EESA07

8 Pages
456 Views
Unlock Document

Department
Environmental Science
Course
EESA07H3
Professor
Jovan Stefanovic
Semester
Fall

Description
Discussion on sept 30 & nov 4 Continuation of last week… Distribution of Water on Earth  Water is only substance that naturally occur as a liquid , solid, or gas  Earth contains 1.39billion km3 of water o The oceans make our earth look blue against the black background of the atmosphere  Not evenly distributed and varies season to season and year to year Consequences  Such disparities lead to water shortages and the need to do: o Store water in reservoirs during wet periods o Rely on groundwater resources if available o Transport water supplies to great distances Oceans  Covers70% of earth’s surface  Uneven distribution of land and oceans is caused by plate tectonics?  Salty or saline (3.5% dissolved salts by weight; salts are: Na, Ca, Mg, and CI)  Human tolerance for salt is less than 2% o Agriculture & industry cannot use salt water  Nearly 97% of earth’s water is salty – difficult, expensive to utilize for drinking, agriculture and industry  If all seawater evaporated  seafloor will be covered with 56m of salt (75% of this salt is common table salt – NaCI) Surface Ocean Currents  Persistent prevailing winds blowing over the ocean produces currents  Prevailing winds generate gyres – circular ovean currents  Coriolis effect (due to Earth’s rotation) influences the paths of surface or shallow ovean currents Glaciers, permanent snow, sea ice, and polar ice caps  Glaciers are created when deep snow recrystallizes due to the weight of overlaying snow  When snow and ice becomes so thick and heavy gravity causes the frozen mass to move  30% of Earth’s surface is in the cryosphere (cold and frozen sphere) : presently 10% are glaciers and 20% permanently snow – covered and frozen ground (permafrost)  Polar ice caps generate cold, dense water that creates deep ocean circulation  Ocean currents affects world’s climate by altering ocean temperatures Groundwater (GW)  Water stored under Earth’s surface  Replenished when precipitation falls on land surface and seeps down into an aquifer o Aquifer: a rock, sand or gravel layer that can store and yield significant amounts of water  GW is 30% of total freshwaters  The quality of GW ranges from salty (3%-30000ppm) in some coastal areas to relatively mineral-free in Iceland  GW is often the main source of water to sustain ecosystems, riparian zones, lakes and rivers (also potable water for approximately 30% of Canadians)  The largest GW deposit in the world is the Ogallala Aquifer  Problems of river waters and surface waters o For fresh water which one will you choose?  Ground water  Pure + easier to transfer into drinkable water  Less expensive o After couples of years, you get less and less water  The timing it takes to recharge the GW Rivers  Surface water transport system  4.8 million km of river channels in the US alone  .0001% fo the world’s water  rivers varies in size, discharge, speed of current, aquatic population, water quality and temperature (T)  Think about T, oxygen level & sediments of the Amazon R. flowing toward the Atlantic Ocean and in headwaters in the Peruvian Andes Mountains o Nile river brings many sediments and is good for the water o More oxygen in the winter o When water is turbulent, there are more oxygen (ex mountain rivers) compared to flat smooth stream  Types of rivers: o Ephemeral streams: not fed by any continuous water source or they flow only after storm events  Ex. dry rivers in Australia  No GW o Intermittent streams  Fed by storm water + GW  Ground water is continuous o Influent or losing rivers  Dry condition when water lever is lower than level of GW o Effluent or gaining rivers  GW discharges to the stream Lakes  Inland body of water found in a topographic depression  Canada contains nearly half of the world’s lakes o part due to the ice sheets that carved depressions in the landscape some 10 000 – 12 000 years ago  Ways to use our water o Our waters come from the lake Ontario through giant pipes o Temperature is always 5-6 degrees o Use this water for cooling purposes  Put pipes around the building  Lake Stratification o There is a layer of water temperature difference, sometimes in the summer the surface is warmer than deeper o Whereas spring there is no stratification because there is a good mix of water temperature throughout, even deeper down o Density versus temperature curve for water Wetlands (natural sponges)  Swamps, marsh, fen, peatland, bog, moor or estuary  Areas which are saturated by surface or GW for long enough periods of time to develop characteristic wetland soils and vegetation  70% - 80% of original wetlands in S. Ontario have been lost since European settlements  Important functions o Flooding or potential areas to treat waste water o Habitat, food, breeding and nesting  What can we use the wetland for?  What can you expect below the wetland? o GW Atmosphere  Gaseous envelope that surrounds a planet  Water vapor moves into the air through evaporation from land and waterbodies  Only 0.1% of the world’s water is found in the atmosphere at any one time, but it is critical to the replenishment of water supplies as precipitation Watersheds  The topographic area within which apparent surface water drains to a specific waterbody  No matter where you live, you are in a watershed  Can cover multiple states, provinces, territories or countries  Why is it important o When calculating the river, you can know the limit and boundaries of the rivers  Conservation Authority Watersheds are in charge and take care of rivers, etc Human Effects on Freshwater Ecosystem  Dam construction, river water diversions and poor water quality alter river regimes and cause degradation of wetlands  Population growth can lead to land conversion for increased food production o Ex. wetlands are drained  Land conversion to urban or other uses can results: o Altered runoff patterns o Siltation of rivers, lakes and wetlands o Loss of aquatic habitats  Pollution caused by population growth can alter the chemistry and ecology of waterbodies Global Population Growth and Human Proliferation  don’t need to know the #’s Settlement Patterns  MEGACITIES – massive, densely populated, urban centers of 10 million or more – increasingly found in less-developed regions  Create environm
More Less

Related notes for EESA07H3

Log In


OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit