Rivers Flashcards
(130 cards)
1
Q
Define precipitation
A
Rain or snow that falls onto the ground and sometimes condenses
2
Q
Define condensation
A
Water which collects as droplets on a cold surface when humid air is in contact with it.
3
Q
Define evaporation
A
The changing of a liquid into a gas.
4
Q
Define interception
A
When rain water is intercepted by trees and plants.
5
Q
Define evapotranspiration
A
The loss of moisture directly from rivers or lakes or from transpiration.
6
Q
Define overland flow/ surface run-off
A
When the water can’t infiltrate into the ground and it flows down hill to the rivers or sea because it is saturated.
7
Q
Define infiltration
A
The downward movement of water though tiny spaces in the soil.
8
Q
Define throughflow
A
The movement of water sideways underground
9
Q
Define percolation
A
The movement of water downwards though soil and rocks.
10
Q
Define groundwater flow
A
This is the movement of water sideways through the soil.
11
Q
Define water table
A
The level below which the ground is saturated with water.
12
Q
Define source
A
The beginning of a stream or river
13
Q
Define mouth
A
The end of a river where it empties into large body of water.
14
Q
Define tributary
A
A river or stream that flows into another stream, river or lake.
15
Q
Define confluence
A
When two rivers or streams meet and flow together.
16
Q
Define watershed
A
The term given to the land that drains water into a particular stream or river.
17
Q
Define attrition
A
When boulders and other materials are being transported along the bed and collide and break up into smaller pieces.
18
Q
Define hydraulic action
A
When the sheer force of the river dislodges particles from the rivers bank and bed.
19
Q
Define corrasion
A
When smaller material carried in suspension rubs against the banks of the river.
20
Q
Define corrosion
A
When acids in the river dissolve rocks.
21
Q
What is a v shaped valley?
A
V-shaped valleys are formed in the upper course where the river channel is narrow and fast flowing. The material is transported downstream by the river. This results in the distinctive v shape.
22
Q
Define a waterfall
A
Occurs when a river meets a band of softer, less resistant rock after flowing over relatively hard rock.
23
Q
Define an interlocking spur
A
Occurs because of the river taking the path of least resistance and looks like protruding hill sides that limit you from seeing further up or down the river.
24
Q
What happens in traction? (River transport process)
A
Large boulders and rocks are rolled along the bed.
25
What happens in saltation? (River transport process)
Small pebbles and stones are bounced along the river bed.
26
What happens in suspension? (River transport process)
Fine light materials are carried along in the water.
27
What happens in solution? (River transport process)
Minerals are dissolved in the water and carried along in solution.
28
Define a meander
A twist or turn in a river.
29
What is a ox box lake?
When a meander is cut through due to the continual erosion and the neck of the meander gets smaller.
30
Define deposition
When the sea loses energy it drops the sand, rock particles and pebbles it has been carrying.
31
When is deposition likely to occur?
When:
Waves enter an area of shallow water
When there's little wind
32
What's a levee?
An embankment built to prevent the overflow of a river.
33
What is a floodplain?
An area of low lying ground adjacent to a river, formed mainly of river sediments and subject to flooding.
34
How is a delta formed?
Formed by deposited material sand and silt that have built up.
35
What is a drainage basin?
An area of land drained by a main river and it's tributaries that can store rainwater within the river channel or lakes.
36
What's a watershed?
The thing that divides one drainage basin from another.
37
Define inputs
Where water enters the system through precipitation
38
Define outputs
Where water is lost from the system to the sea or by evapotranspiration.
39
Define stores
Places where water is held, (soil lakes etc)
40
Fill in gaps:
| As the ________ of the river increase so does the load it can carry and the rate at which it ________.
Velocity
| Erodes
41
What happens in vertical erosion?
When the river erodes vertically and leads to steep sided, narrow valleys shaped like the letter "V".
42
Define storm run off
Rain that falls on streets, parking areas sports fields etc.
43
What is the drainage density?
The total length of all the streams in the basins divided by the total area of the basin.
44
What is surface storage?
When water lies on uneven ground, like puddles
45
What else is the hydrological cycle known as?
The water cycle
46
What is the upper course of a river like?
It has a larger bed load, more roughness, turbulence and friction.
47
What is the lower part of a river like?
Has the greatest cross section
48
Define discharge
Amount of water flowing.
49
What does erosion involve?
The wearing away of rock and soil found along the river bed and banks.
50
What are the four main forms of river erosion?
Hydraulic action
Abrasion
Attrition
Solution
51
What are the four main river transport processes?
Solution
Suspension
Saltation
Traction
52
What do rivers need to transport material ?
Energy
53
What happens when the rivers energy levels are very high?
| And where usually in a river?
Large rocks and boulders can be transported.
| Near the rivers source- steep and narrow
54
What happens when the rivers energy levels are low?
| And where usually in a river?
Only small particles can be transported
| At the mouth
55
When is deposition most common?
Towards the end of a rivers journey - the mouth.
56
Deposition at the mouth can cause what to form?
Deltas
57
What do upper course features include?
Steep sided V shaped valleys, interlocking spurs, rapid,waterfalls and gorges
58
What do middle course features include?
Wider, shallower valleys
Meanders
Ox box lakes
59
What do lower course rivers feature?
Wide flat valleys
Floodplains
Deltas
60
What is the gradient like in the upper course?
Steep and narrow
61
How are interlocking spurs formed?
As the river erodes the landscape in the upper course it winds and bends to avoid areas of hard rock.
62
What is the energy and volume of water like in the middle course?
It has more energy
| High volume of water
63
Fill in the gaps:
| A larger river channel means there is less _________, so the water flows _______.
Friction
| Faster
64
What is the gradient and erosion like in the middle course?
It has a gentle gradient
| And sideways erosion
65
What widens the river channel in the middle course of a river?
Sideways erosion
66
How are meanders formed?
As the river erodes laterally to the right side and then to left side, it forms large bends and then horseshoe like hoops called meanders.
67
The formation of meanders is due to?
Both deposition and erosion
68
Fill in the gaps:
The force of the water _________ and undercuts the river bank on the outside of bend where the to water flow has the most energy due to the _____________ friction.
Erodes
| Decreased
69
Fill in the gaps:
| On the _______ of the bend where the river is slow the material is deposited as there is ________ friction.
Inside
| More
70
After the meander keeps forming what else happens and is formed?
Over the time the horseshoe shape becomes tighter until the ends become very close together. As the river breaks though eg during a flood the ends join and the loop is cut off from the main channel. The cut off loop is called an oxbow lake.
71
Because of the low energy levels in the lower course what happens?
Deposition
72
In the lower course does the river have a high volume?
Yes and a large discharge
73
Why is a floodplain very fertile?
Due to the rich alluvium deposited by floodwaters.
74
What are good places for agriculture?
Floodplains
75
When alluvium builds up on the banks of a river what's formed?
Levees
76
When a river runs over alternating layers of hard and soft rock what is formed?
Waterfalls
77
What features are created when a river erodes laterally creating large sweeping bends in the river channel?
Meanders
78
What is the likelihood of a river bursting it's banks and flooding determined by?
Factors in the surrounding landscape such as steepness of the river valley, the amount of vegetation and rock types.
79
How does a flood occur?
When a river bursts it's banks and the water spills onto the floodplain.
80
What can cause flooding?
Heavy rain
81
Fill in the gaps:
| The _______ the rainwater reaches the river channel the more likely it is to flood.
Faster
82
What factors may encourage flooding?
A steep sided channel - steep slopes cause fast surface run off
Lack of vegetation or woodland- no interception, surface run off high
If Drainage basin made from impermeable rock(allowing no water to pass through) , no water can percolate. Faster surface run off
If you're in an urban area- impermeable concrete, encourages overland flow, sloping areas increase run off, drains and sewers take water quickly and directly to river channel
83
Give some flood management techniques.
Afforestation- deliberate planting of trees and plants
| Restrict urban development on flood plains
84
Give a positive and negative impact of flooding
Pos: deposits alluvium onto floodplain- fertile good for agriculture
Neg: damage homes and possessions and communications
Poor countries don't have resources
85
Give some causes of flooding
Heavy rain
Saturated ground
Rapid surface run off- steep slopes
Too many rivers meeting- high discharge too fast
86
Give some effects of flooding
```
Homes businesses cars lost
Income from tourism lost
Local economy
Insurance claims
Lives lost
Crops roads destroyed
No electricity
No clean water
Trapped
Disease
```
87
Define the hydrological cycle
The continuous process by which water is circulated throughout the earth and it's atmosphere.
88
How is a delta formed?
They're formed when the river deposits it's material faster than the sea can remove it.
89
How is a waterfall formed?
River flows over bands of softer and harder rocks
Softer rock is more quickly eroded
The river undercuts the harder rock leaving an overhang
The river forms a plunge pool below the waterfall
Overhanging rock is unsupported and falls into the plunge pool
The waterfall is moved upstream
This process continues.
90
How is a levee formed?
The river is on it's floodplain with low gradient
River mainly depositing
When river floods a lot of silt is deposited on the river banks
Frequent flooding continues this build up
When river is flowing it usually deposits in the river bed
This raises the river above the flood plain
Usually the built up levees protect the plain from flooding.
91
What features do waterfalls create?
Gorges
92
Rivers erode which side of a river bend?
Outside
93
What is the main activity of a river in the lower course?
Deposition
94
As a river floods what feature is created?
Levee
95
What creates rapids?
Ridges of hard rock on the ground it creates an uneven slope.
96
How are floodplains made?
Floodplains are made by a meander eroding sideways as they travel downstream. When a river breaks it's banks and floods, it leaves behind layers of alluvium. These gradually build up to create the floor of the floodplain.
97
What can you do manage flooding? (Hint: hydrographs)
Trying to lengthen the amount of time it takes for the water to reach the river channel , therefore increasing the lag time.
98
Give two hard engineering (expensive) options to prevent flooding
Dam construction- water is held back and released in a controlled way, controls flooding
Stored in a reservoir behind dam- can be used for hydroelectric power
Sediment is often trapped behind the dam, less erosion downstream
River engineering- channel widened- to carry more water. Channel straightened , faster along course, diverted from settlement
99
Give three soft engineering options to prevent flooding
Afforestation- more interception, low cost
Managed flooding- river easily allowed to flood naturally in places to prevent flooding in other areas eg settlements
Planning - stop urban development near floodplains
Restriction to building homes
100
What would you say is the best option to prevent flooding?
Planting trees, as it causes little damage to the environment and doesn't involve the resettlement of communities.
101
What is Bangladesh
Densely populated LEDC
102
How many rivers from the delta in Bangladesh?
3
103
Why is flooding an annual event in Bangladesh?
The rivers burst their banks
104
Why is the seasonal flooding beneficial ?
It provides water for the rice and crops
| Helps keep the soil fertile
105
What does Bangladesh also experience?
Tropical cyclones- high winds and rainfall
106
Why is Bangladesh easily flooded?
Low land
107
In Bangladesh what has increased the effects of flooding?
Building on floodplains
| Cutting trees down
108
Give advantages of living in Bangladesh
Floodplains of the delta are very fertile rice is grown
| Area used for shrimp farming
109
Give disadvantages to living in Bangladesh
Low land - vulnerable to flood
| Poor communication, locals don't have telephones for give flood warnings
110
How are the risks of flooding being reduced in Bangladesh
Being funded by world bank to project monitoring flood levels, construction of flood banks and artificial levees
Coastal flood shelters built
111
In what year did the river Rhine flood in ?
1995
112
Where is the river Rhine?
In Europe
| Passes through Switzerland, Germany and France.
113
What's the population of river Rhine basin?
40 million
114
How many people were evacuated in river Rhine?
250,000
115
How many deaths did the river Rhine cause?
27 deaths
116
What caused the river Rhine to flood?
Heavy rainfall - saturated soils
Melted snow from the alps
High groundwater stores
117
What other human causes contributed to the flood?
Building- more man made surfaces - impermeable increases run off into rivers
Farming- soils store less water for intensive farming
Clearing off vegetation
Channel changes- straightening , faster
Embankments built- deeper and faster river flow.
118
Give some behavioural methods of flood preventing in rhine
Charities to fund money donations
Flood insurance- insure properties
Flood warnings- police, sirens etc
119
Give structural methods of preventing of flooding in Rhine
Reservoirs- build
Channel enlargement - rivers deepened and widened hold more water
Embankment- cheap
Flood relief channels- fake channels around town to take away excess waters
Dams across rivers
120
What,were the effects of the Rhine flooding?
```
Death
Communication signals died
No clean water
No power supplies
Flood damage
Lost homes
Injured
```
121
List the three main conditions needed for the formation of a delta
River carries Large load
Shallow
Calm sea
122
Why does the Ganges flood often?
Snow melts from Himalayan mountains
123
What are the advantages of the Ganges delta flooded?
Delta has a temp of 20, rich alluvial soils , lots of water allows land to produce three different types of crops a year
Many farmers earn living from producing and selling jute and crops most imp fibre in textile industry
Ponds and fields flooded allows people to farm fish and stripes for balanced diet and sold for income.
124
What is the lag time?
Time it takes from start of rain until river reaches peak discharge.
125
What is the peak discharge?
Max level water will go to after raining
126
What are the conditions that make a river more likely to flood?
```
Heavy rainfall for several hours
Saturated soil
Impermeable rock
Very few plants
Steep slopes
```
127
What are the conditions that make a river less likely to flood?
```
Drizzle
Soil dry before rainstorm
Porous rocks
Lots Plants and trees
Gentle slopes
Countryside
```
128
What is river discharge?
The volume of the water flowing through a river channel it is measured in cumecs.
129
What's on the base, RH ,LH of a hydrograph?
Base- time in hour
RH- rainfall in mm
LH- discharge in cumec
130
What does a flood hydrograph measure?
Measures water flow in rivers and how drainage basin reflects inputs of precipitation.
