River Landscapes in the UK Flashcards
(93 cards)
1
Q
abrasion
A
rocks carried along by the river wear down the river bed and banks
2
Q
attrition
A
rocks being carried by the river smash together and break into smaller, smoother, rounder particles
3
Q
Cross profile
A
the side to side cross section of a river channel and/or valley
4
Q
Dams and reservoirs
A
A barrier (made on earth, concrete or stone) built across a valley to interrupt river flow and create a man-made lake which stores water and controls the discharge of the river
5
Q
discharge
A
the quantity of water that passes a given point on a stream or river-bank within a given period of time
6
Q
embankment
A
raised banks constructed along the river; they effectively make the river deeper so it can hold more water. They are expensive and do not look natural but they do protect the land around them
7
Q
estuary
A
the tidal mouth of a river where it meets the sea; wide banks of deposited mud are exposed at low tide
8
Q
flood
A
occurs when river discharge exceeds river channel capacity and water spills out of the channel onto the floodplain and other areas
9
Q
floodplain
A
the relatively flat area forming the valley floor on either side of a river channel, which is sometimes flooded
10
Q
floodplain zoning
A
attempts to organise the flood defences so that land that is near a river and often floods is not built on
this could be used for pastoral farming, playing fields
11
Q
flood relief channel
A
building new artificial channels which are used when a river is close to maximum discharge
they take the pressure off the main channels when floods are likely, reducing flood risk
12
Q
flood risk/rate
A
the predicted frequency of floods in an area
13
Q
flood warnings
A
providing reliable advance information about possible flooding
flood warning systems give people chance to remove possessions and evacuate areas
14
Q
fluvial process
A
processes relating to erosion, transport and deposition by a river
15
Q
gorge
A
a narrow, steep sided valley
16
Q
hard engineering
A
involves building entirely artificial structures using various materials such as rock, concrete and steel to reduce, disrupt or stop the impact of river processes
17
Q
hydraulic action
A
the force of the river against the banks can cause air to be trapped in the cracks and crevices
the pressure weakens the banks and gradually wears it away
18
Q
hydrograph
A
a graph which shows the discharge of a river, related to rainfall, over a period of time
19
Q
interlocking spurs
A
a series of ridges projecting out on alternate sides of a valley and around which a river winds its course
20
Q
lateral erosion
A
sideways erosion by a river on the outside of a meander channel
it eventually leads to the widening of the valley and contributes to the formation of the floodplain
21
Q
levee
A
embankment of sediment along the bank of a river
it may be formed naturally by regular flooding or man-made to protect against flooding
22
Q
long profile
A
the gradient of a river, from its source to mouth
23
Q
meander
A
a pronounced bend in a river
24
Q
oxbow lake
A
an arc-shaped lake which has been cut off from a meandering river
25
precipitaion
moisture falling from the atmosphere
rain, hail, snow, sleet
26
saltation
particles bouncing down the river bed
27
soft engineering
uses the natural environment surrounding a river, using schemes that work with the rivers natural processes
usually much cheaper and more sustainable
28
solution
soluble particles are dissolved into the river
29
straightening
removing meanders from a river to make the river straighter
allows the river to carry more water quickly downstream, doesn't build up, less likely to flood
30
suspension
fine solid material held in the water while the water is moving
31
traction
the rolling of boulders and pebbles along the river bed
32
vertical erosion
downward erosion of a river bed
33
waterfall
sudden decent of a river or stream over a vertical or very steep slope in its bed
34
Characteristics of waterfalls
steep drop
plunge pool
overhanging hard rock
35
Characteristics of interlocking spurs
steep gradients.
project from alternate sides of the valley.
separated by a narrow valley floor, which is mainly taken up by the river channel.
36
Characteristics of gorges
narrow, steep-sided valleys with bare, rocky walls
fast-flowing water
located downstream of a waterfall.
37
Formation of waterfalls
form where a river flows over alternating bands of hard and soft rock, with the softer rock eroding faster
undercutting creates an overhang
hard rock collapses
plunge pool forms
retreats upstream
38
Formation of interlocking spurs
If there are areas of hard rock which are harder to erode, the river will bend around them
This creates interlocking spurs
39
Formation of gorges
formed by the retreat of waterfalls
40
Characteristics of meanders
bends in the river
lateral erosion
slip-off slopes
river cliffs
migration
oxbow lakes
41
Characteristics of oxbow lakes
horseshoe-shaped
middle course of river
vegetation - can become a marshland
42
Formation of meanders
increased velocity on the outside bend
leads to erosion - like hydraulic action and abrasion
deposition on the inside of the bend - water slows down due to friction with the riverbed and deposits sediment, forming a slip-off slope
43
Formation of oxbow lakes
meander formation
neck narrowing
breakthrough during flood
meander abandonment
oxbow lake formation
deposition and drying
44
Characteristics of levees
raised riverbanks
steep side facing the river
gentle sloping side facing the floodplain
flat top
composed of the sediment deposited by the river, including gravel, sand, and silt
45
Characteristics of floodplains
flat land
rich in nutrients - fertile soil
flood risk
levees
46
Characteristics of estuaries
found at the mouth of the river
contain a mix of freshwater and saltwater
as the river slows down and meets the sea, it deposits sediment, forming mudflats and salt marshes
tidal, therefore water level fluctuates with the tides
estuaries are important habitats for a wide variety of wildlife
mudflats exposed at low tide and submerged at high tide, saltmarshes develop where vegetation grows
47
Formation of levees
a river floods and water spills out of its channel and onto the floodplain
as the water moves onto the floodplain, its velocity (speed) decreases due to increased friction with the land
sediment is deposited
over time, with more floods, more sediment is deposited along the riverbanks, building them up into levees
48
Formation of floodplains
Meanders erode the river banks, widening the valley floor
When a river floods, it loses energy and deposits the sediment it was carrying onto the floodplain
As meanders migrate downstream, they continue to erode and deposit, further widening the floodplain.
Over many years, repeated flooding and deposition build up a thick layer of sediment, creating a wide, flat floodplain
49
Formation of estuaries
rising sea levels
become sediment traps
velocity decreases, causing the river to deposit the sediment it is carrying
the deposited sediment builds up, forming mudflats
vegetation grows on mudflats, leading to the formation of saltmarshes
50
What are the economic costs of hard engineering?
expensive to build
maintenance costs and repairs
potential failure, leading to catastrophic flooding and even greater costs
51
What are the environmental costs of hard engineering?
habitat destruction
ecosystem disruption
sediment deposition issues - dams trap sediment, reducing the amount available downstream, which can lead to decreased soil fertility and erosion problems
visually unappealing
52
What are the social costs of hard engineering?
displacement of people
loss of farmland
reduced water quality - unsuitable for drinking or irrigation
increased flood risk downstream
53
What are the different methods of hard engineering?
dams and reservoirs
channel straightening
embankments
flood relief channels
54
What are the different methods of soft engineering?
flood warnings and preparation
flood plain zoning
planting trees
river restoration
55
How do human factors affect flood risk?
urbanisation
--> surfaces are impermeable
--> water lays on surface increasing flood risk
deforestation
--> less trees = less water soaked up by roots
farming
--> cattle's feet compress ground
--> decreasing permeability
56
What are the benefits of soft engineering?
reduced environmental impacts (Preserves Natural Habitats, Sustainable Solutions, Improved Water Quality)
cost effective (lower initial cost, reduced maintenance cost)
flood risk reduction
57
What are the economic costs of soft engineering?
initial and maintenance costs can be expensive e.g. river restoration, flood warning systems
Floodplain Zoning restricts development in flood-prone areas, can lead to lost opportunities for economic development and housing.
Afforestation: planting trees to increase interception and infiltration can lead to the loss of farmland
58
What are the environmental costs of soft engineering?
Altered Landscapes and Habitats
Habitat Loss
Changes in River Flow
Loss of Grazing Land
59
What are the social costs of soft engineering?
restricted development (housing, planning permission issues)
impact on livelihoods (agriculture, tourism)
limited access
60
What are the different physical factors that affect flood risk?
precipitation
relief of the land
geology - permeable or semi-permeable rock
soil type
vegetation - amount of trees
basin size
61
What are the different physical factors that affect flood risk?
urbanization (impermeable surfaces, drainage systems, reduced green spaces, building on floodplains)
deforestation (soil erosion, reduced interception)
agricultural practices (overgrazing etc)
62
What is an example of a flood management scheme in the UK?
Jubilee River flood-relief channel
63
Management strategy for the Jubilee River.
The Jubilee River acts as a flood relief channel for the River Thames, allowing water levels to be controlled and diverted from the Thames during times of high flow
64
Jubilee River social issue and economic issues: small businesses
small businesses are put under pressure
--> cannot open when premises are flooded
--> insurance costs are incredibly high
--> business insurance costs for Wraysbury alone was £500 million in 2014
--> causes future insurance premiums to increase too
65
Jubilee River social issue: paddle boaters
Paddle boaters had been promised a navigable river
--> however, on two of the five weirs they have to carry boats over with them
--> and Taplow Weir is too dangerous to cross
66
Jubilee River economic issues: initial and repair expenses
most expensive flood-relief scheme in the UK
--> damaged in the floods of 2014 and repairs in Slough Weir alone were £680,000
--> continues to be a economic burden
67
Jubilee River social issue and environmental issues: Concrete weirs
concrete weirs created have are seen as ugly, especially under normal flow conditions when river discharge is lower
--> ongoing repair work at Manor Farm weir has made matters worse
68
An example of a river valley in the UK to identify its major landforms of erosion and deposition
River Severn
69
River Severn upper course characteristics
steep valley
narrow channel
70
River Severn upper course landforms
waterfalls and gorges
V shaped valleys
71
River Severn upper course processes/size of material
mainly erosion
load is large and angular
72
River Severn middle course characteristics
wider, less steep valley
wider and deeper channel
73
River Severn middle course landforms
meanders
oxbow lakes
74
River Severn middle course processes/size of material
erosion and transportation
load is slightly smaller and rounder
75
River Severn lower course characteristics
flat and wide valley
deep and wide channel
76
River Severn lower course landforms
levees - Minster worth
floodplain - Tewksbury
estuary
mudflats
77
River Severn lower course processes/size of material
transportation and deposition
load is small and round
78
Benefits of hard engineering: dams and reservoirs
dams trap water, creating reservoirs that can release water in a controlled manner, reducing the risk of downstream flooding
79
Benefits of hard engineering: embankment
increases channel capacity
80
Benefits of hard engineering: straightening channels
removing meanders speeds up the water flow, allowing large volumes of water to pass through quickly, reducing the risk of flooding in the straightened area
81
Benefits of hard engineering: flood relief channels
diverts excess water, preventing flooding
82
Benefits of hard engineering: other
hydroelectric power, water storage, recreation
83
How many homes does the Jubilee River flood-relief channel protect?
protects approximately 3,200 homes from the risk of flooding
84
Environmental positive of the Jubilee River flood-relief channel protect: How many hectares of reed bed was created?
38 hectares of reed bed created as a part of a wildlife corridor
85
What management plan was created for the Jubilee River flood-relief channel project?
25 year landscape management plan to ensure the continued maintenance of the Jubilee River
86
Environmental positive of the Jubilee River flood-relief channel protect: How many hectares of native woodland was created?
193 hectares of native woodland created as part of the wildlife corridor
87
Environmental positive of the Jubilee River flood-relief channel protect: How many hectares of wildflower grasslands were created?
326 hectares of wildflower grasslands planted to encourage new species to the area
88
Environmental positive of the Jubilee River flood-relief channel protect: How many meters wide does the channel reach?
up to 102m wide in areas such as the Dorney Wetlands
89
Jubilee River environmental issues: How was the Thames affected?
The Thames now experiences much higher discharge
--> due to the merging of the two channels upstream
--> this problem came to light in 2014 when the river experience serious flooding
90
Jubilee River environmental issues: How was the natural ecosystem affected?
natural ecosystem is also affected as algae collects and builds behind the weirs
--> where the flow of water is slowed or stopped
91
Jubilee River social issue and environmental issues: 2014 flooding
In 2014, extensive flooding immediately downstream of the confluence where the relief-channel re-joined the Thames
--> built environment suffered from flooded roads, buildings, fields and habitats
92
Jubilee River economic issues: funding to extend the Jubilee River which protects Windsor and Maidenhead from flooding
was withdrawn in 2014
--> the government will only fund part of the future flood protection schemes, with the remainder coming from local councils and businesses
--> extending the Jubilee River would cost £250m and take 9 years to build
93
Jubilee River social issue and economic issues: ethics
ethics - some properties are protected and not others
--> 3,000 properties in affluent Eton and Windsor are protected
--> but not less wealthy settlements in Wraysbury and Old Windsor
