Water is Life !
Mean Annual Precipitation
Water Topics
•Water cycle
•Goundwater
•Surface water
•Groundwater/surface water
interactions
•Pollution of Streams + groundwater
•Agriculture + Open pit mining
1. Water Supply, Renewal, & Use
Fig. 12–2
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The Atmosphere - Among the
smallest water reservoirs
• Contains 0.001% of total water
supply.
• Has the most rapid turnover
rate.
• Helps cycle fresh water over
landmasses.
Rivers, Lakes, and Wetlands
Lakes have 50x more water than all rivers
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Hydrologic cycle
Figure 3.2
3-1
Use of Fresh Water
United States
•41% agriculture
•38% power plant
cooling
•11% industry
•10% public
China
•87% agriculture
•7% industry
•6% public
World
Some Requirements
•70% agriculture
•800 gallons / lb beef
(60%–80% waste)
•100,000 gallons / car
•1,000 gallons / lb Al
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WATER USE ISSUES TO EXAMINE:
•Groundwater Mining = withdrawal
greater than recharge
•Trees = Flood Prevention = slow
water movement
•Pollution = point and non-point
sources
•Special Problems: Farming, Mining
Surface Hydrology
•precipitation: rain, sleet, hail, & snow
•runoff: movement along surface
•infiltration: movement from
surface to groundwater
•evapotranspiration: evaporation
of water from leaves
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The area that a stream drains is
called its watershed, drainage
basin, or catchment area.
Text: Land area that delivers
water, sediment, and dissolved
substances via small streams to
a major stream or river.
Hydrology
watershed: region from which water
drains into a water body
Fig. 12–3
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Springs may result from
a perched water table
Groundwater Hydrology Terms
•water infiltrates to water table
•aquifer: porous, water–saturated layers of soil
or rock through which groundwater flows
•unconfined aquifers: zone of infiltration above
(unsaturated) & water table below (saturated)
•confined aquifers: bounded above & below by
less permeable rock
•groundwater moves from recharge area
through the aquifer & out to a discharge area
(well, spring, lake, geyser, stream, or ocean)
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Look at the
size of these
PORE SPACES
Factors influencing the storage
and movement of groundwater
• Porosity – percentage of total volume
of rock or sediment that consists of
pore spaces
• Determines how much groundwater
can be stored
• Variations can be considerable over
short distances
Permeability =
the connection of the pore spaces
Interactions of water with soil.
• Groundwater, after
ice, is the 2nd
largest reservoir of
fresh water
– Infiltration - Process of
water percolating
through the soil and into
fractures and permeable
rocks.
• Zone of Aeration Upper soil layers that
hold both air and water.
• Zone of Saturation Lower soil layers
where all spaces are
filled with water.
• Water Table is at the
top of the Zone of
Saturation
Formation of a cone of
depression in the water table
Aquifer Recharge zones
Recharge zones - areas where surface waters
filter into an aquifer
Wetlands –
Play a vital role in hydrologic cycle
Lush plant growth stabilizes soil and
retards surface runoff, allowing more
aquifer infiltration.
–Disturbance (including urban
development) reduces natural
water-absorbing capacity
–resulting in floods and erosion in
wet periods, and less water flow the
rest of the year.
Plants reduce Flooding
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Trees/plants slow rain runoff by:
1. Leaves absorbing rainwaters
2. Waters drip down canopy, trunks,
to roots
3. Roots absorb waters
4. Soil with organic material absorbs
water well and expands
5. Water percolates to water table
Human’s can increase flooding by:
•removing vegetation
•overgrazing
•logging
•forest fires
•mining
•destruction of wetlands
•building on floodplains
•urbanization
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Three dimensions of stream structure
Figure 3.30
3-15
• Rivers, Lakes and Streams –
• Precipitation that does not evaporate
• or infiltrate into the ground
– All eventually toward the sea!
• Best measure of water volume carried by a river is
Discharge.
–The amount of water measured as
cubic feet per second (CFS).
– http://www.americanwhitewater.org/content/River_sho
w-gauge-info_reachid_2209_
Gaining and losing streams
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River flow in moist temperate and semiarid climates
Figure 3.32
3-16
Source: Calow and Petts 1992
Water Availability and Use
• Clean, fresh water is
requisite for human
survival.
• Renewable water supplies
consist of surface runoff and
infiltration into shallow ground
water.
• Picture shows a ditch for irrigation
of crops.
• Water rights for such activities
have long been a source of tension
and conflict.
Water use
issues are
complicated
by many
countries
competing
for limited
resources
Water collecting in Africa is time consuming
Freshwater Shortages
• About 25% of the world's
people lack adequate, clean
drinking water and about
50% lack adequate
sanitation.
• Water stress is a phrase
used to describe countries
where water consumption
exceeds by >20% the
available, renewable water
supply
• Widespread water
shortages are predicted by
2025.
• once world's 4th
largest freshwater
lake;
Aral Sea
• shrinking & getting
saltier since 1960;
• most water diverted
for crops;
• pollutants (pesticides,
fertilizers, etc.)
causing severe health
problems;
• ecological problems 20 of 24 native fish
extinct.
Fig. 13–
14
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Depleting Groundwater
• Groundwater provides nearly 40% of the
fresh water for agricultural and domestic
use in the United States.
• In many areas in the U.S., groundwater is
being withdrawn from aquifers faster than
natural recharge can replace it.
US Groundwater Overdrafts
Fig. 12–
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The Ogallala Aquifer
(a huge aquifer in the US Central
Plains and most agriculture is
dependent on it) –
water usage here is the similar to
mining for a nonrenewable resource
and the water resource is being
depleted rapidly.
• largest known
aquifer;
Ogallawa Aquifer
• 90% withdrawn
for irrigation;
supplies 30% of
irrigation water;
• supports
$32 billion
agriculture;
• most areas
water
withdrawn
much faster
than recharge.
Fig. 12–
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Irrigation Methods:
•Flooding fields
•Sprinklers
•Drip Irrigation
Saltwater intrusion Groundwater Withdrawal
along coastlines where overuse of freshwater reservoirs
draws the water table low enough so saltwater intrudes.
Fig. 12–12
© Brooks/Cole Publishing Company / ITP
Nearly half of Mexico is arid or semiarid, with
scarce waters. At least 92 springs and 2500
km of river have dried in this area.
There are nearly 200 species of freshwater
fishes in this region, 120 under some threat,
15 extinct through human impact. As of 1985,
an average of 68% of species was eradicated
in local fish faunas.
Surface waters have diminished, and
intrusion of saline waters and salinization of
agricultural wells in Sonora, arsenic to
agricultural waters, and threatening
metropolitan Torreon.
Finally, salinization of the lower Rio Bravo del
Norte has replaced 32 native fish of fresh of
slightly brackish water with 54 mainly marine
or highly salt-tolerant species, the salinization
threatens all uses of water. Some marine
fishes invade up to 400 km upstream.
Dried-up Colorado takes toll on giant Mexican fish
June 8, 2008
The Colorado River vanishes before it reaches the Sea
of Cortez in all but the wettest years. Companies in
California and the southwestern U.S. have diverted its
once-vibrant flow to quench their thirst for water and
power.
The damming of the Colorado
River has choked the natural
flow of sediment and nutrients,
causing erosion. Similarly, a
protective estuary in the Gulf of
California no longer exists,
leaving few places for young
totoaba to find food and hide
from predators.
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Tidal level and mangrove distributions
Figure 3.25
3-12
Mangrove wildlife
Mangrove forests are comprised of unique plant species
that form the critical interface between terrestrial,
estuarine, and near-shore ecosystems in the tropics.
Mangrove species are uniquely adapted to tropical and
coasts, and mangrove forests provide at least US $1.6
billion each year in ecosystem services.
Ban on logging necessary “The move for a temporary
as only 30% of forest left ban on logging in Selangor
in Selangor
was made to safeguard the
remaining green lung in
Selangor, state Agriculture,
Natural Resources and
Entrepreneurial Development
committee chairman Yaakob
Sapari said.”
Globally, mangrove areas are declining rapidly as they
are cleared for coastal development and aquaculture
and logged for timber and fuel production.
Along the coasts of Central America, about 40% of
mangroves species present are threatened with
extinction.
Part 5: Water Management and
Conservation
• Watershed management
• Sound farming and
forestry practices
• Wetlands conservation
• Domestic conservation
• Water reclamation and
recycling
• Water rights
Ways to Increase Water Supplies
• Conservation – should it be on the list?
• Building Dams, Canals and Reservoirs
• Seeding Clouds
– Condensation Nuclei
• Towing Icebergs
– Cost
• Desalination
– Most common methods are distillation and reverse
osmosis.
• Three to four times more expensive than most other sources.
Water Conservation
•irrigation efficiency
drip irrigation, central–pivot,
computer monitoring
•recycling
use of “gray” water
•repair leaky pipes
•water conservation
efficient toilets & shower heads
•xeriscaping
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California Water Project
Fig. 12–7
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California Water Project - The Problem
•most rainfall in northern California
•most population growth & agriculture in
southern California
The Solution
•water transferred via dams, pumps, &
aqueducts
The Controversy
•southern California wants more water for
growth
•much of water wasted by inefficient irrigation
•north needs water for fisheries & flushing
pollutants out of San Francisco Bay
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Hetch Hetchy Valley,
1913, before dam was
built. Looking back
towards
yosemite.ca.us
Dams are controversial in terms of environmental
costs, justice, price mechanisms and water policy,
sedimentation, evaporative losses, etc.
Domestic Conservation
• Estimates suggest we
could save half of
current domestic
water usage without
great sacrifice or
serious change in
lifestyle.
Largest domestic use
is toilet flushing.
• Significant
amounts of water
can be reclaimed
and recycled
(purified sewage
effluent)