1. Chapter 9: Water Erosion & Deposition

2. Aim: What affects runoff?

3. Factors that affect Runoff
Runoff is water that doesn’t soak into the ground or evaporate, but flows across earth’s surface
Factors that affect runoff
Amount of rain
Length of time
Light rain over an hour has time to soak up
Heavy rain over less than an hour will run off because it can’t soak into the ground fast enough

4. Slope of land
Gravity causes water to move down slope
Water moves quickly down steeper slopes
Water moves slowly down gentler slopes
Slower movement=water soaked up by ground
Vegetation
Plants slow down runoff and help prevent soil from being carried away
Runoff will carry more soil and sediments in places lacking vegetation

5. Aim: What are the 4 types of water erosion?
Create concept map

6. Aim: How do rivers and streams develop?

7. River System Development
Streams are parts of river systems
Can compare to a tree
Water comes from rills, gullies and small streams
Drainage basin is the area of land from which a stream or river collects runoff
All the water in a river system flows to the trunk (main river)

9. Stream Development
Stages depend on the slope of the ground over which the stream flows
3 classifications:
Young
Mature
Old
The stages of development do not always coincide with the actual age of the river

10. Young Streams Flows swiftly Slope is steep Has a rough bottom
High level of energy
Erodes bottom of stream faster than its side

11. Mature Streams Flows smoothly through its valley
Rocks in the streambed over time are eroded by running water and sediments
Erosion takes place more on the sides than the bottom
This causes curves to develop called meanders

12. Old Streams Flow through broad, flat floodplains
Drops load of silt near its mouth
Dropping of sediments forms a delta
A delta is an area of flat, fertile land extending into the ocean

13. Aim: How do deltas and alluvial fans form?

14. Deposition of Water
As water moves through a river system it loses energy
This lose of energy causes sediments to be dropped along the way
Some sediments are carried a long way, while others only short distances
When sediments are deposited as the water empties into an ocean or lake, a deposit called a delta forms
Deltas are triangular or fan-shaped

15. When a river empties from a mountain valley into a flat plain, the deposit is called an alluvial fan

16. Aim: How do soil and rock permeability affect groundwater?

17. Groundwater
Water that soaks into the ground collects in the pores and empty spaces in the soil or rock is called groundwater
14% of all water exists as groundwater
Groundwater system has connecting pores
Soil and rock are permeable if pores are connected and water can pass through them
Water flows easily through
Ex: sandstone-permeable rock

18. Impermeable rock or soil doesn’t have well connected pores or few pore spaces
Water doesn’t flow easily through
Ex: granite, clay
Groundwater keeps going deeper into Earth’s crust until it reaches a layer of impermeable rock
Zone of saturation is where all the pores in the rock are filled with water
The upper surface of this zone is the water table

19. Aim: Why is the water table so important?

20. Water Table The amount of groundwater is limited
Many people get their water from wells that have been drilled into the zone of saturation
During a draught, the water table drops
This is why it is important to conserve water

21. Wells A good well extends deep into the zone of saturation
Groundwater flows into a well and a pump brings it to the surface
If water is taken out of well faster than it can be replaced, wells can go dry
If too much water is pumped out in area, the land can drop or sink
Artesian well-doesn’t need a pump to bring water to the surface

22. Water in an artesian well rises to the surface due to pressure
Are very rare because the aquifer needs to be located between 2 impermeable layers that are sloping
Water enters at the high part of the slope and exits through a well at the low part of the slope due to the pressure created by the higher part of the aquifer

23. Springs
Springs are found on hillsides where the water table meets a sloping surface
Water flows out of the spring
Source of freshwater
Usually water comes to the surface as a cool temperature
When water comes to the surface after being heated by hot rocks, it is called a hot spring

24. Geysers Is a hot spring that erupts periodically
Groundwater is heated to high temperatures causing it to expand underground
The expansion forces some of the water out of the ground
Most of the water turns into steam
Ex: Old Faithful, Yellowstone National Park

25. Aim: What are the causes of shoreline erosion?

26. Causes of Shoreline Erosion
3 forces shape shorelines
Waves
Crash against the shorelines
Very powerful force
Erode and move away large amounts of material
Currents
Longshore currents are created by waves that hit at a slight angle

27. Carry tons of loose sediments
Tides
Outgoing tides carry sediments away from the shore
Incoming tides bring new sediments to the shoreline
Work with waves to shape shorelines

28. Aim: What is the difference between rocky beaches and sandy beaches?

29. Types of Beaches Rocky Sandy Consist of rocks and cliffs
Smooth, gently sloping beaches
Made up of grains of quartz or shell fragments
Fragments range from stones to fine sand
Some beaches have different colored sands
Ex: Hawaii-black, made of basalt
Ex: Jamaica-white, made of coral and shell
Consist of rocks and cliffs
Waves and sediments slowly wear away rocks
Rock parts that break off are carried away by longshore currents

30. Aim: How do barrier islands form?

31. Barrier islands
Are sand depositions that lay parallel to the shore but are separated from the mainland
Start out as underwater sand ridges
Hurricanes and waves help form the islands
Last only a few years to a few centuries
Storms and waves also erode the barrier islands and cause erosion to beachfront developments