WHAT IS THE Decision Support Framework (DSF)

1. WHAT IS THE Decision Support Framework (DSF)

2. 1. What is a Decision Support Framework? • A suite of computer models linked to a database • Simulates behaviour of the LMB river systems under different development conditions… • Assists prediction of environmental and socio-economic impacts caused by flow and water quality changes

3. Key functions of the DSF • Predict how the river system will behave under different future development scenarios • Assess what impacts are likely to occur • Undertake these analyses in a manner that is transparent and acceptable to all

4. Use of the DSF for Basin Planning • Investigate management options that best achieve policy objectives • Analyse likely transboundary impacts • Audit compliance with: • National policy objectives • Acceptable impact levels & • Mekong Agreement flow rules

5. Examples of what the DSF can look at ? • Land management practices: • Change in catchment runoff factors • Reservoirs (including hydropower): • New reservoirs in China • New reservoirs in LMB • Changes in operation of existing reservoirs • Flood protection (d/s Kratie): • New embankments and roads • Raised embankments and roads • Channel improvements (d/s Kratie): • Dredging and re-profiling • Cross-regulation • Salinity intrusion barriers

6. What are the 3 models that make up the DSF • A hydrologic model (SWAT) • A river simulation model (IQQM) • A hydrodynamic model (ISIS) • What do these models look like ?

7. I’m a SWAT sub-basin • SWAT! • The rainfall-runoff model (hydologic model) covers all the hilly areas – no gaps! • Each sub-basin is like a leaf on a tree which collects water

8. The IQQM river simulation model joins the SWAT sub-basins together • It collect the water from the leaves and shows how that water moves down the river

9. …to my roots – ISIS, the hydrodynamic model • …which spread out wide across the floodplain

10. China inflows • SWAT sub-basins collect water & WQ parameters • IQQM models the flow down the river branches… • iSIS hydrodynamic model moves the water in 2 directions across the floodplain KRATIE Coast

11. Location of SWAT sub-basins relative to potential dams

12. Location of irrigation demand nodes in Isan Province

13. Area covered by the hydrodynamic model Kratie Phnom Penh

14. Hydrodynamic model node structure

15. Things to remember about using the DSF • Each type of model takes different lengths of time to run – the Hydrodynamic model takes the longest – about 40 minutes • Modellers often come back wanting changes usually they need to simplify the analysis • Saving the results to the DSF takes additional time – perhaps as long as it takes to run the models • The more you ask for (locations, short time-steps) the longer they take to run and to save to the DSF • The volumes of data are large – the DSF models & results for 8 scenarios currently use 5 GB

16. What can the DSF tell us ? • Two examples are: • Flow information – how the volume of flow might change if there is some intervention • Spatial information – what changes in flow in the Mekong delta might look like if there is some intervention

17. For example - What if irrigation increases? • If there is an extra 0.5 million ha of dry season irrigation upstream of Kratie.....

18. Kratie Annual Minimum Flows of Scenario 4Vs base line 3 Current min flow at Kratie Q (m /s) BL min SCN min BL avg. min SCN avg. min 2200 2000 1800 1600 1400 Min flow with extra irrigation 1200 1000 800 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 Year Flows at Kratie would change? Annual minimum flows at Kratie DRAFT

19. What if there are changes in flow as the result of dams ? – such as the dams in China

20. The DSF can provide spatial data • Flood depths might change as a result of the Chinese dams

21. Flood durations may change as a result of the Chinese dams