gcse geography: physical landscapes in the uk (copy)

dosnt include cow resovoir

what is a cross profile of a river

shows you what the cross section of the river is like

what is the long profile of a river

shows you how the gradient changes

what are the characteristics of the upper course if a river

• steep gradient

• v shaped valley with steep sides

• narrow and shallow channel

what are the characteristics of the middle course of a river

• medium gradient

• gently sloping valley sides

• wider ,deeper channel

what are the characteristics of the lower course of a river

• gentle gradient

• very wide almost flat valley

• very wide , deep channel

whats vertical erosion

• downwards erosion of a river bed

• happens mostly in the upper and middle course

• makes channel deeper

whats lateral erosion

• sideways erosion by river

• mostly in lower and middle courses

• makes river channel wider

what are the 4 processes of erosion

• hydraulic action

• abrasion

• attrition

• solution

what is hydraulic action

the force of the river water against the banks causes air to become trapped in the cracks in the rock and causes the rock to break apart.

what is abrasion

• eroded rocks picked up by the river scrape and rub against the channel wearing it away

• most erosion happens by abrasion

what is attrition

eroded rocks picked up by the river crash into each other and break into smaller peices. The river load therefore gets smaller from a rivers source to its mouth

what is solution

soluble particles of rock are dissolved into the river

what are the 4 types of river transportation

• traction

• suspension

• saltation

• solution

what is traction

the rolling of large boulders and pebbles along the river bed

what is suspension

when small and lightweight particles are carried in the river flow

what is saltation

small pebbles are bounced along the river bed in a leap frog movement

what is solution

when dissolved particles of rock are carried by the river

what is deposition

• when a river drops the materials its transporting

• occurs when loses velocity and energy

• dominant in the lower course

what are 4 reasons why rivers slow down and deposit material

1. the volume of water falls

2. the amount of eroded material increases

3. the water is shallower

4. the river reaches its mouth

how does deposition happen in order of sized partcles

• heavy particles are dropped first so dont travel far

• the next heaviest is then deposited

• only lightest and smallest particles remain and these can travel further distance downstream

how is a waterfall formed

1. waterfalls form where a river flows over an area of hard rock followed by an area of softer rock

2. the softer rock is eroded (by hydraulic action and abraion) more than hard rock creating a step in the river

3. as water flows over the step it erodes more and more of the sifter rock

4. a steep drop is eventually created which is called a waterfall

5. the hard rock is eventually undercut by erosion and becomes unsupported and collapses

6. collapsed rocks are swirled around at foot of waterfall where they erode the sifter cock by abrasion which created a deep plunge pool

7. over time more undercutting causes more collapses

8. the waterfall retreats creating a steep sided gorge

how are meanders formed

1. the current is faster on the outside of the bend because the river channel is deeper

2. the faster water has more energy so begins to erode the outside of the bend

3. the current is slower on the inside of the bend because the river channel is shallower

4. eroded material is deposited on the inside of the bend forming slip off slopes

how is an oxbow lake formed from meanders

1. erosion causes the outside bends to get closer until theres only a small but of land left between the bends (called the neck)

2. the river breaks through this land usually during a flood and the river flows along the shortest course

3. deposition eventually cuts of the meander forming an oxbow lake

how are interlocking spurs formed

1. In the upper course there is more vertical erosion.

2. The river cuts down into the valley.

3. If there are areas of hard rock which are harder to erode, the river will bend around it.

4. This creates interlocking spurs of land which link together like the teeth of a zip.

whats a flood plain

• a wide valley floor on either side of a river which occasionally floods

• when rivers flood, the water slows down and deposits the material it’s transporting

how are leeves formed

• are natural embankments

• during flood, eroded material is deposited over whole flood plain

• heaviest material deposited closest to river channel as gets dropped first when river loses its energy

• over time , deposited materials builds up creating levees along the edges of the channel

whats an estuary

tidal areas where the river meets the sea

how si an estuary formed

• An estuary is where the river meets the sea.

• The river here is tidal and when the sea retreats the volume of the water in the estuary is reduced.

• When there is less water, the river deposits silt to form mudflats which are an important habitat for wildlife.

what is discharge

the amount of water flowing through a river at any one time

whats interception

a store that holds water from preciptitation

whats infiltration

water transfer from surface to soil

whats percolation

a water transfer from soil to groundwater (rock)

whats surface run off

water transfer overland to surface storage to river / lakes

whats throughflow

water transfer from soil to river

whats groundwater flow

water transfer from rock/soil to river

whats a drainage basin

the area of land around the river that is drained by the river and its tributaries

whats a source

where a river starts, usually in the mountains

what the mouth

where a river ends , usually at a lake or sea

whats a tributary

a smaller river that joins a larger one

whats a confluene

the point at which rivers meet

whats a watershed

the highland seperating one drainage basin from another

what are the 3 physical factors that lead to flooding

1. precipitation

2. geology

3. relief

how does precipitation lead to flooding

• heavy rainfall means the ground is saturated

• means water cant infiltrate the ground

• water travels as surface run off which reaches river quickly

how does geology lead to flooding

• if the rock is impermeable , water cant infiltrate the ground

• leads to more surface run off

how does the relief of the land lead to flooding

• in areas with steep slopes, water cant infiltrate the ground as it dont have time

• thie leads to more surface run off

what are 2 human factors that lead to flooding

1. deforestation

2. urbanisation

how does deforestation lead to flooding

• trees catch water on their leaves and intercept rainfall

• cutting them down means less interception so more water reaches the ground

• leads to more surface run off

how does urbanisation lead to flodding

• replaces grass with impermeable concrete surfaces

• efficient drainage networks mean water reaches river channel quickly

• river levels rise leading to flooding

whats a hydro graph

a graph showing the water levels in a river

whats a flashy hydrograph

• short lag time and high peak dishcharge

whats peak discharge in a hydro graph

maximum amount of water held in the channel.

whats the lag time in a hydro graph

the time taken between peak rainfall and peak discharge.

whats a subdued hydrograph

• long lag time and low peak discharge

what are the factors that affect the lag time for a hydro graph

• Size of drainage basin

• Vegetation

• Valley side steepness

• Soil type

what is hard engineering

man made structures built to control the flow of rivers and reduce flooding

what is soft engineering

schemes set up using knowledge of a river and its processes to reduce the effects of flooding

what are 2 examples of hard engineering to reduce the risk of flooding

1. dams and reservoirs - dams are barriers in upper course of river and reservoirs (artificial lakes )are built behind the dam

2. channel straightening - meanders are removed by building straighter, artificial channels

what are the benefits and disadvantages of dams and reservoirs for flood management

benefits :

• reservoirs store water, control water flow and also prevent floods downstream

• can be used to generate hydroelectric power

disadvantages:

• dams are expensive to build

• creating reservoir can flood existing settlements

what are the benefits and disadvantages of channel straightening for flood management

benefits :

• water leaves the area quickly rather than building up reducing flood risk

disadvantages:

• flooding may happen downstream instead

• faster moving water may cause more erosion downstream

what are 2 examples of soft engineering to reduce the risk of flooding

• flood plain zoning - restrictions prevent building on parts of a flood plain that are likely to be affected by a flood

• planting trees - planting trees in river valley increases amount of interception (and lag time )

what are the benefits and disadvantages of flood plain zoning for reducing flood risk

benefits :

• flood risk reduced as fewer impermeable surface are created (e.g) roads

• impacts of flooding are reduced - there are no building to damage

disadvantages:

• expansion of an urban area is limited if there arent any other suitable building sites

• cant help with areas with existing buildings

what are the benefits and disadvantages of planting trees to reduce flood risk

benefits :

• discharge and flood risk decrease

• vegetation reduces soil erosion in the valley and provided habitats for wildlife

disadvantages:

• less land available for farming

whats the difference between weathering and erosion?

weathering is the breakdown of rocks where they are and erosion is the wearing away of rocks by the action of water / the weather

whats mechanical weathering

the breakdown of rock without changing its chemical composition

what are 2 examples of mechanical weathering

freeze thaw weathering and salt weathering

whats freeze thaw weathering

• water enters rock that has cracks

• when the water freezes it expands which puts pressure on the rock

• when the water thaws it contracts, which releases the pressure on the rock

• repeated freezing and thawing widens the cracks causing the rock to break up

whats salt weathering

• saltwater contains salt which can weather rocks as waves crash onto cliffs

• the seawater evaporates from the cliffs leaving behind salt crystals

• if the crystals get into cracks/holes they expand

• this puts pressure on the rocks and flakes may eventually break off

whats chemical weathering

the breakdown of rock by changing its chemical composition e.g. carbonation

whats carbonation

• rainwater reacts with carbon dioxide in the air in it making a weak carbonic acid

• carbonic acid reacts with alkaline rock

• the rocks are dissolved by the rainwater over time

whats mass movement

when rocks fall down a slope under the influence of gravity

what are the 3 types of mass movement

• slides

• slumps

• rockfalls

when do slides happen

when large chunks of rock slide down the slope/ cliff without any warning

what are the two types of slides

• mud slides

• rock slides

whats a mud slide

are usually wet, rapid and tend to occur where slopes are steep

whats a rock slide

involve a large amount of rock sliding on a straight slip plain. It maintains contact with the cliff

what mass movement does this show?

slide

when does slumping happen

• it happens where the rock in the cliff is very soft, this easily fills with water and slowly slips down into the sea

• is very common in cliffs with slippery clay at the bottom

• follows a concave slip line because it rotates as it slips

what type of mass movement does this show

slumping

when do rock falls happen

• fragments of rock break away from the cliff face, usually from freeze thaw weathering

• as they fall they loose contact with the cliff face as cliffs are normally steep

• due to falling, the rocks fan out at the base of the slope to form a scree slope

what type of mass movement does this show

rock falls

what is erosion

the wearing away if rocks by the action of water or weather

whar are destructive waves

waves that erode the coast

what are the characteristics of destructive waves

• high wave frequency

• weak swash ( brings onshore little material)

• string backwash (removes beach material)

• high and steep waves with high energy

what are constructive waves

waves that deposit materials

what are the characteristics of constructive waves

• lower wave frequency

• more powerful swash than backwash so more material is deposited

• low and long waves with low energy

what type of beach do deconstructive waves create

steep, narrow beach

what type of beach do constructive waves create

a wide gently sloping beach

what is longshore drift

the movement of sediments along a coast by waves that approach at an angle to the shore but then the swash recedes directly away from it

whats the process of longshore drift

1. waves follow the direction of the prevailing wind

2. they usually hit the coast in an angle thats not a right angle

3. the swash carries material up the beach in the same direction as the waves

4. the backwash then carries material down the beach at right angles back towards the sea

5. over time material zig zags along the coast

what is deposition on the coastline

• where waves drop and leave behind the material they were transporting

• results in more sediment staying on the beach than being taken away by backwash

why does deposition happen on the coastline

• takes place where the flow of water slows down

• waves lose energy and are no longer able to transport material

where does deposition happen on the coastline

• waves lose energy in sheltered bays where water is protected by coastal land forms ( headland, spits or bars)

• sediment can no longer be carried or moved

what are the 2 reasons the amount of material deposited on a beach increases

• lots of erosion elsewhere on coast (more material available)

• lots of material transported into area

what is a landform

a feature of the landscape that has been formed by processes of erosion, transportation and/or deposition

how does geology and rock type influence coastal landforms

• hard rocks e.g. granite will take a longer time to erode

• soft rocks e.g. sandstone erode more quickly

• rocks with joints and weaknesses in the rock erode faster

whats differential erosion

when some rocks erode at a faster rate than others

whats a disconcordant coastline

are made up of alternate bands of hard and soft rock at right angles to the coast

whats a concordant coastline

alternating bands of hard and soft rock parallel to the coast

what is folding in rock

• many sedimentary rock formed on the sea bed and were raised to the surface by mountain building tectonic processes

• were so powerful that they folded the rocks so their layers were no longer horizontal

• creates lines of weakness which are more easily eroded

whats fault line in rock

• when tectonic forces caused rocks to fold they sometimes snapped the layers rather than bending them

• movement can then occur as the rock layers are no longer joined and a fault is formed

• creates lines of weakness that are more easily eroded