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The Big Question: “How does fresh water cycle on Earth?”

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Presentation on theme: "The Big Question: “How does fresh water cycle on Earth?”"— Presentation transcript:

1 The Big Question: “How does fresh water cycle on Earth?” http://www.brainpop.com/science/earthsystem/watercycle/

2  Why is water important?  Where is water found?  What is the water cycle?

3 Complete Figure 3 on page 8 throughout the PowerPoint

4 ◦ Allows organisms to:  Break down food  Grow  Reproduce  Get and use materials they need from their environments ◦ Provides habitats (place where organism lives):  Water-dwelling organisms (i.e. sharks)

5  Salt water (97%)  Fresh water (3%) ◦ 2/3 frozen in huge masses of ice (Poles) ◦ 1/3 underground ◦ Tiny amount in lakes and rivers ◦ Tiny amount in the atmosphere (water vapor) Pop Quiz: Do water or land habitats contain more types of organisms? Water Habitats!

6  Water Cycle: A continuous process by which water moves from Earth’s surface to the atmosphere and back, driven by energy from the sun and gravity. ◦ Water moves between land, living things, bodies of water on Earth’s surface, and the atmosphere.

7  Evaporation: Process by which molecules at the surface of a liquid absorb enough energy to change to a gaseous state.  Transpiration: Water is given off through the leaves as water vapor.  Condensation: Water vapor cools and condenses into a liquid (Droplets of liquid water clump around solid particles in the air forming clouds)  Precipitation: Water droplets large enough to fall back to Earth (as rain, snow, sleet, or hail)  Runoff: Small amount of remaining precipitation that runs off the surface into streams and lakes

8 Evaporation Condensation Transpiration Runoff Precipitation

9  Take out the sheet you picked up when you came in and prepare to get wet!

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11 http://www.brainpop.com/science/earthsystem/watercycle/

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13  What is a river system?  What are ponds and lakes?  How can lakes change?

14  A river and all the streams and smaller rivers that flow into it together make up a river system.  Tributaries  Watersheds  Divides

15  Streams and smaller rivers that feed into a main river.

16  The land area that supplies water to a river system. (a.k.a. drainage basins)

17  Ridge of land separating watersheds. ◦ Great Divide (a.k.a. Continental Divide) is the longest divide in North America

18  Contain still water  Form when water collects in hollows and low- lying areas of land  Ponds are generally smaller and shallower than lakes  Source of water: ◦ Rainfall ◦ Melting snow and ice ◦ Runoff ◦ Rivers ◦ groundwater

19  Oxbow Lake: River may bend and loop.  Formed in depressions created by ice sheets that melted at the end of the Ice Age (Great Lakes)  Created by movements of Earth’s crust (rift valleys)  Volcanoes ◦ Lava or mud from a volcano can block a river, forming a lake ◦ Form in the empty craters of volcanoes  Build a dam ◦ A lake that stores water for human use is called a reservoir.

20  Natural processes and human activities can cause lakes to disappear.

21  As lake organisms die, bacteria break down the bodies and release nutrients into the water (such as nitrogen and phosphorus)  Algae use these nutrients and spread, forming a layer on the lake’s surface. ◦ When algae layer becomes so thick that it blocks sunlight, plants cannot carry out photosynthesis and die ◦ Decaying material piles up on the bottom, making the lake shallower ◦ Area fills with plants and a meadow replaces the former lake. ◦ Fertilizer (speed up the growth of algae)

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23  How does water move underground?  How do people use groundwater? http://www.brainpop.com/science/earthsystem/groundwater/

24  Water underground trickles down between particles of soil and through cracks and spaces in layers of rock. ◦ Pore: spaces between particles ◦ Permeable: Materials (sand and gravel) that have large connected pores (water can pass through easily) ◦ Impermeable: Materials (clay and granite) that have very small pores (water can’t pass through easily)

25 PERMEABLE!

26 IMPERMEABLE!

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28  Spring: Where groundwater meets the Earth’s surface.  Aquifers: Any underground layer of permeable rock or sediment that holds water and allows it to flow (aquifer sizes vary) ◦ Not an unlimited source of water…drops if more water is used than replenished Ogallala Aquifer

29  Rate depends on: ◦ Slope of water table ◦ Permeability of the rocks  Some move a few centimeters per day  Groundwater may travel hundreds of kilometers and stay in an aquifer for thousands of years before coming to the surface again

30  Used to obtain groundwater from an aquifer (drilled to an area below the water table)

31  Mechanical pumps bring the water up the well.  Use too much water = well dry up ◦ Need to wait for rainfall to refill the aquifer  Artesian well: Water rises on its own due to pressure in the aquifer Groundwater trapped between two layers of impermeable rock.

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33  Aquifer Diagram ◦ Fill in as many of the questions as you can without using your book or notes.

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35  What are wetlands?  Why are wetlands important?

36  Land area that is covered with a shallow layer of water during some or all of the year ◦ Help control floods ◦ Provide habitats for many species Bill Nye: Wetlands (Safari Montage)

37  Marshes (grassy areas covered by shallow water or streams; cattails and grasslike plants)  Swamps (look more like flooded forests; many are located in warm, humid climates)  Bogs (form in depressions left by pieces of melting ice sheets thousands of years ago; water in bogs tend to be acidic; moss thrives in these conditions)

38  Wetlands along coasts (fresh and salt water) ◦ Salt marshes (found along the east and west coasts of the U.S.; grasses grow in rich mud) ◦ Mangrove forests (found along southeastern coast; thick, tangled roots)

39  Habitat to many (sheltered waters; rich supply of nutrients)  Natural water filter  Control floods (absorb extra water)  Make climates more moderate


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