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Water
Chapter 11
Water Cycle
Evaporation
Condensation
Precipitation
Transpiration- water released by plants
Percolation- water moving through Earth’s surface
World’s Water
Salt Water 97%
Freshwater- 3%
Icecaps and Glaciers- 77%
Groundwater- 22%
Other freshwater- 1%
The amount of water in the world does NOT change- it only changes form and where it is
located.
Surface Water- fresh water on the Earth’s surface
Rivers, streams, lakes, wetlands
Most cities are built near surface water and many depend on surface water for water
needs
River System- flowing network of water
Streams --> small rivers --> larger rivers
Watershed- area of land drained by a river
Mississippi watershed drains water from 30 states (40% of land in lower US)
Groundwater- water stored beneath the Earth’s surface in sediment and rock formations
Water table- a level where rocks and soil are saturated with water.
Wetter areas- higher water table and near surface
Deserts- hundreds/thousands of feet down
Aquifer- an underground formation that contains groundwater
Ogallala Aquifer- one of the largest in world
174,000 square miles
Under 8 plains states (most of Nebraska)
Supplies 1/3 of groundwater used in US
The Ogallala Aquifer holds as much water,
but spreads over an area seven times the size
of Lake Huron.
Page 272
Porosity- the amount of space between the particles that make up a rock
Permeability- the ability of rock or soil to allow water to flow through it
Permeable- allow water flow- gravel, sand
Impermeable- stop water flow- clay, granite
Low permeability
High run-off
High permeability
Low run-off
Aquifers usually form in permeable materials such as limestone, sandstone or layers of
gravel and sand
There are aquifers in most parts of the world. Most do not take up as much constant
area as Ogallala, but do provide a ground water source
Recharge Zone- area of the Earth’s surface where water percolates down into the
aquifer
Well- hole that is dug to reach groundwater
Cone-shaped depression in groundwater
Must be below water table or will be dry
Water Use
Section 2
Water Use
Agriculture- production of food products
67% world wide (US 45%)
Industrial- production of goods and services
19% world wide (US 39%)
Residential-home use, cooking, cleaning
8 % world wide (US 10%)
Other % is water lost due to evaporation
page 277
Water Treatment
Potable- water that is safe to drink
Free of pollutants and diseases
Must remove
Contaminants such as heavy metals (mercury, arsenic, lead) can cause major health
problems even in low levels
Other chemicals- fertilizers, cleaners, runoff
Pathogens- organisms that cause illness of disease
Bacteria, viruses, parasites
Usually contaminated through sewage or animal wastes
Drinking Water Treatment
1.First Filtration- removes trash
2.Coagulation- bacteria and impurities form globs that will settle to bottom of tank
(usually done with Alum)
3.Sedimentation- solids/sludge settle to bottom of tank to be removed
4.Filtration- layers of sand, gravel and coal filter more impurities
5. Chlorination- chlorine is added to prevent bacteria from growing
6. Aeration- air is forced through water to release dissolved gases
7. Additional treatment- add fluoride (prevent tooth decay), sodium or lime (soften water
Open Sewer System
Industrial Use
19% of water used in the world
Used for……
Most is used to cool power plants
To clean ingredients before production and products before shipping
To cool metals when cutting
As a mixing ingredient
Agricultural Use
67% of world water use
Plants require large amounts of water, animals even more
80% of the water used evaporates before it is absorbed by plants
Irrigation
Irrigation- providing plants with water from other sources than direct precipitation
Flooding fields
Shallow ditches
Sprinklers-very inefficient -50%evaporation
Drip irrigation
Water Management
Aqueduct- canals or pipes that move water to a different area
Dam- structure built across a river to control the river’s flow
Flood control
Generate electricity- hydroelectric
Create reservoirs
Reservoir- artificial lake behind a dam
Flood control
Drinking water
Irrigation
Recreation
Hoover
Dam
Hydroelectric
Water for irrigation and residential use
Three Gorges Dam
China
Completed in 2008
Produces energy for 4 large cities
Flooded large areas
Desalination
Process of removing salt from salt water.
Usually through heating the water and collecting the evaporation (freshwater)
Purpose
Used in coastal cities and islands without natural freshwater
Very expensive
Water Conservation
What can you do to conserve water?
Opener 1/7
Write in your notebook
1.What is the largest watershed in the US?
2.What is an aquifer? What can they be used for?
3.Is sand permeable? Why?
4.How much of the earth’s water is freshwater?