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2.1 iwmi aditya rome-gw_study_presentation

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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.

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2.1 iwmi aditya rome-gw_study_presentation

  1. 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. 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. 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. 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. 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. 6. PCR-GLOBWB model (Wada et al., 2012)
  7. 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. 8. 1st constraint: Aquifer volume Estimate of aquifer thickness at 30 arc-min resolution
  9. 9. 2nd constraint: Pumping capacity Regional-scale groundwater abstraction limit (109 m3/yr) for 2005 From IMPACT
  10. 10. 2nd constraint: Pumping capacity Global groundwater abstraction limit for the period 1960-2015
  11. 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. 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. 13. Calibration against total flows (Orinoco) Improvement observed Results:
  14. 14. Calibration against total flows (Congo) No improvement observed Results: Calibration against total flows (Congo)
  15. 15. Calibration against baseflows (Orinoco) Improvement observed Results:
  16. 16. Calibration against baseflows (Ob) No improvement observed Results:
  17. 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. 18. Run 1Results: km3year−1 Total depletion: 375 km3 yr-1 2001-2008
  19. 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. 20. Global Groundwater Scenarios Starting Point: IPCC’s Shared Socioeconomic Pathways (SSPs)
  21. 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. 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. 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. 24. THANK YOU !!

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