physical landscapes

Question 1

what is a confluence?

Answer 1

where two or more streams/rivers meet

Question 2

characteristics of the upper course?

Answer 2

• shallow
• narrow
• steep relief
• large, uneroded rocks
• rough riverbed and banks - high levels of friction - lower velocity
• primarily vertical erosion

Question 3

formation of a waterfall

Answer 3

1) at an area of hard rock and soft rock, the soft rock erodes faster
2) the soft rock undercuts the hard rock, creating a plunge pool
3) this creates an overhang of hard rock, which due to weathering, weakens over time, and eventually collapses due to gravity, forming a waterfall
4) hydraulic action and abrasion attack the base of the cliff, creating another plunge pool, and so the process repeats again, causing the waterfall to retreat

Question 4

what is a gorge?

Answer 4

a steep-sided, narrow valley is left where the waterfall once was, and the river runs through it

Question 5

formation of a V-shaped valley

Answer 5

1) due to vertical erosion, the river bed deepens
2) the sides of the river bed are weakened due to weathering
3) material breaks off and slides down diagonally into the river, forming a V-shaped gap where they once were
4) the sediment added to the river causes further erosion, causing a steeper V-shaped valley

Question 6

formation of a meander

Answer 6

1) the fastest flow of the river (the thalweg) is on the outside of the river
2) hydraulic action and abrasion therefore erode the outside of the river, forming a river cliff
3) the slowest flow of the river is on the inside of the river, therefore this is where the least energy is, and subsequently deposition of sediment occurs, forming a slip off slope
4) as this process repeats, the river moves across the floodplain, and become wider and more sinuous, forming meanders

Question 7

formation of an oxbow lake

Answer 7

1) the erosion on the outside of meanders can create a meander neck
2) in the event of a flood, water may cut through the neck and take a straight route to the other side
3) the spreading of water causes a drop in energy, meaning that deposition occurs, leading to the meander being cut off from the lake, forming an oxbow lake

Question 8

what is alluvium?

Answer 8

• rock particles (clay, silt, sand, etc.) deposited by a river

Question 9

formation of floodplains and levees

Answer 9

1) high discharge causes flooding of the surrounding area
2) the spread out of water over a large area causes a drop in energy, causing deposition, gradually increasing the height of the floodplain
3) the heaviest material is deposited closest to the riverbanks, forming natural embankment called levees

Question 10

what is an estuary?

Answer 10

where the river meets the sea

Question 11

formation of mudflats and salt marshes

Answer 11

1) when saltwater meet freshwater at the mouth of the sea, this causes a drop in velocity
2) deposition occurs and builds up in layers to form mudflats
3) mudflats grow vegetation and form salt marshes

Question 12

River Tees?

Answer 12

• NE England, 85 miles long
• Pennines to the North Sea
• High Force waterfall, highest in the UK
• meanders near Darlington, floodplains and levees

Question 13

what is lag time?

Answer 13

time taken for the precipitation to reach river (shorter lag time = increased discharge = increased flood risk)

Question 14

what are the factors that affect flood risk?

Answer 14

• human: deforestation (less interception), urbanization (impermeable materials), agriculture (soil become more compact), climate change (increase in precipitation)
• physical: steep relief (reduces infiltration), impermeable rock types, frozen/compacted soil, amount of vegetation/trees, amount of precipitation, antecedent conditions (recent rainfall that already saturated the ground)

Question 15

dams?

Answer 15

• large concrete barrier, and there is a valley behind it, creating a reservoir to store floodwaters
• advantages: HEP source, drinking water source, highly effective, boosts tourism
• disadvantages: expensive (167 million pounds), harms habitats, displaces existing people, landslides often occur

Question 16

raising embankments?

Answer 16

• impermeable soil/concrete embankments to contain floodwaters
• advantages: cheaper, earthen embankments provide habitats, attractive walkway
• disadvantages: requires lots of maintenance, displaces natural habitats when built, no easy access to fishing or boating, earthen ones prone to erosion, visually unattractive

Question 17

channel straightening?

Answer 17

• meanders turned into wider, deeper channels
• advantages: water moves faster, improves navigation and increases trade, lower insurance costs
• disadvantages: expensive, constant maintenance, more energy which erodes banks runoff cannot drain into the river easily

Question 18

flood relief?

Answer 18

• another channel built to divert flooded water
• advantages: completely removes risk, footpaths, cycle paths, etc. built along channel, lower insurance costs
• disadvantages: displaces people, causing distress, settlement downstream suffer from more flooding, constant maintenance, unattractive at low tide when concrete is exposed

Question 19

river restoration?

Answer 19

• uses meanders to slow river flow
• advantages: - restores natural habitats, reduces flood risk downstream
• disadvantages: take time to be effective, expensive (1.1 million), loss of agricultural land

Question 20

flood warnings?

Answer 20

• prediction of flood and issues warnings
• advantages: cheap, people feel more in control and secure
• disadvantages: only effective if people listen, not everyone has internet, flooding still damages properties, etc.

Question 21

afforestation?

Answer 21

• planting trees to increase interception
• advantages: increases lag time, low-cost, nature is conserved, also reduces climate change
• disadvantages: limited impact, loss of agricultural land

Question 22

floodplain zoning?

Answer 22

• buffer zone for flooding, protects high-value land
• advantages: decrease in impermeable surfaces, less flood risk, low cost, conserves nature
• disadvantages: lots of cities already built over floodplains

Question 23

different types of erosion?

Answer 23

• hydraulic action - force of water hitting against cliff face
• abrasion - rocks from water being thrown at seawall
• attrition - rocks hitting each other
• solution - chemicals dissolving rocks

Question 24

different types of transportation?

Answer 24

• saltation - rocks bouncing along the seabed
• suspension - small rocks floating
• traction - large boulders rolling along seabed
• solution - dissolved fine particles carried by water

Question 25

reasons for deposition?

Answer 25

• water spreads out/increased surface area
• shade
• decrease in energy
• increase in sediment
• mouth reached

Question 26

what is a concordant vs. discordant coastline?

Answer 26

• concordant - alternating layers of soft ad hard rock parallel to the coast - forms coves
• discordant - alternating layers of soft and hard rock perpendicular to the coast - forms headlands and bays

Question 27

types of mass movement?

Answer 27

• sliding - rain infiltrates soil and makes it heavier, so large blocks of mud or rock slide downhill
• slumping - material travels down a concave slip plane, so it it rotates backwards into the cliff face as it slips, creating layers
• rock falls - bits of rock fall off from cliff face, and fan out at the base to form a scree slope

Question 28

types of beaches?

Answer 28

• sandy beaches - flat gradient and constructive waves (low energy and relatively stronger swash)
• pebble beaches - steep gradient and destructive waves (high energy and stronger backwash, although swash is still stronger than that of a constructive wave)

Question 29

formation of a cave, arch, stack, stump

Answer 29

1) wave is refracted by low energy/wind direction
2) hydraulic action and abrasion attack both sides of the headland
3) eventually, as rock pieces break off, a cave is formed
4) erosion continues until the caves on either side of the headland meet, breaking through the headland and forming an arch
5) the overhang weakens and collapses due to weathering, leaving an isolated rock column called a stack
6) hydraulic action and abrasion erode the base of the stack, leaving the top weakened by weathering and eventually collapses to form a stump

Question 30

longshore drift?

Answer 30

1) waves driven onto the beach at an angle by the prevailing wind direction
2) therefore, swash carries sediment up the beach at an angle
3) materials travels straight down with backwash (due to gravity)
4) sediment continues to travel in the zigzag motion down the beach

Question 31

formation of a spit?

Answer 31

1) when the coastline changes direction, LSD will continue into the sea
2) as it is now surrounded by water, the increase in surface area will cause deposition of sediment, forming a spit
3) recurve caused by prevailing wind direction

Question 32

formation of bars?

Answer 32

1) at a bay, LSD will continue across the sea - the shade in the sheltered area means sediment is deposited
2) this will continue to the other side, forming a bar
3) the bay behind the bar is cut off from the sea, forming a lagoon

Question 33

formation of sand dunes?

Answer 33

1) sand is blown against an obstacle (vegetation)
2) more plants and vegetation grow there which traps more sand, increasing the size of the dune

Question 34

embryo vs. mature dunes?

Answer 34

• embryo dunes - yellow, more sandy, at the front of the beach
• mature dunes - grey, tall, more vegetation at the back of the beach

Question 35

seawall?

Answer 35

• designed to absorb and reflect wave energy
• advantages: low maintenance, strong defense, provides a sense of security, can be used for social activities, doesn’t impede LSD
• disadvantages: very expensive, visually unappealing, restricts access to the beach, impacts nearby species

Question 36

groynes?

Answer 36

• barriers perpendicular to the coastline to trap sediment from LSD
• advantages: maintained beaches are tourist attractions, cheaper than seawalls
• disadvantages: visually unappealing, restricts access, can rot/fall apart, more erosion in beaches further along the coast

Question 37

rock armour?

Answer 37

• boulders act as barrier and dissipate energy
• advantages: can be used to protect seawall (less maintenance), quick and easy, does not impede LSD, relatively cheaper
• disadvantages: safety hazard, transport of rocks is expensive, restricts access

Question 38

gabions?

Answer 38

• wire cages filled with rocks and pebbles, when waves energy their energy is dissipated
• advantages: least cost, long-lasting, looks somewhat natural
• disadvantages: safety hazard, can rust/degrade, easily destroyed by a storm

Question 39

beach nourishment?

Answer 39

• sand taken from another beach and deposited, larger beach dissipates energy
• advantages: provides material for LSD and natural processes, increases tourism, looks natural, can be used to protect hard engineering
• disadvantages: closes beach for weeks, annoying to residents, expensive, deprives a beach somewhere else

Question 40

beach reprofiling?

Answer 40

• reshaping beach for a steeper gradient for a higher, wider barrier
• advantages: protects home and sense of security, cheaper
• disadvantages: steep beach looks unnatural and uninviting to tourists, bulldozers make noise pollution, restricts access to beach

Question 41

sand dune regeneration?

Answer 41

• planting vegetation to trap sediment and encourage sand dunes
• advantages: cheap, sheltered areas for picnics, natural, sustainable long-term solution
• disadvantages: fences deter visitors, needs to be constantly maintained, prone to damage, takes years to grow and establish

Question 42

managed retreat?

Answer 42

• people are moved out and buildings demolished to protect from retreating coastline
• advantages: natural habitats, cheaper in the long-term, takes pressure off flooding in neighboring beaches
• disadvantages: distressed people, damages natural habitats by flooding, compensation costs make it expensive in the short-term