Water: Process, Supply, and Use

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Water Process, Supply, and Use

• There is plenty of fresh water
• Atmosphere 0.001
• Rivers and streams 0.0001
• Lakes 0.009
• Groundwater 0.31

...but rarely where we want it in the right form
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Water Process, Supply, and Use

• Global per capita water use is 2 m3/day
• US is 5 m3/day
• By 2000 will use 6000 km3/yr 5 of total in
  lakes and rivers (including a huge amount in
  uninhabited areas, so locally much higher )
• Of course this is renewable, but also pollutable
• US Water Resources Council est. by 2020 American
  water use may exceed surface resources by 13
• Most of Americans use water that has been used at
  least once before

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Water Process, Supply, and Use
Surface water covered in largely in rivers section

• Surface water supply is controlled largely by
  precipitation

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Water Process, Supply, and Use
How can we make up the difference?
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Water Process, Supply, and Use
Groundwater
Water table top surface of saturated
zone Capillary fringe water drawn up by
capillary action Groundwater usually flows due to
slope of water table
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Water Process, Supply, and Use

• Aquifer high porosity and permeability ( water)

• Clastic sediments
• Fractured igneous or metamorphic
• Basalts and upper brecciated zone, joints,
  soil/interbeds
• Dissolved limestone
• Impermeable layers are called aquitards (or
  aquicludes) clay, igneous

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Water Process, Supply, and Use
Confined vs. unconfined aquifers
potentiometric surface
Artesian wells under pressure beneath an
aquiclude- water rises up the well pipe Flowing
artesian wells actually rise above the ground
surface Water table wells are the common type
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Water Process, Supply, and Use
The same principal works in terms of municipal
water supply
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Water Process, Supply, and Use
Springs occur when the contact between an upper
aquifer and a lower aquitard intersects the
ground surface
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Water Process, Supply, and Use
Where to drill and how deep are difficult
questions and require good subsurface data Cost
of drilling a well averages 15/foot 10 ft. may
be fine in a floodplain Generally deeper on
slopes of hills A 1000 well costs 15,000
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Water Process, Supply, and Use
Pumping usually faster than recharge due to
limited permeability of the aquifer Cone of
depression Effect on neighbors Some recovery when
cease pumping Compaction when lose water support
can cause permanent decrease in porosity and
permeability
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Water Process, Supply, and Use
Perched aquifer held above the normal water
table by an aquiclude
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Water Process, Supply, and Use
Groundwater flows into an effluent stream in wet
climates This is a result of discharge from the
aquifer Groundwater flows out from an influent
stream in dry climates This results in recharge
to the aquifer Recharge areas are often far from
the discharge zone or point
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Water Process, Supply, and Use
Water Supply

• Water supply depends on climate, geology, stream
  flow, subsurface flow...
• Budget annual runoff groundwater
• Cannot contain and use all runoff
• Cannot extract and distribute all of groundwater
• Much groundwater is available where surface water
  is also

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Water Process, Supply, and Use
Water Supply

• In much of the American West there is often
  little surface or groundwater
• In places where there is groundwater and little
  surface water, there is a tendency to overdraw,
  or mine the aquifers (non-renewable)

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Groundwater overdraft for conterminous US in
1975 (Florida in East due to saltwater
encroachment)
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The Ogallala (or High Plains) Aquifer gt 170,000
mi2 and holds gt 7 x 1016 gallons of
water Charged in glacial times (over 12,000 yrs
ago) Current recharge from rainfall (lt
16-20/yr) Main source of water in several arid
states The availability of water from the
Ogallala led to considerable agricultural
development
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What do we do when the Ogallala aquifer runs dry?
One study said that by 2015 the Ogallala will be
so reduced and pumping will be so expensive due
lowering of the water table that crop yields will
be down by 80 and 300,000 people will have to
migrate away
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Water Process, Supply, and Use
Movement of water to people
1. Withdrawal quantity diverted or taken from
surface or groundwater (A) 2. Delivery to point
of use (B) 3. Release to pt. of return (C) 4.
Conveyance loss lost in transit (A B) 5.
Consumptive use portion evaporated, leaked,
transpired, or absorbed by crops, etc. 6. Return
flow amount returned to surface or groundwater
and available for future use
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Water Process, Supply, and Use
Movement of water to people

• California
• Source of water is runoff in north
• S. California indigenous water could support
  250,000 people
• Many cities experiencing shortages, groundwater
  pollution, salinization (from agriculture and
  encroaching seawater), etc.

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Part of Southern Californias answer to its water
problem is an alternative to groundwater
withdrawal aqueducts and canals
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Water Process, Supply, and Use
Water Quality

• Dissolved material in ppm (or ppb)
• TDS total dissolved solids (should be lt
  300-1000 ppm)
• Hard water gt 80-100 CaCO3 MgCO3
• Causes scale in boilers and hot-water pipes
• Prevents soap from lathering rinsing
• Water softeners exchange Na for Ca and Mg

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Water Process, Supply, and Use

• Water conservation is fairly effective since mid
  1970s
• Drip irrigation
• Industrial conservation

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Water Process, Supply, and Use
Movement of water to people

• Water management
• Geologic and climatic factors as well as
  political and economic
• Flood prevention in times of high flow and
  conservation/distribution when low
• Conserve groundwater when surface water is
  available dont mine it
• Desalination may provide fresh water

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Water Process, Supply, and Use
The Colorado a managed river
Mostly rural water is collected and distributed
by dams, reservoirs, aqueducts, canals, and pipes
to agriculture and millions of urban residents
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Water Process, Supply, and Use
The Colorado a managed river

• Flow only 3 of the Mississippi, but lifeline of
  most of the Southwest
• Elaborate system of distribution, allocation,
  rights, legal squabbles, etc. between 7 states
  Mexico
• Glen Canyon dam was built at the political
  boundary between the Upper and Lower Colorado
  districts
• Divided water rights between U L basins
• Highly variable annual flows
• Evaporation and infiltration from reservoirs
• Salinity and pollution

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Water Process, Supply, and Use
The Colorado a managed river

• Allocations made following an unusually wet
  decade
• over-allocation when flows returned to normal
  levels
• Central Arizona Project just finished (S.
  California has used 0.6 Maf of Arizonas
  allocation)

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Dams and Reservoirs

• Dams are multifunctional, but generally designed
  for
• Flood control
• Hydroelectric
• Ancillary uses
• Recreation
• Irrigation and municipal water supply
• Navigation
• Negative effects
• Flood large areas affect human/animal habitat
• Interrupt fish migration
• Interrupt sediment flow

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Water Process, Supply, and Use
Water and Ecosystems

• Natural ecosystems reflect a balance between
  climate, nutrients, soils, biota, hydrology...
• Humans are now degrading most ecosystems on a
  regional and global basis
• The most damaging effects are associated with
  degraded surface water conditions
• The effects can be far-reaching even to the
  oceans (Aswan) and atmosphere (Amazon)