At the Interim Results Workshop, the Modeling Team presented the climate change and hydrological modeling results for the LMB. The modeling team consists of Mr. Tarek Ketelsen, Mr. Jorma Koponen, Mr. Jeremy Carew-Reid, Mr. Simon Tilleard, Mr. Mai Ky Vinh, and Mr. To Quang Toan.

1. Climate and
hydrological
change:
methods and
results
Tarek Ketelsen
Jorma Koponen
Jeremy Carew-Reid
Simon Tilleard
Mai Ky Vinh
To Quang Toan
ICEM – International Centre for Climate Change Impacts and Adaptation Study
Environmental Management Interim Results workshop
31 October – 1 November 2012

2. Contents
1. Climate change and the Mekong Basin
2. Overview of the methodology
3. Basin-wide findings
4. Challenges & limitations
2

3. CLIMATE CHANGE & THE
MEKONG BASIN
3

4. Hydroclimate features of
the Mekong Basin
40,000
35,000 KRATIE
30,000
PAKSE
25,000
20,000
TAN CHAU
15,000
VIENTIANE
10,000
CHIANG SAEN
5,000
CHAU DOC
0
1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec
4

5. Climate
changes
Hydrological
changes
Agricultural Ecological
zones zones
Species “zones”
Commercial Subsistence Aqua- Traditional Live- Crop wild NTFPs Wild fish Wildlife
crops crops culture crops stock relatives catch
Climate
Adaptation options
changes
Hydrological
changes
Agricultural Ecological
zones zones
Species “zones”
Commercial Subsistence Aqua- Traditional Live- Crop wild NTFPs Wild fish Wildlife
crops crops culture crops stock relatives catch
Adaptation options

6. ARCC time-slices
• ARCC Vulnerability Projections centered on 2050 (2045-2069)
– 2050 allows for identification of the CC trends to be established with
confidence
– show us what direction we are moving, helping to set adaptation
response
• ARCC will also consider 2030 and Global 2 C
6

7. 2 C – a compromise with nature to avoid catastrophic climate change
> 2 C → + 2 to 7m SLR
>300yrs
> 3-5 C → +5 m SLR > 2 C → ????
>300yrs
7
Source: Adapted from (Schellnhuber, 2012and Lenton et al 2008)

8. Global CC projections
B1
• Population peaking
at 9bil. and declining
after 2050
• Reductions in
material intensity
• Aggressive
transition to clean &
resource efficient
technologies
• Emphasis on
globally connected
economies
• Over last decade rates of C0₂ emissions have exceeded even the most
extreme scenarios
– 2008 emissions +37% above 1990 levels
– 2010 emissions +5% above 2008 8
– Increased mean global temperatures by 0.8 C
Source: IPCC, 2007

9. Emission thresholds
• Budget of 750Gt C0₂ remaining
before we reach 2°C
• Global emissions for all GHGs
need to peak by 2015-2020
• 5-9% annual emissions
reduction rate
• 25-40% emissions reduction
of developed countries by
2020
• 50% global emissions
reduction by 2050
Source: WBGU Special Report 2009
• Unlikely that climate change can be limited to 2 C
• Vulnerability assessments need to project beyond 2 C to
understand the trends 9
• By 2050, the Mekong Basin is beyond 2 C

10. METHODOLOGY
10

11. Assessment steps
MEKONG HYDROCLIMATE MEKONG SYSTEMS BASELINES
BASELINE
Hydrological Floodplain Crop Yield Crop suitability
modelling modelling modelling modelling
CHARACTERISATION OF EXPOSURE CHARACTERISATION OF
SENSITIVITY
11
MEKONG SYSTEM CAM ASSESSMENT

12. Projections of future emissions
and global GHG concentrations
IPCC EMISSION SCENARIOS
A1 B1 A2 B2
Hydroclimate Projections of future atmospheric climate, atmospheric & ocean
dynamics
assessment process BCCR-
GCMs – GLOBAL CIRCULATION MODELS
CCSM3 CGCM3.1 CGCM3.1 CNRM- CSIRO - ECHMA5/ ECHO-G
BCM2.0 (T47) (T63) CM3 MK3.0 MPI-OM
FGOALS- GFDL- GFDL- GISS- GISS-EH GISS-ER INM- IPSL-CM4
G1.0 CM2.0 CM2.1 AOM CM3.0
MICROC3. MICROC3.2 MRI- PCM UKMO- UKMO-
2 (hires) (medres) CGCM2.3. HADCM3 HADGEM
2 1
Downscaled projections of future climate at
the basin-level
CLIMATE DOWNSCALING
DYNAMICAL STATISTICAL PATTERN
(PRECIS)
PRECIS Vietnam 2009 Mekong Basin 2009
Southeast (WeADAPT) (Cai et al, 2008)
Asia 2003
(SEASTART)
Prediction of future hydrological regime
HYDROLOGICAL MODELLING
VMOD VMOD MRC DSS VMOD SLURP CSIRO
Songkhram Mekong Delta Mekong Mekong Mekong Mekong
2004 2008 Basin 2010 Basin 2011 Basin 2011* Basin 2009
(Aalto Uni & (Aalto Uni & (MRC & (Aalto Uni & (QUEST) 12 (18 sub-
SEASTART) SEASTART) IWMI) ICEM) (no Mekong basins)
floodplain)

13. Key steps
1. Projections of future emissions
• Quantification of future
climate change threats
• Links changes in global 2. Projections of future atmospheric
systems to regional and and ocean dynamics
local areas of interest
• Based on best available 3. Downscaling projections to the
Mekong Basin
science
4. Predicting future changes in the
basin hydrological regime
5. Predicting future changes in the
Delta floodplain environment &
project site
13

14. 1. IPCC Emissions Scenario
A1B
• world of rapid economic growth
• introduction of more efficient technologies
14
• global population peaking by 2050 (9bil.)
• a balance between fossil intensive and non-fossil energy sources Source: CSIRO, 2009

15. 1. IPCC Scenarios – new developments
IPCC AR5 (2014)
• SRES scenarios will be replaced with a set of
Resource Concentration Pathways (RCPs)
– a set of scenarios relating to radiative forcing and
GHG concentrations in the atmosphere
– not directly linked to any socio-economic futures
• Can be linked to IPCC scenarios
15
Source: Moss et al, 2012

16. 2. Global Circulation Models
• Two earlier studies (Cao et al, 2009; Eastham et al, 2008) reviewed the
performance of 17/24 IPCC AR4 GCMs for suitability to the Mekong region
• In general, models perform better for temperature than precipitation
• 6 were chosen based on their ability to replicate daily historical temperature and
rainfall data
Climate model CO2 Scenario Abbreviation Data period Model resolution (degrees)
CCCMA_CGCM3.1 A1b, B1 ccA, ccB 1850-2300 3.75° x 3.75°
CNRM_CM3 A1b, B1 cnA, cnB 1860-2299 2.8° x 2.8°
GISS_AOM A1b, B1 giA, giB 1850-2100 3° x 4°
MIROC3.2Hires A1b, B1 miA, miB 1900-2100 1.1° x 1.1°
MPI_ECHAM5 A1b, B1 mpA, mpB 1860-2200 1.9° x 1.9°
NCAR_CCSM3 A1b, B1 ncA, ncB 1870-2099 1.4° x 1.4°
16

17. 3. Statistical Climate Downscaling
Purpose: reduce the geographical scope so that resolution
can be improved
 Assumes local climate is conditioned by large-scale
(global) climate
 does not try to understand physical causality
 GCM output is compared to observed information for a
reference period to calculate period factors
 Period factors are then used to adjust GCM time-series
 Downscaling undertaken for 166 temperature &
precipitation stations
17

18. 4. Basin wide hydrological modelling
• VMod model
• 15 years of custom development for the Mekong
• area-based distribution of hydro-meteorological
impacts of climate change
• Computes water balance for grid cells (5x5km)
• Baseline:1981 – 2005
• Future CC: 2045 - 2069
• Can predict changes in:
– Rainfall
– Runoff
– Flows
– Infiltration
– evapotranspiration
18

19. 5. Flood modelling
• MIKE-11
• Uses Vmod to establish
boundary conditions
• Divides the floodplain into
zones (>120 in the delta)
• Calculates small area water
balances
– 25,900 water level points
– 18,500 flow points
• Quantifies the changes in depth
and duration of flooding due to
changes in upstream hydrology
and sea level rise
Flooding Assessment scenarios
• Average Flood + 0.3m SLR
• 1 in 100yr Flood + 0.3m SLR 19
• 1 in 100yr Flood + 0.3m SLR + Cyclone event

20. MAIN FINDINGS
20

21. CC assessment parameters
• Max/min daily Temperature
• Seasonal rainfall
• Timing of the monsoon
• Peak rainfall events
• Erosion potential
• Drought
• Storms & cyclones
• Soil water availability
• River flow
• Hydro-biological seasons
• Flooding (depth & duration)
21

22. Interpreting Climate Change: Shifts & variability
1. Shift in the Mean
2. Historic variability 1
3. future variability
 3–2= variability
4. Climate experienced in baseline
but no longer experienced with
CC
5. Climate common in baseline but
less frequent with CC 3
6. Climate becoming more
frequent with CC 2
7. New climate never before
experienced
4 5 6 7
22

23. CHANGES IN TEMPERATURE
23

24. Max temperature
Annual
+ 5-7%
+ 10-15%
24

25. Max temperature
Dry Season
+ 10-13%
25

26. Max Temperature
Wet
+ 14-19%
26

27. Min. temperature
Annual
+ 10-30%
27

28. CHANGES IN RAINFALL
28

29. Mean Annual
precipitation change
+ 10-18%
• Text
29

30. Mean Wet Season
precipitation change
• Text
+ 11-14%
30

31. Mean Dry Season
precipitation change
+ 15-23%
• Text
- 3-10%
31

32. Change in
Monsoon timing
1 • Monthly rainfall >200mm
3
2
4
1. Chiang Rai 6
2. Sakon Nakhon
3. Khammoun 7 5
4. Champassak
5. Mondolkiri
6. Gia Lai
7. Kampong Thom
8. Kien Giang
8
32

33. CHANGES IN
STORMS, DROUGHTS &
EXTREME EVENTS
33

34. Change in peak
precipitation
+ 16-21%
34

35. Change in peak runoff &
erosion potential
+ 40 ++%
35
+

36. Agricultural Drought
Rainfall < 0.5* PET
Increase in areas experience >6months drought
- 3 -25%
+10-100%
36

37. Change in Storm Events
Baseline summary (1956-2009)
Date Intensity Frequency Landfall
June Japan, Korea, China
+ + Eastern Seaboard
July China, Northern Vietnam
++ + & Lao PDR
25%
Aug – +++ +++ Northern & central
Vietnam & Lao PDR –
Sep occasionally Thailand
15%
Oct – ++ ++ Central Vietnam,
Southern Lao &
Nov Cambodia
Dec Southern Vietnam
+ +
41%
With CC:
19% • Frequency will not change
• Become more intense
• Unclear whether trajectories will
change
37

38. CHANGES IN DRY SEASON
SOIL & SURFACE WATER
38

39. Subsurface Soil Water
Availability Dry Season
+ 10-60%
- 10-35%
39

40. Surface Soil Water
Availability Dry Season
+ 5-30%
- 15-30%
40

41. Change in Dry Season
Surface Water Availability
+ 18 -25%
- 4- 6.5%
41

42. CHANGES IN HYDROLOGY,
FLOWS & FLOODING
42

43. % change in seasonal
discharge
+ 20-40% Peak water level
increase (m)
+ 20-40%
43
DRY SEASON WET SEASON WET SEASON

44. Change in Mekong River
Hydrology
1
2
3
4
5
44

45. Hydro-biological
Seasonal Shifts
Source: MRC, 2009
45

46. Hydro-biological
Seasonal Shifts
ONSET
• Wet season: 1-2 weeks earlier
• Dry season: 1-3 weeks later
• Transition Season: <1 week earlier
DURATION
• Wet season: 2-4weeks longer
• Dry season: 1-2 weeks shorter
• Transition Season: 1-2 weeks shorter
46

47. YR 2000 Flood
Depths & extent

48. 2050 Flood Depth &
extent
• 1 in 100yr +
0.3m SLR
48

49. Duration of flood greater
than 0.5 m depth

50. Duration of flood
greater than 1m depth
50

51. CHALLENGES & LIMITATIONS
51

52. Key challenges for climate change modelling
1. Topographical complexity of the basin
2. Variability in Mekong hydroclimate &
selection of appropriate baseline
3. Non-stationarity in hydroclimate
conditions
4. Understanding of Ground water
interactions
5. Application of statistical downscaling
in tropical climates (validity of the
normal distribution assumption)
6. Accounting for system feedback
– projecting changes in the stability of the
Monsoon
– Incorporating ENSO phenomena
52
Source: MRC, 2011

53. • Thank you!
53