1. Water
Chapter 14

2. Essential Question #1
Why is water so important, how much fresh water is available to us, and how much of it are we using?

3. Why is Water Important Major part of organisms (60%) Affects Climate
Without water, chemical reactions can’t occur
Affects Climate
Carves the Land
Removes and dilutes wastes & pollutants
Cycles continuously
Despite it’s importance, water is one of our most poorly managed resources.
We waste it, pollute it, & charge too little for making it available

4. Where is Freshwater Available?
97.4% salt water, 2.6% freshwater
Of that 2.6% freshwater:
75% is frozen
90% of melted freshwater is in lakes, soil & air

5. Readily accessible fresh water
Earth’s Water Budget
All water
Fresh water
Readily accessible fresh water
Groundwater
0.592%
Biota
0.0001%
Rivers
0.0001%
Lakes
0.007%
Fresh water
2.6%
0.014%
Oceans and
saline lakes
97.4%
Atmospheric
water vapor
0.001%
Ice caps
and glaciers
1.984%
Soil
moisture
0.005%
Only about 0.024% of water is available as accessible, liquid freshwater!
Fig. 11-2, p. 238

6. Availability of Water Resources
Percent of world's water resources and population
Continent
36%
Asia
60.5%
10%
Africa
14%
Global
Availability of Water Resources 8%
Europe
11.3%
15%
North and Central America
7.3%
QUESTION: What two major conclusions can you draw from these data?
26%
South America and Caribbean
6.4% 5%
Oceania
0.5%
Fig. 14-2, p. 307

7. Ground Water
Water below the earth’s surface, stored in spaces in soil, gravel, sand & rock
Water table – top of ground water layer (zone of saturation)
Rises & falls w/ precipitation changes
Aquifers – deep layers of porous rock holding water
1/3 of world pumps water from aquifers
Watertight layers of rock or clay below aquifers prevent water from sinking deeper into Earth.

8. Evaporation and transpiration
Groundwater Systems
Unconfined Aquifer Recharge Area
Evaporation and transpiration
Precipitation
Evaporation
Confined
Recharge
Area
Runoff
Flowing
artesian well
Recharge
Unconfined
Aquifer
Stream
Well requiring a pump
Water
table
Infiltration
Lake
Infiltration
Unconfined aquifer
Less
permeable material
such as clay
Confined aquifer
Confining impermeable rock layer
Fig. 11-3, p. 239

9. Accessing Aquifers

10. Aquifers Renewable Aquifers Nonrenewable Aquifers
Natural Recharge – precipitation percolates down to refill (slow process)
Lateral Recharge – refilled from side by streams/rivers
Nonrenewable Aquifers
Receive little to no recharge

11. Surface Water Surface Runoff Watershed / Drainage Basin
Precipitation that doesn’t evaporate or soak into ground
2/3 lost to seasonal flooding
Watershed / Drainage Basin
The region where runoff flows into water bodies
Reliable Runoff
The amount of runoff we can count on as a stable source of fresh water *(1/3 of surface runoff)
2/3 surface runoff lost to floods, 1/3 makes up reliable runoff

12. Water Withdrawal Consumptive Use Nonconsumptive Use
Does not return water to original source
~70% of withdrawn water
Nonconsumptive Use
Temporarily removes water from source
Ex: Power plant using water for cooling
Withdrawal – total amount of water we remove from a river, lake, aquifer, etc.

13. How much water do we use? 70% = Irrigation 20% = Industrial Use
10% = Cities & Residencies
(1lb of beef = 6 months of showers!)

14. How much water do we use?
We currently withdraw 34% of reliable runoff.
But to meet demands of growing population we may be using 70-90% by 2025.

15. Annual Precipitation determines who has & does not have water resources
Precipitation NOT evenly distributed!
Fig. 11-4a, p. 240

16. Freshwater Resources in the United States
17 western states by 2025 could face intense conflict over scarce water needed for urban growth, irrigation, recreation and wildlife.
Figure 14-5

17. Cooperation?
No cooperative agreements exist for 158 of 263 watersheds shared by two or more countries
Conflicts likely to increase as population & demand continue to rise

18. Question #2
What causes freshwater shortages, and what can be done to increase freshwater supplies?

19. Causes of Freshwater Shortages
Dry Climate
Drought
Large Population
Poverty
Drought – a prolonged period in which precipitation is at least 70% lower and evaporation is higher than normal

20. Stress on the World’s River Basins
1 in 6 don’t have access to adequate & affordable supply of clean water.
Buy 2050 this could be 1 in 4.
The Middle East is among the most water impoverished areas globally, already experiencing disagreements over water rights. By 2050, ~60 countries will be suffering from water stress.

21. Could you live on 1 gallon of water/day for all your needs?
Hydrological Poverty
Could you live on 1 gallon of water/day for all your needs?
More than 2/3 of the world’s households do not have running water. When water is scarce, not much is used toward sanitation or hygiene.

22. Ways to Increase Freshwater Supplies
Dams & Reservoirs
Water Transfers
Using Groundwater
Dams & Reservoirs
- Pro: cheap electricity / reduces flooding / increases freshwater supply
- Con: disrupts downstream flow & upsets ecosystems / floods productive land
Water Transfers
- Pro: provides water to areas w/ little
- Con: degrades rivers & disrupts ecosystems / use to grow water needy plants in areas w/ lil natural water
- example: Aral Sea – created major ecological, economic & health disaster
Using Groundwater
- Pro: Renewable if not overpumped / cheap / available most places unless polluted or contaminated by salt
- Con: US 4x replacement rate / causes land to sink / unuseable once

23. Ways to Increase Freshwater Supplies
Desalination
Distillation & reverse osmosis
Import food
Waste Less
Desalination
- Con: high cost / no solution for what to do with resulting salt waste
Importing food
– reduces water waste used for crops / livestock
- takes 1,000 tons of water to produce 1 ton of grain
Waste Less
- charge more to increase conservation
- improve irrigation techniques
- provide govt subsidies for improving water conservation in agriculture / industry
- fix leaks in homes, businesses, infrastructure
- install low-flow toilets, showers, etc

24. What are the advantages and disadvantages of withdrawing groundwater?
Essential Question #3
What are the advantages and disadvantages of withdrawing groundwater?

25. Withdrawing Groundwater To Increase Supplies
Aquifers are Renewable as long as NOT:
Overpumped
Contaminated
Groundwater depletion for Irrigation is a growing problem
At least one-fourth of the farms in India are being irrigated from overpumped aquifers.
Currently provide about ¼ of world’s water

26. Effects of Groundwater Overpumping
Contaminates freshwater aquifers near coastal areas with saltwater.
Sinkholes form when drained aquifers collapse
Sinkholes can also occur naturally in areas high in limestone. Aquifer waters can dissolve limestone causing a cave in.

27. Groundwater Contamination
Example: Contamination from fracking

28. Withdrawing Groundwater
Trade-Offs
Withdrawing Groundwater
Advantages
Disadvantages
Useful for drinking and irrigation
Aquifer depletion from overpumping
Sinking of land (subsidence) from overpumping
Available year-round
Exists almost everywhere
Polluted aquifers for decades or centuries
Renewable if not overpumped or contaminated
Saltwater intrusion into drinking water supplies near coastal areas
No evaporation losses
Reduced water flows into surface waters
Cheaper to extract than most surface waters
Increased cost and contamination from deeper wells
Fig. 14-7, p. 313

29. Groundwater Depletion: A Growing Problem
Areas of greatest aquifer depletion from groundwater overdraft in the continental U.S.
Groundwater is being withdrawn 4x faster than it’s being replenished
The Ogallala, the world’s largest aquifer, is most of the red area in the center (Midwest).
Figure 14-8

30. Groundwater Depletion
Solutions
Groundwater Depletion
Prevention
Control
Waste less water
Subsidize water conservation
Raise price of water to discourage waste
Ban new wells in aquifers near surface waters
Tax water pumped from wells near surface waters
Buy and retire groundwater withdrawal rights in critical areas
Set and enforce minimum stream flow levels
Do not grow water-intensive crops in dry areas
Fig , p. 316

31. Essential Question #4
What are the advantages and disadvantages of using dams to supply more water?

32. Beaver’s are Fans

33. Provides water for year-round irrigation of cropland
Flooded land destroys forests or cropland and displaces people
Large losses of water through evaporation
Provides water for drinking
Downstream cropland and estuaries are deprived of nutrient-rich silt
Reservoir is useful for recreation and fishing
Risk of failure and devastating downstream flooding
Can produce cheap electricity (hydropower)
Trade-offs: advantages (left) and disadvantages (right) of large dams and reservoirs.
The world’s 45,000 large dams (higher than 15 meters or 50 feet) capture and store 14% of the world’s runoff, provide water for almost half of all irrigated cropland, and supply more than half the electricity used by 65 countries. The United States has more than 70,000 large and small dams, capable of capturing and storing half of the country’s entire river flow.
Downstream flooding is reduced
Migration and spawning of some fish are disrupted
Fig a, p. 317

34. Powerlines Reservoir Dam Powerhouse Intake Turbine River
Fig b, p. 317

35. The Colorado Basin – an Overtapped Resource
The Colorado River has so many dams and withdrawals that it often does not reach the ocean.
14 major dams and reservoirs, and canals.
Water is mostly used in desert area of the U.S.
Provides electricity from hydroelectric plants for 30 million people (1/10th of the U.S. population).

36. The Colorado River Basin
The area drained by this basin is equal to more than one-twelfth of the land area of the lower 48 states.
Figure 14-14

37. Dam Removal
Since 1998, U.S. Army Corps of Engineers no longer building dams / water diversion projects in US
Many dams being removed b/c of age or ecological reasons
Difficult & Expensive

38. Essential Question #5
What are the advantages and disadvantages of transferring large amounts of water from one place to another?

39. Advantages of Water Transfer
Makes unproductive areas more productive
Promotes investment / jobs / economy

40. Disadvantages of Water Transfer
Encourages unsustainable use in water scarce areas
Reduces water availability from source
Examples:
Aral Sea Disaster
California Water Project
South-to-North China
Water Diversion Project
($58 billion)

41. Essential Question #6
How can removing salt from water solve our water supply problems? Why or why not?

42. Desalination

43. Disadvantages Not Practical High cost / High Energy
Disposal of waste salts / minerals / toxins
Projects involving desalination by renewable energy means are underway.

44. Other Ideas: Unlikely Cloud Seeding Towing Icebergs Giant Water Bags
Costly, no scientific evidence of success, unintended ecological consequences

45. How can we waste less water?
Essential Question #7
How can we waste less water?

46. Water Waste
65-70% of water used is lost to evaporation, leaks, & other losses
About 60% of water used for crop irrigation is lost due to inefficient methods

47. (efficiency 60% and 80% with surge valves)
Improving Irrigation
Gravity flow
(efficiency 60% and 80% with surge valves)
Figure 14.18
Major irrigation systems: because of high initial costs, center-pivot irrigation and drip irrigation are not widely used. The development of new low-cost drip-irrigation systems may change this situation.
Center pivot
Drip irrigation
(efficiency 80%–95%)
(efficiency 90–95%)
Above- or below-ground pipes or tubes deliver water to individual plant roots.
Water usually pumped from underground and sprayed from mobile boom with sprinklers.
Water usually comes from an aqueduct system or a nearby river.

48. Reducing Water Waste Charge more to increase conservation
Improve irrigation techniques (drip irrigation)
Give financial incentives (subsidies) for improving water conservation in agriculture / industry
Government subsidies keep water prices artificially low to help the agriculture industry. Prices so low, there’s no incentive to invest in water saving technologies.

49. Reducing Water Waste Fix leaks in homes, businesses, infrastructure
Install low-flow toilets, showers, etc
Used recycled water (gray water) for watering home
Plant drought tolerant plants

50. Rain Water Recycling Systems

51. Solutions Reducing Water Waste • Redesign manufacturing processes
• Repair leaking underground pipes
• Landscape yards with plants that require little water
• Use drip irrigation
• Fix water leaks
• Use water meters
• Raise water prices
• Use waterless composting toilets
• Require water conservation in water-short cities
Figure 14.21
Solutions: methods of reducing water waste in industries, homes, and businesses. QUESTION: Which three of these solutions do you think are the most important?
• Use water-saving toilets, showerheads, and front loading clothes washers
• Collect and reuse household water to irrigate lawns and nonedible plants
• Purify and reuse water for houses, apartments, and office buildings
• Don't waste energy
Fig , p. 327

52. What causes flooding, and what can we do to reduce flood risks?
Essential Question #8
What causes flooding, and what can we do to reduce flood risks?

53. What is a flood?
When water leaves its normal channel and spills into its adjacent floodplain
Floodplain – areas in which flood waters spill into; typically contain wetlands that provide natural flood & erosion control

54. What causes flooding? Heavy Rain Rapid Snow Melt Removing Plants
Destroying Wetlands
Impervious Structures
Pavement / Buildings
Since the 1960’s, human activities have contributed to increased flooding:
- damming & altering rivers w/ levees increase flood risks b/c can be easily overwhelmed
- removing water-absorbing vegetation
- draining & removing wetlands that act as natural sponges for flood water

56. Flooding After Deforestation of a Hillside
Fig , p. 253

57. How can we reduce flood risks?
Straighten & deepen rivers/streams
Build Levees
Build Dams
These solutions have ecological problems
Can increase erosion
Can be overwhelmed by excess flood water

58. How can we reduce flood risks?
Preserve & Restore Wetlands (best solution)
Act as a natural sponge for flood waters
Better identify flood plains & think about where we live

59. Preserve forests on watersheds
Solutions
Reducing Flood Damage
Prevention
Control
Preserve forests on watersheds
Strengthen and deepen streams (channelization)
Preserve and restore wetlands in floodplains
Build levees or floodwalls along streams
Tax all development on floodplains
Figure 14.24
Solutions: methods for reducing the harmful effects of flooding. QUESTION: Which two of these solutions do you think are the most important?
Use floodplains primarily for recharging aquifers, sustainable agriculture and forestry, and recreation
Build dams
Fig , p. 331

60. How can we use the earth’s water more sustainably ?
Essential Question #9
How can we use the earth’s water more sustainably ?

61. Sustainable Water Use
Improve monitoring of water sources to improve management
Protect ecosystems involved in water cycle
Regulate withdrawals
Change subsidies to promote water conservation
Improve wastewater treatment
Slow population growth & thus demand

62. What Can We Do? What Can You Do? Fig. 11-21, p. 251
Water Use and Waste
Use water-saving toilets, showerheads, and faucet aerators
Shower instead of taking baths, and take short showers.
Repair water leaks.
Turn off sink faucets while brushing teeth, shaving, or washing.
Wash only full loads of clothes or use the lowest possible water-level setting for smaller loads.
Wash a car from a bucket of soapy water, and use the hose for rinsing only.
If you use a commercial car wash, try to find one that recycles its water.
Replace your lawn with native plants that need little if any watering.
Water lawns and garden in the early morning or evening.
Use drip irrigation and mulch for gardens and flowerbeds.
Use recycled (gray) water for watering lawns and houseplants and for washing cars.
Fig , p. 251

64. The Awesome Water Bottle