1. 1 Water Sustainability Scott Matthews 12-712 / 19-622

2. Administrative Issues  HW 4 Back Today  No HW due this week (taking a week off)  Final HW due next week  Start tracking your expenses AND your general “material/resource” flow starting tomorrow am. Will need to for next HW.  Project Updates  Any left? 2

3. Mass Balance  Fundamental principle of engineering / environmental engineering (law of conservation of mass)  Commoner: “everything must go somewhere”  Physical quantities  Energy  Calories, etc.  Relevant: stocks and flows, ins and outs 3

4. Global Issues (Chap 4 Recap)  250+ International water basins  Means 250+ cross-jurisdictional boundaries  Many water-stressed regions (2/3) by 2025  Amidst global stresses, pushes to increase access to safe, clean drinking water  That is adding service to 300,000+ ppl/day  Much of this urban, with higher demand than rural (and for which we looked at ftprints) 4

5. Water Use Globally  30% of global flow being used for human needs (assuming all ET water available)  Postel expects 70% of runoff in 2025 to be used for humans 5

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7. Hydrologic Cycle: Mostly a fixed, closed system 7

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9. USGS: Water Use  If we care about water, we care about:  Agriculture  Thermoelectric power  Does anything else matter?  Little change since 2000 (report date)  Where does “data” come from?  Helpful: 1 Mgal/day ~ 1000 acre-feet/yr  Think about how large 1000 acre-feet is! 9

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11. Use Categories Relevant  Consumptive Use – not returned to sources after use (lost to evaporation or transpiration by plants)  Non-consumptive Use – returned to surface runoff (not necessarily of same quality) but not “used” 11

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13. More Global Data  Drivers: large population increase, availability decrease  Agriculture: 87% of global use  e.g., rice - 5000 liters/kg produced (wheat about half as much) 13

14. Solutions  More efficient use  Fix the price problem (make it expensive)  Cost of water in different areas  Subsidies of agriculture, etc. 14

15. Water Pricing: Cost of Water  16 oz bottle: about $1  1000 gallons from average US tap $2 15

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17. “Full Cost” Pricing  Goal of getting all costs of product internalized into cost  EPA: Full cost pricing is a pricing structure for drinking water and wastewater service which fully recovers the cost of providing that service in an economically efficient, environmentally sound, and socially acceptable manner, and which promotes efficient water use by customers. 17

18. Matching Quality and Quantity  Current utilities provide drinkable water at a single price  What about:  Drinkable water  Grey water (good enough for washing)  Other low value water  How would costs/etc need to change? 18

19. Water Rights and Sustainability  Is it fair?  Sustainability? 19