APES

Turn in Soil LabAnswer on a separate piece of paper: 1. Calculate how many liters of water are wasted

in 1 month (30 days) by a faucet that leaks 2 drops of water per second.

2. How many gallons is this?

( 1 liter of water = about 3500 drops)

(1 liter = 0.265 gallons)

Use Factor Label Method

2 drops x 60 sec x 60 min x 24 hour x 30 day

1 sec 1 min 1 hour 1 day 1 month

_____ drops x 1 Liter =

1 month 3500 drops

_____ Liters x 0.265 gallons =

1 month 1 Liter

Water Resources

Ch. 13

Properties of Water

HYDROGEN BONDS

– Major factor in determining water’s unique properties

– Strong molecular attraction between molecules

O

H H+ +

--

O

H H+ +

--O

H H+ +

--

Hydrogen Bonds

Covalent bonds

Water’s Unique Properties

Liquid over wide temperature range• High boiling point 100°C (212°F)• Low freezing point 0°C (32°F)

Changes temperature slowly, high heat capacity• Helps protect organisms• Moderates the earth’s climate• Excellent coolant

High heat of evaporation• Absorbs heat as it changes into water vapor• Releases heat as vapor condenses

Water’s Unique Properties

Great dissolving power, Universal Solvent• Carries dissolved nutrients into tissue• Flush waste products out of tissue• All-purpose cleanser• Remove and dilute water-soluble wastes

Balances pH• Helps maintain balance between acids and

bases by ionizing (releasing H+ or OH- ions)Adhesion and cohesion

• Surface tension• Wetting ability

Expands when it freezes• Ice floats – less dense in solid form

Water, a vital resource

Oceans and

saline lakes

97.4%

Fresh Water 2.6%

Water Footprints and Virtual Water

• Water footprint– Volume of water we directly and indirectly

• Average American uses 260 liters per day– Flushing toilets, 27%– Washing clothes, 22%– Taking showers, 17%– Running faucets, 16%– Wasted from leaks, 14%– World’s poorest use 19 liters per day

Water Footprints and Virtual Water

• More water is used indirectly = virtual water– Hamburger, 2400 liters

• Virtual water often exported/imported – Grains and other foods

Fig. 13-A, p. 321

1 tub = 151 liters (40 gallons)

= 1 tub

= 4 tubs

= 16 tubs

= 17 tubs

= 72 tubs

= 2,600 tubs

= 16,600 tubs

Virtual Water

Use

Supply of Water Resources

FreshwaterFreshwater Readily accessible freshwaterReadily accessible freshwater

Biota0.0001%

Biota0.0001%

Rivers0.0001%Rivers

0.0001%

Atmosphericwater vapor

0.001%

Atmosphericwater vapor

0.001%

Lakes0.007%

Soilmoisture0.005%

Groundwater0.592%

Groundwater0.592%

Ice capsand glaciers

0.1.984%

0.014%0.014%

Surface Water

• Precipitation that does not infiltrate the ground or return to the atmosphere by evaporation (transpiration included)

• Flows into streams, lakes, wetlands, reservoirs

Sources of Surface Water

• Surface Runoff– Water flowing off the land into bodies of

water– 1/3 of the world’s annual runoff– Stable source of water

• Watershed (Drainage Basin)– Region from which water drains

Groundwater

• Water that sinks into the soil and is stored in slowly flowing and slowly renewed underground reservoirs (aquifers).

• Underground water in the zone of saturation below the water table

Groundwater

Evaporation and transpiration

Evaporation

Stream

Infiltration

Water tableInfiltration

Unconfined aquifer

Confined aquifer

Lake

Well requiring a pump

Flowingartesian well

Runoff

Precipitation

ConfinedRecharge Area

Aquifer

Less permeable materialsuch as clay Confirming permeable rock layer

Ground Water Resources

Unconfined Aquifer Recharge Area

Groundwater

Aquifers– Confined – located between

impermeable layers of rock– Unconfined – drains from porous

rock above

Recharge Area – area of land through which water passes downward or laterally into an aquifer

Aquifers

Groundwater Reservoir Zones

As ground water moves through soil (infiltration) it can collect in one of two zones divided by the water table

Water TableThe upper level of the saturated zone of groundwater.

Zone of Saturation

• Area where water fills ALL spaces between sediments

• GROUNDWATER found HERE!

Zone of Aeration

• Also called unsaturated zone• Area where air fills ALL spaces

between sediments• Located above the water table.

Movement of Groundwater through Soil can be described using two terms

• Porosity• Permeability

Porosity & Permeability

Porosity• Pore = Opening• Measure of empty

space in a material• Storage ability• Space between the

grains• High porosity = A

LOT of empty space• Measured as a

percentage

Permeability• Ability of a material

(soil) to transmit fluid

• High permeability = water moves through it fast

Porosity

Permeability

Permeability

Use of Water Resources

• Agriculture• Industry• Domestic• Power

Plants

Humans use about 50% of runoff Humans use about 50% of runoff

United States

Industry 11%

Public 10%

Powercooling

38%

Agriculture41%

5,500

5,000

4,500

4,000

3,500

3,000

2,500

2,000

1,500

1,000

500

1900 1920 1940 1960 1980 2000

Wat

er u

se (

cub

ic k

ilom

eter

s p

er y

ear) Total use

Agricultural use

Industrial use

Domestic use

Year

Water in the United

States• Average

precipitation (top) in relation to water-deficit regions and their proximity to metropolitan areas (bottom).

Too Little Water – Shortages

1) Dry climate• Air circulation patterns

2) Drought• 21 days+• Precipitation <70%• Increased evaporation

3) Desiccation• Drying of the soil

4) Water stress• Low per capita

availability• Caused by increased

population• Limited runoff levels

Acute shortage

Adequate supply

Shortage

Metropolitan regions with population greater than 1 million

Water Resource Problems

1. Flooding- Causes property damage- Development of flood plains

(deforestation/industrialization)- Removes vegetation that traps/absorbs

precipitation- surface runoff, erosion, risk of

flooding

Water Resource Problems

2. Water Shortages- Reservoirs are stressed by overpopulation- Diverted water for irrigation of agriculture

fields- Water for livestock who overgraze and

erode soils

Water Resource Problems

3. Overdrawing of surface waters- Diversion of rivers/streams from

their natural flow or patternEX. Mono Lake, CA

www.monolake.org/about/story

Water Resource Problems

4. Aquifer Depletion- Lowering of groundwater table can cause subsidence or sinking (sink holes)

Water Resource Problems

5. Salinization of Irrigated Soils