The Hydrosphere
The Hydrosphere
The hydrophere includes all the watery parts of our planet like oceans,
seas, lakes, rivers, ice packs, snow fields and clouds. Water in all its
forms makes life possible and is one of the major factors responsible
for weathering the lithosphere.
The Water Cycle or Hydrologic Cycle
Water moves between the hydrophere, atmosphere, lithosphere and
biosphere.
Storehouses of the Earth’s Water
Most water on earth is saline in the world’s oceans. Of freshwater,
most is in the form of ice , then in underground water reservoirs. Most
surface freshwater is in the form of snow and ice. Surface liquid
freshwater is mostly in lakes.
Question 1 Page 198
Which storehouse of water do you come in contact with on a regular
basis? The water we daily consume in the Cowichan Valley is from
wells tapping into groundwater which flows underground through the
valley at about a rate of 1 m/s away from the direction of Lake
Cowichan towards Cowichan Bay.
Other Cowichan Storehouses of Water
Lake Cowichan, Somenos Marsh, Quamichan Lake, Cowichan River,
Koksilah River and the Ocean (Maple Bay and Cowichan Bay) are all
water storehouses in the Cowichan Valley.
Water Storehouses and Storage Times
Water is stored briefly in the atmosphere, much longer in oceans, and
the longest in glaciers and ice caps.
Question 2 Page 198
2. In your own words, explain why the hydrologic cycle is considered to
be a closed cascading system. The hydrologic system is a closed
cascading system because water is not added or taken away from the
system.
Question 3a) and b) Page 198
3a) List three ways in which human beings have changed the hydrologic cycle
and b) Briefly explain each change. Humans are responsible for global
warming which is reducing water stored as ice and is increasing the
evaporation rate from oceans. In addition, humans are depleting ground
water storehouses for irrigation and are damming rivers for hydroelectric
power which is creating new lake storehouses. Human cities reduce
infiltration and vegetation removal reduces transpiration from plants.
Question 4 Page 198
4. How might the hydrologic cycle be affected if the net radiation available at the
earth’s surface were dramatically increased? Consider each of the storehouses of
water. Extra surface radiation would increase evaporation which would increase
water in the atmosphere storehouses (more humidity and clouds and precipitationperhaps severe storms). Extra precipitation would increase the storehouses in lakes
and rivers. The extra radiation would warm the planet, melting and reducing the
storehouses of ice (glaciers). The extra water from ice would eventually increase the
storehouses of water in oceans, raising sea level.
Question 6 Page 201
6. List the ten largest saltwater bodies found on earth from largest to
smallest. The largest saltwater bodies on earth from largest to smallest are :
The Pacific Ocean, The Atlantic Ocean, The Indian Ocean, The Southern
Ocean around Antarctica, The Arctic Ocean, The Philippine Sea, The Coral
Sea, The Arabian Sea, The South China Sea, and The Caribbean Sea
Question 7 Page 201
7. Identify those areas of coasts that would be flooded if the sea level
were to rise by 100 m.
Question 8 Page 201
8. What patterns are there between oceanic deep water circulation
and ocreanic surface water circulation? In general, deep ocean
currents run counter to surface ocean currents.
Ocean Depths
Some of the largest plains and deepest canyons are at the bottom of
the ocean. The Marianas Trench (plate subduction) reaches a depth of
11,000 m which is 2,000 m greater than the height of Mt. Everest.
In Complete Darkness
Light penetrates only to 1,000 m below sea level. Deeper than that is
a realm of complete darkness. Surprisingly, organisms survive in this
realm, scavenging on dead bodies and living off food chains that start
with chemosynthetic bacteria which make glucose using the energy of
sulfides emitted by underwater vents (called smokers) and volcanoes.
Marianas Trench Organisms
Strange animals living in total darkness in the Marianas Trench.
Sea Salinity
Oceans and seas are salty due to dissolved salts carried into them by
by rivers. On average the salinity due to dissolved salts is 3.5 %.
Where evaporation is high and precipitation low like the Red Sea,
salinity may exceed 4% whereas with a larger input of freshwater like
the Baltic Sea, salinity can be less than 1%.
Ice Water Storehouses
About 75% of all freshwater is stored in glaciers and ice sheets. Of this frozen
water, about 90% resides in the Antarctica ice sheet (13 million km2) and
about 10% resides in the Greenland ice sheet. The Antarctic ice sheet is
connected to ice shelves like the Ross ice shelf with a surface area of over
500 000 km2. With global warming, the ice shelves will likely be the first ice
to break away, melt and raise ocean levels.
Groundwater Storehouses
About 22-24% of freshwater is stored underground. The water table is the
level beneath the surface in which all pores and spaces are filled with water.
Aquifers are large deep storehouses, often covering large areas. Artesian
wells or springs are formed by aquifers confined and pressurized between
non-porous rock layers, causing the water to rise above the aquifer.
US Aquifers
The Ogallala Aquifer
The Ogallala Aquifer named for the Sioux Indian tribe is the largest
underground aquifer in the US’s Great Plains. It supplies 30% of the
groundwater used for irrigation by Great Plains States. It is being used 50
times faster than nature can replace it. Estimates indicate that 40% of this
stored water has been used with a projected further 40% to be used in the
next 30 years. If drained dry, it will take 6000 years to replenish itself
naturally through rainfall.
River Storehouses
The Amazon River is the second longest world river but it has the
largest drainage basin and discharge of any river in the world.
Lake Storehouses
Lake Superior has the largest surface area and third largest volume of
water worldwide. Lake Baikal has the largest volume of water and
depth of any lake in the world.
Question 9 Page 207
9. Fresh, clean water is becoming a scarce resource. List all the ways in which fresh
water is used in your home. Identify five conservation methods to reduce water
consumption in your household. Water is used for cooking, showers, very infrequent
baths, dishwashing, drinking, toothbrushing, clothes washing, plant watering, toilets,
house cleaning, car washing, hummingbird feeders, and beverages like coffee and
tea. Conservation could include education about water conservation, higher cost for
water, low flow showerheads, low flow faucet aerators, low volume flush toilets,
pressure restrictors in water lines to reduce flow, ban on watering lawns, ban on car
washing, restricted watering for gardens, weekly sink baths.
Question 10 p207
10. Suppose you are the water commissioner for the State of Oklahoma. Recent
studies have shown you that the Ogallala aquifer is fast being depleted. Suggest
5 actions that the state could take to reduce consumption of the Ogallala aquifer.
The state could provide incentives for farmers to move from irrigated land to dry
land farming, for planting perennial grasses for haying and grazing, for
converting to more efficient drip irrigation, outlaw crops requiring large amounts
of water, use recycled waste water for irrigation, outlaw use of aquifer water for
gas/petroleum extraction, require playa lake zones to remain undeveloped since
they are permeable to rains and help recharge the aquifer.
 drip irrigation
playa lake ˅
pivot irrigation
Water Storehouses in the Atmosphere
Although the atmosphere holds little water, it is important in
distributing and circulating water from place to place in the hydrologic
cycle and relies on energy from the sun to evaporate water and to
create winds to move both evaporated and condensed water.
Question 11 p207
11. Identify three forms of condensation besides eyeglasses “fogging up”
when coming into a warm room from the cold outside. Water vapour may
condense into clouds as water droplets or ice crystals. Water vapour may
also condense to form rain. Water vapour may form fog (fine liquid water
droplets) as it is cooled under different conditions. Water vapour may form
frost if the surface objects and air are below the freezing temperature.
Question 11 p207
11. Water vapour may condense to form hail, sleet, freezing rain and snow.
Hail forms within turbulent clouds which alternately freeze water into ice
particles which are updrafted to be coated with water, fall and thjen are
updrafted for more water coats until the ice particles are too heavy to be
updrafted and then fall because of gravity. Snow forms when the lower
atmosphere is below freezing and sleets and freezing rains occur when snow
passes through warmer air to melt and then again into cooler air to refreeze.
Cowichan Valley in Fog
Absolute Humidity
Humidity refers to the water
vapour in the air. The absolute
humidity is the g water/m3 of
air that a sample of air has. As
air warms, it has a greater
capacity to hold suspended
water molecules since its air
molecules (O2 and N2) move
farther apart and move faster
to keep more water particles
aloft (a water particle is lighter
than a nitrogen or oxygen
molecule).
Relative Humidity
Relative humidity is a fraction of the water an air sample has compared to
the water the sample could hold if saturated. If an air sample has a 25%
relative humidity it means that it has only ¼ or 25% of the water in it that it
could possibly hold. A value of 100% humidity means that the air can hold
no more water (it is likely going to rain or it is raining).
Question 12 Page 207
12. As the temperature of an air mass drops, its ability to retain
moisture decreases. Similarly, as the temperature rises, more
moisture can be held. Show this relationship with a diagram.
Eutrophication
Eutrophication is the addition of nutrients to natural waters which
triggers the growth of algae, increasing their death, increasing
decomposer activity which then lowers oxygen levels, suffocating
many aquatic organisms.
Human Impact on Natural Cycles
When humans add extra nutrients to natural waters, this is like
fertilizer for the microscopic algae in these waters. The sudden growth
of algae, gives the water a brownish or greenish color.
(c) McGraw Hill Ryerson 2007
Adding Extra Nutrients to Natural Waters
At first, adding extra nutrients to
natural waters seems like a good
thing since it grows extra algae
which make more food and oxygen
for animals in the water.
(c) McGraw Hill Ryerson 2007
Too many nutrients lead to algae blooms and low O2 levels
But the extra algae die and the bacteria that decompose them use up
so much oxygen that many animals die from lack of oxygen.
(c) McGraw Hill Ryerson 2007
Eutrophication: A Natural Aging of Water Bodies
As Natural bodies of water accumulate nutrients over time,
they become more and more filled with plant material
(fertilizer effect) and eventually fill up. This process naturally
takes from hundreds to thousands of years.
(c) McGraw Hill Ryerson 2007
Oligotrophic lakes are younger, eutrophic lakes are older.
Characteristics of oligotrophic and eutrophic lakes.
(c) McGraw Hill Ryerson 2007
Human activity ages lakes much faster than normal.
Oligotrophic lakes can become eutrophic much sooner because of the
nutrients humans add to natural waters.
• Oligotrophic lakes can become eutrophic much
sooner because of the nutrients humans add to
natural waters.
(c) McGraw Hill Ryerson 2007
Human activity ages lakes much faster than normal.
Oligotrophic lakes can become eutrophic much sooner because of the
nutrients humans add to natural waters.
(c) McGraw Hill Ryerson 2007
Humans need to properly treat their waste waters.
Using three treatment processes on
human/animal waste water produces clean
water that has effect on the environment.
(c) McGraw Hill Ryerson 2007
Primary Sewage Treatment
Primary sewage treatment screens the sewage, removing large
items. It also allows the sewage to settle and removes the
solids by compacting them.
(c) McGraw Hill Ryerson 2007
Secondary Sewage Treatment
Secondary treatment is aerating sewage, giving aerobic bacteria
(bacteria needing oxygen) the oxygen they need to decompose it
down into chemical nutrients. This helps the environment, since
secondary-treated sewage will not take oxygen from natural waters to
decompose the sewage (like primary-treated sewage does).
(c) McGraw Hill Ryerson 2007
Aerating sewage reduces sewage smell.
Aerating sewage stimulates aerobic bacteria and kills anaerobic
bacteria. Aerobic bacteria do NOT produce smelly wastes but
anaerobic bacteria do produce smelly wastes.
(c) McGraw Hill Ryerson 2007
Secondary-treated waters can cause algae blooms.
Since Secondary-treated water still contains nutrients, it can cause
algae blooms and oxygen loss in natural waters when the algae die.
(c) McGraw Hill Ryerson 2007
Tertiary Sewage Treatment
In Tertiary treatment,
decomposed sewage
rich in nutrients is
further treated
(sometimes with
chemicals) to remove
the nutrients. This
treated sewage is clean
enough to drink and
has no harmful effects
on natural waters.
(c) McGraw Hill Ryerson 2007
Sewage treatment in BC
Duncan uses primary and secondary sewage treatment.
Victoria and Vancouver only use primary treatment of sewage.
(c) McGraw Hill Ryerson 2007
A
A