Chapter 7 Water: Hydrologic Cycle and Human Use

Introduction The Aral Sea

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

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

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.

Water: A Vital Resource Lesson 7.1 Water: A Vital Resource

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

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

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

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.

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.

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.

Section Two The Hydrologic Cycle: Natural Cycle, Human Impacts

Water cycle or 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

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

Water cycle

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

Physical Processes and Loops 3 Physical Loops Evaporation Condensation Precipitation Gravitational flow 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

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

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.

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.

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).

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

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

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

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

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

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

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

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

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.

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

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

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.

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

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.

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.

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.

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)

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

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

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.

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.

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

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.

Type of land subsidence that happens rapidly and dramatically Sink hole

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

Salt water intrusion

Section Four Water Stewardship: Public Policy Challenges

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

How can we make water use sustainable: Capture more runoff Gain better access to groundwater aquifers Desalt seawater (microfiltration/reverse osmosis) Conserve present supplies by using less water. (drip irrigation)

Why build dams? Combination of flood control, water storage, and hydropower. Three Georges Dam

Three Georges Dam Yangtze River in China Completed in 2006 Largest hydroelectric project in the world Generates 22,000 MW of electricity More than 1.2 million people have been displaced Critics point to the huge human, ecological, and aesthetic costs of the dam and claim alternative sources of energy are cheaper

US Dam Removal 500 dams have already been removed in the US and many await the same fate. Pros for removal: reestablish historic fisheries and reestablish the river for recreational and aesthetic value Cons: massive sediment from upriver that will be washed downstream, difficult.

Wild and Scenic Rivers Act 1968 Keeps rivers labeled as “wild and scenic” from being dammed or affected by other harmful operations. 11,300 miles of rivers have been protected, 60,000 more miles are eligible. Like national parks, they need supporters and defenders such as the organization American Rivers

Threats to irrigated agriculture Greatest: ground water depletion Happening in many parts of the world Other threats: pollution from fertilizers, pesticides, animal wastes, and industrial chemicals.

Genetically modify plants? Scientists are trying to modify plants to be tolerant of salts. The trend however is to desalinate until this is an actual possibility. Desalinating: microfiltration (reverse osmosis)-great pressure forces seawater through a membrane filter fine enough to remove salt…and distillation-evaporation and recondensation of water vapor Under the best circumstance it costs $2 per 1,000 gallons (2-4 x’s as much as US city dwellers pay but by far cheaper than bottled water Cost efficient for city dwellers but not for crop owners who need to irrigate.

Water used per day per person Developing nation: 1 gallon (includes cooking and washing) US: 100 gallons per person per day If all indirect uses such as irrigation are added in it goes up to 1,300 gallons

Agricultural water conservation Drip irrigation: network of plastic pies with pin holes in them that literally drip water at the base of the plant. Treadle pump: works like an exercise machine pumping water from just a few feet below the surface.

Municipal water conservation Flushing 3-5 gallons Showering 2-3 gallons per minute Laundry 20-30 gallons per load Conserve: fix leaky faucets, low-flow shower heads and faucets, replace lawns with xeriscaping, ban use of water during draughts, gray-water recycling.

xeriscaping Landscaping with desert species that require no extra watering (lawn replacement)

US water policy No US water policy  Clean water act and its subsequent amendments authorize the US EPA to develop programs and rules to carry out its mandate for oversight of the nation’s water quality. EPA does not deal with water quantity.

Issues to be addressed The last time a water policy report was issued was in 1950 by Harry S. Truman The issues that need to be addressed by a water policy report…7 on page 190 Promote efficiency Water subsidies reduced or eliminated Polluters charged according to effluents Watershed management Regulate dam operations International development aid More research and monitoring