Topic 4 - UK's Physical Environment Flashcards
(214 cards)
1
Q
How does limestone form?
A
Limestone rocks in the north of England where formed in the carboniferous periods when the seas where warmer. When coral and fish died there skeletons fell to the sea floor, weight from above crushed these into rock. Calcium carbonate from rocks cemented them together, sand was then laid down on top of these rocks. These layers are known as strata.
2
Q
How does the limestone get above the sea bed?
A
Tectonic processes pushed the limestone above from the sea bed.
3
Q
How have tectonic processes shaped the UK landscape?
A
500 million years ago the UK was where Antarctica is now, it has slowly moved to its current position through tectonic processes. Furthermore, the UK was in separate parts and they slowly moved together. Between these collisions huge volcanoes occurred, erupting massive amounts of lava and creating mountains. Convection currents have also caused uplift of some land, shoving it upwards and further out of the sea
4
Q
How has glaciation shaped the UK landscape?
A
12,000 years ago the uk had just come out of an ice age. during the ice age massive glaciers plucked rocks and altered the landscape. They left features such as u-shaped valleys, troughs, corries and eretes
5
Q
What is igneous rock?
A
Magma cools and hardens. Rocks form crystals as it cools down. Igneous rocks are usually hard e.g granite
6
Q
What is Sedimentary rock?
A
Layers of sediment are compacted together until they become solid rock e.g limestone and chalk are formed from tiny shells and skeletons of sea creatures. Limestone is hard, chalk is softer.
7
Q
What is Metamorphic rock?
A
Metamorphic rock is formed when other ricks are changed by heat and pressure. New rock becomes harder and more compact. e.g shale becomes slate and with further pressure and heat, slate becomes schist
8
Q
What is Chalk?
A
Chalk is a purer, younger from of limestone. It is very porous and has a medium resistance
9
Q
What is Limestone?
A
Limestone is formed from layers of strata made from living organisms inn the water. It is permeable. It is generally resistant.
10
Q
What is Clay?
A
It is formed from muds deposited by rivers or at sea. It is soft and crumbly and when compacted it becomes shale. It is generally weak.
11
Q
What is Granite?
A
It is formed from magma cooling deep underground. It contains crystals of quartz, feldspar and mica. It is very resistant
12
Q
What is Schist?
A
It is formed from further metamorphosis of slate, where it is partly melted and solidified. It is very resistant.
13
Q
What is Slate?
A
It is formed from heated muds or shale. It is very resistant
14
Q
What is the tees-exe line?
A
The line that separates the main rock types in the uk.
15
Q
Is rock more or less resistant in upland areas?
A
more resistant
16
Q
Is rock more or less resistant in lowland areas?
A
less resistant
17
Q
What is the relief like in upland areas?
A
steeper
18
Q
What is the relief like in lowland areas?
A
flatter
19
Q
What is an example of an upland area?
A
The Lake District
20
Q
What is an example of a lowland area?
A
The Weald
21
Q
What is the highest point in UK upland areas?
A
Scaffel Pike (978m)
22
Q
What is the highest point in UK lowland areas?
A
Crowborough Beacon (225m)
23
Q
What is the geology like in The Lake District?
A
Igneous basalt rock from surface eruptions at Borrowdale and igneous granite from eruptions below the surface at eskdale. These are both resistant. There is sedimentary rock present too, formed when the UK was under tropical seas (350-250 million years ago) such as mud and sandstone.
24
Q
What are tectonic processes like in The Lake District?
A
Large volcanoes 450-300 million years ago erupted in the Lake District in areas such as Borrowdale, this caused mountains to form - these are the mountains we see today.
25
What are the effects of the ice age in The Lake District?
The last ice age ended 12,000 years ago. It left a glaciated landscape. This includes: corries, U-shaped valleys and hanging valleys
26
What is the shape of the landscape like in The Lake District and how did they form?
After the ice age a glaciated landscape was left. An example of a glaciated feature is a corrie, they are armchair shaped and have very steep sides with a deep lake at the bottom. Another example is a U-shaped valley that is formed as a glacier moves through a valley and erodes the landscape
27
What are weathering processes like in The Lake District?
freeze thaw weathering - water falls into cracks in the rocks. At night the water freezes and expands by 9%. This increases the pressure on the rock. At day the water melts. This process is repeated until the rock finally breaks.
28
What are slope processes like in The Lake District?
mass movement e.g. landslides - They are common in upland areas as there is a lot of rainfall. This saturates the rocks/soil and increases their weight. This increased weight causes landslides
29
What are post glacial river processes like in The Lake District?
Due to upland areas previously having glaciers, they have U-shaped valleys. In these U-shaped valleys there are misfit rivers. They are called misfit rivers as they did not erode the valley.
30
What is climatological like in The Lake District?
There is increased rainfall in upland areas as there are many mountains, these mountains cause relief rainfall. Furthermore, the temperature is lower as the altitude is higher.
31
What is the effect of ice age in The Weald?
During glacial periods the gaps in the chalk froze making it impermeable. When seasonable snow melted it couldn't infiltrate the chalk and instead ran over the top and eroded the valleys. Now it is warmer the water runs through the chalk and cannot be seen. These are called dry valleys
32
What is the shape of the landscape in The Weald and how did they form?
After the ice age there was a glaciated landscape. Dry valleys are valleys with no visible streams (they flow underground in the permeable chalk). Flood plains are formed when heavy rain leads to flooding, the overflowing river deposits silt on the valley floor, this forms a floodplain.
33
What are the weathering processes in The Weald?
Biological weathering -Burrowing animals burrow into a crack in the rock, making it larger and cracking the rock. Also, plant roots can grow into the cracks, and push them open, making them wider and deeper. Chemical Weathering - Rainwater absorbs CO2 as a by product of pollution, rain becomes a weak carbonic acid, acid reacts with the calcium carbonate in limestone/chalk and dissolves the rock.
34
What are slope processes like in The Weald?
Soil creep - soils such as as sandstone and clay can absorb large amounts of moisture and become saturated, they can then move down the slope. Soil creep is the slowest of all mass movements
35
What are post glacial river processes like in The Weald?
The UK climate is very wet. Heavy rain can lead to flooding. When the rivers flood the overflowing water carries sediment and deposits silt on the valley floor forming a flood plain. The flood plain is very fertile
36
What are settlements like in upland areas?
Many farms and barns are isolated , not in villages. There are dispersed settlement patterns.
37
What are the building materials in upland areas?
Building material consists mostly of local slate, stone and wood as delivering from a distance would be difficult.
38
What are field boundaries like in upland areas?
Field boundaries are walls made of stone as they do not use cement. The boundaries work with the land and are not uniform
39
What is farming like in upland areas?
Animals such as sheep are farmed as they can survive in harsh conditions. They are less likely to farm crops.
40
What is Economic Activity like in upland areas?
They can sell products from their farm animals, this could consist of wool, meat and milk
41
What are settlements like in Lowland Areas?
more likely to have villages and shops rather than having isolated and dispersed settlements
42
What are the building materials in Lowland Areas?
They can use sand, clay and cement due to the lands geology. It is also much easier to import materials for building
43
What are field boundaries like in Lowland Areas?
The field boundaries are much more uniform and do not need to work with the land as the land is much flatter
44
What is farming like in Lowland Areas?
They are more likely to grow crops as the environment is much more habitable
45
What is Economic Activity like in Lowland Areas?
Both primary and tertiary sectors as in villages there are shops, schools and churches
46
How does seasonality impact coastal erosion?
Temperature in the UK varies with the seasons. Temperatures are coldest in the winter and hottest in the summer. Differences in temperature have an impact on processes. e.g. salt weathering
47
How does Storm frequency impact coastal erosion?
Storms are more frequent in the winter. The string winds cause high energy, destructive waves which increase erosion of the cliffs. Intense rainfall can cause cliffs to become saturated and therefore increase mass movement
48
How does Prevailing wind and fetch impact coastal erosion?
The prevailing winds in the UK are mostly warm south westerlies which bring storms from the Atlantic ocean. The UK's south coast is exposed to these winds
49
What are sub aeriel processes?
Processes of weathering and mass movement
50
How does Rotational Slumping impact coastal erosion?
Rain falls and it accumulates at the boundary between sand and clay which lubricates the boundary. The sad is permeable and allows water to pass through. Clay is impermeable and prevents water moving through it. The sand becomes saturated and will dramatically slump diagonally.
51
How do rock slides impact coastal erosion?
Joints or bedding planes are aligned diagonally to the sea. Erosion at the base, or weathering at the top of the cliff causes the cliff to become unsupported. The rocks then slide in a straight diagonal line. (It is sometimes lubricated by rain)
52
What are the 3 different types of erosion?
Abrasion, Hydraulic Action and Attrition
53
What is abrasion?
Abrasion is when broken rock fragments and pebbles carried in the wave batter and scour the land; breaking off other pieces of rock and rubbing the surface
54
What is Hydraulic Action?
Hydraulic action is when a wave crashes against the land and compresses air and water trapped in the cracks in the rock. When the wave moves away teh air expands explosively and enlarges the cracks. Eventually it will break off the rock
55
What is attrition?
Attrition is when rock fragments grind and rub each other down into smaller and smaller fragments. Eventually rocks are smoothed into pebbles, then reduced to shingle, and finally end up as sand
56
What are the characteristics of destructive waves?
The waves that carry out erosional processes are called destructive waves. They are high, steep and have a high frequency (10-14 waves per minute). Their backwash is more powerful than their swash, this means that material is removed from the coast. Storms increase the erosional power of destructive waves which can lead to increased rates of coastal retreat.
57
What are the characteristics of constructive waves?
Deposition is when material being carried by the seawater is dropped on the coast, It occurs when water carrying sediment slows down so that it isnt moving fast enough to carry the sediment. Waves that deposit more material than they erode are called constructive waves. Constructive waves are low, long and have a low frequency (6-8 waves per minute). The swash is more powerful than the backwash and it carries the material up the coast. The backwash is weaker and does not take much material down the coast. Constructive waves deposit material such as sand and shingle along the coast to form beaches
58
How are destructive waves formed?
They are formed by strong winds that have blown over long fetches
59
How are constructive waves formed?
.They are formed by light winds that have blown over short fetches
60
What are more resistant rocks?
Resistant rocks such as igneous granite, and resistant sedimentary such as sandstone or limestone
61
What are less resistant rocks?
less resistant rocks such as clays or shales are more easily eroded
62
What are joints?
joints are small, usually vertical cracks found in many rocks. The more joints there are, the weaker the rock is
63
What are Faults?
Faults are larger cracks caused by past tectonic movement, where rocks have moved. The more faults there are, the weaker the rock is
64
What is a discordant coastline?
a discordant coastline is a coastline with alternating layers of rock perpendicular to the coastline
65
What is a concordant coastline?
a concordant coastline is alternating layers of rock parallel to the coastline
66
What is an example of a discordant coastline?
Bantry Bay
67
What is an example of a concordant coastline?
Lulworth cove
68
What features and landforms are found at discordant coastlines?
arches, stacks and stumps
69
What features and landforms are found at concordant coastlines?
coves but can also be featureless
70
How do headlands and bays form?
the sea attacks a section of coast with alternating bands of hard and soft rock. The bands of soft rock erode quicker than the bans of hard rock. This leaves a section of land jutting out into the sea called a headland. The areas where soft has eroded, next to the headland, are called bays.
71
How do arches, stacks and stumps form?
Waves are very strong where headlands jut out into the sea. These waves crash into the headlands and enlarge any cracks/faults in the rock through hydraulic action and abrasion. Repeated erosion and enlargement of these cracks causes a cave to form. Continued erosion deepens the cave until it breaks through the headland - forming an arch, e.g durdle door. Erosion and weathering continue to wear away the rock supporting the arch until it eventually collapses. This leaves behind a rock pillar called a stack. The base of the stack is weathered and eroded until the top falls off, leaving a stump.
72
How do wave cut notch's and platforms form?
Weathering weakens the top of the cliff. Hydraulic action and abrasion caused by the sea erode the foot of the cliff. This forms a wave-cut notch. As erosion continues the notch is enlarged. The rock above the notch becomes unstable and eventually collapses. The collapsed material is carried back towards the sea by the backwash, this forms a wave cut platform. This process repeats and causes the cliff to retreat.
73
How does long shore drift work?
Waves follow the direction of the prevailing wind. This causes them to hit the coast at an oblique angle. The swash carries the material up the beach in the same direction as the waves. The backwash then carries material back down the beach at right angles, back towards the sea. Over time, material zigzags along the coast.
74
How is a spit formed?
A spit is formed at sharp bends in the coastline, e.g. At a river mouth. Longshore drift transports sand and shingle past the bend and deposits it in the sea. Strong winds and waves can curve the end of the spit, forming a recurved end. The sheltered area behind the spit is protected from the waves - lots of material accumulates in this area, which means plants can grow here. Over time, this sheltered area can become a mud flat or a salt marsh
75
How does a bar form?
A bar is formed when a spit joins 2 headlands together. The bar cuts off the bay between the headlands from sea. This means a lagoon can form behind the bar.
76
What is deposition?
Deposition is when material is deposited by constructive waves and forms landscapes such as: beaches, spits and bars
77
What is solution?
Parts of rock are dissolved by the weak acidity or salt in the water and are carried by the water
78
What is Suspension?
Suspension is when small particles are carried (suspended) in the water and carried along
79
What is Saltation?
Saltation is when slightly heavier particles are too heavy to be picked up by the sea but are light enough to bounce/hop along the sea bed
80
What is Traction?
Traction is when large pebbles that are too heavy to be picked up or bounced along, are rolled along the sea bed
81
What is a direct impact?
something caused by humans
82
What is an indirect impact?
something caused as a result of a direct impact
83
What is a direct impact of industry on the coastal landscape?
Easington Gas Works increases weight on the cliff which adds to rotational slumping mass movement. Pollution of the water, air and noise is a big problem and threatens wildlife in the surrounding area. These impacts are negative.
84
What is an indirect impact of industry on the coastal landscape?
Sand was dredged from the beach and under the sea to build up the height of the gas works. This has a consequence of increasing the height of the waves and making them more destructive. These impacts are negative
85
What is a direct impact of agriculture on the coastal landscape?
a decision has been made to not protect Tunstall farm as it is poor quality and low value. When the farmer ploughs the farm, it exposes the soil and rock. These impacts are negative
86
What is an indirect impact of agriculture on the coastal landscape?
ASA a result of no coastal defences, Tunstall farm is eroding at 2m a year. The eroded material is then transported along the coast and deposited which is adding material to beaches further down the coast. When soil and rock is exposed by ploughing, it exposes soil and rock causing it to be vulnerable to to rain, weathering and mass movement. These impacts are negative, however the deposition of material further down the coast is positive for those living further down the coast.
87
What is an direct impact of coastal management on the coastal landscape?
a decision was made to protect Mapleton village by building a groyne. This is a positive impact
88
What is an indirect impact of coastal management on the coastal landscape?
The groyne at Mapleton has reduced erosion at Mapleton village but sped it up further down the coastline in great cowden where erosion is now much quicker and land is being lost. This is a negative impact
89
What is an direct impact of development on the coastal landscape?
A harbour was built in Bridlington by extracting and dredging sediment. Having this harbour increased tourism. This is a positive impact
90
What is an indirect impact of development on the coastal landscape?
Building a harbour negatively impacted the stability of the cliffs which collapsed more. The boats and run off from the land has also polluted the water quality
91
Why is the earth's average temperature rising?
Due to the enhanced greenhouse effect
92
What is the enhanced greenhouse effect?
The enhanced greenhouse effect is when greenhouse gases are added to the atmosphere, these then trap solar radiation form bouncing back out into space. This then causes the global average temperature to rise
93
How much is the sea predicted to rise in our lifetime?
1-4 feet
94
Why is the average seas level rising?
thermal expansion and ice melting
95
What is thermal expansion?
Thermal expansion is when water expands due to an increase in temperature, due to the water now having a larger volume, sea levels rise
96
How does ice melting cause the sea level to rise?
increased temperatures cause ice bergs and glaciers to melt and release more water into the sea. Ice sheets and glaciers cause the sea to rise more as they are stored on land rather than in the sea.
97
What are the impacts on people from rising sea levels?
Low lying coastal areas could become permanently flooded and impossible to inhabit. Coastal industries may have to shut down due to damaged equipment and buildings. Infrastructure such as roads and rail networks may be damaged or destroyed. Flooding could reduce the amount of tourism in the area and cause tourism businesses to close.
98
What are the impacts on the environment from rising sea levels?
Ecosystems will be affected as saltwater has a high salt content, this causes organisms to be damaged or even die, it could also reduce soil fertility. The force of the floodwater could uproot trees and plants, standing floodwater could drown trees and plants. Some conservation areas could be threatened by coastal erosion, i.e lagoons
99
How does temperature increase erosion?
A warmer atmosphere would have more energy and create larger storms and larger waves more frequently. This can cause cliffs that are already being undercut and collapsing will continue to retreat but now at a faster rate. Rising waters due to the temperature can also put landforms such as beaches, spits and bars at risk from erosion and submergence.
100
What are the 4 coastal defence options for a local council?
Hold the line, Advance the line, Strategic Retreat/realignment, no active intervention
101
What is Hold the Line?
Hold the line is when you use defences to stop erosion so the coast stays where it is - expensive
102
What is Advance the Line?
Advance the line is when you build new defences on the seaward side of the original defences - very expensive
103
What is Strategic Retreat/Realignment?
Strategic Retreat/Realignment is when you gradually let low value areas of the shoreline erode backwards to help protect high value area. Compensation is given
104
What is No active intervention?
No investment in coastal defences or operations
105
What are the 5 Coastal Engineering techniques?
Groynes, Sea Walls, rock armour. Beach Nourishment, Slope Stabilisation
106
How do Groynes reduce erosion?
Groynes stop longshore drift moving sediment along the coast and increases deposition on the beach. This causes the beach to increase in size and absorb wave energy, protecting the coast.
107
How do Sea Walls reduce erosion?
They reflect wave energy and stop the wave hitting the cliff. They are curved so that the wave energy is focused out to sea, not to the cliff
108
How does Beach Nourishment reduce erosion?
Adding sediment to a beach builds up the beach height. The beach absorbs wave energy and prevents waves breaking at the base of the cliff.
109
How does Slope Stabilisation reduce erosion?
Vegetation is planted by laying geomeshes and planting grasses and shrubs - the roots stabilise the soil. Drainage pipes are placed which reduces water pressure and prevents saturation. Together these reduce mass movement slumping
110
What are the benefits of Groynes?
Groynes are the cheapest form of hard engineering (around £100,000). They create larger beaches for tourists and prevent erosion.
111
What are the benefits of Sea Walls?
They provide long term protection from erosion. You are also able to walk along them as a coastal walk.
112
What are the benefits of Beach Nourishment?
It looks natural and attracts tourists to the beach by making a larger beach. They are relatively cheap at between £500,000 and £1 million per kilometre. It doesn't increase erosion further down the coast, in fact it actually adds sediment.
113
What are the benefits of Slope Stabilisation?
They do not interfere with coastal processes such as long shore drift and do not increase erosion further down the coast. They keep the cliff in place, making it safer for beach users walking along the cliff.
114
What are the problems and costs of Groynes?
They trap sediment and starve beaches further down the coast from receiving deposition and therefore increase erosion further down the coast. This means that more money has to be spent. They do not look nice and prevent beach walks.
115
What are the problems and costs of Sea Walls?
They are extremely expensive, around £5 million per km. Many people say that they area ugly and make it hard for tourists to get down to the beach.
116
What are the problems and costs of Beach Nourishment?
Winter storms transport material away and sediment is often in need of replacement very often
117
What are the problems and costs of Slope Stabilisation?
They cost almost £1 million to fully stabilise a slope. They are quite difficult to install, this means that the parts of the beach might be closed for a while whilst they are installed.
118
What are the 2 soft engineering techniques?
Beach Nourishment, Slope Stabilisation
119
What are the 2 hard engineering techniques?
Groynes, Sea Wall
120
How is Bridlington being defended and why?
Bridlington is being defended with groynes and sea walls. This is because it has a large population (35,000), Tourism jobs, fishing income and important bird life
121
How is Mappleton being defended and why?
Mappleton is being defended with Groynes and Rock Armour. This is because it has agricultural land at risk from erosion, it has been subject to severe erosion (2m a year) and the access road is only 50m from the cliff edge.
122
How is Great Cowden being defended and why?
Great Cowden is not being defended and are suffering from Mappletons defences. This is because it only consists of farmland and caravan parks
123
How is Easington being defended and why?
Easington is being defended by rock armour. This is because it is home to one of 6 main gas terminals in the UK and accounts for approximately 25% of all of Britain's gas supply
124
Why does the Holderness coastline have one of the highest rates of coastal erosion in Europe?
The Holderness coastline is 61km long. Erosion is causing the the cliffs to collapse, about 1.8m a year are lost to the sea. The cliffs are mostly made of boulder clay which is easily eroded and likely to slump when wet. The beaches along the coastline are very thin meaning that they do not provide much protection. The holderness coastline faces the prevailing wind direction which brings waves from the Norwegian sea, these waves increase in power over this long distance causing them to be highly erosive. The eroded material is moved south by longshore drift, exposing a new area of cliff to erosion
125
What is a River Course?
The path the river follows as it flows downhill
126
What is the upper course of a river?
The upper course of the river is the course closest to the source of the river
127
What is the middle course of the river?
The middle course of the river is the course inbetween the upper course and the lower course
128
What is the lower course of the river?
The lower course is the course closest to the mouth of the river
129
What is the River Valley?
Rivers erode and form River Valleys as they flow downhill
130
What is the long profile of the river?
The long profile shows you how the gradient changes over different courses
131
What is the Cross Profile of the River?
The cross profile shows you what a cross section of the river looks like
132
What is the Discharge of the River?
The volume of water flowing in a river at one particular point and time. It is measured in m³/s or cumecs
133
What is Vertical Erosion?
Vertical erosion deepens the river valley (and channel) making it v-shaped. Its dominant in the upper course of the river. High turbulence causes the rough, angular particles to be scraped along the river bed, causing intense downward erosion.
134
What is Lateral Erosion?
Lateral erosion widens a river valley (and channel) during the formation of meanders. Its dominant in the middle and lower courses.
135
Describe the Upper Course?
The discharge is lowest in the upper course as there are less tributaries, there is a smaller drainage basin and it has a smaller channel size. The channel size is smaller in the upper course as there is less vertical and lateral erosion. The velocity is lowest in the upper course as there is less kinetic energy. The sediment is larger and not as smooth in the upper upper course as there is less erosion. The river channel is not as smooth in the upper course as there is not as much traction and erosion. The gradient is steeper in the upper course. Valleys are steeper in the upper course. The rock is more resistant in the upper course
136
Describe the Lower Course?
The discharge is highest in the lower course as there are more tributaries, there is a larger drainage basin and it has a larger channel size. The channel size is larger in the lower course as there is more vertical and lateral erosion. The velocity is the highest in the lower course as there is more kinetic energy. The sediment is smaller and smoother in the lower course as there is more traction and erosion. The gradient is not as steep in the lower course. Valleys are not as steep in the upper course. The rock is not as resistant in the lower course.
137
What is soil creep?
Individual particles of soil move slowly down a slope under the force of gravity. They collect at the base of the valley sides. The river may then erode this material.
138
What is Slumping?
Slumping happens when the bottom of a valley side is eroded by the river. The slope becomes unstable and the material above slumps downwards, rotating as it does so. This often happens when the material is saturated.
139
How does a Waterfall form?
Waterfalls form when a river flows over and area of hard rock followed by an area of softer rock. The softer (less resistant) rock is eroded faster (by hydraulic action and abrasion) than the hard rock, creating a "step" in the river. As more water goes over the step it erodes more and more of the softer rock. A steep drop is eventually created which is known as a waterfall. The hard rock is eventually undercut by erosion, it is unsupported and collapses. The collapsed rocks are swirled around the foot of the waterfall where they erode the softer rock by abrasion. This creates a deep plunge pool. Over time, more undercutting causes more collapses. The waterfall will retreat leaving a steep-sided gorge
140
How do v-shaped valleys and interlocking spurs form?
In the upper course of a river most of the erosion is vertically downwads. This creates steep-sided, v shaped valleys. The rivers arent powerful enough to erode laterally - they have to wind around the high hillsides that stick out into their paths on either side. The hillsides that interlock with each other as the river winds around them are called interlocking spurs.
141
How do meanders form?
When rivers enter their middle and lower stages they begin to erode laterally and form large bends called meanders. The river erodes on the outside of the bend along the thalweg (line of fastest flow). This washes away the river bank, creating a river cliff. On the inside of the bend where the water flows slowest, it deposits its load, forming a slip off slope. Over time the erosion and deposition continue, changing the course of the river and moving it slowly down the valley. When a river meander reaches the side of a valley, it erodes them, widening the valley floor and floodplain.
142
How do oxbow lakes form?
Meanders get larger over time and can eventually turn into into an ox-bow lake. Erosion causes the outside bends to get closer, until there is only a small bit of land between the bends (called the neck). The river breaks through this land (usually during a flood), and the river flows along the the shortest course. Deposition eventually cuts off the meander and forms an oxbow lake
143
How do Floodplains form?
Floodplains form due to both lateral erosion and deposition. Lateral erosion erodes into teh hillside, removing any interlocking spurs, creating a very wide and flat area on either side of the river, this is called the river floodplain. When the river floods, the water spreads out over the floodplain and slows due to increased friction. This causes deposition of sediment and materials being carried by the water. Over time, the height of the floodplain increases as material is deposited on either side of the river. The floodplain is very fertile.
144
How do Levee's form?
Floodplains and levee's are formed by deposition in times of river flood. The river's load is composed of different sized material When a river floods it suddenly spreads out and the water slows down because of an increase in friction. it deposits the heaviest of these particles first. The larger particles, often shingle, will form the levee which is a natural enbankment. The sands, silts and clays are similarly sorted with the sands being deposited next, then the silts and finally the smallest clays.
145
How do delta's form?
When a river reaches another body of water such as a sea or an ocean, it loses velocity and deposits sediment . If the river deposits sediment faster then coastal processes erodes it, sediment builds up in layers in a fan-shaped delta. The river splits into many river channels called distributaries and creates a larger area of wetland.
146
What is peak rainfall?
Peak rainfall is the highest amount of rainfall
147
What is Peak discharge?
Peak discharge is the largest volume of water in the channel at one point
148
What is lag time?
Lag time is the difference in time between the peak rainfall and the peak discharge
149
What is the rising limb?
The rising limb shows rising water after rainfall
150
What is the Falling limb?
The falling limb shows discharge falling as less water reaches the channel.
151
What is the Ground water flow?
Water level flowing under the surface
152
What is a storm hydrograph?
Storm hydrographs show how the discharge of a river changes over time. We use them to see how the river responds to rainfall events
153
How is rainfall represented on a storm hydrograph?
By the bars
154
How is discharge represented on a storm hydrograph?
By the line
155
How does precipitation effect the shape of a hydrograph?
Large amounts of rainfall, sudden snow melt or heavy rainfall will lead to a steeper hydrograph. On the other hand, smaller amounts of gentle rainfall or gradual snow melt will lead to a flatter hydrograph
156
How does geology effect the shape of a hydrograph?
Impermeable rocks (such as granite) that cannot absorb water will lead to a steeper hydrograph. On the other hand, Permeable rocks (such as sandstone) that can absorb and store water will lead to a flatter hydrograph.
157
How does Drainage basin size and shape effect the shape of a hydrograph?
In a small drainage basin, water will reach the river channel quickly this will lead to a steeper hydrograph. On the other hand, a larger drainage basin will create a high river discharge but over a longer period of time, also a more circular drainage basin will make the water to reach the main channel more slowly as it has further to travel this will lead to a flatter hydrograph.
158
How does soil effect the shape of a hydrograph?
Frozen and saturated soil cannot hold much rainfall; clay soils have a smaller pore space meaning that less water infiltrates into it and increases surface run off. This will lead to a steeper hydrograph. On the other hand, Dry soil can absorb much more water and sandy soils have large pores so more water can infiltrate and be stored. This will lead to a flatter hydrograph
159
How do slopes and soil depth effect the shape of a hydrograph?
Stepp slopes and thin soils cause rapid surface run off, this will cause a steeper hydrograph. On the other hand, gentle slopes and deep soils lead to slower surface run off. This will result in a flatter hydrograph.
160
How does vegetation effect the shape of a hydrograph?
Little vegetation cover results in more surface run off , this can be caused by deforestation and overgrazing by animals. This will lead to a steeper hydrograph. On the other hand, Woodland intercepts rainfall, and tree roots encourage water to infiltrate into the soil. This will lead to a flatter hydrograph
161
How do towns and cities affect the shape of a hydrograph?
Many urban surfaces such as roads and roofs are impermeable, so water runs quickly off into drains and rivers. This will result in a steeper hydrograph. On the other hand, Rural land mainly has permeable surfaces, so water permeates the soil and surface runoff is reduced. This will result in a flatter hydrograph.
162
How do antecedent conditions effect the shape of a hydrograph?
If recent high rainfall has already saturated the ground, infiltration is reduced, so any new rainfall causes rapid surface run off. This will lead to a steeper hydrograph. On the other hand, When there has been little recent rainfall, the ground can absorb and store more water so there is less surface run off. This will lead to a flatter hydrograph.
163
How did physical factors increase the chance of the River Eden flooding?
There where wet antecedent conditions, November 2015 was the second wettest November ever recorded. Storm Desmond (a depression) caused very heavy rainfall, 341mm of rain fell in 24 hours, a record for the UK. Impermeable rock is common in this area, mainly igneous in the lake district and limestone in Pennines.
164
How did human factors increase the chance of the River Eden flooding?
* The reservoirs in the lake district quickly became full and couldn't store any more water.
* The rivers in the area had not been dredged effectively after previous storms this caused the river capacity to be reduced.
* Drainage ditches had been dug in the drainage basin to increase the surface flow to the main river.
165
Describe the location of the River Eden
The river Eden is located in north west England, in Cumbria. It flows between 2 national parks (The lake district and the North Pennines)
166
What impacts would flooding have on people?
Floods can cause death and injury, People can get trapped in their houses by the quick rising waters. As flood waters rise they can flow into low-lying properties. The river will be carrying huge amounts of pollution and silt that will destroy floors, walls and any electrical gear. Some people who live close to river courses find it difficult to get insurance whilst others cannot afford the insurance premiums. The cost of repairing and rebuilding damaged buildings can push up insurance premiums.
167
What impact would flooding have on the environment?
Floods will wash chemicals and sewage into the water. The contaminated water will spread quickly over an area – causing public health issues and killing fish. Floods will destroy places where river animals and fish might have breeding grounds. Even slight changes to river temperature and water patterns can upset natural ecosystems. Floods can bring water back to dry areas (e.g. along the course of the river Nile in Egypt). Floods will ensure that there is water for irrigation or for drinking water in dry places.
168
What is an embankment (Levee)?
An embankment is a high bank built on or near river banks
169
What is a Flood Wall?
A flood wall is an artificial barrier designed to raise the height of the river banks so that they can hold more water
170
What is a Demountable Flood Barrier?
A temporary barrier that is only put up when needed
171
What is a Flood Barrier/Storm Surge barrier?
Floodgates built near river mouth to prevent a storm surge flooding behind the barrier
172
What is flood-plain retention?
Strategies to maintain or restore a rivers floodplain
173
What is River Restoration?
Strategies to restore a rivers original course
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What are the advantages of Embankments (Levees)?
They stop water from spreading into areas where it could cause problems, such as in settlements. They blend in with the environment
175
What are the advantages of Flood Walls?
They prevent water reaching areas where it would cause a large impact, ie houses/buildings
176
What are the advantages of Demountable Flood Barriers?
They are non-permanent so they can be put up and taken down when needed. This eliminates the need for a permanent flood wall that would ruin the viem
177
What are the advantages of Flood Barriers/Storm Surge Barriers?
They are able to protect large areas from a storm surge. They can be opened and closed depending on the weather conditions
178
What are the advantages of Flood plain retention?
Due to the fact that they allow rivers to flood, they helps slow down the flood waters and recover a rivers natural sedimentation processes. This helps restore the soil structure in the flood plain, making it more efficient at storing water.
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What are the advantages of River Restoration?
The aim is to restore rivers to a more natural course by taking away embankments and restoring meanders: this allows rivers to flood but slows them down. Natural rivers are more attractive for recreation. and create natural habitats which benefit wildlife.
180
What are the disadvantages of an Embankment (Levees)?
Water may go over the top of them or get trapped behind them. They can burst under pressure which could cause even more damage.
181
What are the disadvantages of a Flood Wall?
They do not look natural and contrast with the natural river. They are also very expensive to build and can cause flooding further down the river
182
What are the disadvantages of a Demountable Flood Barrier?
They can only be used in specific locations where it has been set to be deployed. There is also a risk that they may not be put up in time.
183
What are the disadvantages of Flood Barriers/Storm Surge barriers?
They are extremely expensive and need regular maintenance
184
What are the disadvantages of Flood-plain retention?
Allowing land to flood may mean a change of land use, for example a change in farmland
185
What are the disadvantages of River Restoration?
Some flood banks are often still needed, and changes in land use may bring some disadvantages.
186
What is a cost-benefit analysis?
a technique used to compare the total costs of a programme/project with its benefits
187
What are the 3 EA warning levels for a flood?
Flood Alert, Flood Warning, Severe Flood Warning
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How do the EA reduce the impact of flooding?
The EA works with the government to educate people about what they should do before, during and after a flood. This information is released through the internet, leaflets, helplines and training exercises. Local governments will only give planning permission for buildings near river is a full flood risk assessment has been carried out. A law set out in 2010 states that all new properties built near rivers must be flood resistant
189
What is the EA?
The Environment Agency
190
How do you reduce the impacts from flooding in houses?
Use tiles or rugs instead of carpets on ground floors, Fit plastic window frames and doors instead of wooden, Fit stainless steel or plastic units and cupboards in the kitchen instead of wooden ones, electrical sockets should be fitted 1.5m above ground floor level, install boilers for heating systems on the first floor, fit non-return valves to drain and water inlet pipes, install flood door barriers
191
What is the channel shape in The Upper Course?
Narrow and Shallow
192
What is the channel shape in The Middle Course?
Wide and Deep
193
What is the channel shape in The Lower Course?
Very Wide and Very Deep
194
What is the valley profile in The Upper Course?
V-shaped, steep sides
195
What is the valley profile in The Middle Course?
Gently Sloping sides
196
What is the valley profile in The Lower Course?
very wide almost flat valley
197
What is the gradient like in The Upper Course?
Steep
198
What is the gradient like in The Middle Course?
medium
199
What is the gradient like in The Lower Course?
gentle
200
What is the discharge like in The Upper Course?
low
201
What is the discharge like in The Middle Course?
medium
202
What is the discharge like in The Lower Course?
high
203
What is the velocity like in The Upper Course?
low
204
What is the velocity like in The Middle Course?
medium
205
What is the velocity like in The Lower Course?
high
206
What is the sediment size in The Upper Course?
big
207
What is the sediment size in The Middle Course?
medium
208
What is the sediment size in The Lower Course?
small
209
What is the sediment shape like in The Upper Course?
angular
210
What is the sediment shape like in The Middle Course?
roundish
211
What is the sediment shape like in The Lower Course?
round
212
What is flood risk?
Flood risk = Flood likelihood x Flood magnitude
213
Why is the flood risk getting higher?
Since 2000, the UK is twice as likely to experience severe flooding. This is because of changes in land use, urban development creates more impermeable surfaces and increases surface run off rates. Changes in weather patterns attributed to climate change can increase the likelihood of extreme weather events, these can bring more storms and therefore hind wind and rainfall - these increase the chance of flooding. An increasing population causes more people to be affected by the flooding
214
What are 4 ways in which a river can transport its load?
Solution, suspension, saltation, traction
