Chapter 15 Water Resources G. Tyler Miller’s Living in the Environment 14th Edition Chapter 15

Chapter 15 Key Concepts The physical properties of water Availability of fresh water Methods of increasing freshwater supplies Using water more efficiently Problems associated with flooding

Sections 1 and 2 Key Ideas Why is water so important? What makes water unique? How much fresh water is available to humans? What are some of the sources of fresh water? How do we use the world’s fresh water? What are some water resource issues faced in the United States?

Water’s Importance No species can live without water. Plays a key role in shaping the earth’s surface, moderating climate, removing and diluting wastes. Takes huge amount to provide food, shelter and other needs. 71% of our planet

Water’s Unique Properties Hydrogen bonding: water’s unique properties comes from the strong attractive forces between molecules.

Water’s Unique Properties Liquid over wide temperature range: without its high boiling point the oceans would have evaporated long ago. Changes temperature slowly: high specific heat means slow temperature changes. Helps moderate climate.

Water’s Unique Properties High heat of evaporation: evaporation takes a lot of heat. This explains why sweating makes you feel cooler. Great dissolving power: known as the universal solvent because so may things dissolve well in it. Leads to pollution problems as well.

Water’s Unique Properties Filters out ultraviolet radiation: protecting aquatic organisms from sun’ rays. Adhesion and cohesion: strong forces of attraction between molecules allows water to rise up inside plants from roots to leaves.

Water’s Unique Properties Expands when it freezes: most substances contract when frozen, not water. Water expands and is less dense in its solid form. Hence, ice floats. Water is also one of few substances found commonly as a solid, liquid and gas.

How Much Water Is Available? 71% of earth is water 97.4% of that is in oceans Most of the remaining 2.6% is in ice caps and glaciers. Only about 0.014% is easily available fresh water. If earth’s water was 26 gallons, 2.5 teaspoons would be available.

Supply of Water

Supply of Water Resources Freshwater Readily accessible freshwater Biota 0.0001% Rivers Atmospheric water vapor Lakes 0.0007% Soil moisture 0.0005% Groundwater 0.592% Ice caps and glaciers 0.014% Fig. 15-2 p. 307

Water Cycle: Renewing Water

Surface Water Surface runoff: precipitation that does not infiltrate the ground or return to the atmosphere. Reliable runoff: the amount of water that can be counted on each year as a stable source.

Surface Runoff Watershed: the region of land from which surface water drains into a river, lake, wetland or other body of water

Watershed

Delaware River Watershed

Groundwater One of the most important source of water. Precipitation filters down through pores and cracks in soil and rocks. Groundwater found within 1km of the surface contains 100 times more water than all the rivers, streams and lakes

Evaporation and transpiration Ground Water Evaporation and transpiration Evaporation Stream Infiltration Water table Unconfined aquifer Confined aquifer Lake Well requiring a pump Flowing artesian well Runoff Precipitation Confined Recharge Area Aquifer Less permeable material such as clay Confirming permeable rock layer Fig. 15-3 p. 308

Use of Water Resources Humans use about 54% of reliable runoff United States Industry 11% Public 10% Power cooling 38% Agriculture Agriculture: worldwide about 70% of water is used to irrigate crops. 85% of that is not returned to the water ways. Fig. 15-4 p. 309

Use of Water Resources Industry: 20% of water withdrawn each year is used by industry. Domestic: 10% is used by cities and residencies.

Uses of Water

Water in US East vs. West Eastern US most water is used for energy production, manufacturing. Western US most water is used for irrigation.

Water in US East vs. West

Chapter 15 Sections 1-2 Review Where is the world’s usable water located? Describe several properties of water that make it unique. How much water is available for human usage? What is runoff? What is a watershed? What is groundwater? Describe the water cycle. How is most of the world’s water used? What are some water differences between the eastern and western US?

Key Concepts Chapter 15 Sections 3, 4 and 5 What causes fresh water shortages? How many people do not have access to clean water? How can we increase clean water supplies? What are advantages and disadvantages of large dams and reservoirs? Case Studies: 1) Water Conflicts in the Middle East, 2) Colorado River Basin, 3) China’s Three Gorges Dam, 4) Aral Sea, 5) California Water Transfer, 6) Canada’s James Bay Watershed.

Access to Freshwater About 1 in 6 people (1 billion people) do not have access to regular, clean water supplies.

Too Little Water What causes fresh water shortages? Acute shortage Adequate supply Shortage Metropolitan regions with population greater than 1 million Fig. 15-6 p. 310

Areas of US where there are conflicts over water Areas of US where there are conflicts over water. “Water Wars” competing for a scarce resource.

Too Little Water: 4 Reasons Dry climate: people living or growing crops in areas where little precipitation naturally falls San Diego averages just 8 inches of rain a year compared to over 35 inches in Camden. Las Vegas averages less than 5 inches of rain yearly.

Too Little Water Drought: prolonged periods of below average precipitation.

Too Little Water Desiccation: drying of exposed soil because of activities such as deforestation and overgrazing.

Too Little Water Water stress: low per capita availability of water due to increasing population demands. Some regions get plenty of water, but not near where people live Some regions get plenty of water, but not at the right time of year Some regions have no capacity to store water.

Natural Capital Degradation. Stress on the world’s river basins.

Increasing Water Supplies Build dams and reservoirs Transfer water to places it is needed Withdraw groundwater Desalinization Reduce water waste Import food from regions where irrigation is not needed.

Using Dams and Reservoirs Large dams can produce cheap electricity, reduce downstream flooding and provide a year-round source of water, but they completely alter the river ecosystem.

Using Dams and Reservoirs to Supply More Water: The Trade-offs Large losses of water through evaporation Flooded land destroys forests or cropland and displaces people Downstream flooding is reduced Downstream cropland and estuaries are deprived of nutrient-rich silt Reservoir is useful for recreation and fishing Can produce cheap electricity (hydropower) Migration and spawning of some fish are disrupted Provides water for year-round irrigation of cropland Fig. 15-9 p. 313

Transferring Water from One Place to Another Watershed transfer North Bay Aqueduct South Bay California Aqueduct CALIFORNIA NEVADA UTAH MEXICO Central Arizona Project Colorado River Los Angeles Shasta Lake Sacramento Fresno Phoenix Tucson ARIZONA Colorado River San Francisco San Diego California Water Project Central Arizona Project James Bay Fig. 15-13 p. 317

Sections 3,4 and 5 Review What causes fresh water shortages? How can we increase clean water supplies? What are advantages and disadvantages of large dams and reservoirs? Case Studies: 1) Water Conflicts in the Middle East, 2) Colorado River Basin, 3) China’s Three Gorges Dam, 4) Aral Sea, 5) California Water Transfer, 6) Canada’s James Bay Watershed.

Key Concepts Chapter 15 Sections 6 and 7 What are advantages and disadvantages of using groundwater? Deep water or shallow water aquifers, what about desalinization? “Weird” Water Solutions? What are the benefits of reducing water waste? How can we reduce wasting irrigation water? What about in homes, industry and businesses?

Tapping Groundwater: Benefits Most aquifers are renewable sources unless the water is removed faster than it is replenished

Tapping Groundwater: Benefits Year-round use: aquifers provide reliable year-round use. ¼ of world’s drinking water In US groundwater is being withdrawn 4 times its replacement rate.

Tapping Groundwater: Benefits Little Water Loss: there is no loss of water due to evaporation. Often Cheaper: groundwater is often cheap to extract.

Tapping Groundwater: Costs Using ground water has tradeoffs. Water tables around the world are falling.

Problems Using Groundwater

Problems with Using Groundwater Water table lowering Depletion Subsidence Saltwater intrusion Chemical contamination Reduced stream flows

Potential Sources of Groundwater Contamination

Problems with Using Groundwater As groundwater is pumped out of the ground, the ground may subside. This picture shows ground subsidence in CA.

Problems Using Groundwater Salt Water Intrusion: As water is pumped out of ground, saltwater can move inland to “pollute” the well.

Problems Using Groundwater

Increasing Water Supplies Distillation desalination: removing salt from seawater by evaporation of water leaving salt behind.

Increasing Water Supplies Reverse osmosis desalination: pumping saltwater under high pressure through a membrane to take out salt.

Increasing Water Supplies Desalination is very expensive: only several oil-rich and water poor countries use large-scale desalinization. TAKES TREMENDOUS AMOUNT OF ENERGY Future Potential???

Increasing Water Supplies Cloud Seeding: releasing tiny particles into air to produce rain clouds. Towing Icebergs: moving ice around world. Using Oil Tankers Filled with water.

Using Water More Efficiently Reduce losses due to leakage: we waste about 2/3rd of the water we use, but simple steps could reduce that to 15%.

Using Water More Efficiently Reform water laws: Higher water prices Typically US farmers only pay 1/5th of true water costs. Encouraging conservation Reward people for using less water

Using Water More Efficiently Improve irrigation efficiency: 60% of water applied to land does not reach crops. Evaporation Seepage Runoff

Using Water More Efficiently Improve irrigation efficiency: Center pivot sprinklers Time controlled irrigation Soil moisture detectors Drip Irrigation

Using Water More Efficiently Water efficient landscaping (xeriscaping): using vegetating that does not require much water. About 1/5th of all US water houses do not have water meters and pay a flat rate.

Using Water More Efficiently Water efficient appliances: Low Flow Toilets Washers that use less water Reusing water: Using “brownwater” for non-drinking water usages.

Chapter 15 Sections 6, 7 Review What are advantages and disadvantages of using groundwater? Deep water or shallow water aquifers, what about desalinization? “Weird” Water Solutions? What are the benefits of reducing water waste? How can we reduce wasting irrigation water? What about in homes, industry and businesses?

Chapter 15 Section 8 and 9 What causes flooding? How do humans exacerbate flooding? How can flood risks be minimized? What are solutions for sustainable water use?

Too Much Water: Floods Natural phenomena Aggravated by human activities Natural floodplain, altered floodplain and flooded. Reservoir Dam Levee Flood wall Floodplain Fig. 15-24 p. 327

Too Much Water: Floods Natural Events: heavy rainfall, melting snow are major causes of flooding. Floodplain: the natural area around a river where flooding normally occurs.

Too Much Water: Floods Floodplains are usually fertile, have ample water for irrigation and therefore often developed. Floods bring nutrients onto surrounding land.

Too Much Water: Floods Flooding Worsens With Human Impacts: Removing wetlands Building levees Making more land impermeable (development)

Downstream Impacts

Too Much Water: Floods Reducing Risks: Channelization Floodwalls Build Dams Preserve wetlands Identify and restrict building in floodplains Restore natural land

Solutions: Achieving a More Sustainable Water Future Efficient irrigation Water-saving technologies Improving water management See Fig. 15-26 p. 329