Nam Songkhram model application and field work National consultation with TNMC 20th of April 2006, Bangkok MRCS WUP-FIN

2 Outline Models applied and model areas Input data Cross sections Field measurements Satellite images Etc. HBV and VMod hydrological models Calibration results Validation results Scenarios VMod manual 3D Hydrodynamic model Calibration results Validation result Scenarios Development and continuation 3D EIA model manual

3 Nam Songkhram application areas Area: 13,126 km 2 Elevation: min 135 m amsl max 675 m amsl

4 HBV Hydrological Model Simple lumped hydrological model HBV model has been set up for five subcatchments in the Nam Songkhram watershed The size of the model areas varies 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

5 VMod Hydrological model 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

6 EIA 3D Hydrodynamic model 3D hydrodynamic model coupled with a water quality model 500 m grid resolution for floodplain, for rivers 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

7 Input data Models applied and model areas Input data Cross sections Field measurements Satellite images Etc. HBV and VMod hydrological models Calibration results Validation results Scenarios VMod manual 3D Hydrodynamic model Calibration results Validation result Scenarios Development and continuation 3D EIA model manual

8 Input data status – Hydrological models Digital elevation model 50 m resolution Landuse maps (several years, newest from 2002) Soil map Weather data 16 precipitation stations Temperature data from one station Evaporation, few stations Flow and water level data five stations

9 New data Pumping data Data from irrigation projets and structures Total volumes 675 million m 3 Most (520 million m 3 ) is from Nam Oon Water Quality data Satellite images to show the flood extent Field measurements Ground water depth

10 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

11 Input data status – EIA 3D Hydrodynamic model Digital elevation model 50 m resolution Channel cross-section data Landuse maps (several years, newest from 2002) Boundary conditions Upstream (discharge): Ban Tha Kok Daeng + sub-tributaries & Mekong upstream Downstream (rating curve): Mekong at Nakhom Phanom Water level Flood extent based on satellite images Field data

12 Field work at Ban Chai Buri - location

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

14 Current speed & direction Mekong

15 HBV and VMod hydrological models Models applied and model areas Input data Cross sections Field measurements Satellite images Etc. HBV and VMod hydrological models Calibration results Validation results Scenarios VMod manual 3D Hydrodynamic model Calibration results Validation result Scenarios Development and continuation 3D EIA model manual

16 HBV calibration results The R2 in calibration period ( ) was 0.92 for Nam Songkhram at Ban Tha Kok Daeng 0.80 for Nam Oon at Ban Phok Yai 0.75 for Nam Yam at Ban Khon Sai 0.84 for Huai Khong at Ban Tha Sri Chomchun 0.86 for Huai Hi at Ban Nong Yang red line observed, black line calculated

17 HBV validation results The R2 of the validation period ( ) was 0.83 for Nam Songkhram at Ban Tha Kok Daeng 0.81 for Nam Oon at Ban Phok Yai 0.70 for Nam Yam at Ban Khon Sai 0.70 for Huai Khong at Ban Tha Sri Chomchun 0.76 for Huai Hi at Ban Nong Yang red line observed, black line calculated

18 VMod program: 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 / reservoirs (Nam Oon reservoir) Improvements in the model calculations

19 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

20 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 red line observed, black line calculated

21 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 red line observed, black line calculated

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

23 HBV and VMod hydrological models Models applied and model areas Input data Cross sections Field measurements Satellite images Etc. HBV and VMod hydrological models Calibration results Validation results Scenarios VMod manual 3D Hydrodynamic model Calibration results Validation result Scenarios Development and continuation 3D EIA model manual

24 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

25 Flood duration Flood arrival time

26 Calibration results 17/09/2000

27 Calibration results 04/11/2000

28 Verification results 20/09/2001

29 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

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

31 Reverse flow maximum 1999 Reverse flow maximum 1997

32 Scenarios SRES A2 and B2 climate scenarios for provided by Hoanh et al. (2003) 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)

33 Procedure First changes made to VMod input data Example of the Climate change scenario A2, results from VMod VMod results used as a new boundary conditions to the EIA 3D model

34 Climate change A2 Baseline 20/08/2001

35 Baseline Climate change B2 20/08/2001

36 Baseline 20/08/2001 Land use change

37 Baseline 05/08/1997 Upstream development

38 Baseline 05/08/1997 Irrigation

39 Future tasks Calibrate the water level in the locations where data available Calibrate the water quality and erosion components to the model Clarify and execute official scenarios (e.g. irrigation, land use and climatological changes)

40 Potential use of the model set Impact of the local and basin wide development on the flooding, water quality, etc Impact of the climate change (better data of climate change scenarios from SEA START RC) Landuse change impacts on the hydrology and water quality Fisheries research Ecosystem functions and productivity issues (productivity related to the flooded area, vegetation, water quality) Model basis of the possible flood forecasting work

41 Working paper All the information collected there Will be updated continuosly Newest version by request

42 Content of the project’s two phases Personnel & contact details Documents downloadable Training portfolio: presentations, documents, exercises

MRCS/WUP-FIN Thank You!