1. De mondiale watercyclus Arjen Hoekstra - IHE Delft Gastcollege in de collegeserie ‘Duurzaamheid van Energievoorzieningssystemen’ Utrecht, 17 september 2001

2. Overzicht Overzicht van waterbeschikbaarheid op aarde Overzicht van typen watergebruik Wat is waterschaarste? Wat gebeurt er bij intensief watergebruik? Dynamiek van watersystemen. Wat betekent klimaatsverandering voor de watervoorziening? Wat weten we eigenlijk over zeespiegelstijging? Zijn oorlogen over water waarschijnlijk? Water in de context van wereldhandel en globalisering

3. Water on earth

4. Position of planets in the phase diagram of water

5. Global annual hydrological cycle

6. Terrestrial water balance

8. Available water stocks Available water flows

9. Water use by man

10. Global water demand

11. 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 1900 1920 1940 1960 1980 2000 2020 2040 2060 2080 2100 e12 kg/yr Falkenmark and Lindh (1974) A Falkenmark and Lindh (1974) B Korzun et al. (1978) L'vovich (1979) I L'vovich (1979) II L'vovich and White (1990) Shiklomanov (1989, 1990, 1993) Shiklomanov (1997) Margat (1994) Low Margat (1994) High Raskin et al (1995, 1996) Raskin et al. (1997) Low Raskin et al. (1997) Mid Raskin et al. (1997) High Hoekstra (1998) Hierarchist Hoekstra (1998) Egalitarian Hoekstra (1998) Individualist Water demand projections

12. Volume of large reservoirs (in km 3 )

13. Global hydropower generation capacity

14. Adequate water supply and sanitation in developing countries

15. Why do poor people have no access to public water supply?

16. Why do rich people use so much water?

17. The rainbow of water Blue water runoff (surface water, groundwater) Green water transpiration by plants White water evaporation through interception or directly from the soil Black water fossil groundwater Brown water wastewater Grey water treated wastewater, for reuse Virtual water water ‘hidden’ in an agricultural or industrial product (the quantity of water used in the production process)

18. Water scarcity

19. Causes of ‘water scarcity’ Aridity Permanent water shortage due to a dry climate. Drought An irregular phenomenon occurring in dry years. Dessication Drying up of the landscape, particularly the soil, due to activities such as deforestation, overgrazing, lowering groundwater tables. Water stress Scarcity due to increasing number of people relying on limited resources.

20. Arid and semi-arid areas

21. Aridity P= precipitation E a = actual evapotranspiration E p = potential evapotranspiration S= moisture surplus (in the wet season) D= moisture deficit (in the dry season)

22. The importance of ‘evaporative demand’

23. Growth factors (relative increase since 1900)

24. Indicators of water scarcity Utilisation level (use-availability ratio) = Water demand / total runoff Alternatives: –stable runoff instead of total runoff –consumptive instead of total demand Water competition level = Population / total runoff Water availability per capita = Total runoff / population Marginal cost of water supply

26. Use of water compared with internal water availability

27. Utilisation of total (internal+external) water resources

29. Conflicts over water

32. Water conflicts in international rivers

33. National water availability

35. Rivers in the Middle East

38. Southeast Anatolia Project Euphrates and Tigris: Turkey, Syria, Saudi Arabia, Iraq, Iran. 1992: Atatürk Dam in Turkey. Turkey: “Allah gave oil to them, but water to us.”

39. The Atatürk Dam

40. River Euphrates: Change of water distribution

42. Criteria for a fair water distribution

43. Effects of intensive water use

44. Human pressures on the hydrological cycle Direct diversion of water flows Water withdrawals. Transformation of the stream network Dams and reservoirs, river canalisation. Changing drainage basin characteristics De-/reforestation, urbanisation, drainage of wetlands, agricultural practices. Activities altering regional or global climate Burning fossil fuels, consumptive water use, land cover changes.

45. Historical change of the Ganges river runoff

46. Historical change of the Colorado river runoff

47. Shrinking of the Aral Sea

48. Shrinking of the Aral Sea

51. Effect of groundwater abstraction on groundwater table

52. Water pollution

53. P.m.

54. Effects of land use changes

55. P.m.

56. Effects of climate change

58. Global annual hydrological cycle

59. ‘Predicted’ change of the annual hydrological cycle

60. River runoff calculation by a GCM

61. Predicted change of Rhine river runoff (near Lobith)

62. Impacts of climate change on terrestrial hydrology

63. Distribution of the world’s major biomes

64. Impact of global warming on water supply

65. Global freshwater vulnerability

66. Sea level rise

67. Mechanisms of anthropogenic sea-level change

68. Sea level rise (mm) IPCC assessment 1995

69. Contribution of groundwater losses to sea level rise Korzun et al. (1978): Period 1900-1964:52 mm Gornitz et al. (1982): Period 1880-1980:‘a few centimetres Sahagian et al. (1994): Period 1900-1990:at least 9 mm Hoekstra (1998): Period 1900-2000:35-95 mm Period 2000-2100:240-390 mm

71. Sea level rise (mm)

72. Cost of protection against 1 m sea level rise