1. Multifunctional Hydrological Roles in Cambodian Flood Plain Project (TSLV) Flood Mapping and Function of Flood Plains Manithaphone Mahaxay, MRCS

2. Water Level Observation Stations, Mekong River and Floodplain St. 7 89 13 11 15 16 7 1 2 3 4 5 6 17 14 10 20 12 18 19 Phnom Penh Kampong Cham Zone 2 Zone 3Zone 4 Zone 5 Zone 1 Tonle Sap Bassac Mekong River Chrui Changvar Neak Leung Koh Norea

3. Water Level (2002) Mekong River Floodplain Mekong-Tonle Sap Zone 2East Side Zone 5 July August Sept. Oct. Nov. Dec.

4. RADARSAT Image in July 2002 to January 2003 were used to check the extent of floodplain lands inundated Rising Flood Condition in 2002 – RADARSAT ScanSAR Image Derived Hydrology ScanSAR Narrow B, August 27, 2002 Major Roads Open Water Floods

5. Discharge Measurement Campaign (2002 ) Flood Plains by TSLV Project Main Stream by Other Projects TSLV Project Teams Site A (National Road 6 & 6A Site B (National Road 1 & 11) Site B + (National Road 70) Kompong Cham Prek Kdam Zone 5 Neak Luong Chaw Doc Tan Chaw WUP-JICA Project Team Kompong Cham Chrui Changvar Phnom Penh Port Monivong Bridge Koh Norea Koh Khel (Bassac) Neak Luong Prek Kdam Zone 2 Kratie Zone 4 Component 1 Project Teams Kratie Moat Kumong (National Road 7) Measuring weekly discharge around zone 2 & 5 Site A Site B,B+ Moat Kumong Tonle Sap Bassac Mekong River

6. Mekong River Hydrographs 2002 Results of the flow gaugings for a few mainstream sites

7. Koh Khel Zone 5 Zone 2 Kg Cham Neak Leung Zone 4 Estimation of Net flow Volume (July 10 to Nov.17, 2002) 4 35 15 12 365 305 3 269 17 5 14 3 51 7 282 13 -10 Observed by WUP JICA team Observed by TSLV team Estimated by Water Balance 8 5 5 Prek Kdam Reverse- 42 Normal+ 32 Phnom Penh Port Reverse -34 Normal +37 Unit: Billion m 3 Moat Khmong Bridge Reverse -12 Normal +16 Observed by Component1 5 Tonle Sap Mekong River Bassac

8. Layout of hydraulic river & flood plain model

9. Discharges (ADCP) Koh Norea Chrui Changvar Monivong Bridge Koh Khel Observation (ADCP) Simulation Tonle Sap showing flow reversal Bassac showing effect of flood plain spill Mekong River u/s and d/s of junction showing storage function of Great Lake Model results (discharges) in main rivers Flow towards lake Flow from lake Observations shown with dots Model results shown with lines Mekong River Reasonable accuracy on hydraulic conditions and the conditions of flood plain such as water levels, flows & flood extent

10. P3 P10 P1 Flood plain results Discharges at selected bridges Water levels at selected stations d d d Levels relative to Hatien MSL datum Similarly observed and simulated water levels and discharges

11. Depth [m] Flood plain inundation An example of observed and model predicted flood extent Observed August 15th 2002 Simulated Observed September 20th 2002 Simulated Observed October 14th 2002 Simulated Observed November 20th 2002 Simulated Observed December 25th 2002 Simulated

12. Flow Regulation Function  Flood Peak Cut by storing water in the Flood plain Wet SeasonDry Season Channel flow Without flood plain Channel flow Regulated by flood plain Flood Peak cut Flood Mitigation volume by flood plain Flow increase in dry season by flood plain Flow increase effect  Flow increase in dry season by releasing water from flood plain