Nam Songkhram model application and field work MRCS WUP-FIN

2 Outline New data Cross sections Field measurements Satellite images Etc. HBV and VMod hydrological models Validation results Scenarios VMod manual 3D Hydrodynamic model Validation result Scenarios Development and continuation

3 Nam Songkhram application area

4 New data Pumping data Data from irrigation projets Total volumes 675 million m 3 Most (520 million m 3 ) is from Nam Oon Water Quality data Satellite images Field measurements

5 New data, cross sections Cross sections 400 cross sections from Nam Songkhram and its tributaries Have now been digitalized and quality checked The general information of the cross sections was added to the model

6 Field work at Ban Chai Buri - location

7 Current meter RCM9 Current speed Current direction Temperature Conductivity Pressure Turbidity Oxygen

8 Current speed & direction Mekong

9 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 Simple optimisation of the model parameters completed with good results Ban Tha Kok Daeng Ban Tha Sri Chomchun Ban Phok Yai Ban Khon Sai Ban Nong Yang

10 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. 1 km model grid Flow network computed from DEM and corrected 5 landuse classes and 5 soil classes Calibration with five discharge stations is finished

11 VMod: new developments Pumping it is now possible to substract (or add) water from the river (for irrigation) Regulation it is now possible to regulate lakes (Nam Oon reservoir) Improvements in the model calculations

12 VMod: New development in Nam Songkhram River data and friction coefficients have been modified Model has been calibrated Water quality component has been included, but not yet calibrated Preliminary (sensitivity) scenarios have been simulated

13 Calibration of the VMod application for Nam Songkhram is ready The R2 in calibration period ( ) was 0.90 for Nam Songkhram at Ban Tha Kok Daeng 0.69 for Nam Oon at Ban Phok Yai 0.66 for Nam Yam at Ban Khon Sai 0.78 for Huai Khong at Ban Tha Sri Chomchun 0.82 for Huai Hi at Ban Nong Yang VMod calibration

14 The R2 in test period ( ) was 0.86 for Nam Songkhram at Ban Tha Kok Daeng 0.76 for Nam Oon at Ban Phok Yai 0.78 for Nam Yam at Ban Khon Sai 0.71 for Huai Khong at Ban Tha Sri Chomchun 0.58 for Huai Hi at Ban Nong Yang VMod verification

15 VMod manual New version of the VMod manual has been prepared

16 EIA 3D Model Latest developments Calibration, verification and scenario results

17 Digital elevation model and model area

18 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 Input data River and floodplain topography Boundary conditions Landuse Wind

19 Flood duration Flood arrival time

20 Modelling: 3D new developments Channel dimensions and elevations have been modified Model parametrization has been modified to stabilize the model Model has been calibrated and validated against satellite data from flood extent and water levels Preliminary scenarios have been calculated

21 Calibration results 17/09/2000

22 Calibration results 04/11/2000

23 Verification results 20/09/2001

24 Effect of Mekong to Nam Songkhram Backwater effect (Mekong prevents Nam Songkhram outflow) Has clear effect to flooded areas in Nam Songkhram The effects can be seen in the model simulations Reverse flow (Mekong flows into Nam Songkhram) Depends on the size of the Mekong flood and on the timing of Mekong and Nam Songkhram floods Greatest when Mekong flood is ahead on the flood in Nam Songkhram

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

26 Reverse flow maximum 1999 Reverse flow maximum 1997

27 Scenarios Climate change A2: T = 4.0 C, E = +9.5 %, P = 6.6 %, Mekong = 17 % B2: T = 2.9 C, E = +6.9 %, P = 0.9 %, Mekong = 6 % Land use change Decidious forest – 80 % (from 6 % to 1 %) Upstream development DSF upstream development scenario (high development) Irrigation (upstream and in basin) DSF upstream irrigation scenario + more irrigation in Nam Songkhram (-5 % NS at BTKD, Nam Yam and Huai Hi)

28 Climate change A2 Baseline 20/08/2001

29 Baseline Climate change B2 20/08/2001

30 Baseline 20/08/2001 Land use change

31 Baseline 05/08/1997 Upstream development

32 Baseline 05/08/1997 Irrigation

33 Future tasks Calibrate the water quality and erosion components to the model (more data?) Clarify and execute official scenarios (e.g. irrigation, land use and climatological changes)

MRCS/WUP-FIN Thank You!