1. Unified Science: Get out your study guides Part 1
Today 12/12/13
Describe Freshwater Ecosystems

2. Fresh Water
Lake below Mt. St. Helens…hummock in lake

5. Fresh Water on the Earth’s Surface
Water is one of the most abundant substances on Earth’s surface
From space, astronauts describe the Earth as the BLUE planet.

6. Freshwater (Cont’d) OCEANS cover more than 70% of the Earth’s surface.
97% of all of Earth’s water is in the oceans (salt).
FRESHWATER makes up only about 3% of the Earth’s water.
Of the freshwater, only 15% is readily available for direct use by living things mainly because much of the freshwater is FROZEN in the ice caps near the North and South Poles and in GLACIERS.

7. Alaskan glacier

9. Half Dome as viewed from Glacier Point…Yosemite National Park

10. Yosemite falls in the height of spring melt.

11. The white areas show where glaciers and ice sheets form around the world.
(National Geographic image)

13. Note how clear the iceberg is…
Note how clear the iceberg is….remember that when ice freezes, it leaves the salt behind.

14. The Water Cycle
WATER Cycle: The continuous movement of water from OCEANS and FRESHWATER sources to air and land and BACK into the oceans.
This is called the HYDROLOGIC cycle.

15. RUNNING WATER
What are our sources of running water? How do we use them?
Freshwater rivers and streams are used for: IRRIGATION, electricity, DRINKING, and recreational purposes. They can also be used for TRANSPORTATION and for cooling. Hopefully, they will not be used to carry WASTE products.
SURFACE RUNOFF: The water that enters a river or stream after a heavy rain or during a spring thaw of snow or ice. (Yosemite)

16. What Affects Surface Runoff?
A). TYPE of soil:
PORE space: The space between particles of soil.
In general, there will be MORE runoff when soil has
SMALL pore space.
B). CONDITION soil: Is it wet or dry?
There will be more runoff if the soil is already WET. (saturated)
C). Number of PLANTS in an area
When there are more plants to absorb water in their roots, there is LESS runoff.
D). SEASON of the year
There will be MORE runoff during the RAINY season or when large amounts of snow are melting.

17. WATERSHED 3. There are three major watersheds in the United States:
Is a land area in which surface runoff drains into a RIVER or system or rivers and streams.
Watersheds are very LARGE in size. The largest ones can cover millions of acres and they drain into oceans. Watersheds PREVENT floods and WATER shortages by controlling the amount of water that goes into streams and rivers..
3. There are three major watersheds in the United States:
a. COLUMBIA River watershed
b. Colorado River watershed
c. MISSISSIPPI River watershed.
Which of these is the largest?

20. RIVERS Rivers are a source of freshwater.
Which type of river is the best source of freshwater?
Since FAST MOVING rivers tend to pick up a lot of rock, soil, and other sediment as they travel, the water in them is very cloudy.
SLOW MOVING rivers stir up less materials and so are better sources of water.
Pollution definitely affects a rivers usefulness.

21. MISSISSIPPI RIVER

22. Standing Water
In any watershed, some runoff will get caught in low spots. These low spots will form LAKES OR PONDS. Continued runoff keeps the lakes and ponds from drying up.
LAKES: Generally LARGE, deep depressions in the Earth’s crust that have filled with fresh water.
What fills them? RAIN, snow melt, springs, RIVERS, and surface runoff. Lakes are found most frequently at relatively high altitudes where glaciers once were. Lakes can be formed by a NATURAL OBSTRUCTION of a river or a stream.

23. LAKE OF THE OZARKS

24. PONDS: Typically SHALLOW depressions that fill with fresh water.
Since ponds are shallower, SUNLIGHT can reach the bottom of ponds. This allows PLANTS to grow on the bottom of ponds.

25. RESERVOIR
Is an ARTIFICIAL lake used as a source of fresh water.(Carlyle Lake/Tom Sauk Reservoir)
2. These are generally built by DAMMING a river or stream that runs into a low area.
3. Reasons to build a reservoir:
*to help prevent FLOODING
*to provide a DRINKING source
*to provide irrigation
*to generate ELECTRICITY

26. Tom Sauk Reservoir

27. HYDROELECTRIC Generator
A generator that runs on WATER. Water flows through TURBINES that are connected to a dam and these generate ELECTRICITY.
Can a reservoir be used for all 4 purposes?

30. FRESHWATER BENEATH THE SURFACE
Where does the water go that does not run off into lakes, ponds, rivers and streams?
GROUNDWATER – water that soaks into the ground and stays in the ground
How? Precipitation travels downward through the pores in the rock and soil of the ground
Soil with many spaces (sand and gravel) will hold MORE groundwater.

31. PERMEABLE VS IMPERMEABLE
Water continues to travel downwards as long as it is going through a PERMEABLE layer: a material through which water FLOWS quickly.
Impermeable: A material through which water does NOT FLOW quickly.

32. PERMEABLE - IMPERMEABLE

33. Groundwater will seep down until it reaches an impermeable layer.
When it reaches that layer, the water will begin to fill ALL THE PORES above the impermeable layer.

34. Bedrock is an impermeable layer!

35. ZONES
Zone of Saturation: An underground region in which all the pores of the soil and rocks are filled with water (sponge)
Water above the zone of saturation will not be as wet. The pores in this layer will be mostly filled with air known as the Zone of Aeration. (air-filled)
Boundary between these 2 zones is called the water table.

37. Water Table Depth Varies
Near oceans or lakes, water table may be just a few inches below the surface
In hills or mountains, the water table may be very deep.
In swamps or marshes, the water table is usually close to the surface
Can vary with climate. Deserts vs Rainforest
Varies with seasons: Spring vs summer
Low-lying areas water table is close to the surface (All surrounding water flows downhill)
Number of wells in that area
In moist climates, water table may come to the surface and form a swamp or lake

38. WELLS
Is a hole drilled or dug into the water table to bring water to the surface
Wells are less expensive to dig where the water table is HIGH. Most expensive if you have to dig deep.
Water tables are always present somewhere below the surface… you just have to dig deep enough.

39. AQUIFER
Is layer of rock or sediment that allows groundwater to pass freely through it sideways
Aquifers are typically layers of sandstone, gravel, sand or cracked limestone
It’s where a lot of freshwater is located.

40. How do Aquifers form?
1. Layer of permeable rock is sandwiched between two layers of impermeable rock and it contains water = CONFINED aquifer OR 2. When soil is saturated with groundwater is above an impermeable rock layer = UNCONFINED aquifer

42. ARTESIAN WELL
Is a well that flows on its own without pumping – always has a CONFINED aquifer
Formed when an aquifer is trapped in between 2 layers of impermeable rock carrying water from higher to lower place, pressure builds up in the aquifer.
Well is drilled into a point where the in the aquifer where pressure is high and it flows without needing to be pumped.

45. FUN FACT!
There is more fresh water below the surface of the land than water in all the lakes and reservoirs on the Earth’s surface!