Theme 2 - Rivers Flashcards
(72 cards)
1
Q
water cycle
evaporation
A
sun’s energy warms oceans and lakes, turning it into water vapor.
2
Q
water cycle
transpiration
A
Water evaporates from the leaves of plants
3
Q
water cycle
evapotranspiration
A
water moving from the surface into the atmosphere through evaporation + transpiration
4
Q
water cycle
condensation
A
The water vapor rises, cools, and condenses into clouds
5
Q
water cycle
precipitation
A
The water falls back to Earth as rain, snow, sleet, or hail
6
Q
water cycle
surface runoff / overland flow
A
water that flows over the land’s surface and into bodies of water
7
Q
water cycle
interception
A
water is caught / intercepted
by vegetation such as trees
8
Q
water cycle
infiltration
A
water seeps into the ground through the soil
9
Q
water cycle
throughflow
A
the movement of water through the soil
10
Q
water cycle
percolation
A
water seeping through permeable rocks beneath the surface
11
Q
water cycle
groundwater flow
A
moving water that has seeped into the ground and is stored in aquifers
12
Q
water cycle
aquifer
A
a body of rock and/or sediment that holds groundwater
13
Q
water cycle
surface storage
A
water held on the Earth’s surface in lakes, ponds, and puddles
14
Q
water cycle
fastest flow of water
A
throughflow
15
Q
water cycle
slowest flow of water
A
groundwater
16
Q
water cycle
impermeable rock
A
rock that doesnt allow water to pass through
17
Q
water cycle
permeable rock
A
rock that allows water to pass through
18
Q
drainage basics
source
A
where the river begins, up in the mountains
19
Q
drainage basics
mouth
A
the point where the river ends, flowing into the sea
20
Q
drainage basics
confluence
A
where two river channels meet
21
Q
drainage basics
tributary
A
small channels that branch off from the main channel
22
Q
watershed
A
the boundary of the drainage basin
23
Q
drainage basics
floodplain
A
a generally flat area of land next to a river or stream
24
Q
river basics
discharge
A
the volume of water that flows through a river channel in a given time
25
# river basics
load / bedload
the sediment that moves along the bottom of a river or stream, carried by the force of flowing water
26
# river basics
silt
fine-grained dirt, soil, or sediment that rivers carry and drop along their courses
27
# river basics
long profile
a line that shows the slope of a river from its source to its mouth
28
# river basics
cross profile
a section taken sideways across the river channel or valley
29
# river basics
gradient
a measure of how steeply it loses height
30
# river basics
velocity
how fast the flow of water of a river is moving
31
# river long profiles
downstream
- greater discharge
- greater width
- greater depth
- greater velocity
- greater load quantity
- smooth bed
- smaller load size
- flat relief/gradient
32
# river long profiles
upstream
- less discharge
- smaller width
- shallower
- slower velocity
- less load
- rough bed
- larger load size
- steep gradient
33
# erosion processes
hydraulic action
the sheer power of the water as it smashes against the river banks
34
# erosion processes
abrasion
river's flow, pebbles, and stones wear away the river's banks and bed
35
# erosion processes
corrosion / solution
certain types of rocks, like limestone or chalk, dissolve in a river's water
36
# erosion processes
attrition
rocks and pebbles in a river's flow collide with each other
37
# erosion processes
factors influencing the speed of erosion
- faster velocity = more erosion
- steeper slope = more erosion
- more acidic water = more erosion (solution)
38
# transportation processes
traction
large, heavy rocks are rolled or dragged along the river bed
39
# transportation processes
saltation
small rocks and pebbles bounce along the river bed
40
# transportation processes
suspension
the carrying of fine, light particles in the water
41
# transportation processes
solution
when certain types of rock, like limestone or chalk, dissolve in a river's water and are carried along
42
deposition in rivers
- greatest in the lower course
- heaviest particles deposit first
- occurs in low energy water / low velocity
- inner bend of river
- forms slip off slope
43
upper course features
- v shape valley
- steep relief
- interlocking spurs
44
# upper course features
interlocking spurs
extend from opposite sides of a V-shaped valley, creating a zip-like pattern
45
# upper course features
pot hole
a circular depression in a river bed or exposed rock layer that is formed by vertical erosion
46
# upper course features
rapids
areas of a river or stream where the water flows quickly and shallowly over rocks
47
# upper course features
formation of a waterfall explained
1. river's sediment erodes softer rock, e.g. sandstone or limestone
2. river undercuts hard rock, creating an overhang that eventually collapses
3. falling water creates a plunge pool at the base of the waterfall.
4. falling water and sediment erode the plunge pool, causing more erosion.
5. waterfall retreats upstream as the soft rock erodes further.
6. a steep-sided gorge forms behind the retreating waterfall.
48
hard rock example
granite
49
soft rock example
limestone
50
# upper course features
overhang
when erosion undercuts rock, leaving rock hanging over, unsupported
51
# upper course features
undercut
the process of erosion on the lower layer of rock
52
# upper course features
plunge pool
deep pool of water at the base of a waterfall that's formed by erosion from falling water, rocks, and other sediment
53
middle course features
- u shaped valley
- gentle hills
- meanders
54
# middle course features
meander
a bend in the river
caused by deposition and erosion on the inner and outer bends of the river, due to the thalweg.
55
where does erosion occur?
outside bend
line of greatest velocity
"thalweg"
creates river cliff due to undercutting
56
# middle course features
oxbow lake formation explained
when the meander neck is broken through by erosion and deposition causes sediment to built up, separating the original channel from the previous meander.
eventually, the previous meander will be completely separate from the channel.
this is called an oxbow lake
57
# middle course features
marsh
wetlands that form in shallow areas along the edges of lakes, rivers, or seas.
58
lower course features
- flat floodplains
- deltas
- levees
- flat relief
59
# lower course features
delta
landforms that form when a river or other body of water slows down and empties into a larger body of water, such as an ocean or lake
this results in mass deposition of sediment
60
# middle course features
formation of delta explained
1. As a river approaches a larger body of water, its velocity decreases, causing it to lose the ability to carry sediment
2. The river drops the sediment it's carrying at its mouth, creating a deposit
61
# middle course features
levee
natural embankments on the sides of rivers
62
# middle course features
formation of levee explained
1. When the river floods, the sediment spreads out across the floodplain.
2. friction between the ground + water causes it to slow down, depositing the most heavy sediment first
3. this eventually builds up, forming embankments made up of deposited sediment
63
causes of river hazards
- steep/very flat relief
- hard baked soil (drought)
- deforestation/lack of vegetation
- underlying impermeable rock
- urbanisation
64
features of a hydrograph
- rising limb
- faling/recessional limb
- lag time
- peak rainfall
- peak discharge\flashy rivers rise faster and higher
- flat rivers have a longer lag time
65
# flooding management
hard engineering
- dams
- storage reservoirs + channels
- dredging
- embankments + levees
- flood walls
- straightening / channelisation
66
# flooding management
soft engineering
- wetland / marsh management
- afforestation
- land use zoning
- sandbags
- evacuation warnings
67
opportunities of living near a river
- fertile soil (alluvium)
- drinking water
- tourism + leisure
- transportation route
- floodplain provides flat land
68
# CASE STUDY: Opportunities + Hazards - **Ganges River** in **Bangladesh**
Introduction
- 2,510km long
- flows through India and Bangladesh
- drainage basin covers 1.2 million km2
- source is in himalayan mounters
- mouth enters the bay of bengal
69
# CASE STUDY: Opportunities + Hazards - **Ganges River** in **Bangladesh**
Opportunities
- water supply
- agriculture + fishing -> flooding leaves alluvium which is very rich in nutrients
- sacred to hindus
- rafting and river cruises are popular among tourists
- flat flood plains are easy to build on
- many dams along the river that provide HEP
70
# CASE STUDY: Opportunities + Hazards - **Ganges River** in **Bangladesh**
Hazards
- regular floods
- 1998: 75% of bangladesh flooded, 30 million made homeless
- these floods cause deaths and the loss of agriculture + crops
71
# CASE STUDY: Flood Hazard Management - **Ganges River** in **Bangladesh**
Introduction
- 2,510km long
- flows through India and Bangladesh
- drainage basin covers 1.2 million km2
- source is in himalayan mounters
- mouth enters the bay of bengal
72
# CASE STUDY: Flood Hazard Management - **Ganges River** in **Bangladesh**
Management
- better flood forecasting + warning systems
- well stocked food shelters
- constructing levees + embankments
- 5000 flood shelters built
- dams to store water
