Theme 1: Landscapes and Physical Processes Flashcards
Define a cross-profile.
A cross-profile is a cross-section of the valley and channel of a river.
Define erosion.
The wearing away of pieces of rock, soil or other solid materials.
Define the hydrological cycle.
The continual movement of water between the rivers, oceans, atmosphere and land.
Define lateral erosion.
The wearing away of the landscape when a river erodes sideways.
Define ‘load’.
The particles of rock carried by a river.
Define the mouth and the source!
m= the place where a river meets the sea. s= the place where a river starts in its upper course.
Define transportation!
To move objects or people from one place to another.
Define tributary.
A small river that joins the main river channel.
Define valley and because that’s fairly simple, also define vertical erosion :)
Valley= A low area of land between hills or mountains, typically with a river flowing through it
Vertical Erosion= When the land is eroded or worn away in a downwards direction, eg a river that is high up will erode vertically because gravity pulls the water downwards.
Define long profile.
A section of the course of a river drawn from source to mouth.
Define confluence and watershed
Confluence= the point where two rivers meet. Watershed= the area of high land forming the edge of a river basin.
What are some things you know about the upper course?
- has a large load
- start of the river
- often in upland areas
- often downhill, so there’s more vertical erosion
- channel is narrow and shallow
- not much water at this stage
What are some things you know about the middle course?
- some vertical erosion but more lateral erosion
- the channel is wider and deeper
- more water than the upper course
What are some things you know about the lower course?
- flatter land
- load is fine sediment
- little erosion, mostly lateral
- greater influence of deposition
- channel is at its widest and deepest
Types of River Erosion 1: Hydraulic Action
This is the sheer power of the water as it smashes against the river banks. Air becomes trapped in the cracks in the rock of the river bank and bed, and causes the rock to break apart.
Types of River Erosion 2: Abrasion
When pebbles are picked up by the flowing water and smash against the river bank and bed, wearing it away.
Types of River Erosion 3: Attrition
When rocks that the river is carrying knock against each other. They break apart to become smaller and more rounded.
Types of River Erosion 4: Solution
When the water dissolves certain types of rock, eg limestone.
Types of River Transportation 1: Traction
Large, heavy pebbles are rolled along the river bed. This is most common near the source of a river, as here the load is larger.
Types of River Transportation 2: Saltation
Pebbles are bounced along the river bed, most commonly near the source.
Types of River Transportation 3: Solution
The transport of dissolved chemicals. This varies along the river depending on the presence of soluble rocks.
Types of River Transportation 4: Suspension
Lighter sediment is suspended (carried) within the water, most commonly near the mouth of the river.
Define deposition.
As the river loses energy, it ‘deposits’ the material it has been carrying.
When a wave transports sediment/ sand up the beach but has not got enough energy to bring it back, so leaves it there.
What are the factors that lead to deposition?
- shallow water
- at the end of the river’s journey, or at its mouth
- when the volume of water decreases
What is alluvium/silt?
The sediment deposited by rivers/ fertile sand-sized particles found in the lower course of a river.
Define floodplain
An area of low-lying land next to a river which is prone to flooding.
Define gorge.
A deep, narrow passage that usually has a river running through it.
Define levee.
Ridges or banks formed by deposits of alluvium left behind by the periodic flooding of rivers. Can also be artificially constructed banks or walls.
What is a meander?
~ a bend in a river ~
Define ‘plunge pool’.
The pool of water found at the bottom of a waterfall. It is an erosional feature which has been created by a combination of hydraulic action and the abrasion of the plunging water.
What is a slip-off slope?
Gently sloping bank found on the inside of a river bend because of slow-flowing water, depositing sediment.
Define river cliff.
Steep bank created on the outside of a river bend by the erosive effect of fast-flowing water undercutting the bank.
Suspension (not the transportation one, the other one) means…
A mixture of two substances, one of which is finely divided throughout the other.
Define discharge.
The volume of water in a river passing a point in a given time. Measured in cumecs (cubic metres per second).
The process of creating a waterfall and then a gorge is… pt 1
- The soft rock is eroded quicker than the hard rock and this creates a step.
- As erosion continues, the hard rock is undercut forming an overhang.
- Abrasion and hydraulic action continue to erode the soft rock to create a plunge pool (small scale landform).
The process of creating a waterfall then a gorge is… pt 2
- Over time this gets bigger, increasing the size of the overhang until the hard rock is no longer supported and it collapses.
- This process continues and the waterfall retreats upstream.
- A steep-sided valley is left where the waterfall once was. This is called a gorge.
How do you create a v-shaped valley?
In the upper course, traction and saltation are most common, eroding vertically. This erosion, and the movement of weathered material from the banks, create a V-shaped valley. The river will bend around any hard rock.
~ How do you make a meander? ~
As the river goes around a bend, most water is pushed to the outside thus increased speed and consequent erosion resulting in a river cliff. On the inside, there’s less water + energy so the river deposits hence a gentle slope called a slip-off slope.
How do you make a floodplain?
Erosion creates a wide, flat area on either side of the river. During a flood, material being carried by the river is deposited, heightening the floodplain.
Floodplains are often used by which industry?
Agriculture! The land is very fertile because of alluvium/ silt.
How to make a levee? pt 1
In the lower course, there is an increased volume of water flowing downstream and flooding occurs. During floods, energy is lost and sediment spreads over the floodplain.
How to make a levee? pt 2
Larger material is deposited first on the river’s banks and smaller material further away. Over time, sediment builds up to increase the height of the river banks, heightening the channel, leading to a greater discharge and smaller chance of flooding in future.
What factors affect the rate of landform change?
Geology – e.g. hard and soft rocks in the formation of waterfalls.
Climate – seasonal (UK), affects the discharge of a river and the level of energy it has to erode/deposit.
Human activity – intended and unintended consequences, e.g. building a dam which traps sediment and controls the flow of a river.
What do you know about waves?
- erode the landscape
- shape coast
The size and energy of a wave depend on different factors, they are…
- the fetch (defined on another card)
- the strength of the wind
- how long the wind has been blowing for
What does fetch mean?
How far a wave has travelled!
What is swash?
Water flowing up a beach in the direction of the prevailing wind.
Define backwash.
The perpendicular movement of water down a beach due to gravity.
What are constructive waves?
Waves with a strong swash and weak backwash, which help to build up material on the beach.
What are destructive waves?
Waves with a weaker swash than backwash, which remove material from the beach.
What are the characteristics of a destructive wave?
- occur in stormy conditions, with strong winds
- tall, with short wavelength
- arrive quickly, at a high frequency
What are the characteristics of a constructive wave?
- occur in calm conditions, without much wind
- short with long wavelength
- low frequency
Define longshore drift.
The movement of material along a coastline due to the angled approach of waves.
Define prevailing wind.
The wind direction that occurs most often throughout the year, or occurs most often at this time of year, in a certain geographical region.
What is mass-movement?
A large-scale downward movement of rocks and material.
other contexts vary
What is freeze-thaw weathering? ❄
The water enters the gaps in porous (contain holes) or permeable (allow water to pass through) rocks, freezes and splits the rock.
A detailed description of the process of freeze-thaw weathering. ❄
- Water enters cracks in the rock.
- When temperatures drop, the water freezes and expands causing the crack to widen.
- The ice melts and water makes its way deeper into the cracks.
- The process repeats itself until the rock splits entirely.
What is biological weathering? 🌿
Plants and animals can have an effect on rocks e.g. roots burrow into the rock, weakening the structure of the rock until it breaks away.
A detailed process of biological weathering. 🌿
- Plant roots can get into small cracks in the rock.
- As the roots grow, the cracks become larger.
- This causes small pieces of rock to break away.
What is chemical weathering? 🧪
Rainwater and sea water can act as weak acids. If a coastline is made up of rocks such as limestone or chalk, over time they can become dissolved by the acid in the water.
What is a landslide?
Large blocks of rock become detached and slide downhill.
Types of Coastal Erosion 1: Abrasion
Bits of rock and sand in waves grind down cliff surfaces like sandpaper.
Types of Coastal Erosion 2: Hydraulic Action
Air may become trapped in joints and cracks on a cliff face. When a wave breaks, the trapped air is compressed which weakens the cliff and causes erosion.
Types of Coastal Erosion 3: Attrition
Waves smash rocks and pebbles on the shore into each other, and they break and become smoother.
Types of Coastal Erosion 4: Solution
Acids contained in sea water will dissolve some types of rock such as chalk or limestone.
How does transportation at the coast work?
Sediment is carried by the waves along the coastline. This movement is known as longshore drift. Waves approach the coast at the angle of the prevailing wind. The swash will carry the material towards the beach at an angle. The backwash then flows back to the sea, down the beach. The process repeats itself along the coast in the zig-zag movement.
Types of Coastal Transportation 1: Solution.
When minerals in rocks like chalk and limestone are dissolved in sea water and then carried in solution. The load is not visible.
Types of Coastal Transportation 2: Saltation
Where small pieces of shingle or large sand grains are bounced along the sea bed.
Types of Coastal Transportation 3: Suspension
Small particles such as silts and clays are suspended in the flow of the water.
Types of Coastal Transportation 4: Traction
Where pebbles and larger material are rolled along the sea bed.
Factors leading to coastal deposition…
- waves start to slow down and lose energy
- shallow water
- sheltered areas, eg bays
- little or no wind
Factors that affect landforms on the coast (1)
- The rock type/geology (see map below). Hard rock types are less likely to erode.
- The fetch of the wave and the strength of the wind. Powerful winds and a long fetch create the most damaging (erosive) waves.
- The angle of the slope – steep slopes erode more violently and frequently.
Factors that affect landforms on the coast (2)
- Weather conditions – freezing temperatures and heavy rain increase weathering and the rate of erosion.
- The amount of vegetation – the presence of vegetation helps stabilise slopes but also increases the occurrence of biological weathering.
Factors that affect landforms on the coast (3)
The amount of human interference – if there are no man-made structures (eg sea walls) to protect the coast, then the coast is more vulnerable to attack. However, the construction of houses, industry and other man-made structures in the first instance are the reasons why coastal erosion is a concern.
Define a bay.
A low-lying inlet of land on the coast.
Define a berm
A flat strip of land or raised bank bordering a river or canal.
Define a berm
A flat strip of land or raised bank bordering a river or canal.
Discordant Coastline
A discordant coastline is a coastline where the geology alternates between strata (or bands) of hard rock and soft rock. The types of rock are not parallel to the coast.
Concordant Coastline
A concordant coastline has the same type of rock along its length. Concordant coastlines tend to have fewer bays and headlands. The types of rock are parallel to the coast.
Define mouth.
The place where the river meets the sea.
Define spit.
A stretch of beach at one end of a coastline caused by waves depositing material
Define stack.
A pillar of rock left standing in the sea when the top of an arch has collapsed.
Define wave-cut notch.
An area of erosion at the base of a cliff formed by the waves.
Define wave-cut platform.
A flat area in front of a cliff, just below the low tide mark. These were formed when the waves eroded the cliff, but left a flat platform behind.
Define weathering.
The wearing down of rocks in situ.
How bays are formed…
Bands of soft rock such as clay and sand are weaker, therefore can be eroded quickly. This process forms bays. A bay is an inlet of the sea where the land curves inwards, usually with a beach. Formed on discordant coastlines in the softer rock’s area.
How headlands are formed…
Hard rock such as chalk is more resistant to the processes of erosion. When the softer rock is eroded inwards, the hard rock sticks out into the sea, forming a headland. These form on discordant coastlines in the harder rock parts.
How are cliffs and wave-cut platforms formed?
They’re formed by weathering and erosion! Soft rock erodes quickly and forms gentle sloping cliffs, whereas hard rock is more resistant and forms steep cliffs. A wave-cut platform is a wide gently-sloping rocky surface found at the foot of a cliff.
Process of forming a wave-cut platform… (1)
1 The sea attacks the base of the cliff between the high and low water mark.
2 A wave-cut notch (small scale landform) is formed by erosional processes such as abrasion and hydraulic action, this is a dent in the cliff usually at the level of high tide.
3 As the notch increases in size, the cliff becomes unstable and collapses, leading to the retreat of the cliff face.
Process of forming a wave-cut platform… (2)
4 The backwash carries away the eroded material, leaving a wave-cut platform.
5 The process repeats. The cliff continues to retreat.
6 Rock pools (a small scale landform) are left which often home a wide range of marine life as well as attracting many tourists.
Use this link to see what the landforms on the coast look like :) - stacks, arches etc.
https://www.bbc.co.uk/bitesize/guides/zwrg6yc/revision/2
The formation of landforms like caves, stacks and arches.
1 Cracks are formed in the headland through the erosional processes of hydraulic action and abrasion.
2 As the waves continue to grind away at the crack, it begins to open up to form a cave.
3 The cave becomes larger and eventually breaks through the headland to form an arch.
The formation of landforms like caves, arches and stacks
4 The base of the arch continually becomes wider through further erosion, until its roof becomes too heavy and collapses into the sea. This leaves a stack (an isolated column of rock).
5 The stack is undercut at the base until it collapses to form a stump.
What are the two depositional landforms on the coast?
Beaches and spits
What do you know about beaches?
- Made from eroded material that’s transported from elsewhere + deposited
- The sea must have limited energy, so they form in sheltered areas (bays)
- The size of the material increases up the beach as the larger particles are moved by powerful storms.
Why do different types of beach form? (pebble + sandy)
Sandy beaches are usually found in bays where the water is shallow and the waves have less energy. Pebble beaches often form where cliffs are being eroded, and where there are higher-energy waves.
What do you know about spits?
A spit is an extended stretch of sand or shingle jutting out into the sea from the land. Spits occur when there is a change in the shape of the landscape or there is a river mouth or estuary.
How are spits formed?
1 Sediment is carried by longshore drift.
2 When there is a change in the shape of the coastline, deposition occurs. A long thin ridge of material is deposited. This is the spit.
3 A hooked end can form if there is a change in wind direction.
4 Waves cannot get past a spit, therefore the water behind a spit is very sheltered. Silts are deposited here to form salt marshes or mud flats.
How does the geology affect the rate of landform change?
A DISCORDANT COASTLINE
The soft rock is made of clay and sands, and the hard rock is chalk and limestone. As erosion processes take place, the clay erodes away quicker than the limestone and chalk. This forms headlands and bays.
Define strata…
The bands of rock (hard or soft) on a coastline.
Define a drainage basin…
The area of land that is drained by a river and all its tributaries.
Define afforestation…
When trees are planted near to the river so that they will intercept rainfall and help to lower the discharge in the river (soft engineering).
Define confluence…
Where two rivers meet and join together
Define dam
A high wall that is built across the river channel to stop the river from flooding. Dams are built from concrete and the risk of flooding is nearly completely reduced (hard engineering).
define embankment
This is a large area of material that is built up alongside rivers in rural areas to protect the river from flooding (hard engineering).
Define evapotranspiration
Water vapour is evaporated from the trunk and the leaves of trees and other vegetation, back into the atmosphere.
Define flood wall
A wall built along a river bank to stop the river from flooding. This can be incorporated into the design of an area or can be temporary (hard engineering).
Define flooding
Floods will happen when there is a temporary increase in the amount of water in the river. The water will overflow from the river channel onto the surrounding land (flood plain).
Define floodplain
An area around a river that is covered in times of flood. Alluvium (silt) is deposited when floodwater covers the area.
Define groundwater flow
When water is able to move slowly through the soil and porous rocks to move back towards the sea (transfer).
what is a hard-engineering method?
When a river is managed in such a way so that it needs major building work to stop the river from flooding. Usually machinery and concrete/ building materials are used. It is more expensive, has a greater impact on the surroundings and requires more extensive alterations.
Define hydroelectric
electricity generated from water
define impermeable
Rock type in which water cannot pass through.
Define infiltration
Water soaks or filters into the soil (transfer).
define interception
When water is absorbed and collected by vegetation (store).
define percolation
Water moved from the soil into the spaces (pores) in the rock (transfer
define precipitation
Moisture that falls from the air to the ground. Includes rain, snow, hail, sleet, drizzle, fog and mist
define resevoir
man-made pool of water used to store drinking water.
define river discharge
The amount of water that passes a point in a river at a particular time.
what is a river management strategy
A technique/method that is used to reduce the likelihood of flooding and damage due to flooding.
what is a settlement?
A settlement is a place where people live and work. They come in all shapes and sizes – they can be as large as megacities like London or as small as individual houses dispersed across the Lake District.
what is a soft-engineering method?
When a river is managed in such a way so that it needs limited building work and floods are more prevented than managed. These measures are usually more sustainable than hard engineering methods.
define stoplog
Hydraulic engineering control elements used in floodgates to adjust the water level or discharge in a river, canal, or reservoir.
what is straightening and deepening the river?
The river channel can be widened or deepened to help it carry the water downstream more efficiently (hard engineering).
define surface run-off
The water that runs over the surface of the land when the soil is unable to absorb it.
surface run-off/ overland flow????
Water moves across the surface of the earth becoming a stream, tributary or river (transfer).
what is surface storage?
The total volume of water held on the Earth’s surface.
define throughflow?
Water moves downhill through the soil (transfer).
drainage basin inputs…
How water is introduced into the drainage basin system. This is known as precipitation.
drainage basin stores…
How water is stored or held for a period of time within the drainage basin system - interception (by vegetation), soil moisture, surface storage (lakes), groundwater.
drainage basin transfers…
A process or flow of water from one place to another in the drainage basin system - surface run-off/overland flow, infiltration, percolation, through-flow, groundwater flow.
drainage basin outputs…
How the water is released either back to the sea or back into the atmosphere - river discharge, evapotranspiration.
images of the hydrological cycle (important diagrams)
https://www.bbc.co.uk/bitesize/guides/z74g2sg/revision/1
sorry i would copy + paste this but no premium :(
physical factors that affect flooding:
- climate
- a steep-sided channel
- a lack of vegetation/ woodland
- impermeable rock
how does climate affect flooding?
Flooding is caused by heavy rainfall. The faster the rainwater reaches the river channel, the more likely it is to flood. The nature of the landscape around a river will influence how quickly rainwater reaches the channel.
how does the steepness of the sides of the channel affect flooding?
A river channel, surrounded by steep slopes, causes fast surface run-off.
how does a lack of vegetation/ woodland affect flooding?
Trees and plants intercept precipitation, ie they catch or drink water. If there is little vegetation in the drainage basin then surface run-off will be high.
how does the permeability of the rock affect flooding?
A drainage basin, consisting of mainly impermeable rock will mean that water cannot percolate through the rock layer, and so will run faster over the surface.
human factors that affect flooding:
- drainage basins in urban areas
- deforestation
how do urban areas affect flooding?
A drainage basin in an urban area consists largely of impermeable rock and concrete, which encourages overland flow. Drains and sewers take water quickly and directly to the river channel. Houses with sloping roofs further increase the amount of overland flow.
how does deforestation affect flooding?
In areas where trees and forests have been purposely cut down and destroyed by humans, flood risk dramatically increases. This is because trees intercept and absorb water as part of photosynthesis. Without trees, rainfall directly hits the surface and may quickly saturate soils or run-off into nearby rivers, causing the rivers to rise quickly.
hydrographs! as they are very visual, i have attached the links to the pages on them, as i can’t copy and paste what they look like :)
https: //www.bbc.co.uk/bitesize/guides/z74g2sg/revision/4
https: //www.bbc.co.uk/bitesize/guides/z74g2sg/revision/5
what are the methods of hard-engineering for flooding?
- dams
- river engineering
- levees or embankments
- flood walls
what is some information about dams?
- Built along the course of a river to control the amount of discharge. Water is held back by the dam and released in a controlled way.
- Water is usually stored in a reservoir behind the dam. This water can then be used to generate hydroelectric power or for recreation purposes.
- Expensive to build.
- Settlements and agricultural land may be lost when the river valley is flooded to form a reservoir.
what is some information about flood walls?
- Can be used to raise the height of the river bank to a level where the river might not burst its banks.
- Can be permanent features or incorporated into the design of an area and become invisible.
- Can also be temporary structures where flood gates or removable ‘stoplogs’ are built to protect a stretch of river.
what is some information about levees and embankments?
- Artificial levees can be built along river banks so that if the river floods, the water will not be able to breach the wall and cause damage. Levees can be expensive and can spoil the look of rivers.
- Flood embankments are usually used in rural areas. They can take up a lot of space and are cheaper than flood walls but they can also cause the speed of the water in the river to be increased which will just move any potential flooding further downstream.
what is some information about river engineering?
- The river channel may be widened or deepened allowing it to carry more water. A river channel may be straightened so that water can travel faster along the course. The channel course of the river can also be altered, diverting floodwaters away from settlements.
- Altering the river channel may lead to a greater risk of flooding downstream, as the water is carried there faster.
soft engineering options for flooding:
- afforestation
- managed flooding
- planning/ land-use zoning
- washlands
what is some information about afforestation?
- Trees are planted near to the river. This means greater interception of rainwater and lower river discharge. This is a relatively low cost option, which enhances the environmental quality of the drainage basin.
- Afforestation cannot prevent flooding but it can help reduce its likelihood.
what is some information you know about managed flooding?
The river is allowed to flood naturally in places, in order to prevent flooding in other areas - for example, near settlements.
what is some information about planning/ land- zoning?
- Local authorities and the UK government introduce policies to control urban development close to or on the floodplain. This reduces the chance of flooding and the risk of damage to property.
- There can be resistance to development restrictions in areas where there is a shortage of housing.
- This is effective when making decisions about new building in an area but does not work in areas that are already built up.
the red/yellow/green system for planning regarding floods!
When planning for a new settlement in an area, this can be used to divide up the flood plain into areas which experience different levels of flood risk. Red areas will be places that are likely to experience a high degree of flood risk. Yellow areas will be places where flooding is possible but unlikely. Green areas are places where it is very unlikely that any flooding will take place.
what is some information about washlands?
- These are areas of land where water can wash into during a flood. They are usually found in the lower course of a river. Sluice gates will be opened to allow excess water to flow into the area and flood marginal land.
- It is not always easy to find acceptable areas for this to happen – especially in areas where there are many cities.
what do governments and developers favour in terms of flood protection?
They tend to favour large hard engineering options, such as dam building. Building a dam and a reservoir can generate income. Profits can be made from generating electricity or leisure revenue.
what do environmentalists and local people tend to favour when it comes to flood-protection?
They tend to prefer softer options, such as planting trees. Soft options cause little damage to the environment and do not involve the resettlement of communities.
the things to consider when choosing a flood protection method:
Effective flood management strategies should be economically, environmentally and socially sustainable. Sustainable strategies allow management without compromising the needs of future generations.
