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Water Sustainability

Scott Matthews12-712 / 19-622

Administrative Issues

HW 4 Back TodayNo 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?

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Mass Balance

Fundamental principle of engineering / environmental engineering (law of conservation of mass)

Commoner: “everything must go somewhere”

Physical quantitiesEnergyCalories, etc.

Relevant: stocks and flows, ins and outs

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Global Issues (Chap 4 Recap)

250+ International water basins Means 250+ cross-jurisdictional boundaries

Many water-stressed regions (2/3) by 2025Amidst 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)

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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

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Hydrologic Cycle: Mostly a fixed, closed system

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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!

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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”

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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)

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Solutions

More efficient useFix the price problem (make it

expensive) Cost of water in different areas Subsidies of agriculture, etc.

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Water Pricing: Cost of Water

16 oz bottle: about $11000 gallons from average US tap $2

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“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.

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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?

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Water Rights and Sustainability

Is it fair? Sustainability?

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