The Global Futures and Strategic Foresight (GFSF) team met in Rome from May 25-28, 2015 to review progress towards current work plans, discuss model improvements and technical parameters, and consider possible contributions by the GFSF program to the CRP Phase II planning process. All 15 CGIAR Centers were represented at the meeting.

1. Edwin H. Sutanudjajaa, Rens van Beeka, Karen G.
Villholthb, Aditya Soodc, Tingju Zhud
a Faculty of Geosciences, Utrecht Univ., The Netherlands
b IWMI, South Africa
c IWMI, Sri Lanka
d IFPRI, Washington DC
Progress and challenges in modelling global
groundwater depletion - experience with
PCR-GLOBWB
25th May, 2015

2. 1. How are constraints in groundwater
availability and access influencing global
groundwater depletion?
2. How is groundwater depletion
influencing global food production?
3. How can better groundwater
management improve food security?
Objective/Research questions

3. Groundwater depletion occurs when the rate of groundwater
abstraction is greater than the rate of replenishment
Groundwater depletion: What is it?
S
R
D
Natural conditions
Averaged over long term,
R=D and S is constant
S
R
D
Stable groundwater
pumping
Qnet is equivalent to
reduction in D and S
Qnet
S
R
D
Unsustainable
condition
Qnet is greater than R, D
reduces to 0 and S
decreases continuosly
Qnet

4. 0
50,000
100,000
150,000
200,000
250,000
300,000
1960
1963
1966
1969
1972
1975
1978
1981
1984
1987
1990
1993
1996
1999
Mm3//year
Total groundwater depletion
Source: Wada et al., 2012
Results from the PCR-GLOBWB model
Depletion = Abstraction - Recharge
Source:
Shah et al., 2007
Groundwaterwithdrawal(cubickmperyear)
in selected countries
at global scale

5. Production
Of Total
(Rainfed &
Irrigated)
Of Irrigated
Of Irrigated by
Groundwater
From GW abstraction 13.3% 44.4%
From GW depletion 4.3% 14.5% 32.6%
CROP PRODUCTION FROM GROUNDWATER
AND GROUNDWATER DEPLETION
Results from Phase I of our work

6. PCR-GLOBWB model
(Wada et al., 2012)

7. 1. Non-renewable GW is implicitly assumed
to be unlimited (same as in IGHM)
2. GW pumping is not constrained by socio-
economic and technical factors.
Shortcomings of PCR-GLOBWB model

8. 1st constraint: Aquifer volume
Estimate of aquifer thickness at 30 arc-min resolution

9. 2nd constraint: Pumping capacity
Regional-scale groundwater abstraction limit (109 m3/yr) for 2005
From IMPACT

10. 2nd constraint: Pumping capacity
Global groundwater abstraction limit for the period 1960-2015

11. River flow stations for calibration and validation
Locations of GRDC discharge stations used in this study. Black dots represent stations
selected for calibration and yellow dots represent stations selected for validation.

12. Recursive filter method by Nathan and McMahon (1990):
qd = β qd-1+ (1+ β) (Qd - Qd-1)/2 separated surface flow
qb = Qd - qd separated baseflow
Baseflow separation
Calibration parameters
fD: Pre-factor for degree day factor
fW: Pre-factor for soil water capacities
fK: Pre-factor for upper soil sat. hydraulic conductivity
fJ: Pre-factor for groundwater recession coefficient

13. Calibration against total flows (Orinoco)
Improvement observed
Results:

14. Calibration against total flows (Congo)
No improvement observed
Results: Calibration against total flows (Congo)

15. Calibration against baseflows (Orinoco)
Improvement observed
Results:

16. Calibration against baseflows (Ob)
No improvement observed
Results:

17. 1. Run without constraints
2. Run with limited non-renewable GW
3. Run with limited non-renewable GW
and limited pumping capacity
4. Run 3., but calibrating parameters
Approach to simulations

18. Run 1Results:
km3year−1
Total depletion: 375 km3 yr-1
2001-2008

19. Adding constraintsResults:
km3year−1
Run 1 Run 2
Run 3
Total depletion: 285 km3 yr-1
2001-2008
Total depletion: 375 km3 yr-1
2001-2008
Total depletion: 146 km3 yr-1
2001-2008
Run 4
(Calib)
Total depletion: 183 km3 yr-1
2001-2008

20. Global Groundwater Scenarios
Starting Point: IPCC’s Shared Socioeconomic Pathways (SSPs)

21. Managed Aquifer
Recharge (MAR)
Implemented in scenarios emphasizing
sustainability/adaptation
Pumping control
Implemented in scenarios emphasizing
sustainability/mitigation
New GW development
Implemented to various degree, dep. on scenario
Trade/virtual water
Implemented in scenarios with good
global/international institutions
Water productivity Improved in scenarios emphasizing
sustainability/mitigation
Issues/Interventions considered

22. SSP5
 Pumping in depleted regions is not controlled
 MAR/UTFI is implemented on a large scale,
mostly to control extreme flooding
 Balanced new GW dev. in potential regions to
adapt to CC
 Trade/virtuous virtual water flows
constrained by dominant economic
development imperatives
 Water productivity from GW (and SW) not
improved
SSP3 (worst case)
 Pumping in depleted regions is not controlled
 MAR is not practised
 Unbalanced new GW dev. in potential regions
 Trade/virtuous virtual water flows
constrained by dominant self-sufficiency
strategies
 Water productivity from GW (and SW) not
improved
SSP1
 Pumping in depleted regions is controlled
through regulations and incentive-based
methods
 MAR is implemented on a large scale
 Balanced new GW dev. in potential regions
 Trade is deliberately used to control GW
depletion (virtuous virtual water flows)
 Water productivity from GW (and SW)
improved
SSP4
 Pumping in depleted regions is controlled
through effective energy policies
 MAR is not implemented
 Unbalanced/unequal new GW dev. in
potential regions, e.g. for biofuels
 Trade is deliberately used to control GW
depletion (virtuous virtual water flows), but
not benefitting the smallholders
 Water productivity from GW (and SW)
improved to save energy in commercial
farming
Scenario Storyline

23. 1. Availability and access constraints to GW are critical to
consider in future food security scenarios
2. Adding constraints and calibration improved the model’s
handling of groundwater.
3. This compares well to previous estimates (145+/-39 km3
yr-1, Konikow (2011)).
4. Once included in IMPACT, global scenarios for different
SSPs will be created and analyzed
5. Focus on country and regional level studies.
Conclusions

24. THANK YOU !!