How much water is there on Earth?

• Estimates show about 1-1/3 billion cubic km!
• About 97% of it is salty ocean water
• About 2% is fresh water in the ice caps
• …and 1% is found in the ground, lakes, rivers
• The amount of groundwater is 50x more than all the lakes, streams, and rivers combined!

The Hydrosphere

• The water of Earth's surface
• This includes ALL of Earth's water
• The movement of water from one part of the hydrosphere to another is called the Water Cycle
• Sunlight is the main source of energy for the cycle to operate
• Water evaporates from the oceans and other water sources up to the atmosphere
• Water can also be released into the atmosphere by plant life - process is called Transpiration
• Often this return of water is simply called Evapotranspiration
• Water then condenses into clouds that float around the earth's atmosphere
• When a change in atmospheric temperature or pressure occurs, the clouds release their water vapor in the form of precipitation (rain)
• The rain then pours water back to earth's surface as runoff and groundwater
• This completes one rotation of the water cycle
• Of course, the cycle never ends!

Water Budgets

• A statement of expected income verses expected spending or expenses
• This describes the income and spending of water for a region
• Income = Rain, snow and groundwater
• Expense = Runoff, loss, & evapotranspiration
• Evapotranspiration in an area is notably controlled by air temperature; high temps = more water loss
• Rain that falls during periods of low water usage will result in excess water supply that will be stored as groundwater for later use
• This is a time of soil Recharge
• Once the soil and groundwater are full, this is a time of Surplus (extra water)
• Then when water conditions lessen, the surplus is used during what is called Usage
• Once the usage is maxed out, it is possible for a Deficit to occur (shortage of water)
• Summary: this is a never ending cycle as well; Areas go through it in a given order:

1. Recharge
2. Surplus
3. Usage
4. Deficit
5. ….then back to Recharge

Water Budget Graphs

• Every place on earth can be shown by a graph
• Graphs illustrate two things:

1. Moisture needed
2. Moisture supplied

• In areas of dry climates, graphs will show much more "moisture needed" for the year
• In areas of wet climates, graphs will show much more "moisture supplied" for the year
• In areas of moderate wet climate with dry periods, equal amounts of "supplied" and "needed" will be seen
• Let's look at the graphs on Pages 151-152!

Water in the Ground

• Amount of water that the ground can hold depends on the pore space available
• This is called the grounds "Porosity" - % of the grounds open air space
• Factors that affect porosity:

1. Particle shape - square has less porosity than round shapes
2. Sorting - well-sorted materials will have more porosity than non-sorted material which is a mixture of coarse and fine materials, thus using more pore space
3. Permeability is the rate at which water and other liquids pass through the pore spaces
4. Materials that water cannot pass through is called Impermeable - like clays and shale

The Water Table

• When water fills up areas of the ground above impermeable layers, the water table is formed
• The area below the water table that has its pore space completely filled by water is called the Zone of Saturation
• The area above the Zone of Saturation and the Water Table that has air in its pore spaces is called the Zone of Aeration
• Water even has the ability to draw upwards in what is called Capillary Fringe - usually found just above the water table, seeping into the zone of aeration
• Where is the water table in your area? It depends on a number of factors:

1. amount of rainfall
2. the season
3. slope of the ground
4. thickness of the soil
5. the climate
6. time between rainfall events

• Desert - 100's of meters deep
• Woods/Farmland - few meters deep
• Hilly - near surface in the valleys
• Water sources - water is at the surface

Wells and Springs

• Ordinary Wells - well that is drilled or dug to retrieve water from the water table by pumping
• On a hillside, where the water table meets the surface, groundwater may flow out as a Hillside Spring (common in mountain areas)
• Aquifers are permeable materials that contain and carry groundwater - like sands and gravels
• An Artesian Formation forms when an aquifer is trapped under pressure between two impermeable layers (natural squirting bubbler)
• See picture on Page 156
• Artesian Wells form when this occurrence happens - usually found in areas of rock outcrops or mountainous regions

Groundwater Conservation

• We must use water in a respectable fashion
• We cannot remove (or use) more water than what that water cycle can recharge in a given year - a shortage will occur
• Because water tables are charged by rain water that seeps through the soil, any pollutants will be leached into the water table
• Pollutants can come in many forms:

1. nitrates from farmland fertilizers
2. industrial wastes
3. hazardous material spills
4. rotting underground storage containers
5. improper landfill safe-guards
6. careless personal disposal of waste
7. salt from highway ice-melting use

Groundwater Characteristics & Features

• Because groundwater is found at such depths underground, it remains at consistent temperatures no matter what the climate conditions are: about 40-50 degrees F
• This keeps the water from warming in the summer or freezing solid in the winter
• Permafrost is found in regions where water is frozen in the ground because freezing travels to depths of 100s of meters underground

• Below about 20 meters underground, the water in the ground may be affected by the interior heat of earth
• At some points, the super heated water from deep beneath the surface may rise as hot springs
• If the hot water combines with wet, sticky clays, it may form a Paint Pot
• Geysers are boiling hot springs that periodically erupt as gushers of hot water and steam - they erupt through a constricted tube or crack in the bedrock of the region
• Geysers may erupt as often as every hour and may shoot water as high as 45 meters!
• Fumaroles are fissures in the ground from which steam and hot gases escape
• An entire cycle seems to have formed then where these features have happened:

1. Volcanic activity produces a hot spring
2. Minerals collected in the hot spring, constricting the crack in the bedrock
3. Decreased water supply and heat pressure produces a geyser
4. Loss of water creates a fumarole of heat without water

Mineral Springs

• A spring that has so much dissolved minerals in it that it is not usable for anything is called a Mineral Spring
• Various minerals dissolve easily in hot water from the springs
• Many minerals are good for your skin and are often the reason of some mineral springs being turned into a health spa!
• Still many other minerals dissolved in the water will cause the water to become poisonous - usually gives off a bad odor

Caverns and Deposits

• Limestone is a very common form of bedrock
• It is a very weather-easy rock
• Water will weather limestone because of its calcite composition
• This process easily creates tunnels called Caverns or Caves
• Sinkholes form when parts of a cave roof collapse, forming a hole or depression in Earth's surface - often form lakes when in contact with the water table
• Some common places for caverns to form are New Mexico, Kentucky, Virginia, New York, Oregon, and South Dakota
• Regions populated by sinkholes are said to have Karst Topography - regions largely composed of limestone - like Florida, Tennessee, and Indiana

Mineral Deposits

• The minerals dissolved in groundwater are deposited in a variety of ways
• Deposits shaped like icicles hanging from the roof of a cavern are called Stalactites
• Icicles "growing up" from the floor of the cavern are known as Stalagmites
• When stalactites and stalagmites meet or join in the center of the cavern, a Column forms
• Calcite deposits around mineral springs are called Travertine - looks like ice on the rocks

Let's Get a Drink!!!