UK Physical landscapes- Rivers Flashcards

1
Q

What is a Water Table

A
  • Upper level of saturated rock/soil where no more water can be absorbed
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2
Q

What is groundwater flow

A

Water flowing through the rock layer parallel to surface

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3
Q

What is through flow

A
  • Water flowing through soil layer parallel to surface
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4
Q

What is surface runoff

A
  • Water flowing on top of the ground
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5
Q

What is evaporation

A
  • Water lost from ground/vegetation surface
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6
Q

What is transpiration

A
  • Water lost through pores in vegetation
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7
Q

What is groundwater storage

A
  • Water stored in rock
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8
Q

What is percolation

A
  • Water seeping deeper through rock
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9
Q

What is soil moisture

A
  • Water held in the soil layer
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10
Q

What is infiltration

A
  • Water sinking into the soil/rock from ground surface
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11
Q

What is surface storage

A
  • Water held on the ground surface eg. puddles
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12
Q

What is interception

A
  • Water being prevented from reaching surface by vegetation or trees
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13
Q

What is precipitation

A
  • Any source of moisture reaching the ground e.g rain
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14
Q

What is the source

A
  • Start of river
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15
Q

What is a drainage basin

A
  • Area of land drained by a river and its tributaries
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16
Q

What is a confluence

A
  • Where a tributary joins a larger river
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17
Q

What is the mouth of a river

A
  • end of a river- usually where it meets the sea
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18
Q

What is the watershed

A
  • The edge of a river basin
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19
Q

What is a tributary

A
  • A small stream that joins a larger river
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20
Q

How many courses of the river are their

A
  • 3
    -Upper, middle, lower
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21
Q

How does relief of river valley change from source to mouth

A
  • Starts steep and becomes flatter
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22
Q

Characteristics of upper course of river

A
  • Steep, V shaped valley
  • Narrow channel
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23
Q

Characteristics of middle course of river

A
  • Less steep, more U shaped valley
  • Wider channel
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24
Q

Characteristics of lower course of river

A
  • Flat valley
  • Very wide channel
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25
Q

What does fluvial mean

A
  • To do with rivers
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26
Q

What is erosion

A
  • the wearing away of the river’s banks and beds
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27
Q

Type of erosion in upper course of river

A
  • Vertical erosion
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28
Q

Why does vertical erosion happen

A
  • Higher up and steep gradient means higher gravitational store, therefore water cuts through the land in order to get down
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29
Q

Type of processes in middle course of river

A
  • Lateral erosion
  • transportation
  • (some) deposition
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30
Q

Why does lateral erosion happen

A
  • A more gentle gradient means the water moves from side to side, eroding the side of bank
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31
Q

What process occurs in lower course of river

A
  • Deposition
  • transportation
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32
Q

Why does deposition occur

A
  • happens in lower courses of river, as river loses its energy and drops material that has been eroded
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33
Q

What is hydraulic action

A
  • When force of the river compresses air trapped in cracks in the banks, meaning increased pressure with gradually wears away the bank
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34
Q

What is abrasion

A
  • When rocks carried buy river scrape and rub along the bed and bank of river, wearing them down
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35
Q

What is solution (erosion)

A
  • Where water is slightly acidic, and dissolves certain types of rock on river bed
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36
Q

What is attrition

A
  • When rocks carried by the river collide with each other and break into smaller pieces
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37
Q

What is a river’s load

A
  • Material carried by a river
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38
Q

What is a river’s discharge

A
  • Amount of water in a river at a given time
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39
Q

What is traction

A
  • Large boulders and rocs being rolled along the river at times of high discharge
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40
Q

What is saltation

A
  • Small rocks and sand particles bounced along the river
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41
Q

What is suspension

A
  • Fine clay and sand particles suspended in the water even at low discharges
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42
Q

What is solution (transportation)

A
  • Some minerals dissolving in water
43
Q

Reasons for deposition

A
  • Flooding
  • Meanders
  • at river mouth
44
Q

How does flooding cause deposition

A
  • Friction with the land slows water down and so material deposited
45
Q

How do meanders cause deposition

A
  • on the inside of the bend, the river is moving at a slow speed, and so material deposited
46
Q

How do river mouths cause deposition

A
  • River slows down as it reaches large body of water
47
Q

What is a floodplain

A
  • The land that gets flooded when the river overflows
48
Q

Upper course of severn landforms

A
  • Waterfalls
    -Severn breaks its neck
49
Q

Middle course of severn landforms

A
  • Meanders near Welshpool
  • Oxbow lake near Caersws
50
Q

Lower course of severn landforms

A
  • Levees near Minsterworth
  • Floodplain in Tewkesbury
  • Severn estuary
  • Mudflats in Chepstow
51
Q

What are interlocking spurs

A
  • Steep sided hills which interlock with each other as river winds round them
52
Q

How are interlocking spurs formed

A
  • Vertical erosion
    -cuts into landscape at angles
53
Q

How is a waterfall formed

A
  • Water running over hard rock on the top, and softer rock on the bottom
  • soft rock erodes faster due to hydraulic action and abrasion, causing the soft rock to undercut the hard rock
  • hard rock left unsupported, and so collapses into river bed
54
Q

How are gorges formed

A
  • When a waterfall retreats, it causes a steep sided gorge to be left behind
55
Q

What is Thalweg

A
  • Fastest flow of river
56
Q

What is a meander

A
  • A large curve in river
57
Q

Characteristics of meander

A
  • Thalweg on outside bends, leading to erosion of bank- undercut ledge
  • Slow water flow on inside bend, leading to deposition
58
Q

What is an Oxbow lake

A
  • An old meander that’s neck has been cut through as river has taken fastest course and not gone around meander
59
Q

What is a levee

A
  • A raised embankment next to a river
60
Q

How does a levee form

A
  • During a flood, water passes over surface causing deposition of material due to friction, causing areas around the river channel to have raised embankments
61
Q

How does a floodplain form

A
  • A build up of sand, silt and clays which have been deposited around a river due to a flood, resulting in a flat piece of land around river
62
Q

What is an estuary

A
  • When the river meets the sea
63
Q

What are mudflats

A
  • When there is less water at a river estuary, causing the river to deposit silt forming a mudflat
64
Q

What is flooding

A
  • When amount of water in a river exceeds capacity of river channel, causing banks to burst
65
Q

Physical factors effecting flood risk

A
  • Relief of land
  • Rainfall
  • Basin size
  • Rock type
  • Saturation of soil
66
Q

Human factors effecting flood risk

A
  • Urbanisation
  • Deforestation
67
Q

How does urbanisation increase flood risk

A
  • More impermeable rock means water flows over roads and into drains to rivers
68
Q

How does deforestation increase flood risk

A
  • Less interception means water is transferred more rapidly to river channels
69
Q

How does rock type effect flood risk

A
  • Impermeable rocks don’t allow water to pass through them, meaning water will not seep into rock and so increases flood risk
70
Q

How does basin size effect flood risk

A
  • Small river basins cannot store as much water meaning more likely to overflow, increasing flood risk
71
Q

How does soil saturation effect flood risk

A
  • When soil cannot absorb any more water it becomes over saturated and causes flow of water over land
72
Q

How does relief effect flood risk

A
  • Steep slopes allow for water to run over land quickly leaving little time to seep into soil, therefore more water enters river channels
73
Q

How does precipitation effect flood risk

A
  • Torrential rainstorms can lead to sudden flash floods as channels cannot contain volume of water falling into them
74
Q

What is lag time

A
  • Number of hours between peak rainfall and peak discharge
75
Q

What is the rising limb

A
  • The increase of Discharge in comparison to time
76
Q

What does steep rising limb mean

A
  • Short lag time- flood happened quickly as discharge increased rapidly
77
Q

What are hard engineering strategies

A
  • Involves manmade structures to control flow of river and prevent flooding and erosion
78
Q

What are soft engineering strategies

A
  • Involves managing a river using natural materials and mimicking natural processes to protect more vulnerable areas
79
Q

Examples of hard engineering strategies

A
  • Dams
  • Channel straightening
  • Embankments
  • Flood relief channels
80
Q

Examples of soft engineering strategies

A
  • flood plain zoning
  • planting trees
  • river restoration
  • flood warning and preparation
81
Q

How do dams prevent flooding

A
  • Large concrete barrier built to create a reservoir
  • The amount of water released is monitored to control the amount flowing downstream
82
Q

How does channel straightening prevent flooding

A
  • Meandering areas are made more widened, straightened and deepened meaning more water can be carried
83
Q

How do embankments prevent flooding

A
  • Increasing height of river banks means more water is contained in the channel
84
Q

How does flood relief channel prevent flooding

A
  • another channel built to move water away from human settlements at times of high discharge
  • essentially a back-up channel for a river that frequently floods
85
Q

What are the 3 levels of flood warnings

A
  • Flood watch
  • Flood warning
  • Severe flood warning
86
Q

What is ‘flood watch’

A
  • Expectance of people in low-lying areas to watch river channels and be prepared
87
Q

What is ‘flood warning’

A
  • When there is a threat to homes and businesses
  • People advised to move valuables upstairs and turn of electricity and water
88
Q

What is ‘severe flood warning’

A
  • Extreme danger to life and property expected-
  • proper informed to turn of electricity and water, and leave property
89
Q

What is flood plain zoning

A
  • Restriction of land uses in high flood risk areas to prevent damage to high value land uses such as housing
90
Q

Positives of flood plain zoning

A
  • Low cost
  • reduces insurance costs
91
Q

Negatives of flood plain zoning

A
  • Restricts economic development
  • hard to implement where urban areas already in flood plains
  • contributes toward UK housing crisis
92
Q

Where is Jubilee river relief channel

A
  • Flows through old Windsor, Eton and Wraysbury
93
Q

Average house price in Windsor

A
  • £547,000
94
Q

Average house price in Wraysbury

A
  • £430,000
95
Q

Cost of Jubilee river

A
  • £330 Million- exceeded budget
96
Q

Length of Jubilee river

A
  • 11.7 Km
97
Q

Cost of repairing jubilee channel after flooding

A

£680,000

98
Q

When was Jubilee river completed

A

2002

99
Q

Width of Jubilee river

A
  • 50m
100
Q

How many homes does Jubilee river protect from flood risk

A
  • 3,200 Approx
101
Q

Issues with Jubilee river relief scheme

A
  • Increases risk of flooding downstream in less wealthy areas such as Wraysbury and Old Windsor due to merging to two channels, shown in intense flooding in 2014
  • Means insurance more expensive in these areas- Business insurance costs £500m in Wrasybury in 2014
102
Q

Positives of Jubilee scheme

A
  • protects 3,200 homes from flooding
  • 38 hectares of reed bed created as part of landscape corridor
  • 193 hectares of native woodland created
  • 326 hectares of wildflower grasslands planted
103
Q

Length of River severn

A
  • 354KM