Water is fundamental to life

A human baby is

75% water

Water is used in chemica

l reaction

s

Water moves up 300’

tall plants

Water regulates

temperature

What do you know about water chemistry? The ends are

charged

Its POLAR

2. Capillary action: cohesion=surface tension

adhesion= sticks to surface

5. Universal Solvent

3. Expands when frozen

1. Polar molecule: attracts other polar molecules

4. High specific heat

Water’s unique properties

Geographic factors determine precipitation amounts

I. Proximity to water sourceII. Global Wind patternsIII. Topography : Mountains create

rain-shadows

Dew Point= Temperature

where the condensation

exceeds evaporation and

condensation occurs

Mass of water vapor divided by mass of dry air = absolute

humidity

absolute humidity to maximum potential

humidity in air = relative humidity

Major Water Compartments

How much water is available for our use? Of the 2.5% freshwater 1.7% ice: unavailabe 0.7% surface waterMarine water = 97.5%Fresh water = 2.5%

How can you define where a watershed is located?

a. Topographyb. Where the water collectsc. Where the water exits

The Oceans are a Major Water CompartmentThe oceans hold 97% of all liquid water on

the earth.90% of the earth’s biomass is found in the

oceans.The oceans play a major role in moderating

earth’s climate.Ocean currents moderate the climate by

redistributing warm and cold water around the earth like a global ocean conveyor belt.

Global Ocean Conveyor System

Community’s water sourceGeographical vs. Political BoundariesHow many bathtubs did it rain last night?

What controls how much water flows in a stream (watershed)? Precipitation: Infiltration:

Shallow: moves to streamDeep: moves to groundwater

Soil characteristics Soil saturation Land cover Slope

What are the effects of increased run-off to a stream?

Sediment load Reduced lightChanges substrateIncreased PM

Increased velocityErodes river banks

Increased nutrients Eutrophication

Less available waterConflicts over water use

Reduce runoff Buffer zonesRain gardens Swales Pervious paver

Personal water use Global average : 1,385 m3 / yr; A person needs 2.5 qts per day (from all sources)

Water trivia facts How much does it take to produce one ton of

steel?62,600 gallons How much water does it take to process one

chicken?11.6 gallons

Demand for water is specific, availability is not

Consumptive or Withdrawal?

Consumptive water, according to the text is water that is made unavailable for human use due to evaporation, tied up in plants or animals, chemical changes,

Renewable water is the total of readily available surface and groundwater minus evaporation.

Water scarcity = demand exceeds availableWater Stress = Water scarcity + increased competition for demand.

Water withdrawals

Conflicts in water valueAgricultural demand

Aral sea: CA

Lake Owen dried up by1924

Lake Mono lost 41% of its volume between 1941 & 1982 Today the San Joaquin valley is in jeopardy

Land subsidence The San Joaquin Delta, produces 25 %of the nation’s table food on only 1 % of the country’s farmlandThe maximum subsidence, near Mendota, was more than 28 feet.Subsidence has slowed or reversed because surface water is being pumped in

Env. factors affect

Porosity: volume of all of the open spaces Material Porosity (%)

well-sorted sand 25-50

sand and gravel 20-35

clay 33-60

Permeability: Connectivity of pores & pore size

Groundwater

Groundwater Stores Large Water ResourcesAquifers - porous layers of sand, gravel, or

rock lying below the water tableArtesian - Pressurized aquifer intersects

the surface (water flows without pumping).

Recharge zones - area where water infiltrates into an aquiferRecharge rate is often very slow.

Presently, groundwater is being removed faster than it can be replenished in many areas.

Ground Water Compartments Ground water is the second largest

reservoir of fresh waterInfiltration - process of water percolating

through the soil and into fractures and permeable rocksZone of aeration - upper soil layers that hold both air and water

Zone of saturation - lower soil layers where all spaces are filled with waterWater table - top of zone of saturation