News

• http://blogs.discovermagazine.com/80beats/2009/01/28/dumping-iron-into-the-ocean-might-not-save-the-climate-after-all/

• http://www.boston.com/bostonglobe/magazine/articles/2009/08/09/trapped/

• http://www.nytimes.com/gwire/2009/09/15/15greenwire-white-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 CycleThe Global Water Cycle

Circulation of water among the sea, atmosphere, and landCirculation of water among the sea, atmosphere, and land

Image courtesy of www.cityofwoodland.org/

Why is water important?

Water

• Water needed for life• 80% of your body

weight• Personal hygiene• Universal solvent• Cooking• Fire safety• Shapes geology

• Grow plants

• 3 phases-solid, liquid, gas

• Climate

• Photosynthesis

• CO2 + H2OCH2O + 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 CycleRoles of the Water Cycle

1. Supply of Freshwater

2. Driving Force Behind2. Driving Force Behind Primary ProductionPrimary Production

FoodFood

Image courtesy of David Medcalf, Wikipedia

Source: Wikipedia

Global mean Annual Air Temperature = 15° C!!!Global mean Annual Air Temperature = 15° C!!!

3. Water Vapor Creates Climate for Life 3. Water Vapor Creates Climate for Life ““Greenhouse Effect”Greenhouse Effect”

Water Vapor – Absorbs Heat Lost From Earth’s SurfaceWater Vapor – Absorbs Heat Lost From Earth’s Surface

Without it, Surface Air Temperature would be 16Without it, Surface Air Temperature would be 16° C Colder° C Colder(36-66% of greenhouse warming due to water vapor)(36-66% of greenhouse warming due to water vapor)

Life would not exist in most areas.Life would not exist in most areas.

Key Greenhouse Gases

Water vapor

Ozone

Carbon dioxide

Methane

Nitrous oxide

Chlorofluorocarbons (CFCs)

4. Water as a Major Transporter of Heat4. Water as a Major Transporter of Heat

Images removed due to copyright restrictions.

OceansOceansTerrestrial WatersTerrestrial Waters

Terrestrial IceTerrestrial Ice

AtmosphereAtmosphere

The Global Water Cycle - Water FluxesThe Global Water Cycle - Water Fluxes

Units: 1021 l/yr or 1000 km3/yrImage courtesy of Scientific American (September 1989, p. 82)

SNOW / ICE27,500

1,350,000

8,200

SOIL 70

The Global Water Cycle – ResevoirsThe Global Water Cycle – Resevoirs

Net transfer from ocean to land

Units = 1,000 KM3

205

Image courtesy of Scientific American (September 1989, p. 82)

“Juvenile water”

The Global Water SupplyThe Global Water Supply

Finite, yet seemingly unlimited supplyImages removed due to copyright restrictions.

Residence Time

• 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:Residence Time:

Ice / oceans / GW – thousands of years

Atmosphere – days to weeks

Residence Time – Turnover RateResidence Time – Turnover Rate

• • average amount of time water spends within a reservoiraverage amount of time water spends within a reservoirRT=Amount/RateRT=Amount/Rate

PrecipitationPrecipitation EvapotranspirationEvapotranspiration

RunoffRunoff SnowpackSnowpackInfiltrationInfiltration

Soil MoistureSoil MoistureStorageStorage

RechargeRecharge

ThroughfallThroughfall

Terrestrial watersTerrestrial waters

Types of Terrestrial WaterTypes of Terrestrial Water

GroundwaterGroundwater

SoilSoilMoistureMoisture

SurfaceWater

Image courtesy of www.enviroblog.org

Image courtesy of USDA

Image courtesy of Chris Downer

Images removed due to copyright restrictions.

Holistic Approach – all water interrelatedHolistic Approach – all water interrelated

River Flow = Surface Runoff + BaseflowFlashy

VariableRegulated

StableLess Variable

Discharge of Neponset River

Quabbin ResevoirMWRA 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.