1. MENA Water Outlook 2050 Future Water Availability
Peter Droogers, Walter Immerzeel, Wilco Terink
The Netherlands

2. Climate Change

4. Current Problems

6. Shiklomanov, I.A World Water Resources at the Beginning of the 21st Century. Cambridge University Press

7. Food Water Requirements

8. Existing Water-Climate Change studies limitations:
Not only climate change, but global changes
increased population
increased GDP
increased consumption: domestic, industry
Conceptual limitations
focus on economics, not on water resources
focus on annual numbers
focus on limited sectors
Impact and not adaptation

9. concepts

10. Study Design Objectives Steps Limitations
Detailed water supply and demand analysis
Identification of potential options to overcome water shortage
Steps
Climate and other change projections
Hydrological impact model
Water resources supply/demand analysis
Cost and benefits adaptation options
Limitations
Large scale so simplifications, generalizations

11. Study design

12. Monthly approach 20 mm shortage? Month Renewable (mm)
Irrigation requirement (mm)
Water stress (mm)
January 30 10
February 20
March
April
May 40
June
July
August
September
October
November
December
TOTAL
240
260
120
20 mm shortage?

13. Downscaling of climate change scenarios

14. Projected climate change in the MENA
IPCC (Intergovernmental Panel on Climate Change) uses four scenario families (A1, A2, B1 and B2)
Each scenario family explores alternative development pathways
This study uses the A1B scenario because:
It is widely used and recommended by the IPCC
It is the most likely scenario:
Assumes a world of rapid economic growth
Global population that peaks in mid-century
Rapid introduction of new and more efficient technologies

15. Projected climate change in the MENA
All of MENA is likely to warm during the 21st century
Warming is very likely to be larger than the global, annual mean warming throughout the continent and in all seasons, with drier subtropical regions warming more than the moister tropics
Annual rainfall is likely to decrease in much of Mediterranean Africa and northern Sahara
There is likely to be an increase in annual rainfall in East Africa
Temperature and precipitation changes over Africa. Differences between and , averaged over 21 GCMs

16. Selection of General Climate Models
GCM performance in North-East Africa:
GCM Model
r (-)
MSE (mm /day)
Included
BCCR CM2.0
0.81
1.12 1
CCCMA CGCM 3.1 T47
0.79
CNRM CM3
1.23
CSIRO Mk3.0
0.75
0.97
GFDL CM2.0
0.82
1.00
IPSL CM4
0.78
0.84
MPI ECHAM5
0.88
0.59
HadCM3
0.76
0.90
HadGEM1
CCCMA CGCM 3.2 T63
1.22
GFDL CM2.1
0.68
1.03
GISS AOM
1.60
GISS EH
0.65
1.19
GISS ER
0.71
1.18
IAP FGOALS 1.0g
0.60
INM CM3.0
0.58
1.07
MIROC 3.2 (hires)
0.83
1.59
MIROC 3.2 (medres)
1.17
MIUB ECHO-G
0.61
1.56
MRI CGCM 2.3.2a
1.78
NCAR CCSM 3
0.54
1.79
NCAR PCM1
0.55
2.11
9 GCMs were selected, because of the large variation in climate projections between the GCMs
The table shows the mean of monthly correlation and mean squared difference of 20th century GCM experiments with the CRU TS 2.1 analysis
The first nine GCMs are included in the current study

17. Why downscaling?
GCMs generate forcing data (precipitation, temperature) at a coarse spatial resolution (>100 km)
Hydrological processes occur on a higher spatial resolution
The statistics of the coarse GCM forcing data do not match the statistics of the observed forcing data

20. Downscaling approach Temperature Reference evapotranspiration
Precipitation
Reference period is (NCEP/NCAR and TRMM)
Monthly GCM data from
Monthly absolute anomalies with respect to (ΔTy,m)
Select random year
For each day in :
Future ETref using Hargreaves assuming no change in diurnal temperature range (Tmax-Tmin)

21. Climate change in the MENA region

22. Climate change in the MENA region

23. Climate change in the MENA region

24. Changes in Population, Domestic and industrial water demand

25. Changes Irrigation water demand changes
FAO: Agriculutre Towards 2050
Industrial water demand changes
AquaStat: f(GDP, GDP/cap)
Domestic water demand changes
Population growth
Environmental Assessment Agency

27. Hydrological model

28. The MENA hydrological model
PCRaster - Water Balance
Distributed water balance model
Daily time step
10 km x 10 km resolution
Model domain includes MENA including upstream basins (5210 km x 8770 km)

29. The MENA hydrological model
Model resolution:
Regular grid of 10 km
Daily time step
Each cell describes:
The vertical flow of water through four compartments
Canopy
Three soil compartments
Soil and canopy are fed by rainfall and depleted by evapotranspiration
The transfer of runoff to the drainage network
Sub-grid processes at 1 km:
Short and tall vegetation
Fraction of soil type
Topography
Open water

30. Key process: vegetation and evaporation
Etr
Interception: Es Ei
Imax I
Etr Ei
Transpiration and soil evaporation:
F(s) s 1
Evapotranspiration:

31. Model domain

32. Validation of model results

33. Location of GRDC discharge stations
Validation of model results using stream flow

34. Validation results

35. Water availability

36. Aridity (current)

37. Total and irrigated evapotranspiration

38. Internal water resources and per capita water availability (current)

39. Future water availability

40. Total Renewable Water Resources
Total change from 2010 to 2050 in % in total renewable water resources

41. Main Findings Changes MENA (2010-2050):
Internal renewable water resources: 20% reduction
(8% less rainfall)
(12% more evapotranspiration)
Total renewable water resources: 8% reduction
Large variation between countries
Large year-to-year variability
Per capita water availability will drop even further below critical levels in the future

42. Thank You