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TRANSCRIPT
UAU102F Fall
Introduction to Environmental Sciences and Natural Resources
Throstur Thorsteinsson [email protected]
WATER!
• Water is the most distributed
substance on earth
• Is available everywhere
• Life impossible without it
– there are no substitutes
NILE
RIVER
Nile river running
through Egypt.
Note the green area
around the river, desert
all around.
PRECIPITATION – ONE WEEK
• Precipitation 1 – 7 February 2010
DISTRIBUTION OF WATER ON EARTH
WATER USE – SOME NUMBERS
• A person needs about 3 liters per day
• Single flush of a toiled may use 23 liters
• Typical daily use for a person is about 200 – 300 l/d
• Industry over 5000 l/d
• The Hidden Water We Use
– http://environment.nationalgeographic.com/environment/fresh
water/embedded-water/
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ACCESS TO WATER AND SANITATION
See also http://www.emag.suez-environnement.com/en/wp-content/uploads/2013/03/SUEZ-ENV-
Eau_Assaini-ENG-Web1.pdf (infographic March 2013)
OUTHOUSE, BANGLADESH
Photograph by Karen Kasmauski
Forty percent (40%) of
the world’s population
has no way to properly
dispose of their own
waste.
Pathogenic bacteria from
untreated human and
animal waste often
contaminates water used
for drinking and food
preparation and spawns
illnesses like typhoid,
which impacts some 17
million people each year.
WATER FOR IRRIGATION
Used
45%
Application
25%
Transmission
15%
Distribution
15%
55% lost during irrigation !
Fairly old number, but a lot is lost
PIPING
The residents of this Shanxi Province hillside in
China enjoy fresh water in their homes, thanks to a
communal well and a plastic piping system that
delivers water to their doors.
Plastic Piping System, China
Photograph by Greg Girard
WATER
• The key to averting a
global food crisis may
simply be a matter of
storing more water
• Drip Irrigation to Solve
Famine in the Sahel? – http://newswatch.nationalgeographic.com/2
010/09/01/drip_irrigation_to_solve_famin/
Amhara region of Ethiopia. Photograph courtesy Organization for Rehabilitation and Development of Amhara
WATER
Gathering Drinking Water, Bangladesh Photograph by Karen Kasmauski
Some 5,000 children
die each day of
diarrheal disease
alone—an average of
one child every 20
seconds.
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PUBLIC / PRIVATE WATER
In many parts of
the developing
world, the poorest
must pay high
prices to buy water,
which is held in the
hands of corrupt
governments and
private “water
mafias.
FRESHWATER STRESS
WATER USE - EUROPE
Total water abstraction (surface
and groundwater) by economic
sectors in European countries
WATER RESOURCES IN EUROPE
The amount of
natural water
resources
available per
inhabitant in
Europe, in cubic
meter per year
SOIL MOISTURE, GROUND WATER
Soil
mois
ture
WATER FOR PLANTS
• Soil water is the water that is immediately available
to plants.
• Can be further sub-divided into three categories
1. hygroscopic water,
2. capillary water,
3. gravitational water.
HYGROSCOPIC WATER
• Found as a microscopic film of water surrounding soil particles.
• Tightly bound to a soil particle by molecular forces so powerful that it cannot be removed by natural forces.
• Hygroscopic water is bound to soil particles by adhesive forces that exceed 31 bars and may be as great as 10,000 bars (Recall that sea level pressure is equal to about 1 bar!)
CAPILLARY WATER
• Held by cohesive forces
between the films of
hygroscopic water.
• The binding pressure for
capillary water is much less
than hygroscopic water.
• This water can be removed by
air drying or by plant
absorption, but not by gravity.
• Plants extract this water
through their roots until the
soil capillary force is equal to
the extractive force of the plant
root (wilting point)
GRAVITY WATER
• Water moved through the soil by the force of gravity.
• The amount of water held in the soil after excess water has drained is called the field capacity of the soil.
• The amount of water in the soil is controlled by the soil texture
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SURFACE TENSION
• Molecules in the interior experience an
attractive force from neighboring
molecules which surround on all sides
Water strider
Capillary fringe can saturate the
soil above the water table, but the
fluid pressure will be negative
w.r.t. local atmospheric pressure,
indicating that the capillary fringe
is part of the vadose zone.
At the wilting point the moisture
is too tightly bound to the soil
particles for plant roots to
withdraw it.
WATER PROPERTIES
• High heat capacity
– High capacity to absorb and hold heat
• Universal solvent – naturally acidic
– Minerals, salts
• High surface tension
– droplets
• Lighter as a solid - than as liquid
– Without this, water would freeze bottom up!
THE HYDROLOGICAL CYCLE • Evaporation - transpiration - evapotranspiration
– Transfer to the atmosphere
• Condensation – Vapor to liquid
• Advection - movement in the atmosphere
• Precipitation - rain, snow, hail, sleet….
• Runoff – Variety of ways water moves across the land
AQUIFER
• Is a body of groundwater that can be withdrawn mechanically or under pressure.
• Soil and rock saturated with water – Unconfined
• Upper boundary is the water table
• No confining layer between it and the surface
• Water directly from the surface
– Confined • Water table above their upper boundary
• Confined by an impermeable layer
AQUIFERS
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WATER WITHDRAWAL
• Common to withdraw groundwater but too fast or
extensive withdrawal (mining) can lead to:
– Cone of depression
– Wells can go “dry”
– Lower water table
• Serious consequences for vegetation
– Increased concentration of chemicals in water
– Saltwater intrusion
– Subsidence
• Saltwater flowing inland into aquifers
• Sea water has higher density than freshwater - and
thus the pressure under saltwater is higher than with
freshwater
• The withdrawal of freshwater and this pressure
difference triggers a flow from the saltwater column to
the freshwater column
SUBSIDENCE
• Drained soil compacts
• Water table falls, peat exposed to oxygen
• Decomposes
• Subsidence
• Water supply services
• Supply of goods other than water
• Nonextracted or Instream benefits
– Pollution dilution
– Transportation
– Recreation
– Provision of habitat
– Option, bequest and existence values
HU
MA
N A
PP
RO
PR
IAT
ION
OF
TH
E
PR
OD
UC
TS
OF
FR
ES
HW
AT
ER
Postel et al 1997
• Is drying up due to diversion for irrigation
• Over 50% gone in terms of volume
• Dumping ground for waste
• Trying to restore
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FRESHWATER AVAILABILITY FRESHWATER WITHDRAWAL
WATER SCARCITY IN EUROPE W
AT
ER
US
E
WATER USE PER CAPITA
• Of OECD countries
USA consumes
most
– 2x more than
average French
– 3x more than
average German
– 8x more than
average Dane
Territory size shows the proportion of worldwide
water use occurring there.
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INCREASING WATER SCARCITY
DUE TO
• Demand
– too fast withdrawal, extensive diversions
• Pollution
• Land degradation/deforestation
• Climate change?
SCARCITY IMPLICATIONS
• Food production?
• Growing of energy crops?
• Impact on human health?
• Increased levels of water pollution?
• Social unrest - the next conflict over water?
WATER MANAGEMENT
• Fresh water is in limited quantity
– Holistic management
– Integrated approach
– Conservation
• Foreign concept in Iceland
– Increased efficiency
– Increased awareness in developed countries
– Increase supply
AGRICULTURE
• Improve irrigation
efficiency
– Proper pricing
– Schedule irrigation
properly
– Proper irrigation
systems
– Capture runoff
– Improve land
preparation –
increase infiltration
INCREASE SUPPLY:
DESALINATION AS A WATER SOURCE
• Desalination: a technology to remove salt from water
– Traditional - simple distillation
– Modern - use of membranes
• Saudi Arabia accounts for 24% of total capacity
• Expensive
SUSTAINABLE WATER USE
• The use of water resources by people in a way that allows society to develop and flourish into an indefinite future without degrading the various components of the hydrologic cycle or the ecological systems that depend on it
Sustainable water use criteria
• Develop resources in sufficient volume to maintain
human health and well-being
• Provide water resources to ecosystems
• Ensure minimum standards for water quality
• Ensure long-term renewability
• Promote use of efficient technology
• Ensure proper pricing
ETHIOPIA
African
women walk
an average of
6 km to reach
the nearest
well
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DAMS AND THE ENVIRONMENT
• Loss of land, habitat, cultural resources and biological
resources.
• Storage behind the dam of sediment and nutrition
that would otherwise move downstream
• Fragmentation of ecosystems below and above a dam
(e.g. salmon migration)
• Relocation of people
SEDIMENT
• Rock and mineral
fragments
• Most common
pollutant
• Chokes streams, fills lakes, reservoirs, ponds, ...
• From
– Erosion – depleted soils
– Land conversion e.g. deforestation
http://youtu.be/J9cudp1eCdc
Condit dam is breached, letting the White Salmon River run free
ICELANDIC WATER
RESOURCES
• Abundant
• Different chemical
composition
– pH much higher than
elsewhere
– In drinking water
pollutants in most
cases minimal.
WATER POLLUTION
Remember: Extremely important as it has e.g.
direct impact on human health
HOW DO WE MEASURE WATER
QUALITY?
1. Bacterial counts – e coli – fecal coliform bacteria – Predetermined safe levels (200 cells per 100 ml of
water)
2. Measuring DO or BOD (Biological Oxygen Demand)
– Level of dissolved oxygen, or demand of biological oxygen by microorganisms as they break down organic matter
3. Chemcial analysis – Presence of toxic metals, sediment content etc.
4. Presence of Indicator species
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ACID MINE DRAINAGE
• Water with a high concentration of sulfuric acid that
drains from mines
• Due to normal chemical weathering
• Serious water pollution problem
• Damages aquatic
ecosystems, pollutes
bodies of water and
degrades water
quality
Acid mine drainage from a copper-nickel mine.