Chapter 7 Water: Hydrologic Cycle and Human Use

1. Chapter 7Water: Hydrologic Cycle and Human Use

2. Introduction The Aral Sea

3. Death of the Aral Sea • Located in present-day Kazakhstan and Uzbekistan. • 1930’s it was decided that the area surrounding the sea could be used to grow cotton. • By 1960, millions of acres of land were irrigated using water from the two large rivers that fed the Aral Sea. • The sea began to shrink

4. Aral Sea Impacts • Salinity increased as water was not replenished • Hurt the 60,000 employee fishery industry. • 3x saltier than the ocean. • Lost 90% of it’s original volume. • Many health impacts for the people as the dried salt/pesticide/fertilizer/herbicide laden dust is carried by winds • Increased cancer, higher infant mortality • Local climate changed, growing season shortened, switch from cotton to rice

5. Other dry runs: • Aral sea not unique: • Rio Grande shorter because of withdraw for domestic use and irrigation. • Colorado river almost completely drained before it can reach Mexico leaving a dried baked mud area in the gulf of California. • Dead Sea is being diverted by Israel and Jordan. May disappear by 2050 without any action taking place to prevent it.

6. Lesson 7.1 Water: A Vital Resource

7. Objectives for the chapter (Threefold) • To understand the natural water cycle, its capacities, and its limitations • To understand how we are over drawing certain water sources and to understand the consequences • To understand how water must be handled if we are to achieve sustainable supplies

8. Water is fundamental to life • Earth has about 325 million cubic miles/ covers about 71 % of its surface • 97.5% of this water is salt water • Fresh water- water that has a salt content of less than 0.1% • 97.5% Salt water • 2.5% Fresh water • 1.7% Polar ice caps and glaciers • .77% Accessible fresh water

9. Where does the 0.77% fresh water come from? • Lakes • Wetlands • Rivers • Groundwater • Biota • Soil • Atmosphere

10. How do we use it? • Human societies must draw fresh water for energy through hydroelectric, transportation, recreation, waste processing, and habitats for aquatic plants and animals. • Over the past two centuries these uses have led us to try to control the water through infrastructure: dams, canals, reservoirs, sewer systems, treatment plants, water towers, etc.

11. What water does for land: • Provides drinking water, water for industry, and water to irrigate crops. • Bodies of water provide energy through the hydroelectric power and control flooding by absorbing excess water.

12. There are two ways to consider water issues: • Quantity (this chapter) • On the Global water cycle and how it works, on the technolgies we use to control and manage its use, and on public policy • Quality (chapter 17) • Water pollution and its consequences, on sewage treatment technologies, and on public policy for dealing with pollution issues.

13. Section Two The Hydrologic Cycle: Natural Cycle, Human Impacts

14. Water cycle or Hydrologic cycle • Hydrologic Cycle: • Consists of water rising to the atmosphere through either evaporation or transpiration and returning to the land and oceans through condensation and precipitation. • Water vapor-green water • Liquid water-blue water

15. Humidity: • Humidity- amount of water vapor in the air • measured as relative humidity (amount of water vapor as a % of what the air can hold at a particular temperature) •Humidity increases as air warms decreases as air cools

16. Water cycle

17. Water Terms • Table 7-1 page 172 • Add the following terms: • Potable • Gray • Black

18. Physical Processes and Loops 4 Physical Processes 3 Physical Loops Evapotranspiration loop Evaporates and returns as precipitation Surface runoff loop Water runs across the ground surface and becomes part of the surface water system Ground water loop Water infiltrates, percolates down to join the ground water traveling through aquifers and then exiting through seeps, springs, or wells • Evaporation • Condensation • Precipitation • Gravitational flow

19. Green House Gas • Water is a powerful greenhouse gas: it provides about 2/3 of the total warming from all greenhouse gases.

20. Aerosols • Microscopic liquid or solid particles originating from land and water surfaces that attract water vapor and promote the formation of droplets of moisture (AKA-condensation nuclei) May originate naturally through volcanic eruption, wind-stirred dust and soil, and sea salts or may occur anthropogenically through sulfates, carbon, and dust.

21. Natural water purification • One very important aspect of • evaporation & condensation is water • purification. • When water in an ocean or lake evaporates, only the water molecules leave the surface. May pick up impurities again as it falls. • Water turn over in the atmosphere happens every 10 days, so water is constantly being purified.

22. Ground Water • Water that infiltrates the ground has two alternatives. • It may be held in the soil and returned to the atmosphere through one of the following methods… • Transpiration: air picks up water vapor from vegetation (green water flow) • Evaporation: Air picks up water vapor from the soil (green water flow) • Evapotranspiration: the combination of the two above terms. • Or it may percolate (blue water system).

23. Salt Lakes • Created as salts are picked up and carried to inland lakes the same way that they are carried to the ocean.

24. Hadley Cell Rising air over the equator is pushed from beneath by more rising air causing a “spill over” to the North and South. The two halves of the system (rising and falling air) make up the Hadley cell

25. Rain Shadow • Causes rising and falling air currents when moisture laden trade winds encounter mountain ranges

26. Aquifers • Layers of porous material through which groundwater moves through. • Hold 99% of the liquid fresh water • The rest is found in lakes, wetlands and rivers

27. Surface Runoff and Ground Water: • Both are blue water systems. • Both are the usual focus for human resource management. • Infiltration-runoff ratio: the amount that soaks in compared to the amount that runs off

28. Human Impacts • Four categories that either directly or indirectly impact the water cycle: • Changes to Earth’s surface • Changes to Earth’s climate • Atmospheric pollution • Withdraws for human use

29. Deforestation • As land is cleared or overgrazed, the pathway for the water cycle shifts from infiltration and groundwater recharge to runoff. • Consequences include flooding, decreased ground water, increased salinization, loss of biodiversity

30. Section Three Water: A Resource to Manage, a Threat to Control

31. Major Uses • Table 7.2 • Homes/industry: • washing and flushing away wastes. (nonconsumptive) • Irrigation. (consumptive) • We use less water today than in 1975…even though population has increased.

32. Water Usage Consumptive Nonconsumptive Water is returned to its source Electric power generation Industrial use Domestic use (public and self-supplied) • The applied water does not return to the water source • Irrigation • Other agricultural use

33. Trends in water use: • US: industry followed by agriculture by domestic • World: agriculture, industry, domestic • Europe: similar to US • South America & Africa: agriculture, domestic, industry • Asia: similar to world pattern of use • Figure 7-11 page 179

34. Sources • US: 40% ground, 60% surface for domestic use. • Developing countries: 90% of the waste water is released directly to surface waters without treatment…cholera, etc. 1.1 billion people drink this unsafe water. Saris used to filter cholera in Bangladesh.

35. Technologies for water collection • Industrialized countries: • dams are built across rivers to create reservoirs (hole water in times of excess flow and can be drawn out in times of lower flow). • Water is piped to treatment plants. • Water is distributed through the water system to homes, schools, and industry. • Water is collected by sewage-treatment plant, retreated, and sent back out for distribution

36. Municipal Water Treatment • Figure 7-13 page 180. • Know the steps of the water treatment plant…Alum, mixing tank, settling basin, sand filter, lime/fluoride added, distribution.

37. Dam Impacts • US: 75,000 dams at least six feet in height, another 2 million smaller structures. • Fresh water habitats lost, increased salt concentration, etc.

38. Glen Canyon • Closed its gates in 1963 (meaning it became operational). • Stores excess water in Lake Powell • Spans the Colorado River at Lee’s Ferry, AZ, just above Grand Canyon National Park. • Operated by Federal Bureau of Reclamation. • Generates hydropower and stores water for distribution to CA, NE, AZ, and Mexico.

39. Glen Canyon Continued • A study in the late 1980’s to early 1990’s concluded that the operation of the dam had greatly impacted the downstream ecology and its recreational resources. • 1996, Secretary of the Interior issued new rules that established minimum and maximum water-release rates (GCMRC)

40. GCMRC • 1996 • Secretary of the Interior, Bruce Babbitt • Grand Canyon Monitoring and Research center • Provides scientific monitoring for the dam’s operations and operates within the guidelines of adaptive ecosystem management. • Outcome: successful

41. Dam building around the world • US: 75,000 dams at least 6 feet in height and an estimated 2 million other smaller structures. • Around the world: more than 45,000 large dams (50ft high). • 3,000 of these contain storage reservoirs with volumes greater than 25 billion gallons, 120 million acres of land and containing more than 1,500 mi3 of water

42. CALFED • CALFED Bay-Delta Program • Established to “develop and implement a lon-term comprehensive plan that will restore ecological health and improve water management for beneficial uses of the Bay-Delta System” • Bay-Delta is a huge estuary in the San Francisco Bay.

43. Ground Water • Can be nonrenewable, such is the case for the Ogallala aquifer. • Originally charged during the last ice age melt (fossil water). • Used to irrigate 1/5 of US land. Cannot recharge at a fast enough rate to be sustainable.

44. Falling water table • Wet lands dry up. • Structural support is lost. • Land subsistence. • Sink holes. • Salt water intrusion (figure 7-18 page 184).

45. Subsidence • Land subsidence is where ground water has leached into cavities in the ground, helping to support the above lying rock and soil. As the water table drops, the support is lost. This is the gradual settling of the land.

46. Sink hole • Type of land subsidence that happens rapidly and dramatically

47. Salt water intrusion • Results from dropping water tables. • Springs of outflowing ground water may lie under the ocean. As long as the water table is high it will maintain enough head pressure in the aquifer and water will flow into the ocean. When tables are low the pressure is not enough and ocean water flows backward into the aquifer

48. Salt water intrusion

49. Section Four Water Stewardship: Public Policy Challenges

50. How is there not enough? • If the water cycle is sufficient to provide water for all human needs, why do some go without? • Not distributed evenly • Scarcity of water in many parts of the world • Deficit in infrastructure • Expanding populations