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MENA Water Outlook 2050

MENA Water Outlook 2050. Future Water Availability Peter Droogers, Walter Immerzeel, Wilco Terink The Netherlands. Climate Change. Current Problems. Food Water Requirements. Existing Water-Climate Change studies limitations: Not only climate change, but global changes

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MENA Water Outlook 2050

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

  2. Climate Change

  3. Current Problems

  4. Food Water Requirements

  5. 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

  6. concepts

  7. Study Design • Objectives • Detailed water supply and demand analysis 2010-2050 • 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

  8. Study design

  9. Monthly approach 20 mm shortage?

  10. Downscaling of climate change scenarios

  11. 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

  12. 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 1980-1999 and 2080-2099, averaged over 21 GCMs

  13. Selection of General Climate Models GCM performance in North-East Africa: • 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

  14. 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

  15. Downscaling approach • Temperature • Reference evapotranspiration • Precipitation • Reference period is 2000-2009 (NCEP/NCAR and TRMM) • Monthly GCM data from 2000-2050 • Monthly absolute anomalies 2010-2050 with respect to 2000-2009 (ΔTy,m) • Select random year 2000-2009 • For each day in 2010-2050: • Future ETref using Hargreaves assuming no change in diurnal temperature range (Tmax-Tmin)

  16. Climate change in the MENA region 2020-2030 2040-2050

  17. Climate change in the MENA region

  18. Climate change in the MENA region

  19. Changes in Population, Domestic and industrial water demand

  20. Changes • Irrigation water demand changes • FAO: AgriculutreTowards 2050 • Industrial water demand changes • AquaStat: f(GDP, GDP/cap) • Domestic water demand changes • AquaStat: f(GDP, GDP/cap) • Populationgrowth • Environmental Assessment Agency

  21. Hydrological model

  22. 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)

  23. The MENA hydrological model Model resolution: • Regular grid of 10 km • Daily time step Each cell describes: • Thevertical 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

  24. F(s) 1 0 s 0 1 Key process: vegetation and evaporation Etr Interception: Ei Es Imax I Etr Ei Transpiration and soil evaporation: Evapotranspiration:

  25. Model domain

  26. Validation of model results

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

  28. Validation results

  29. Water availability

  30. Aridity (current)

  31. Total and irrigated evapotranspiration

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

  33. Future water availability

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

  35. MainFindings • Changes MENA (2010-2050): • Internal renewable water resources: 20% reduction • (8% lessrainfall) • (12% more evapotranspiration) • Total renewable water resources: 8% reduction • Large variation between countries • Large year-to-yearvariability • Per capita water availability will drop even further below critical levels in the future

  36. ThankYou

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