# Module 28: Humans and water in the future
Water footprint: the amount of water used per capita (per head) in a country, including irrigation, industry and residential use.
Check out these two images:
Screen Shot 2022-11-26 at 2.15.35 PM.pngScreen Shot 2022-11-26 at 2.18.40 PM.png
What do you notice about use and availability?
Often, humans waste what they have available (water, timber, food)
As the need for food increases (population just passed 8 billion), creative methods will be needed to conserve water:
Irrigation:
- Furrow irrigation: 65% of water goes to plants
- Flood irrigation: 70% goes to plants
- Spray irrigation: 75% goes to plants (if not windy)
- Drip irrigation: 95% goes to plants
So...why not use the last two? Expensive (materials and labor)
But: as food prices rise along with water needs, these will become more widespread
Hydroponics: takes soil out of the equation, how?
Closed system with water, aeration and nutrients, everything a plant needs
Issues: small scale but very high productivity, often enclosed in greenhouses which prevent pests, can be organic (no pesticides) and can be grown where weather prevents normal crops
Industrial water use (huge):
Copper: 440 l (116 gallons) per kg of Cu for wiring
Aluminum: 410 l per kg
Steel: 260 l per kg
Paper: 125 L per kg
Most folks don't see these water uses, and they show up as pollution sources as well as water users
Household water use:
White water: pure water, can be used for drinking
Grey water: soapy wash water, can be used for irrigation or flushing, but not clean enough for drinking
Black water: raw sewage, can be treated to become usable for irrigation or flushing, even drinking (see rivers next semester)
Japan has created washing machines and sinks ABOVE toilets, so grey water use used for flushing. Cool!
Screen Shot 2022-11-26 at 2.31.14 PM.png
Water ownership:
Water wars will be fought more and more, current conflicts:
Screen Shot 2022-11-26 at 2.32.41 PM.png
Deep wells and horizontal drilling are two sneaky ways to steal water from your neighbors.
Outright warfare is another, more obvious method.
Climate change will impact many of the rivers in the world as glaciers retreat, so water diversion will become a global issue:
Screen Shot 2022-11-26 at 2.34.44 PM.png
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