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Living in the Environment
Water Resources G. Tyler Miller’s Living in the Environment 14th Edition Chapter 15
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Key Concepts The physical properties of water
Availability of fresh water Methods of increasing freshwater supplies Using water more efficiently Problems associated with flooding
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Water’s Unique Properties
Hydrogen bonding Liquid over wide temperature range Changes temperature slowly High heat of evaporation Great dissolving power Filters out ultraviolet radiation Adhesion and cohesion Expands when it freezes
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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 p. 307
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Surface Water Surface runoff Watersheds Reliable runoff
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Evaporation and transpiration
Ground Water Fig p. 308 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
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Use of Water Resources Humans use about 54% of reliable runoff
United States Industry 11% Public 10% Power cooling 38% Agriculture Agriculture Industry Domestic Power plants Fig p. 309
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Too Little Water Dry climate Drought Desiccation Water stress
Acute shortage Adequate supply Shortage Metropolitan regions with population greater than 1 million Water stress Fig p. 310
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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 p. 313
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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 p. 317
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Tapping Groundwater Year-round use No evaporation losses
Often less expensive Potential Problems! Refer to Fig p. 319
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Problems with Using Groundwater
Water table lowering (See Fig p. 319) Depletion (See Fig p. 320) Subsidence (See Fig p. 320) Saltwater intrusion (See Fig p. 320) Chemical contamination Reduced stream flows
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Converting Salt Water to Fresh Water and Making it Rain
Distillation desalination Reverse osmosis desalination Desalination is very expensive Cloud seeding
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Using Water More Efficiently
Reduce losses due to leakage Reform water laws Improve irrigation efficiency (Fig p. 324) Improving manufacturing processes Water efficient landscaping (xeriscaping) Water efficient appliances
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Too Much Water: Floods Natural phenomena
Aggravated by human activities Reservoir Dam Levee Flood wall Floodplain Fig p. 327
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Solutions: Achieving a More Sustainable Water Future
Efficient irrigation Water-saving technologies Improving water management See Fig p. 329
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