1. LT 6E: Discuss the sustainability of freshwater resources
LT 6F: Identify possible solutions to the sustainability of freshwater resources and discuss the benefits and consequences of each..

2. Importance of Freshwater
Necessary for life
60% of us is composed of water
Could only survive a few days without it
Takes huge amounts to supply us with food, energy etc..

3. Management of Freshwater
Poorly managed
Charged less than its worth
How would charging less than water’s worth contribute to the mismanagement of water?

4. Issues with water Global Economic National and global security issue
Environmental
Global: Lack of access to safe drinking water in less developed countries
Economic: vital for reducing poverty and producing food and energy
National and global security issue: increasing tensions both within and between nations over access to limited water resources they share
Environmental: Water loss/water pollutiondeclining water quality, lower fish populations, species extinctions and degradation of aquatic ecosystems

5. Availability of Freshwater
Only about 0.024% of the planet’s water is available to us as liquid freshwater
Sources:
Groundwater deposits
Lakes
Rivers
Steams

6. Groundwater
Precipitation that seeps into the ground and moves downward through spaces in soil, gravel and rock until an impenetrable layer of rock stops it.
Spaces deep in the earth hold more water than at the top
Zone of saturation: Deep; Completely filled with water
Water zone: top of this groundwater zone
Aquifer: Deep; Groundwater flows through them; pumps used to bring water to surface; replenished mainly by precipitation

7. Groundwater
Surface water: freshwater from precipitation and melted snow that flows across the earth’s land surface and into lakes, wetlands, steams, rivers, estuaries, and into the ocean.
Surface runoff: precipitation that does not infiltrate the ground
Watershed (drainage basin): land from which surface water drains into a body of water

8. Reliable Runoff Usable
1/3 of surface runoff  2/3 lost by seasonal flooding
World-wide averages
Domestic: 10%
Agriculture: 70%
Industrial use: 20%

9. Water Footprint Volume of water we directly and indirectly
Average American uses 260 liters per day
Flushing toilets, 27%
Washing clothes, 22%
Taking showers, 17%
Running faucets, 16%
Wasted from leaks, 14%
World’s poorest use 19 liters per day

10. Virtual Water Water is used indirectly
Hamburger, 2400 liters
Virtual water often exported/imported
Grains and other foods

11. Water Shortages Main factors Dry climates Drought
Too many people using a normal supply of water
Wasteful use of water

12. Water Shortages More than 30 countries face water scarcity
Rapid urbanization, economic growth and drought are expected to put more stress on water resources in developing countries like China and India
30% earth’s land area experiences severe drought
Will rise to 45% by 2059 from climate change
Potential conflicts/wars over water
Refugees from arid lands
Increased mortality

13. Think Box What do you think we can do to increase freshwater supplies?
Reducing unnecessary waste
Extracting groundwater
Building dams and reservoirs to store runoff in rivers
Transporting surface water from one area to another
Converting salt water to freshwater (desalination)

14. Extracting Groundwater
Advantages
Disadvantages
Useful for drinking and irrigation
Exists almost everywhere
Renewable if not overpumped or contaminated
Cheaper to extract than most surface water
Aquifer depletion from overpumping
Sinking of land from overpumping
Pollution of aquifers lasts decades or centuries
Deeper wells are nonrenewable
More than have of the world’s population relies on aquifers for drinking water
Overpumping: Limits future food production, Bigger gap between the rich and the poor, Land subsidence (sinking),
Groundwater overdrafts near coastal regions (Contamination of groundwater with saltwater)

15. Building Dams and Reservoirs
Dams are large structures built across a river to control the river’s flow.
Reservoirs are created behind dams.
Main Goals
Capture and store runoff
Release water as needed to control floods
More than 45,000 large dams in world (22,000 of them in China)

16. Building Dams and Reservoirs
Advantages
Disadvantages
Provide irrigation water
Provide drinking water
Provide recreation and fishing
Can produce cheap electricity (hydroelectricity)
Reduces down-stream flooding of cities and farms
Displaces people, destroys forests or cropland
Water loss to rivers and stream
Deprive downstream cropland and estuaries of nutrient-rich silt
Risk of failure and devastating downstream flooding
Disrupts migration of some fish
1 out of five of the world’s freshwater fish and plant species are either extinct or endangered because dams and water withdrawal have sharply reduced the flow of many rivers
Reservoirs behind dams also eventually fill up with sediments such as mud and silt, typically within 50 years, which makes them useless for storing water or producing electricity.

17. Transferring Water
Transportation of water through aqueducts
California Water Project
Transports water from northern California to southern California
Northern CA: Degrades rivers in northern CA
Southern CA: More need for water
Think Box: What do you think the effects of this might be on both parts of California?

18. Transferring Water Advantages Disadvantages
Supply water to areas that lack enough usable water
Allow farmers to grow water-intensive crops in area that lack sufficient water
Water waste
Degradation to the source
Subsidies for the cost of water transfers encourage overuse
Lettuce grown in southern CA despite the fact that it is water intensive

19. Desalination
Removing of dissolved salts from ocean water or from brackish (slightly salty) water in aquifers or lakes.
Two widely used methods:
Distillation: involves heating saltwater until it evaporates leaving behind salts in solid form and then condenses as freshwater
Reverse osmosis: uses high pressure to force saltwater through a membrane filter with pores small enough to remove the salt
14,450 desalination plants in more than 125 countries (250 in the U.S.)
Meet less than 0.3% of the world’s demand and 0.4% of the U.S. demand for freshwater.

20. Desalination Advantages Disadvantages More access to freshwater
High cost
Energy intensive
Pumping system kills many marine organisms
Produces huge quantities of salty wastewater that must go somewhere