News
• http://blogs.discovermagazine.com/80beats/2009/01/28/du
mping-iron-into-the-ocean-might-not-save-the-climateafter-all/
• http://www.boston.com/bostonglobe/magazine/articles/200
9/08/09/trapped/
• http://www.nytimes.com/gwire/2009/09/15/15greenwirewhite-house-rolls-out-details-of-auto-fuel-eco-13342.html
• http://www.boston.com/news/local/massachusetts/articles/
2009/09/17/ready_to_produce_a_fresh_start/
• http://www.nytimes.com/2009/09/17/science/earth/17trash.
html?_r=1&ref=science
The Global Water Cycle
Image courtesy of www.cityofwoodland.org/
Circulation of water among the sea, atmosphere, and land
Why is water important?
Water
• Water needed for life
• 80% of your body
weight
• Personal hygiene
• Universal solvent
• Cooking
• Fire safety
• Shapes geology
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Grow plants
3 phases-solid, liquid, gas
Climate
Photosynthesis
CO2 + H2OCH2O +
O2
Aquatic life
Cooling agent
Potable
Filters UV rays
Properties of Water
• Hydrogen Bonding
– High heat capacity
– Universal solvent
– Ice less dense than water
• Greenhouse Gas
• Clouds reflect light
Roles of the Water Cycle
1. Supply of Freshwater
Source: Wikipedia
Food
Image courtesy of David Medcalf, Wikipedia
2. Driving Force Behind
Primary Production
3. Water Vapor Creates Climate for Life
“Greenhouse Effect”
Key Greenhouse Gases
Water vapor
Ozone
Carbon dioxide
Methane
Nitrous oxide
Chlorofluorocarbons (CFCs)
Water Vapor – Absorbs Heat Lost From Earth’s Surface
Without it, Surface Air Temperature would be 16° C Colder
(36-66% of greenhouse warming due to water vapor)
Global mean Annual Air Temperature = 15° C!!!
Life would not exist in most areas.
4. Water as a Major Transporter of Heat
Images removed due to copyright restrictions.
The Global Water Cycle - Water Fluxes
Atmosphere
Terrestrial Ice
Terrestrial Waters
Oceans
Image courtesy of Scientific American (September 1989, p. 82)
Units: 1021 l/yr or 1000 km3/yr
The Global Water Cycle – Resevoirs
Units = 1,000 KM3
SNOW / ICE
27,500
205
SOIL 70
8,200
Image courtesy of Scientific American (September 1989, p. 82)
Net transfer from ocean to land
1,350,000
The Global Water Supply
Images removed due to copyright restrictions.
Finite, yet seemingly unlimited supply
“Juvenile water”
Residence Time
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Hot Tub is 1000 liters
Pumps 10 liters/min through filter
How long does it take to filter all the water?
Write the equation to describe calculation.
• Ocean is 1021 liters of water
• Rivers add 4 x 1016 liters of water per year
• How long does water stay in the ocean before it is
re-circulated through land?
Residence Time – Turnover Rate
Atmosphere – days to weeks
Ice / oceans / GW – thousands of years
Residence Time:
• average amount of time water spends within a reservoir
RT=Amount/Rate
Terrestrial waters
Precipitation
Runoff
Infiltration
Evapotranspiration
Snowpack
Throughfall
Soil Moisture
Storage
Recharge
Types of Terrestrial Water
Surface
Water
Image courtesy of Chris
Downer
Images removed due to copyright restrictions.
Soil
Moisture
Image courtesy of USDA
Groundwater
Image courtesy of
www.enviroblog.org
Holistic Approach – all water interrelated
River Flow = Surface Runoff + Baseflow
Flashy
Stable
Variable
Less Variable
Regulated
Discharge of Neponset River
Quabbin Resevoir
MWRA Water Supply to Boston
Image courtesy of MWRA
Homework (1 point)
• Your watershed (address)
• Print a map (google earth, topo map, street
map, etc) of your home and delineate your
watershed.