Rivers Flashcards
(90 cards)
1
Q
Evaporation
A
process in which liquid water turns into vapour
2
Q
Condensation
A
process in which water vapour turns into liquid
3
Q
Precipitation
A
process in which water (liquid or solid) falls to the ground due to gravity
4
Q
Interception
A
Where precipitation is stopped from reaching the ground due to the presence of plants (like trees)
5
Q
Infiltration
A
Where water seeps into the ground
6
Q
Percolation
A
Downward movement of water from the soil layer into the groundwater
7
Q
Surface run-off
A
Where water runs over ground into rivers
8
Q
Surface storage
A
Collection of water on the surface
9
Q
Throughflow
A
where infiltrated water flows through soil
10
Q
Groundwater flow
A
where infiltrated water flows through rocks
11
Q
Groundwater storage
A
Collection of water stored underground
12
Q
What is a drainage basin?
A
the area of land drained by a river and its tributaries
13
Q
What is a closed system?
A
Where there is always the same amount of water inside
14
Q
Is the hydrological system open or closed?
A
Closed
15
Q
Is a drainage basin open or closed?
A
Open
16
Q
What are watersheds?
A
The highest land that forms a natural dividing line between drainage basins.
17
Q
What is a tributary?
A
A river that joins a river
18
Q
Whats a confluence?
A
The point where a river meets its tributary
19
Q
What is a source?
A
Source is where river water comes from
20
Q
What is a mouth
A
A mouth is where water enters or exits
21
Q
What does erosion mean?
A
To tear down
22
Q
Name the four types of erosion
A
Hydraulic Action
Abrasion
Corrosion
Attrition
23
Q
What is hydraulic action
A
Simple:
Where water/debris is forced into cracks
Detailed:
The force of water on bed & banks of river, powerful when in flood, force of water removes from bed & banks.
24
Q
What is abrasion
A
Simple:
Where rocks/stones erode the bed + sides of a river bank
Detailed:
When river is particularly full, pebbles and boulders are carried along by water. These rub against the bed and banks of river and wear them away
25
What is corrosion
Simple:
where rocks get smaller by chemical action
Detailed:
River water sometimes causes rocks to slowly dissolve (like limestone in slightly acidic water), carried away in solution (calcium hydrogen carbonate)
26
What is attrition
Simple:
Where rocks get smaller when knocked together
Detailed:
Where rocks rub against each other, breaking into smaller and smaller pieces, eventually reduced to sand
27
What is a river's long profile diagram showing?
The upper, middle, and lower course of a river.
28
What is vertical erosion?
It is in the upper course of the river, where erosion is primarily downward, because it's trying to get to the sea.
This produces steep valleys.
29
What is lateral erosion?
It occurs often in the lower and middle course of the river. River has a lot of energy and widens the channel & creates meanders.
30
Name the types of transportation
- Traction
-Saltation
-Suspension
- Solution
31
What is traction
Large rocks/boulders rolled along river bed
32
What is saltation
Smaller stones bounced along river bed like leap frog
33
what is Suspension
Very small grains of sand/silt carried with water
34
What is solution
where some material is dissolved and carried downstream
35
What is deposition?
The force of water slows so the power to carry materials is gone.
The river will deposit materials when:
- it reaches sea
- there is friction
- it is as low flow (drought/dry season)
36
What is discharge?
The volume of water that passes through a cross-section per unit of time. (Measured in cubic meters per second)
37
What is Occupied channel width?
distance across the actual channel, measured at water's surface
38
What is channel depth?
The height from water surface to bed
39
What is average velocity?
speed of water flow
40
What is load quantity?
the capacity of a river
41
What is load particle size?
The size of the materials carried by a river
42
What is channel bed roughness?
How rough/smooth the bed of a river is
43
What is the slope angle/gradient?
The angle or gradient of the river
44
When going from upstream to downstream, does the discharge increase or decrease? Why?
Increase due to input from a greater amount of the river basin above that point
45
When going from upstream to downstream, does the occupied channel width increase or decrease? Why?
Increases due to the increase in discharge, input from tributaries, etc.
46
When going from upstream to downstream, does the channel depth increase or increase? Why?
Increase downstream as more water is added as the river erodes a big channel
47
When going from upstream to downstream, does the average velocity increase or decrease? Why?
Steadily increases downstream because there's less friction
48
When going from upstream to downstream, does the load quantity increase or decrease? Why?
Increases with discharge and velocity because river has more energy
49
When going from upstream to downstream, does the load particle increase or decrease? Why?
Decreases considerably downstream due to attrition
50
When going from upstream to downstream, does the channel bed roughness increase or decrease? Why?
decreases d=because load gets smaller & rounder due to attrition + bed/banks smoothed by abrasion
51
When going from upstream to downstream, does the gradient increase or decrease? Why?
Decreases as river moves from steep mountains/hills to flatter, low-lying areas
52
What causes V-shaped valleys?
Verticle erosion
53
What part of the river can you find v-shaped valleys?
The upper course
54
Name the 4 steps of valley creation
1- A river's discharge is low in the upper course so the river only has enough energy to erode downwards.
2- The valley's sides are slowly broken down through weatherings
3- The weathered material is transported via gravity and rainfall towards the river channel. This process steepens the river sides.
4- The steep-sided and narrow valley shape that is created is typical of upland rivers
55
What part of the river can you find interlocking spurs in?
The upper course
56
Name the four steps of how interlocking spurs are formed
1) river flows through hilly area
2) River encounters hard rock mountains/hills
3) River goes around, not through them
4) The winding causes the zipper-like interlocking spurs
57
How are waterfalls formed?
1)River flows over hard and soft rocks
2) Soft rocks erode faster, creating a step
3) step deepens into a waterfall & erosion continues
4) plunge pool is created at base due to hydraulic action and abrasion
58
How are gorges formed?
1) Hard rock above gets undercut by erosion and collapses
2) Waterfall moves backward, creating gorge
3) gorge gets longer and deeper
4) weathering causes gorge sides to widen
59
What is a levee?
A natural embankment formed when river floods
They keep rivers from flooding as the sides are risen
Can be manmade
60
What is an oxbow lake?
Formed when a wide meander of a river is cut off
Shaped like a horseshoe/C/U/etc
61
What is a meander?
The winds/curves in a river's course, formed through erosion
62
What is a floodplain?
An area of flat land adjacent to river, prone to flooding
63
What is alluvium?
a deposit of clay, silt, and sand left by flowing floodwater in a river or delta, producing fertile soil
64
What is a delta?
a landform created at the mouth of a river where it meets a larger body of water, like a sea or lake, as the river's velocity decreases and sediments are deposited
65
Is the water faster on the inside or outside of a meander bend?
It is faster on the outer edge and slower on the inside
66
What is a thalweg?
The fastest flow in a river
67
With the thalweg on the outside of a meander, is there erosion or deposition?
Erosion due to the flow being faster and more powerful, and there is deposition on the inside where the flow is calmer and not powerful enough to carry the material
68
What part of the river will you find floodplains in?
lower
69
What part of the river will you find levees in?
lower
70
What two things does the rate of deposition depend on?
The speed and amount of water
71
What is a flood?
When the discharge is greater than the size of the river channel, so the river overtops its banks and spills out onto the nearby floodplain
72
Name 4 potential causes of floods
- Excessive precipitation
- Broken levees/banks
- Excess silt
- dam overflow
73
Name 6 potential impacts of flooding
- makes land more fertile (alluvium)
- destruction
- loss of life/injuries
- damages ecosystems
-contaminated water
- bioaccumulation
-money loss (repairing)
74
What is the time in between peak rainfall and peak discharge called on a flood hydrograph?
Lag time
75
What 5 factors can effect/influence storm hydrographs?
-land use
-type of rain (intensity/duration)
- soil moisture
- climate
- drainage basin
76
What is hard engineering?
Engineering that works against natural processes
77
What is soft engineering?
Engineering that works alongside natural processes
78
Name 3 examples of hard engineering
-dams
-levees
-channel straightening
79
Name 3 examples of soft engineerings
- afforestation
- land use zoning
- river restoration
80
What is the location of the Three Gorges Dam?
Yangtze River in Central China
## Footnote
The Three Gorges Dam is situated on the Yangtze River, which is the longest river in Asia.
81
What is the width of the Three Gorges Dam?
1,335m wide
## Footnote
This measurement indicates the dam's significant structural scale.
82
How tall is the Three Gorges Dam?
60 stories high
## Footnote
This height emphasizes the dam's impressive vertical dimension.
83
What is the thickness of the Three Gorges Dam?
115m thick
## Footnote
The thickness contributes to the dam's stability and strength.
84
What is the length of the reservoir created by the Three Gorges Dam?
660km long
## Footnote
The reservoir extends significantly along the Yangtze River.
85
Name the site advantages of the Three Gorge Dam (6)
- Valley wide and low
- Yangtze has huge HEP potential
- Bedrock is firm with limited cracks making firm foundation
- Seismically active area but few earthquakes near dam
- There was a small island which made building a diversion channel easy
- workers could easily get to site
86
how many generators does the three gorge dam have?
34 generators
87
name Seven advantages of the three gorge dam
- Has become a tourist attraction
- Produces clean renewable energy
- Improve navigation and trade as far as Chongqing
- Amount of flooding downstream of the dam has decreased reducing costs and saving lives
- Water is stored behind dam which can be used for drinking farming etc
- Damn created a lot of new jobs both during construction and permanent maintenance operation jobs
- Created a sense of national pride as it is the largest dam in the world
88
Name Seven disadvantages of the three gorge dam
- The Yangtze freshwater dolphin has gone extinct
- sturgeon and alligator are severely threatened because of pollution and disruption of breeding patterns
- Damn cost around 39 billion to build
- Near fault line so vulnerable to earthquakes
- Many archaeological sites were covered in water
- 1,.3 million people had to be relocated as reservoir flooded
- Farmland downstream less fertile as less aluminium will be deposited
89
name four changes upstream of the three gorge dam
- Artificial store created behind dam
- Gradient reduced
- Velocity of river reduced
- Evaporation rates behind them will increase because there is a large surface area of water
90
Name four changes downstream of the three gorge dam
- discharge reduced
- Discharge more regular
- Less load and alluvium
- velocity reduced
