Chapter 20: Water Supply, Use and Management

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Chapter 20 Water Supply, Use and Management
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Properties of Water

• To understand water, we must understand its
  characteristics, and roles
• Water has a high capacity to absorb and store
  heat.
• Water is the universal solvent.
• Water has a high surface tension.
• Water is the only compound whose solid form is
  lighter than its liquid form.
• Sunlight penetrates water to variable depths,
  permitting photosynthetic organisms to live below
  the surface.
• Water is basis of earths weather

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A Brief Global Perspective

• We are facing a growing global water shortage
  linked to the food supply.
• Global hydrologic cycle
• Transfers water from the atmosphere, to land, to
  oceans and back to atmosphere
• 97 in oceans
• 3 fresh water
• Most fresh water frozen (70)

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The Hydrologic Cycle
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At Earths surface water can be found in liquid,
solid or gaseous form. Residence time varies from
a few days to thousands of years
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A Brief Global Perspective

• Amount of water for which all people compete is
  small
• Industrial production increases water use
• Irrigation increases water use

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Groundwater and Streams

• Groundwater refers to the water below the water
  table where saturated conditions exist
• Recharge zones - locations where surface waters
  move into the ground
• Discharge zones - places where water flows or
  seeps out are (example streams and rivers)
• Vadose zone - unsaturated zone above water table)

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Groundwater and Streams

• Aquifer - underground zone from which groundwater
  can be obtained
• When water is pumped from an aquifer forms a cone
  of depression

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Streams

• Effluent stream (gaining stream)
• Perennial stream
• Influent stream (losing stream)
• Ephemeral stream

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Interactions Between Surface Water and Groundwater

• Should be considered part of the same resource.
• Nearly all surface water environments are
  connected w/ ground water
• E.g. withdrawal of groundwater can lower stream
  flow or lake levels
• Pollution can spread from one source to the other

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Your water quality depends on what is upstream
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Water Supply US

• Water budget
• A model that balances the inputs, outputs, and
  storage of water in a system.
• Precipitation - evaporation runoff

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What happens to water across the US?
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Managing WaterPrecipitation and Runoff Patterns

• Developing water budgets for water resources
  management you must consider
• - Annual precipitation and runoff patterns.
• Potential problems can be predicted in areas
  where average runoff is high and precipitation
  is low.
• Total storage of runoff not possible because of
  evaporative losses.

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Droughts

• Unique to location and unpredictable
• Because there are large annual and regional
  variations in stream flow, even areas with high
  precipitation and runoff may suffer from droughts.

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Groundwater Use and Problems

• 30 of all precipitation enters surface or
  groundwater
• 50 of people in the US use groundwater as a
  primary source of drinking water
• In many parts of the country withdrawal from
  wells exceeds natural inflow
• Why?
• Overdraft
• Nonrenewable resource
• Problems include damage to river basins and land
  subsidence

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Land subsidence
Salt water intrusion
Overdrafting of ground water in Arizona
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Colorado River Basin the politics of water
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Desalination as a Water Source

• Seawater is 3.5 salt
• Desalination- a technology to remove salt from
  water
• Must be reduces to 0.05 to be fresh water
• Requires large amount of energy, tied to fuel
  prices
• Has place value- price increases quickly with
  transport distance
• Discharge may affect local salinity

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Water Use

• Off-stream use
• Refers to water removed from its source for use
• May be returned to source after use
• Or consumptive use- water enters tissues, product
  or evaporates during use and not returned

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Water Use

• In-stream use
• The use of the river for navigation,
  hydroelectric power, fish and wildlife habitats,
  and recreation.
• Multiple uses can create controversy

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Water Use

• Another problem with off stream use is how much
  water can be removed w/o damaging the stream
  ecosystem.
• E.g. Aral Sea. Diverting water for agriculture
  caused sea to dry up
• Surface area of sea reduces 90 in 50 years

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Aral Sea

• Salt content of the water has increased
• Dust storms from dry salt flats
• Climate changes
• Winters colder, summers warmer
• Loss of fishing and decline of tourism

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Transport of Water

• Ancient civilizations constructed canals and
  aqueducts to transport water
• From distant river to where it is needed
• In modern civilization water moved from areas of
  abundant rain and snow fall to areas of high
  usage
• E.g. California moves water from north to south
• E.g. New York City has had to obtain water from
  farther and farther away

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Some Trends in Water Use

• Withdrawal of surface water far exceeds
  withdrawal of groundwater
• Since 1980 use has decreases and leveled off
• Suggests improvement in water management and
  conservation

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Some Trends in Water Use

• Trends in freshwater withdrawals by water-use
  categories suggests that
• 1. The major uses of water are for irrigation and
  the thermoelectric industry.
• 2. Water use for irrigation increased from
  1950-1980. It decreased and leveled off from
  1985-2000
• due to better irrigation efficiency, crop type
  and higher energy costs.

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Some Trends in Water Use

• 3. Water use by thermoelectric industry decreased
  slightly in 1980, and stabilized in 1985.
• Due to reticulating water for cooling
• 4. Water for public and rural supplies continued
  to increase through the period from 1950 to 2000
• presumably related to the increase in human
  population.

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Water Conservation

• The careful use and protection of water resources
• Involves the quantity of water used and the
  quality
• Important component of sustainable water use
• Expected that a number innovations will reduce
  the total withdrawals

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Agricultural Use

• Improved irrigation could reduce agricultural
  withdrawals by 20 to 30
• Tremendous savings because ag is the biggest user

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Agricultural Use

• Suggestions for conservation
• Price agricultural water to encourage
  conservation
• Use lined or covered canals that reduce seepage
  and evaporation.
• Use computer monitoring and schedule release of
  water for maximum efficiency.
• Integrate the use of surface water and
  groundwater to more effectively use the total
  resource.

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Agricultural Use

• Irrigate at times when evaporation is minimal,
  such as at night or in the early morning.
• Use improved irrigation systems, such as
  sprinklers or drip irrigation, that more
  effectively apply water to crops.
• Improve the soil to increase infiltration and
  minimize runoff.
• Encourage the development of crops that require
  less water or are more salt tolerant.

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Domestic Use

• Accounts for about 10 of total national water
  withdrawals
• But concentrated in urban areas
• May pose major local problems

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Domestic Use

• Water use can be substantially reduced by
• In semiarid regions, replace lawns with
  decorative gravels and native plants.
• Use more efficient bathroom fixtures.
• Turn off water when not absolutely needed.
• Flush the toilet only when really necessary.
• Fix all leaks quickly.

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Domestic Use

• Purchase dishwashers and washing machines that
  minimize water consumption.
• Take a long bath rather than a long shower.
• Sweep sidewalks and driveways.
• Using gray water to water vegetation.
• Water lawns and plants at cool times to reduce
  evaporation.

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Domestic Use

• Use drip irrigation and place water-holding mulch
  around garden plants.
• Plant drought-resistant vegetation.
• Learn how to read the water meter to monitor for
  unobserved leaks and record your conservation
  successes.
• Use reclaimed water

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Industry and Manufacturing Use

• Water conservation measures that can be taken by
  industry
• Using cooling towers that use little or no water
• In-plant water treatment and recycling

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Perception and Water Use

• Perception of water is based partly on its price
  and availability.
• If water is abundant and inexpensive, we dont
  think much about it.
• If water is scarce or expensive, it is another
  matter.
• E.g. people in Tucson pay about 100 more for
  water than people in Phoenix.
• Tucson residence use less water per person per day

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Sustainability and Water Management

• From a water supply use and management
  perspective, sustainable water use defined as
• use of water resources by people in a way that
  allows society to develop and flourish into an
  indefinite future
• W/o degrading the various components of the
  hydrologic cycle or the ecological systems that
  depend on it.

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Sustainable Water Use

• General criteria
• Develop water resources in sufficient volume to
  maintain human health and well-being.
• Provide sufficient water resources to guarantee
  the health and maintenance of ecosystems.
• Ensure minimum standards of water quality for the
  various users of water resources.

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Sustainable Water Use

• Ensure that actions of humans do not damage or
  reduce long-term renewability of water resources.
• Promote the use of water-efficient technology and
  practice.
• Gradually eliminate water pricing policies that
  subsidize the inefficient use of water.

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Groundwater Sustainability

• Sustainability involves a long term perspective
• For groundwater even longer
• Effects of pumping might not be seen immediately
• Long-term approach involves balancing withdrawal
  with recharge

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Water Management

• Management of water resources is a complex issue
  that will become more difficult as demand for
  water increases in the coming years.
• Especially in areas like the Southwestern US and
  other semi arid regions

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Water Management

• Options for minimizing potential problems
• Alternating water supplies and managing existing
  supplies better
• Towing icebergs
• As price goes up many innovative programs are
  possible.

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Variable-water-source approach
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A Master Plan for Water Management

• New management philosophy is that surface water
  and groundwater are both subject to natural flux
  with time.
• In wet years, there is plenty of surface water,
  and the near-surface groundwater resources are
  replenished.
• During dry years, specific plans to supply water
  on an emergency basis must be in place and ready
  to use.

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A Master Plan for Water Management

• Advanced planning may include
• Drilling to wells that are presently isolated
• Reuse of waste water
• Develop surface water and use groundwater in dry
  years
• In wet years pump excess surface water
  underground to recharge groundwater

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Water Management and the Environment

• Often a good deal of controversy surrounds water
  development
• Dams, canals, wetlands modification
• Resolution of development involves input from a
  variety of government and public groups

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Wetlands

• Wetlands is a comprehensive term for landforms
  such as salt marshes, swamps, bogs, prairie
  potholes, and vernal pools.
• Common feature is that they are wet at least part
  of the year
• Have a particular type of vegetation and soil

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Wetlands

• Wetlands - defined as areas that are inundated by
  water or where the land is saturated to a depth
  of a few cm for at least a few days per year.
• Three major components used to determine the
  presence of wetlands are
• Hydrology
• Type of vegetation
• Type of soil.

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Natural Service Functions of Wetlands

• Freshwater wetlands are a natural sponge for
  water.
• Reducing flooding.
• Many freshwater wetlands are important as areas
  of groundwater recharge or discharge.
• Wetlands are one of the primary nursery grounds
  for fish, shellfish, aquatic birds, and other
  animals.
• Wetlands are natural filters that help purify
  water.

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Natural Service Functions of Wetlands

• Wetlands are often highly productive and are
  places where many nutrients and chemicals are
  naturally cycled.
• Coastal wetlands provide a buffer for inland
  areas from storms and high waves.
• Wetlands are an important storage site for
  organic carbon.
• Wetlands are aesthetically pleasing to people.

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Wetlands

• Freshwater wetlands are threatened in many areas.
• Over the past 200 years gt 50 of all wetlands
  have disappeared, 90 of freshwater wetlands
• Diked, drained or filled
• SF bay estuary considered the most modified by
  human activity

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Wetlands

• Mississippi River delta includes major coastal
  wetlands
• Historically maintained by flooding
• Accretion processes counter natural subsidence
• If accretion decreases area of open water
  increases and wetland in reduced
• Levees block sediments and costal wetlands are
  being lost

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Restoration of Wetlands

• Number of projects have attempted to restore
  wetlands.
• In freshwater marshes recovery linked to
  availability of water
• Salt marshes more complex
• EPA of 1969 states if wetlands destroyed by
  development must be replaced elsewhere

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Restoration of Wetlands

• Constructing wetlands to clean up ag waste
• Natural ability to remove excess nutrients, break
  down pollutants, and cleanse water.
• In Florida, human-made wetlands designed to
  intercept and hold nutrients so they dont damage
  the Everglades.

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Dams and the Environment

• Dams and their accompanying reservoirs generally
  are designed to be multifunctional structures.
• Used for recreational activities
• Generating electricity
• Providing flood control
• Ensuring a more stable water supply
• Often difficult to reconcile various uses at a
  given site.

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Dams and the Environment

• The environmental effects of dams include the
  following
• Loss of land, cultural resources, and biological
  resources in the reservoir area.
• Larger, dams and reservoirs produce a potential
  serious flood hazard should they fail
• Storage behind the dam of sediment that would
  otherwise move downstream to coastal areas.

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Dams and the Environment

• Downstream changes in hydrology and in sediment
  transport that change the entire river
  environment and the organisms that live there.
• Fragmentation of ecosystems above and below a
  dam.
• Restrict movement upstream and downstream or
  organic material, nutrients and aquatic
  organisms.

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Dams and the Environment

• Many people vehemently against building new dams.
• But if present water use practices continue we
  will need new dams.
• Few acceptable sites for dams
• Expensive to build and operate, many people dont
  want tax dollars spent on subsidized water.

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Canals

• Water from upstream reservoirs may be routed
  downstream by way of natural water ways or canals
  and aqueducts.
• Not hydrologically the same as creeks
• Smooth, steep banks water moves fast
• Canals can spread and carry disease
• schistosomiasis

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Removal of Dams

• Recent dam removals include
• Edwards Dam in Maine
• Marmot Dam in Oregon
• After removal both river saw return of fish as
  they migrated upstream
• Large fish runs transport nutrients upriver from
  ocean to forest ecosystems.

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Removal of Dams

• Trapped sediment behind dams must be dealt with
  in dam removal.
• If released quickly it could damage downstream
  ecosystem and fill pools.
• Slower release minimizes damage.
• Matilija Dam in Ventura County cost 300,000 to
  build but 10 times that to remove.
• Removing dams is simple in concept but involves
  complex problems relating to sediment and water.

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Channelization and the Environment

• Channelization of streams consists of
  straightening, deepening, widening, clearing, or
  lining existing stream channels.
• Engineering technique that has been used to
  control floods, improve drainage, control
  erosion, and improve navigation

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Channelization and the Environment

• Adverse environmental effects, including the
  following
• Degradation of the streams hydrologic qualities
• nearly all riffle flow, resulting in loss of
  important fish habitats.
• Removal of vegetation along the watercourse,
  which removes wildlife habitats and shading of
  the water.
• Downstream flooding where the channelized flow
  ends.
• Damage or loss of wetlands.
• Aesthetic degradation.

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Channelization and the Environment

• Case study in problems w/ Channelization
• Kissimme River in Florida
• Meandering river turned into straight ditch
• Failed to provide flood protection, damaged
  wildlife habitat, water quality problems and
  aesthetic degradation.
• In 1990 efforts to restore river began.

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The Colorado River Water Resources Management
and the Environment

• The history of the Colorado River emphasizes
  linkages among physical, biological, and social
  systems that are at the heart of environmental
  science.
• Major river of the southwestern US
• Ends in the Gulf of California

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The Colorado River

• For its size has a modest flow but is one of the
  most regulated and controversial bodies of water
  in the world.
• Total flow was apportioned among various users in
  1922
• No water allowed for environmental purposes
• Water rarely flows into the Gulf, all stored and
  used upstream.
• Damaged delta

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The Colorado River

• Two largest reservoirs- Hoover Dam and Glen
  Canyon Dam
• Stored about 80 of total in the basin
• Represents a buffer of several years water
  supply.
• Changing hydrology of the river changed other
  aspects
• Rapids, sediment load, and vegetation

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The Colorado River

• Record snowmelt in the Rocky Mountains in 1983
  forced the release of water from Glen Canyon Dam
• Three times normal but similar to spring floods
  before the dam was built.
• Beneficial to the river, highlighted the
  importance of floods in maintaining a natural
  state.

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The Colorado River

• As an experiment flood waters released in 1996
• Two weeks at full flood
• As a result 55 new sandbars formed and 75 of
  existing sandbars increased in size, rejuvenated
  marshes and backwaters.
• Hailed a success hoped that what was learned can
  help restore other river impacted by dams.

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Global Water Shortage Linked to Food Supply

• Both surface water and groundwater are being
  stressed and depleted
• Groundwater in the United States, China, India,
  Pakistan, Mexico, and many other countries is
  being mined
• used faster than it is being renewed
• Large bodies of waterfor example, the Aral
  Seaare drying up.
• Large rivers, including the Colorado in the US
  and the Yellow in China, do not deliver any water
  to the ocean in some seasons or years.

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Global Water Shortage Linked to Food Supply

• As human population grows there is growing
  concern that there wont be sufficient water to
  grow the food to feed 8-9 billion people.
• Food shortage linked to water resources a real
  possibility.
• Water also linked to energy (fuel to pump) as
  energy cost goes up so does cost of food.

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Global Water Shortage Linked to Food Supply

• Solution
• Control human population growth
• Conserve and sustain water resources
• Need to be proactive now before significant food
  shortages develop.