WEEK 8 - Rivers Flashcards
1
Q
What Do Streams in the Earth System Do?
A
- Streams carry water across land and connect it to the sea.
- They move excess water (from rain) that doesn’t soak into the ground or evaporate.
- Act as major water flow pathways on Earth’s surface.
2
Q
What is a Stream?
A
- A stream is flowing water that moves downhill in a channel.
- It carries rock particles and dissolved ions (from weathered rocks).
3
Q
Why Are Streams Important?
A
- Move water from land to sea
- Erode and move sediment (helps form sedimentary rocks)
- Carry dissolved minerals to oceans (why oceans are salty)
- Provide water and are used for transportation
→ Many cities are built along streams
4
Q
Origin of Streams – Where Does Rainwater Go?
A
- Evaporate into the air
- Soak into the ground (becomes groundwater)
- Stay on the surface as runoff → flows into streams
5
Q
How Runoff Becomes a Stream
A
- Runoff first spreads out in a thin layer = sheetflow
- Then it gathers into small channels = rills
- These rills may grow into larger streams over time
6
Q
How Streams Grow Larger
A
- Rills merge into larger, more permanent stream channels
- These streams become tributaries of bigger rivers
- A river is just a stream with multiple tributaries
7
Q
What Are The Stream Characteristics?
A
- Ability to downcut
- Gradient
- Load
- Stream Flow
- Channels
- Valleys
8
Q
Stream Characteristics – Ability to Downcut
A
- Streams erode downward to reach base level (sea level)
- The higher the elevation above sea level, the faster the downcutting
- Erosion is strongest at the headwaters (highest points)
9
Q
Stream Characteristics – Gradient
A
- Gradient = the slope of the stream
- Higher gradient at the headwaters (upper part of stream)
- Lower gradient near the mouth (where the stream meets the sea)
10
Q
Stream Characteristics – Load (Three Types)
A
- Stream Load
- Bedload
- Suspend Load
11
Q
What is Stream Load? (Load)
A
- How streams carry sediment
12
Q
What is Bedload? (Load)
A
- Large/dense particles
- Move by tumbling or saltation (bouncing)
- Stay mostly on the bed of the stream
13
Q
What is Suspended Load? (Load)
A
- Small/light particles
- Stay suspended in the water (small and light particles (e.g., dirt, sand, clay) float in the water, carried by the flow, instead of sinking to the bottom)
14
Q
What do Bedload and Suspended Load have in common?
A
Both decrease in size as the stream moves downstream (away from sediment source).
15
Q
Stream Characteristic - River Flow (Two Types)
A
- Turbulent Flow
- Laminar Flow
16
Q
What is Turbulent Flow? (River Flow)
A
- Occurs near the bottom and sides of the stream.
- Water moves in swirling, chaotic patterns (called eddies).
17
Q
What is Laminar Flow? (River Flow))
A
- Occurs in areas away from turbulence.
- Water flows in smooth, straight lines.
18
Q
Common Misconception: River Speed
A
- In The House at Pooh Corner, it says streams are faster near their source and slower farther down.
- But actually, rivers can flow faster downstream because they get more water from other streams, even though the slope may be gentler.
19
Q
Stream Characteristics - Channels (Two Types)
A
- Headwaters
- Lower Course
20
Q
What is Headwaters? (Stream Channel)
A
- Small, shallow channels
- Coarse bedload (larger particles)
- Turbulent flow (swirling water)
- Low overall velocity (drag affects most of the water)
21
Q
What is Lower Course? (Stream Channel)
A
- Large, deep, wide channels
- Fine bedload (smaller particles)
- Laminar flow (smooth water)
- High overall velocity (drag near the stream bed)
22
Q
Stream Characteristics - Valleys
A
- River channels are surrounded by valleys.
- Valleys form when streams wear away the river banks.
- The weakened banks crumble and fall into the river.
- This material becomes sediment the river carries.
23
Q
Valleys at Headwaters
A
- High above base level.
- Tend to be deep and V-shaped.
- Rapid downcutting creates this shape.
- No strong meandering (snake like) pattern
24
Q
Valleys in Lower Parts of Stream
A
- Close to base level.
- Tend to be broad due to less downcutting.
- More lateral movement (sideways erosion).
- Meandering pattern more noticeable.
25
What are Floodplains?
- Flat areas next to rivers formed by flood sediment.
- Built up when floods deposit sediment.
26
What is Pooh Sticks?
- A game from Winnie the Pooh
- Invented in The House at Pooh Corner by A.A. Milne (1928).
- Chapter 6: Pooh invents a game and Eeyore joins.
27
How to Play Pooh Sticks
- Players drop sticks into a river from one side of a bridge.
- Run to the other side.
- First stick to float out wins!
28
The Real Life Poohsticks Bridge
- Located near Hartfield, West Sussex, UK.
- Crosses Steel Forge Stream (a tributary of the River Medway).
29
Nifty Fact: Fastest Flow in a Meandering Stream
- The middle of the river isn't always the fastest.
- The fastest water flows in a path called the thalweg.
- In curving (meandering) rivers, the thalweg shifts toward the outer bank of the bend.
30
Pooh Sticks Tip: How to Win
- Drop your stick into the thalweg – the fastest-moving part of the river.
- It's usually near the outer curve of the river, not the center.
- Your stick will reach the other side of the bridge quicker!
31
How a Meandering Stream Moves Sideways (Lateral Movement)
- The thalweg (fastest flow) shifts toward the outer bend of a curve.
- Water moves faster on the outer bend (high pressure), and slower on the inner bend (low pressure).
- This difference in speed and pressure causes the stream to erode the outer bank and deposit sediment on the inner bank.
32
Helical Flow: The Corkscrew Motion of Water
- To balance pressure, water flows downward on the outer bend, across the stream bottom, and upward on the inner bend.
- This creates a helical flow – a circular or spiral water movement (like a corkscrew).
- Helical flow helps the river slowly shift its course sideways over time.
33
How Meanders Shift Over Time
- Fast flow on the outer bend cuts into the bank, creating a steep cut bank.
- Slow flow on the inner bend drops sediment, building up land.
- Over time, the whole meander shifts sideways toward the cut bank.
34
WHAT IS CAM'S FAVOURITE RIVER?
St. Mary River, Alberta
35
What is an oxbow lake?
- A curved, U-shaped lake.
- Formed when a river meander gets cut off from the main river.
36
What is discharge in a river?
- Discharge is the amount of water flowing past a point in the river over time.
- It’s usually measured in cubic meters per second (m³/s).
- More water = higher discharge.
37
What happens in the lowest part of a river’s course?
- The river loses coarse sediment.
- It still carries lots of fine sediment (bedload + suspended load).
38
Why is river discharge highest in the lowest course?
- Because many tributaries add water along the way.
- More water = higher discharge (total water volume passing a point).
39
Example of a high-discharge river
The Mississippi River – collects water from many tributaries across North America.
40
What is the Mississippi River Drainage Basin?
- It’s the largest drainage basin in the U.S.
- Most U.S. rivers eventually flow into the Mississippi River.
41
What does the lower Mississippi River carry?
- A huge amount of water (high discharge).
Lots of fine sediment:
- Fine sand and silt = bedload
- Mud = suspended load
42
Why is the Mississippi River so muddy?
- It carries a huge amount of fine sediment, like mud, silt, and fine sand.
- This gives the river its brown, murky look.
43
How has the muddy Mississippi influenced local culture?
It inspired the name of the Mississippi Mud Pie, a popular dessert in the region
44
What is floodplain deposition?
- During a flood, water flows over the riverbanks onto the floodplain.
- As the water slows down, it drops sediment.
45
Why is floodplain deposition important?
- It mostly happens in low-gradient (flat) parts of a river.
- Helps build up new land around the river.
46
What types of sediment are deposited during floods?
- Sand and silt (heavier stuff) is dropped near the river.
- Mud (finer stuff) spreads farther out across the floodplain.
47
What are levees?
- Levees are raised ridges made of sand and silt that sit next to a river channel.
- They are part of the floodplain and are usually visible when water levels are normal.
48
How do levees form?
- During a flood, the river spills over its banks.
- As the water slows down, it drops its heaviest sediment (sand and silt) close to the river.
- This builds up over time to form levees.
49
What is the "Levee" in Don McLean’s song American Pie?
- In the song, “the Levee” refers to a bar where Don McLean used to go to drink and listen to music.
- The song connects to a big moment in music history — the 1959 plane crash that killed Buddy Holly, Ritchie Valens, and The Big Bopper.
50
Why is “the Levee” symbolically important in the American Pie?
- The word levee also connects to Louisiana, a state with many actual levees along rivers.
- Louisiana is where rock and roll really developed — thanks to its mix of music styles and cultures.
- So “the Levee” isn’t just a bar — it also nods to the roots of rock and roll.
51
How did Louisiana’s culture influence music?
- Louisiana has many cultures because it's a historic hub for immigration.
- This cultural mix led to a fusion of music styles — a big reason rock and roll developed here.
52
Why did so many people settle in Louisiana?
- The Mississippi River was an important transportation route, attracting immigrants.
- It created floodplains with fertile soil, perfect for farming — especially cotton.
53
What role did African Americans play in early music?
- Enslaved African Americans brought spiritual songs, which later influenced rhythm and blues.
- Many worked in cotton fields that existed because of Mississippi River floodplain soil.
54
What influence did Cajuns have on the development of rock and roll?
- Cajuns brought lively music and culture (a "joie de vivre") to Louisiana.
- Their style blended with other music traditions in the region.
- This mix helped shape the unique sound that eventually led to rock and roll.
55
What other styles blended into early rock and roll?
- Add some bluegrass (like in Hank Williams' "Jambalaya")
- Add some jazz — another Louisiana classic
- Mix it all together = Rock and Roll 🎸
56
What does the Mississippi River have to do with modern music?
- The Mississippi made the region what it is — full of culture, people, and music.
- Without it, rock and roll (and even pop music) might never have happened!
