Water of the Earth

Water covers approximately 71% of the Earth’s surface

Earth’s water • Earth’s water is:  •   97% is saltwater.

   3% is freshwater (2.1% = glaciers, 0.6% = groundwater, and 0.3%

= lakes and rivers). • Ground water- Water that lies beneath the earth’s surface, filling pore

spaces between the grains of sediment or within the voids of sedimentary rock.  Groundwater may also fill fractures in rock.

 • Water becomes groundwater when precipitation infiltrates the

geosphere.  • Ground water is a source of drinking water…it is usually purer than

freshwater in lakes and rivers. 

• Hydrologist- A geologist that studies the behavior of ground water.

Groundwater

• Hydrologists estimate, according to the National Geographic Society, U.S. groundwater reserves to be at least 33,000 trillion gallons — equal to the amount discharged into the Gulf of Mexico by the Mississippi River in the past 200 yearsGroundwater is used for drinking

water by more than 44% of the people in the United States, including almost everyone who lives in rural areas. The largest use for groundwater is to irrigate crops( irrigation) according to the NGWA.

Properties of Aquifers

• What is an aquifer?– Body of rock or sediment in which

large amounts of water can flow and be stored

– Factors that affect flow of water-porosity and permeability

• Porosity– Percentage of total volume of a rock

or sediment that consists of open spaces

– 3 factors that affect porosity: 1. Sorting2. Particle packing (loosely packed

particles leave many open spaces that can store water

3. Grain shape : the more irregular the grain shape the more porous the rock or sediment is .

Properties of Aquifers cont.

• Permeability– Ability of rock or sediment to let fluids

pass through its open spaces or pores– Factors that affect permeability: 1. For a rock to be permeable the open

spaces must be connected. 2. Size and sorting: The larger and

better sorted the particles are the more permeable the rock or sediment tends to be.

- The most permeable rocks , such as sandstone are composed of coarse particles; whereas rocks that contain clay are considered impermeable because they are composed of flat, very fine-grained particles.

Zones of Aquifers

• Zone of saturation-layer of aquifer in which the pore space is completely filled w/ water

• Zone of aeration-lies between the water table and Earth’s surface– Top layer holds soil moisture– Bottom region above water table is capillary fringe– Dry area in between fills w//water when it rains

• Water table-upper surface of underground water• Recharge zone- anywhere that water from the

surface can travel through permeable rock to reach an aquifer

Zones of Aquifers

Topography and the Water Table

The depth of the w.table depends on four things:

• Surface topography

• Permeability of the aquifer

• Amount of rainfall

• Rate at which humans use the water

Water tables• In most areas only one

water table exist.• Some areas have a layer

of impermeable rock that lies above the main water table, this zone of rock prevents water from reaching the main zone of saturation. Water collects on the top and creates a second water table , called a perched water table.

Conserving Groundwater

• In many communities, groundwater is the only source of fresh water.

• Although it is renewable, its long renewal time limits the supply.

• Groundwater collects and moves slowly, and the water taken from aquifers may not be replenished for 100’s or 1000’s of years.

Land subsidence- A negative consequence of extraction of ground water too fast is land subsidence.  Without ground water filling pore space, the aquifer compacts and the surface of the land drops (and the aquifer is ruined)

Recharge zone

• Surface water enters an aquifer through an area called a recharge zone.

• They are environmental sensitive areas because pollution in the recharge zone can enter an aquifer.

Wells and Springs

• Well-hole that is dug to below level of water table and through which groundwater is brought to Earth’s surface

• Cone of depression- water table lowers below the well, it goes dry

• Spring-Natural flow of groundwater to Earth’s surface in places where ground surface dips below water table

Artesian Wells and Springs

• Artesian formation-sloping layer of permeable rock sandwiched between 2 layers of impermeable rock and exposed at surface

• Artesian well-well through which water flows freely w/out being pumped

• Artesian formations are also the source of water for some springs. When cracks occur naturally in the caprock, water from the aquifer flows though the crack forming artesian springs

Artesian Wells

Hot Springs and Geysers

• Hot springs-groundwater is heated when it passes through rock that has been heated by magma– At least 37 deg C and rises to surface before

cooling

69.8 °C (157.6 °F)[1]

Morning Glory Pool, Yellowstone National Park

Depth 23 ft.

• Geysers-hot springs that periodically erupt from surface pools or through small vents– Narrow vent that

connects 1 or more underground chambers w/ surface

Eruption height

106 feet (32 m) to 185 feet (56 m)

Frequency45 to 125 minutes

Duration1.5 to 5 minutes

Discharge

3,700 US gallons (14 m3) to 8,400 US gallons (32 m3

Old FaithfulYellowstone National Park

Results of Weathering by Groundwater

• Caverns-large cave that may consist of many smaller connecting chambers– Carbonic acid slowly dissolves the limestone

and enlarges cracks in the rock

Stalactites/Stalagmites

• Stalactites-suspended cone-shaped deposit of calcite on ceiling of cavern

• Stalagmites-upward pointing cone of calcite on floor/ground of cavern

• Column –place where a stalactite and stalagmite join

Sinkholes/Natural Bridges

• Sinkholes-circular depression that forms at the surface when rock dissolves, when sediment is removed, or when caves or mines collapse

• Natural bridges-uncollapsed rock between each pair of sinkholes forms an arch of rock

Karst Topography• Irregular topography caused by the

chemical weathering of limestone or other soluble rock by groundwater.

• Closely spaced sinkholes and caverns• Climate humid and limestone

formations exist can also form in dry regions in these areas sinkholes may form very close together and leave dramatic arches and spires (hoodoos).

Do You Think that Water is important?

Gathering Drinking Water, Bangladesh

Waterborne diseases are a human-health crisis, particularly in the developing world. Some 5,000 children die each day of diarrheal disease alone—an average of one child every 20 seconds

Water tank in Baghdad Iraq

The U.S. State Department estimated that only 5.5 million of Iraq’s 28 million people had regular access to potable water in the immediate postwar period. Reconstruction efforts, including a new treatment facility in Sadr City, had upped that number to more than 21 million by 2009.

Water Pump , Ghana

A Ghanaian woman works a village water pump and prepares to fill a lineup of containers. She is luckier than many—African women walk an average of 3.7 miles (6 kilometers) to reach the nearest well.Water shortages and lack of sanitation facilities have afflicted about half of all Africans with some type of water-related disease, from infant diarrhea to cholera.

Drinking Water Distribution, India

The tap of a water truck is mobbed by India’s Untouchables and other resource-poor citizens.Despite attempts at reforming India’s caste system, the Dalits are still denied many basic rights, including the ability to get water from wells used by other Indians.In many parts of the developing world, the poorest must pay high prices to buy water, which is held in the hands of corrupt governments and private “water mafias.”

Outhouse, Bangladesh

Forty percent of the world’s population has no way to properly dispose of their own waste. Pathogenic bacteria from untreated human and animal waste often contaminates water used for drinking and food preparation and spawns illnesses like typhoid, which impacts some 17 million people each year.

Waiting for Water, China

In many parts of the world, where reliable natural water sources or permanent infrastructure are lacking, people depend on trucked water deliveries by governments or private entrepreneurs.

http://environment.nationalgeographic.com/environment/photos/drinking-water

What does this mean?

Aqua Potable