1. Chapter 9
Water Resources

2. Unconfined Aquifer Recharge Area Evaporation and transpiration
Precipitation
Evaporation and transpiration
Evaporation
Confined Recharge Area
Runoff
Flowing artesian well
Recharge Unconfined Aquifer
Stream Well requiring a pump
Figure 14.3
Natural capital: groundwater system. An unconfined aquifer is an aquifer with a permeable water table. A confined aquifer is bounded above and below by less permeable beds of rock where the water is confined under pressure. Some aquifers are replenished by precipitation; others are not.
Infiltration
Water table
Lake
Infiltration
Unconfined aquifer
Less permeable material such as clay
Confined aquifer
Confining impermeable rock layer
Fig. 14-3, p. 308

3. Usable Water is Rare

4. WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL
Comparison of population sizes and shares of the world’s freshwater among the continents.
Figure 14-2

5. WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL
We currently use more than half of the world’s reliable runoff of surface water and could be using 70-90% by 2025.
About 70% of the water we withdraw from rivers, lakes, and aquifers is not returned to these sources.
Irrigation is the biggest user of water (70%), followed by industries (20%) and cities and residences (10%).

6. “It is not until the well runs dry that we know the worth of water”
Why Care about Water?
“It is not until the well runs dry that we know the worth of water”
Ben Franklin
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7. Water Renewal Rates Groundwater 100,000 years
Groundwater near surface years
Lakes – 100 years
Glaciers- 40 years
Water in the soil- 70 days
Rivers- 16 days
Atmosphere- 8days

8. Groundwater
Aquifers- small spaces found within permeable layers of rock and sediment where water is found.
Unconfined aquifers- an aquifer that is simply porous rock covered by soil.
Confined aquifers- an aquifer surrounded by a layer of impermeable rock or clay.

10. Groundwater
Water table- the uppermost level at which the water in an area fully saturates the rock or soil.
Recharge- the input process of water percolating into an aquifer.
Springs- water from an aquifer that naturally percolates up to the surface.

11. Groundwater
Cone of depression- an area where there is no longer any groundwater.

12. Groundwater
Saltwater intrusion- when the pumping of fresh water out of a well is faster than the recharge. Near coastal areas this can cause salt water to infiltrate the aquifer.

13. Recharging of Aquifers
Aquifers are naturally recharged by precipitation.
It is a slow process- ground water moves ~ 3 feet/year from higher elevations to lower elevations.
Removing ground water faster than it is replenished disrupts the water cycle. Result- dry streams, lakes, etc.
Provide drinking water to more than 1/4 of world’s population.
Ogallala is the world’s largest aquifer and allowed many parts of the US (arid regions) to become fertile farming areas. Water is being removed 8-10X faster than its natural recharge rate.

14. Ogallala Aquifer

15. Groundwater Depletion: A Growing Problem
Areas of greatest aquifer depletion from groundwater overdraft in the continental U.S.
Figure 14-8

16. Supplying More Water Groundwater supplies
Groundwater in the U.S. is being withdrawn at about four times its replacement rate
Consequences:
aquifer depletion
aquifer subsidence land sinks when water is withdrawn
saltwater intrusion

17. Other Effects of Groundwater Overdrafts
Sinkholes form when the roof of an underground cavern collapses after being drained of groundwater.
Figure 14-10

19. Questions for discussion
Who does the water underground belong to?
Should aquifers be allowed to deplete?
How would you regulate this?

20. Surface Water
Streams, rivers, ponds, lakes and wetlands.

21. Surface Water: Lakes Productivity in a lake:
Oligotrophic- low amounts of nutrients such as phosphorous and nitrogen.
Mesotrophic- a moderate level of productivity
Eutrophic- high levels of productivity

22. Rivers
The world’s largest three rivers are as measured by volume of water
Amazon
Congo
Yangtze
Floodplain: area where the excess water spreads onto land, these areas become nutrient rich fertile plains

23. Altering the Availability of Water
Levees- an enlarged bank built up on each side of the river.
Dikes- similar to a levee but built to prevent ocean waters from flooding adjacent land.

24. Altering the Availability of Water
Dams- a barrier that runs across a river or stream to control the flow of water.
Reservoir- the area where water is stored behind the dam.

25. Altering the Availability of Water
Fish ladders- a set of stairs with water flowing over them that have been added to some dams to help migrating fish such as salmon get upstream.

26. Using Dams and Reservoirs
800,000 dams currently restrict the world’s rivers.
Positives and negatives for creating these.
Storage of water for human use, but slows downstream flow and disrupts reproductive cycle of many fish. Ex: Salmon difficulty swimming upstream and get caught in turbines.
World Commission on Water in the 21st Century states that ½ of world’s rivers will dry out because of flow reduction due to building of dams
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27. How Electricity Works:
/electricity.htm
Figure 14-13

28. Pros and Cons of Dams and Reservoirs

29. Case Study: Aswan Dams
Two dams on the Nile River: Aswan High Dam and Aswan Low Dam
Dammed river to protect valley from flooding, provide water and hydroelectric power.
The Aswan High Dam is 3,600 m in length, 980 m wide at the base, 40 m wide at the crest and 111 m tall. It contains 43 million m3 of material. At maximum, 11,000 m³ of water can pass through the dam every second.
The reservoir, named Lake Nasser, is 550 km long and 35 km at its widest with a surface area of 5,250 km² and holds 132 km³.

30. Aerial View
Aswan High Dam

31. Environmental Issues
It flooded much of lower Nubia and over 90,000 people were displaced.
Lake Nasser flooded valuable archeological sites.
Silt deposited in the reservoir is lowering the water storage capacity of Lake Nasser
Poor irrigation practices are waterlogging soils and bringing salt to the surface.
Mediterranean fishing declined after the dam was finished because nutrients that used to flow down the Nile to the Mediterranean were trapped behind the dam.

32. Dams on the Columbia Watershed

33. Idaho Power
IPC's 17 hydroelectric power plants and it is one of the nation's few investor-owned utilities with a significant hydroelectric generating base. Idaho Power built the majority of its hydroelectric facilities during the 1940s, 1950s and 1960s, culminating with completion of the three-dam Hells Canyon Complex in 1968.
American Falls Dam ,Milner Dam ,Twin Falls, Shoshone Falls ,Clear Lake, Thousand Springs, "Mid-Snakes Project" in Central Idaho on the Snake River consisting of the Upper Salmon Falls power plant and the Lower Salmon Falls, Bliss Dam, "The Malads": Upper Malad and Lower Malad, C. J. Strike Dam , Swan Falls Dam, and Cascade Dam on the Payette River
"Hells Canyon Complex": Brownlee Dam power plant at river mile 285.0, Oxbow Dam power plant at river mile 272, and the Hells Canyon Dam

35. The Colorado River Watershed

36. Dam Removal
Some dams are being removed for ecological reasons and because they have outlived their usefulness.
In 1998 the U.S. Army Corps of Engineers announced that it would no longer build large dams and diversion projects in the U.S.
The Federal Energy Regulatory Commission has approved the removal of nearly 500 dams.
Removing dams can reestablish ecosystems, but can also re-release toxicants into the environment.

37. Dam Removal
The Elwha River flows into the Strait of Juan de Fuca, carrying sediment once trapped behind dams. The gradual release has rebuilt riverbanks and created estuary habitat for Dungeness crabs, clams, and other species.

38. Discussion Questions Are dams a necessary evil?
How do we decide when a river has too many?

39. Altering the Availability of Water
Aqueducts- canals or ditches used to carry water from one location to another.

40. Water transfer – California Water Project
The Problem
most of the rainfall is in northern California
most of the population growth and agriculture is in southern California
The Solution
water transferred to the south via dams, pumps, and aqueducts
The Controversy
southern California wants more water for growing cities
much of the water transferred is wasted by inefficient irrigation
the north needs the water for fisheries and flushing pollutants out of San Francisco Bay
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41. Case Study: The California Experience
A massive transfer of water from water-rich northern California to water-poor southern California is controversial.
Figure 14-16

42. Discussion Questions
California and Nevada are very interested in getting water from elsewhere, should they be able to do this or have to live with the current water they already have?
How would you solve the California crisis?

43. Case Study: The Aral Sea Disaster
The Aral Sea was once the world’s fourth largest freshwater lake.
Figure 14-17

44. Case Study: The Aral Sea Disaster
Diverting water from the Aral Sea and its two feeder rivers mostly for irrigation has created a major ecological, economic, and health disaster.
About 85% of the wetlands have been eliminated and roughly 50% of the local bird and mammal species have disappeared.
Since 1961, the sea’s salinity has tripled and the water has dropped by 22 meters most likely causing 20 of the 24 native fish species to go extinct.

45. Desalination
Process of removing salt from salt water to make it suitable for drinking.
2 most common practices are
1. Distillation- heat/evaporates/condenses
2. Reverse osmosis- use of
high pressure and thin membrane. Membrane acts like strainer.

46. Desalination-

47. Desalination
Middle Eastern countries produce 60% of world’s desalinated water.
Tampa, Fl has a plant to supplement supplies.
Cons against plants:
1. Process requires a lot of energy- $$$$$
2. Waste product- where to dump????
-Ocean- increases salinity- effects ecosystems
-Land- contaminate groundwater supplies.

48. Desalinization
Sci Show….

49. Agriculture, Industry, and Household Use of Fresh Water
69% for agriculture most does not reach crops (60%–80% wasted)
23% for industry (energy production and various industry)
8% for domestic and municipal use
© Brooks/Cole Publishing Company / ITP

50. Agriculture
Agriculture- the largest user of water around the world.

51. Agriculture Needs Irrigation techniques-
Furrow irrigation- a trench that is flooded with water.
Flood irrigation- the entire field is flooded with water.
Spray irrigation- an apparatus that sprays water across a field.
Drip irrigation- using a slow dripping hose that is laid on or buried beneath the soil. This is the best.
Hydroponic agriculture- crops grown in fertilized water and no soil.

52. Irrigation Techniques
Center Pivot
(efficiency 80% with low-pressure
sprinkler and 90–95% with
LEPA sprinkler)
Low-Energy Precision Application
Water usually pumped from
underground and sprayed from
mobile boom with sprinklers.
Drip Irrigation
(efficiency 90-95%)
Above- or below-ground pipes
or tubes deliver water to
individual plant roots.
Gravity Flow
(efficiency 60% and 80% with surge valves)
Water usually comes from an
aqueduct system or a nearby river.
Start up cost is expensive, but long term benefits

53. Central Pivot with LEPA System: 90-95% Efficient
Central Pivot Without LEPA
System: 80% Efficient

54. Industry Needs
Industry- the second largest user of water worldwide.

55. Household Needs
Households- the third largest user of water worldwide .
Toilets- highest water use in households.

56. Increasing Water Efficiency
increase efficiency of irrigation (~40% is wasted with old techniques- flooding)
drip irrigation, central–pivot, computer monitoring
use recycled water (Gray water)
treat gray water from showers, washing machines for reuse
fix leaky pipes
water–saving toilets, faucets, and shower heads
xeriscaping
plant drought–tolerant vegetation in residential communities located in arid and semi–arid areas

57. Xeriscaping

58. TOO MUCH WATER
Human activities have contributed to flood deaths and damages.
Figure 14-23

59. Human activities that have increased flooding
Rapid population growth
Deforestation
Overgrazing
Unsustainable farming on steep hills
Clearing coastal mangrove forests

60. 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

61. The Future of Water Availability
Water ownership- people can have rights to water use, but they do not own the water.
Water conservation- using techniques such as more efficient water fixtures, faucets and washing machines.

62. SOLUTIONS: USING WATER MORE SUSTAINABLY
We can use water more sustainably by cutting waste, raising water prices, preserving forests and wetlands in water basins, and slowing population growth.
Figure 14-25

63. Discussion Questions How would you regulate water?
Do you think the future will have water wars?