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Water Footprints

Water Footprints. The water footprint of an individual or community is defined as: the total volume of freshwater that is used to produce the foods and services consumed by the individual or community.

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Water Footprints

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  1. Water Footprints The water footprint of an individual or community is defined as: • the total volume of freshwater that is used to produce the foods and services consumed by the individual or community. For an individual, it can be estimated by multiplying all goods and services consumed by their respective virtual-water content.

  2. Relating Virtual Water to Water Footprints

  3. Global Water Use Mostly Agricultural

  4. Individual water footprint • What results did we get? • How different when using the Extended Calculator? • What differences when changing your country of origin? Changing other inputs? http://www.waterfootprint.org/?page=cal/waterfootprintcalculator_indv

  5. Water Footprints A national water footprint can be assessed in 2 ways. • The bottom-up approach is to consider the sum of all goods and services consumed multiplied with their respective virtual-water content. • In the top-down approach, the water footprint of a nation is calculated as the total use of domestic water resources plus the gross virtual-water import minus the gross virtual-water export.

  6. Major factors contributing to National Water Footprint? Volume of consumption • Consumption pattern (e.g., meat consumption) • The production of one kilogram of beef requires 16 thousand liters of water. • To produce one cup of coffee we need 140 liters of water. • Climate • Agricultural Practice (water use efficiency) • Contamination (wastewater/industry/ag/land use practices, regulations and enforcement)

  7. Internal and external water footprint • The total water footprint of a country includes two components: • the part of the footprint that falls inside the country (internal water footprint) and • the part of the footprint that presses on other countries in the world (external water footprint). • The distinction refers to the appropriation of domestic water resources versus the appropriation of foreign water resources. What is our external water footprint?

  8. U.S. Water Footprint Global average water footprint • 1243 m3/cap/yr U.S. Water Footprint • 2483 m3/capita/yr U.S. External water Footprint • 19% Japan with a footprint of 1150 m3/capita/yr, has about 65% of its total water footprint outside the borders of the country.

  9. Average National Water Footprint

  10. Differences in Allocation of H20

  11. Shades of Water? • Blue Water= fresh surface and groundwater • Green Water= the portion of precipitation on land that does not run off or recharge the groundwater but is stored in the soil or temporarily stays on the soil or vegetation • Grey Water= the volume of water that is required to dilute pollutants to such an extent that the quality of the water remains above agreed water quality standards

  12. More on Gray Water Footprint • GWF is an indicator of appropriated assimilation capacity • The assimilation capacity of a receiving water body depends on the difference between the maximum allowable and the natural concentration of a substance. • Assumes we have standards for all pollutants. • We don’t.

  13. Calculating Gray Water Footprint • the load of each pollutant (mass/time) L = (Qeff x Ceff) / (Cmax – Cback) • Qeff = discharge of effluent (volume/time) • Ceff = concentration of pollutant in effluent (mass/volume) • Cmax = maximum concentration allowable in the receiving water body (mass/volume) • Cback = natural background concentration for the chemical considered (mass/volume)

  14. Table 1: Selected Water Footprints of National Consumption per Country (Mm3/yr)

  15. Worksheet Questions • What are the top 4 countries in terms of total water footprint in Mm3/yr (million cubic meters/year)? In other words, who uses the most water? • What are the top 4 countries in terms of grey water footprint? In other words, which countries are polluting the most water? • What are the top 4 countries in terms of external water footprint? In other words, who receives the most via imports and is exerting the greatest pressure on water resources of other nations? • What are the top 4 countries in terms of ratio of external water footprint to total water footprint? In other words, which countries are the most dependent on external sources for their water needs?

  16. Table 2: Selected Per Capita Water Footprints of National Consumption per Country (Top 9 and Bottom 9 Countries with > 1 million citizens, plus World Average) ?

  17. Worksheet Questions • So the U.S.A. is 3rd in the world in terms of total water footprint, and number 1 in terms of total external water footprint, but “only” 8th in the world in terms of per capita footprint. Still, it is clear that we enjoy a rather water intensive lifestyle. What are 3 reasons for countries like ours to have a higher than average per capita water footprint?

  18. Worksheet Questions • Have a look at the per capita water footprint breakdown by percent in Table 2. Note the different ratios of water use for agricultural products vs. industrial products vs. domestic consumption. What are the ramifications of these different ratios? • How does this constrain the opportunities for people in the bottom six countries vs. the United States? • How does a high ratio of industrial use appear to influence the grey water component of the footprint?

  19. The global blue (top map) and grey (bottom map) water footprint of U.S.A. citizens related to the consumption of crop and animal products (1996-2005) Where within the U.S.A. is our water footprint most evident? Where outside of the U.S.A. is our water footprint most evident?

  20. The Water Footprint of U.S. Consumption of Agricultural and Industrial Products, Specified Per Basin (Mm3/yr) What are 2 reasons that the Mississippi River Basin provides an order of magnitude more to our water footprint than does the Columbia?

  21. Grey water footprint of Japan between 1996 and 2005 Why do we tolerate this water resource use and pollution in the United States for the needs of foreign countries?

  22. Which Foods are Most Water Efficient? • Pulse = peas, beans, lentils, chickpeas…

  23. What Goes into the Water Footprint of Animal Products? • About 98% of the water footprint of animal products relates to water use for feed

  24. But what’s up with this? Not so bad, relatively

  25. Vegetarian vs. Meat Diet • How much water is saved by going vegetarian? • 1,300 liters per day per person in an industrial country • 36% of total used in meat diet

  26. Water Requirements for Food in the European Union

  27. Geography of Water Stress

  28. Geography of Water Stress

  29. Temporal Variability in Water Scarcity Water scarcity over the year for the Murray River Basin in Australia (average for the period 1996–2005). Net available water – that is natural runoff minus environmental flow requirement – is shown in in the bottom color below the dashed line. From October until May, the blue water footprint exceeds net available water.

  30. Water Scarcity Varies Throughout the Year

  31. What to Do? • Do we have a moral obligation to eliminate starvation and water stress in far distant lands? If so, what are the best ways to address these problems and should that include establishing a cap on the U.S.A.’s “reasonable share of the globe’s water resources?” • If you don’t think we have that moral obligation, what lets us off the hook?

  32. National Differences in Allocation of H20 Do we need to use twice as much water per person as the Japanese?

  33. How Can We Reduce our Use? Break it down – Internal and External • What are the benefits of reducing our internal use? • What are the drawbacks of reducing our internal use?

  34. Our Internal Water Footprint vs. Water Stress How much of the stress is due to the footprint? How about relying more on external sources?

  35. How Can We Reduce our Use? Break it down – Internal and External • What are the benefits of reducing our external use? • What are the drawbacks of reducing our external use?

  36. Comparing USA External Water Footprint to Water Stress What is wrong here?

  37. If We Want to Reduce Our National Water Footprint, How Do We Do It? • Grassroots up • Community and Individual Efforts • Cultural Change • Top Down Approach • Government Policy • Business Priorities

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