood events for stations from Phnom Penh Bassac/Phnom Penh Port, Koh Khel/Neak Luong to Prek Kdam of Imax Imax Iaverage Comment Rising Flood Date (m) Hb Date (m) Hp (day) Tp (m) (Date) (m/day) (m/day) 03-Sep 7.8203-Sep 07-Sep 6.92 8.30 07-Sep 4 7.41 0.48 4 04-Sep - 05-Sep 0.18 0.49 03-Sep - 04-Sep 0.12 0.14 0.12 SW, ITCZ SW, ITCZ Beginning of Flood Even Peak offlood event Intensity of Flood Rising ID Station Time Amplitude Interval 020101 Phnom Penh Port 03-Aug033402 4.91 Koh Khel 06-Aug019806 04-Aug 6.47 Neak Luong 5.28 3020102 04-Aug 07-Aug Prek Kdam 1.56 4.10 6.50 - 05-Aug 04-Aug 03-Aug 07-Aug 3 0.75 5.18 4.71 0.52 1.22 07-Aug 3 - 05-Aug 04-Aug 6.09 1.08 0.64 TS-VICENTE 4 - 05-Aug 04-Aug 0.41 0.62 1.38 0.36 - 05-Aug 04-Aug TS-VICENTE 0.62 0.35 TS-VICENTE TS-VICENTE 033401Chaktomuk Bassac 03-Aug 5.73 07-Aug 7.39 4 1.66 - 05-Aug 04-Aug 0.79 0.42 TS-VICENTE
Page 39 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Table A6 The characteristics of flood events for stations from Tan Chau and Chau Doc (**) 012 flood season. Rising Flood Date Hb (m) Date Hp (m) Tp (day) (m) (Date) (m/day) (m/day) Beginning of Flood Even Peak of flood event Intensity of Flood Rising ID Station Time Amplitude Interval of Imax Imax Iaverage Comment 019803 Tan Chau039801 Chau Doc 04-Aug 04-Aug 1.55 07-Aug 1.15 2.14 07-Aug 1.48 3 3 0.59 - 05-Aug 04-Aug 0.33 0.27 - 06-Aug 05-Aug 0.20 0.20 0.11 TS-VICENTE TS-VICENTE Water(**)Chau Doc Tan are influencedWL levels at tidal and Chau by TableA6 the effect; recorded were the in at during 7AM 2
Page 40 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
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 whole flood season from the 1st June to the 31st October shows the normal pattern.
In general terms, the accuracy is good for all forecasts lead time at most stations along Mekong River, however the accuracy for 2‐day to 3‐day forecasts start from Chiang Saen to Neak luong. The detail analysis is presented in paragraph 2.2.
Figure B1 Average flood forecast accuracy along the Mekong mainstream.
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 B2).
Page 41 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Table B1 Achievement of daily forecast against benchmarks
Page 42 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Table B2 Benchmarks of success (Indicator of accuracy in mean absolute error)
e
Chau Doc Chau
Unit in cm Unitcm in
Tan Chau Tan
Prek Kdam Prek Neak Luong Neak
d forecasting system and th Koh Khel Koh
he MekongRiver Basin, applied is
Phnom Penh Port Penh Phnom
Phnom Penh (Bassac) Penh Phnom
Kompong Cham Kompong
Kratie
Stung Treng Stung
Pakse
Khong Chiam Khong
Savannakhet
Mukdahan
Thakhek
Nakhon Phanom Nakhon Paksane
Nongkhai
Vientiane
Chiang Khan Chiang
Luang Prabang Luang Chiang Saen Chiang An indication of the accuracy given in the Table B2 is based on the performance of the forecast made in 2008 from the new floo new set of performance indicators that is established by combining international standards and the specific circumstances in t 1-day2-day3-day4-day 255-day 50 25 50 50 25 75 50 50 75 10 75 50 25 75 10 50 25 25 50 10 50 25 25 50 10 50 25 25 50 10 50 25 25 50 10 50 25 25 50 10 50 25 25 50 10 50 25 25 50 10 50 25 25 50 10 50 25 25 50 10 50 25 25 50 10 50 25 25 50 10 50 25 10 50 10 50 10 10 50 10 10 10 10 25 10 25 10 10 25 10 10 10 10 25 10 25 10 10 25 10 25 10 10 25 10 10 25 10 25 Note: configuration for the 2009 flood season and is published on the website of MRC (http://ffw.mrcmekong.org/accuracy.htm). A officially for the flood season of 2011 onward.
Page 43 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Performance Performance is assessed by evaluating a number of performance indicators, see Table and graphs below:
Table B3 Overview of performance indicators for flood season 2012 from June to October
NCHMF
Viet Nam - - Nam Viet
WR DW
T h a ila n d - - d n ila a h T
DMH
Lao PDR - - PDR Lao
DOM
Cambodia - - Cambodia
DHRW
Cambodia - - Cambodia
China
NO AA data AA NO
NCHMF
Viet Nam - - Nam Viet
WR DW
T h a ila n d - - d n ila a h T
DMH
Lao PDR - - PDR Lao
DOM
Cambodia - - Cambodia
DHRW
Cambodia - - Cambodia
China
NO AA data AA NO
nmber) (num
available available
nf maii n itio a rm fo in
Weather Weather
n et(i e) (tim sent and
FF2 com pleted pleted com FF2
forecast
stations without without stations
n et(i e) (tim sent and FF com pleted pleted com FF 10:24 0 - 26 08:12 08:12 07:19 06:15 08:45 07:26 07:03 0 2 37 125 567 13 558 Flood Forecast: time sent time Forecast: Flood (average) data input time of Arrival (number) data Missing e July 10:32 1 - 17 07:37 07:57 07:19 06:03 08:46 07:13 07:12 6 0 8 84 515 8 391 June 10:42 0 - 19 07:12 08:12 07:29 06:16 08:56 07:34 07:19 1 0 69 497 579 3 414 2012 August 10:32 0 - 16 08:12 08:12 07:14 06:13 08:45 07:24 07:35 3 1 8 77 508 5 446 season 10:31 1 - 96 07:52 08:08 07:17 06:12 08:49 07:22 07:16 10 3 123 1201 2747 50 2294 eptemb October 10:25 0 - 18 08:12 08:11 07:07 06:15 08:51 07:10 07:09 0 0 1 418 578 21 485 S
Page 44 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012 NOAA China CAM DHRW CAM DOM LAO DMH DWR THAI NCHMFVN Date DataDe live r y - De live r yTim e s June July August September October season 10:00 09:00 08:00 07:00 Time Figure B2 Data delivery times for flood season 2012 from June to October.
Page 45 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012 NOAA China DHRW CA, CAM DOM LAO DM H DWR THAI NCHMFVN Date Data De live r y - M is s ingData June July August September October season 0 Num be r 3000 2000 1000 Figure B3 Missing data for flood season 2012 from June to October.
Page 46 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Time Flood Forecast - Completion Time 11:00
10:00
09:00 Date June August October
Figure B4 Flood forecast completion time.
Flood Forecast - Stations without Forecast
10
8
6
4
2
0 Date June August October
Figure B5 Flood forecast stations without forecast.
Time Flood Forecast - Second Forecast Needed 15:00 14:00 13:00 12:00 11:00 10:00 09:00 Date June August October
Figure B6 Second forecast needed.
Page 47
Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Annex C Season Water Level Graphs
This Annex has the water level and rainfall 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 1 JUNE TO 31 OCTOBER
Water level at 7am of Mekong at Jing Hong
548
546
544
542
540 Gauge height in metres in Gauge height 538
536
534 15-Jun 15-Jul 15-Aug 15-Sep 15-Oct 15-Nov Time in days
Av98-11 1998 2000 2011 2012
14 Water level at 7am of Mekong at Chiang Saen
12
10
8
6 Gauge height in metres in Gauge height 4
2
0 01-Jun 16-Jun 01-Jul 16-Jul 31-Jul 15-Aug 30-Aug 14-Sep 29-Sep 14-Oct 29-Oct 13-Nov
Time in days
Alarm Flood Av80-11 19 9 2 19 9 8 2000 2011 2012
Page 49 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
20 Water level at 7am of Mekong at Luang Prabang
18
16
14
12
10
8 Gauge heightmetres in 6
4
2
0 01-Jun 16-Jun 01-Jul 16-Jul 31-Jul 15-Aug 30-Aug 14-Sep 29-Sep 14-Oct 29-Oct 13-Nov
Time in days
Alarm Flood Av80-11 1992 1998 2000 2011 2012
Water level at 7am of Mekong at Chiang Khan 20
18
16
14
12
10
8 Gauge metres height in 6
4
2
0 01-Jun 16-Jun 01-Jul 16-Jul 31-Jul 15-Aug 30-Aug 14-Sep 29-Sep 14-Oct 29-Oct 13-Nov
Time in days Alarm Flood Av80-11 19 9 2 19 9 8 2000 2011 2012
Water level at 7am of Mekong at Vientiane 14
12
10
8
6 Gauge metres height in 4
2
0 01-Jun 16-Jun 01-Jul 16-Jul 31-Jul 15-Aug 30-Aug 14-Sep 29-Sep 14-Oct 29-Oct 13-Nov
Time in days Alarm Flood Av80-11 1992 1998 2000 2011 2012
Page 50 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Water level at 7am of Mekong at Nong Khai 14
12
10
8
6 Gauge height in metres in Gauge height 4
2
0 01-Jun 16-Jun 01-Jul 16-Jul 31-Jul 15-Aug 30-Aug 14-Sep 29-Sep 14-Oct 29-Oct 13-Nov
Time in days Alarm Flood Av80-11 19 9 2 1998 2000 2011 2012
Water level at 7am of Mekong at Paksane 16
14
12
10
8
6 Gauge height in metresGauge in height
4
2
0 01-Jun 16-Jun 01-Jul 16-Jul 31-Jul 15-Aug 30-Aug 14-Sep 29-Sep 14-Oct 29-Oct 13-Nov
Time in days Alarm Flood Av80-11 19 9 2 19 9 8 2000 2011 2012
Water level at 7am of Mekong at Nakhon Phanom 14
12
10
8
6 Gauge height metres in 4
2
0 01-Jun 16-Jun 01-Jul 16-Jul 31-Jul 15-Aug 30-Aug 14-Sep 29-Sep 14-Oct 29-Oct 13-Nov
Time in days Alarm Flood Av80-11 1992 19 9 8 2000 2011 2012
Page 51 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Water level at 7am of Mekong at Thakhek 16
14
12
10
8
6 Gauge metres in height
4
2
0 01-Jun 16-Jun 01-Jul 16-Jul 31-Jul 15-Aug 30-Aug 14-Sep 29-Sep 14-Oct 29-Oct 13-Nov
Time in days Alarm Flood Av80-11 19 9 2 19 9 8 2000 2011 2012
Water level at 7am of Mekong at Savannakhet 14
12
10
8
6 Gauge metres in height 4
2
0 01-Jun 16-Jun 01-Jul 16-Jul 31-Jul 15-Aug 30-Aug 14-Sep 29-Sep 14-Oct 29-Oct 13-Nov
Time in days Alarm Flood Av80-11 19 9 2 19 9 8 2000 2011 2012
Water level at 7am of Mekong at Mukdahan 14
12
10
8
6 Gauge metres in height 4
2
0 01-Jun 16-Jun 01-Jul 16-Jul 31-Jul 15-Aug 30-Aug 14-Sep 29-Sep 14-Oct 29-Oct 13-Nov
Time in days Alarm Flood Av80-11 19 9 2 19 9 8 2000 2011 2012
Page 52 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Water level at 7am of Mekong at Paksé 14
12
10
8
6 Gauge metres height in 4
2
0 01-Jun 16-Jun 01-Jul 16-Jul 31-Jul 15-Aug 30-Aug 14-Sep 29-Sep 14-Oct 29-Oct 13-Nov
Time in days Alarm Flood Av80-11 1992 1998 2000 2011 2012
Water level at 7am of Mekong at Stung Treng 14
12
10
8
6 Gauge metres in height 4
2
0 01-Jun 16-Jun 01-Jul 16-Jul 31-Jul 15-Aug 30-Aug 14-Sep 29-Sep 14-Oct 29-Oct 13-Nov
Time in days Alarm Flood Av80-11 1992 1998 2000 2011 2012
Water level at 7am of Mekong at Kratie 26
24
22
20
18
16
14
12 Gauge metres in height 10
8
6
4 01-Jun 16-Jun 01-Jul 16-Jul 31-Jul 15-Aug 30-Aug 14-Sep 29-Sep 14-Oct 29-Oct 13-Nov
Time in days Alarm Flood Av80-11 1992 19 9 8 2000 2011 2012
Page 53 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Water level at 7am of Mekong at Kampong Cham 18
16
14
12
10
8
Gauge height in metresGauge in height 6
4
2
0 01-Jun 16-Jun 01-Jul 16-Jul 31-Jul 15-Aug 30-Aug 14-Sep 29-Sep 14-Oct 29-Oct 13-Nov
Time in days Alarm Flood Av80-11 1992 19 9 8 2000 2011 2012
Water level at 7am of Mekong at Phnom Penh Chaktomuk 14
12
10
8
6 Gauge height in metres 4
2
0 01-Jun 16-Jun 01-Jul 16-Jul 31-Jul 15-Aug 30-Aug 14-Sep 29-Sep 14-Oct 29-Oct 13-Nov
Time in days Alarm Flood Av80-11 1992 19 9 8 2000 2011 2012
Water level at 7am of Tonle Sap at Phnom Penh Port 14
12
10
8
6 Gauge height in metres 4
2
0 01-Jun 16-Jun 01-Jul 16-Jul 31-Jul 15-Aug 30-Aug 14-Sep 29-Sep 14-Oct 29-Oct 13-Nov
Time in days Alarm Flood Av80-11 19 9 2 1998 2000 2011 2012
Page 54 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Water level at 7am of Bassac at Koh Khel 9
8
7
6
5
4
Gauge height in metresGauge in height 3
2
1
0 01-Jun 16-Jun 01-Jul 16-Jul 31-Jul 15-Aug 30-Aug 14-Sep 29-Sep 14-Oct 29-Oct 13-Nov
Time in days Alarm Flood Av80-11 1992 19 9 8 2000 2011 2012
Water level at 7am of Mekong at Neak Luong 9
8
7
6
5
4
Gauge height in metresGauge in height 3
2
1
0 01-Jun 16-Jun 01-Jul 16-Jul 31-Jul 15-Aug 30-Aug 14-Sep 29-Sep 14-Oct 29-Oct 13-Nov
Time in days Alarm Flood Av80-11 1992 19 9 8 2000 2011 2012
Water level at 7am of Tonle Sap at Prek Kdam 12
10
8
6
Gauge height in metresGauge in height 4
2
0 01-Jun 16-Jun 01-Jul 16-Jul 31-Jul 15-Aug 30-Aug 14-Sep 29-Sep 14-Oct 29-Oct 13-Nov
Time in days Alarm Flood Av80-11 1992 19 9 8 2000 2011 2012
Page 55 Seasonal Flood Situation Report for the Lower Mekong River Basin, 1 June – 31 December 2012
Water level at 7am of Mekong at Tan Chau 6
5
4
3
2 Gaugemetres in height 1
0
-1 01-Jun 16-Jun 01-Jul 16-Jul 31-Jul 15-Aug 30-Aug 14-Sep 29-Sep 14-Oct 29-Oct 13-Nov
Time in days Alarm Flood Av80-11 19 9 2 1998 2000 2011 2012
Water level at 7am of Bassac at Chau Doc 6
5
4
3
2 Gauge metres height in 1
0
-1 01-Jun 16-Jun 01-Jul 16-Jul 31-Jul 15-Aug 30-Aug 14-Sep 29-Sep 14-Oct 29-Oct 13-Nov
Time in days Alarm Flood Av80-11 19 9 2 1998 2000 2011 2012
Page 56