Outline of the training. 6 October 2005, TNMC, Bangkok

2 Training objectives updating the data and model development issues deepening the knowledge of the EIA 3D hydrodynamic models with practical training planning of the future activities

3 Schedule

4 Brushing up.... HBV and VMod hydrological models Validation results Development and continuation VMod manual 3D Hydrodynamic model Current status of the application Validation Development and continuation Field work Preliminary results from the field work in Si Songkram

5 Nam Songkhram application area

6 HBV and VMod Data Latest results Continuation

7 Elevation km 2 Heights min 135m max 675 m

8 Weather data 16 precipitation stations Temperature data from one station Evaporation, three stations used Some data gaps Temperature missing Some days and months missing in Pan evaporation

9  1175  1432  2366  1339  1254  1128  1564  2290  2665  1796  1446  2943  1976  1984  1850  1979 Average yearly precipitation

10 Modelling: HBV HBV model has been set up for five subcatchments in the Nam Songkhram watershed The size of the model areas is between 625 and 5029 km 2 Ban Tha Kok Daeng Ban Tha Sri Chomchun Ban Phok Yai Ban Khon Sai Ban Nong Yang

11 Modelling: HBV Simple optimisation of the model parameters completed Model results in calibration period ( ) very good to moderately good Model result in test period ( ) good to moderately good

12 The R2 in calibration period was 0.92 for Nam Songkhram at Ban Tha Kok Daeng 0.81 for Nam Oon at Ban Phok Yai 0.74 for Nam Yam at Ban Khon Sai 0.86 for Huai Khong at Ban Tha Sri Chomchun 0.86 for Huai Hi at Ban Nong Yang The R2 of the test period ( ) was 0.83 for Nam Songkhram at Ban Tha Kok Daeng 0.81 for Nam Oon at Ban Phok Yai 0.73 for Nam Yam at Ban Khon Sai 0.77 for Huai Khong at Ban Tha Sri Chomchun 0.76 for Huai Hi at Ban Nong Yang HBV results

13 Modelling :VMod 2D distributed hydrological model coupled with a 1D hydrodynamic river, reservoir and lake model Physical model of the application area that takes into account variability in elevations, soil properties, vegetation, land use etc.

14 Landuse/Irrigated area Landuse (1997) types are Water Agriculture Irrigated agriculture Evergreen/mixed forest Deciduous forest/scrub 89% of landuse agriculture or irrigated agriculture Irrigated 3280 km 2 (24% of catchment, 2001) New landuse data (2002)

15 Soils Five soil types 80 % acrisol/plintic acrisol Low water retention and conductivity water floodplain alluvial soils (plinthic) acrisol slope complex

16 Modelling: VMod 1 km model grid (resolution can and probably will be increased) Flow network computed from DEM and corrected The number of landuse and soil classes has been reduced to make the calibration and use of the model easier and clearer 5 landuse classes 5 soil classes

17 Modelling: VMod, newest developments Data from four new discharge station added to the model Calibration of the model has continued with this new data New developments of the irrigation practices include the possibility to subtract water from the river to be used in irrigation

18 Computed flow at Ban Tha Kok Daeng compared to measured data The results are much better than the previous results, but there is still room for more improvement R2 is 0.91 in calibration period, 0.84 in test period VMod flow computations, Ban Tha Kok Daeng

19 The other four stations with discharge measurement have been included in the model and their calibration is only in the beginning The computed vs. measured in these new stations is not as good as in Ban Tha Kok Daeng The R2 in calibration period was 0.55 for Nam Oon at Ban Phok Yai (there are still problems with irrigational practices and with the Nam Oon dam here) 0.65 for Nam Yam at Ban Khon Sai 0.58 for Huai Khong at Ban Tha Sri Chomchun 0.80 for Huai Hi at Ban Nong Yang VMod flow computations, other stations

20 VMod: Future tasks Develop further the agricultural water practices (water trapping, discharge and evaporation from paddy fields etc.) Check the floodplains in the hydrological model Add structures that may affect flow Check river dimensions (cross sections) Further calibration of the model Include water quality and erosion components to the model and calibrate these Clarify and execute scenarios (e.g. irrigation, land use and climatological changes)

21 EIA 3D Model Latest development Some preliminary results

22 3D hydrodynamic and WQ application 3D hydrodynamic model coupled with a water quality model 3D hydrodynamics flood arrival time, duration and depth in different locations of the modelled area, other flood characteristics Water quality: sediment concentration, net- sedimentation, oxygen, etc Run through a GIS-type graphical user interface

23 Input data for the 3D model River and floodplain topography Hydrographic atlas data river cross-sections for Nam Songkhram digital elevation map (DEM) for floodplain Boundary conditions Upstream discharge and water level in Mekong Upstream dishcarge in Nam Songkhram Downstream rating curve (in Mekong) Landuse Wind (Precipitation)

24 Modelling: 3D The main tribuaries of the Nam Songkhram have been included in the model (Nam Oon, Nam Yam, Huai Hi...) Model calculation have been visually compared to data from inundated areas Effect of Mekong mainstream waterlevel (backwater effect) Sensitivity to parameter values has been analysed Channel dimension and elevations have been modified (still in progress)

25 Digital elevation model and model area

26 3D view on the wetlands

27 Inundation on Sept 2000

28 3D model grid for NSK model

29 Model animation window

30 Flood duration Flood arrival time

31 Flood depth- Mekong water level low Flood depth- Mekong water level high

32 Output Tool to understand the hydrodynamic of the Nam Songkhram flood plains Scenarios and their impact on the flooding Landuse Climate change Irrigation development Reservoir development Interaction between Nam Songkhram and Mekong Reverse flow Back water effect

33 EIA 3D modelling: Future tasks Include new river cross sections in to the model Check grid heights Include structures that affect flow (enbankments, dams, weirds) Calibrate and verify the model Include water quality calculations Clarify and execute scenarios (e.g. irrigation, land use and climatological changes)

34 Field work at Si Songkram - location

35 Current meter RM9 Current speed Current direction Temperature Conductivity Pressure Turbidity Oxygen

36 Current speed & direction Mekong

37 Vientiane – Nong Khai bank erosion study

38 Vientiane – Nong Khai: 50m grid

39 Vientiane – Nong Khai: model results

40 Field work at Vientiane – Nong Khai

41 Field work at Vientiane – Nong Khai Flow velocity

42 Field work at Vientiane – Nong Khai Backscatter

MRCS/WUP-FIN