Rivers and Coasts

Question 1

A) what are the inputs in a river basin system/hydrological cycle?

Answer 1

Precipitation

Question 2

A) what are the flows in a river basin system/hydrological cycle?

Answer 2

Channel flow (rivers)
Surface runoff (water flowing overground)
Through flow (water in soil flowing downhill)
Groundwater flow (water in rock flowing downhill)
Infiltration (from ground to soil)
Percolation (from soil to rock)
Wind

Question 3

A) what are the outputs in a river basin system/hydrological cycle?

Answer 3

Transpiration
Evaporation
=evapotranspiration
River flow into the sea

Question 4

A) where is wate stored in a river basin system/hydrological cycle?

Answer 4

Interception (trees)
Surface storage (lakes, reservoirs)
Groundwater storage (in soil and rock - rock that holds soil is an aquifer)
Channel storage (held in a river)

Question 5

A) What are the key features of a storm hydrograph?

Answer 5

Rainfall (shown as bar graph)
Discharge in cumecs = main line graph, discharge: volume of water that flows in a river per second
Rising and falling limb (increase and decrease of discharge)
Peak flow
Lag Time (Delay between peak rainfall and peak discharge)

Question 6

A) what factors could make a storm hydrograph more dramatic and therefore dangerous?

Answer 6

High/ intense rainfall
Impermeable rock
Previously wet conditions
Steep slope
Less vegetation

Question 7

B) What are the natural causes of river flooding?

Answer 7

Prolonged rainfall - saturated ground, water can’t infiltrate, increases runoff, increases discharge rapidly
Heavy rainfall - lots of runoff, increases discharge quickly
Snowmelt - increases discharge quickly
Relief (I.e. Steep sided valley) - increases runoff, increases discharge quicker
Geology - more prone to flooding if the rock is impermeable because there less percolation, more surface run off

Question 8

B) What are the human causes of river flooding?

Answer 8

Deforestation - less interception (and therefore evaporation/output), increased discharge. Also causes soil erosion, soil gets washed into river which decreases carrying capacity
Urbanisation - concrete and tarmac are impermeable, increases runoff no increases discharge quickly. Also building on flood plains

Question 9

What is a tributary?

Answer 9

A smaller river that joins a larger river

Question 10

What are the types of weathering in a river? Briefly explain

Answer 10

Mechanical - without changing chemical composition (freeze - thaw weathering)
Chemical - by changing the chemical composition (carbonation weathering)
Biological - through living things (plant roots)

Question 11

What are the four processes of erosion in a river basin? Briefly explain

Answer 11

Hydraulic action - the force of water breaks rock particles away from the river channel
Corrosion - eroded rocks picked up by the river scrape against the channel and wear it away
Attrition - eroded rocks smash into each other and break into smaller fragments
Corrosion - river water dissolves some types of rock like chalk and limestone

Question 12

What are the four types of transportation?

Answer 12

Traction - large particles are pushed along the river bed
Saltation - pebble-sized particles are bounced along the river bed
Suspension - small particles are carried along by the water
Solution - soluble materials dissolved in the water are carried along

Question 13

Why/when do rivers deposit material?

Answer 13

If the volume of water falls
If the amount of eroded material in the river increases
If the water is shallower
If the river reaches its mouth

Question 14

How are waterfalls and gorges formed?

Answer 14

A river flows from hard to soft rock
Soft rock erodes more and a ‘step’ is created which erodes more so there is a steep drop
The hard rock gets undercut by erosion and it collapses because it is unsupported
The collapsed rocks erode the soft rock at the bottom to create a plunge pool (corrasion)
The waterfall undercuts more so a gorge is created

Question 15

How are meanders created?

Answer 15

The current on the outside of the bend flows faster because it is deeper (less friction to slow down water so more energy)
More erosion takes place on the outside of the bend to form river cliffs
The slower current on the inside of the bends means eroded materials gets deposited to form slip of slopes

Question 16

How are oxbow lakes formed?

Answer 16

Erosion causes the outside bends of a meander to get closer
The small area of land as the neck eventually breaks through (often during a flood)
Deposition cuts of the meander and forms an oxbow lake

Question 17

What are flood plains?

Answer 17

A flood plain is a wide valley floor on either side of a river
The river floods onto the plain and water slows down and deposits material making the flood plain higher
Meanders migrate across the plain, making it wider and the slip off slopes also make it wider

Question 18

What is a delta?

Answer 18

The deposition from when a river slows down (when meeting the sea/lakes) and doesn’t get washed away builds up and blocks the channel so distributaries form. The material builds up more so low areas of flat land are formed.

Question 19

What are the three types of delta?

Answer 19

Arcuate - rounded shape, lots of distributaries
Cuspate - triangular shape, fewer distributaries
Birds foot - lots of separate parts jut out into the sea

Question 20

What are dams and reservoirs and what are the advantages and disadvantages of them as flood management?

Answer 20

Reservoirs release water slowly, the water can be used as drinking water or for hydroelectric power, they are also used for recreation. However, dams are expensive and cresting reservoirs can flood existing settlements, eroded material isn’t deposited so farmland downstream is less fertile

Question 21

What is channel straightening and what are the advantages and disadvantages of it as flood management?

Answer 21

Artificial straight channels replace meanders
Water moves out of the area more quickly because it doesn’t travel as far but flooding downstream may happen since water is carried there faster

Question 22

What are man made levees and what are the advantages and disadvantages of them as flood management?

Answer 22

They are man made embankments on either side of the river
They increase the rivers carrying capacity and are quite cheap
If the levees fail it can cause catastrophic flooding

Question 23

What are flood warnings and what are the advantages and disadvantages of them as flood management?

Answer 23

People are warned about floods by TV, radio, newspaper, and the internet
The impacts are reduced because people move possessions and use sand bags
They don’t stop the flood from happening and some people may not have access to the warnings

Question 24

How can homes and businesses be modified as part of flood management?

Answer 24

People can make plans for what to do in a flood so that the impacts are reduced but it’s expensive and doesn’t guarantee safety

Question 25

What is flood plain zoning and what are the advantages and disadvantages of it as flood management?

Answer 25

Restrictions prevent building on parts of flood plains so the risk of flooding is reduced and there are less impermeable surfaces but it means expansion of urban areas is limited and it doesn’t help areas that have already been built on.

Question 26

What are the properties of destructive waves?

Answer 26

They have a high frequency of 10-14 waves per min
They are high and steep
Backwash > smash
Created by string winds and large fetches

Question 27

What are the three types of mass movement?

Answer 27

Slides - shifting in a straight line
Slumps - shifting with rotation
Rockfalls - shifting vertically

Question 28

explain longshore drift

Answer 28

The process of material moving along a coastline

1) waves follow the direction of prevailing wind
2) waves hit the coast at an oblique angle
4) swash carries material up the beach
5) backwash carries material back at a right angle
6) the material gradually moves along in zig zags

Question 29

When does the amount of deposition increase?

Answer 29

Where there is lots of erosion elsewhere and when there’s lots of transportation of material into the area and when there is less energy

Question 30

What are the properties of constructive waves?

Answer 30

They have a low frequency of 6-8 waves per minute
They are low and long
Swash > backwash
Made by weaker winds and shorter fetches

Question 31

What are the characteristics of sand beaches?

Answer 31

They are flat and wide because the particles are small so weak backwash can move them back down
Long and gentle slope

Question 32

What are the characteristics of shingle beaches?

Answer 32

Steep and narrow because backwash can’t move them back down the beach
Steep slope as particles build up

Question 33

What are the economic reasons to protect coastlines?

Answer 33

To prevent loss of tourism
To stop businesses falling into the sea
So that coastal flooding doesn’t reduce soil fertility (farming)
To stop property prices falling if there is risk of flooding or erosion (and so that people can get their homes insured)

Question 34

What are the social reasons to protect coastlines?

Answer 34

To prevents deaths
To keep water supplies clean
To prevent loss of housing
To prevent loss of jobs due to the termination of coastal industry
To prevent damage of infrastructure

Question 35

What are the environmental reasons to protect coastlines?

Answer 35

To keep ecosystems healthy (no plants uprooted, no saltwater damage)
To stop SSSIs falling into the sea (I.e. The lagoon in Yorkshire, Holderness)

Question 36

What are sea walls and what are the advantages and disadvantages?

Answer 36

Reflects wave energy back to sea
Prevents erosion and flooding
Creates strong backwash and erodes under barrier, expensive to build and maintain

Question 37

What is rip rap and what are the advantages and disadvantages?

Answer 37

Boulders piled along the coast
Absorb wave energy, reduce erosion and flooding
Can be moved around so must be replaced

Question 38

What are groynes and what are the advantages and disadvantages?

Answer 38

Fences built to trap material deposited by long shore drift
Create wider beaches to slow waves = protect from flooding and erosion
Starve beaches elsewhere of material so they are more likely to erode or flood

Question 39

What are revetments and what are the advantages and disadvantages?

Answer 39

Slanted structures at the foot of cliffs
Absorb wave energy so reduce erosion
Expensive and create strong backwash so it erodes underneath

Question 40

What are gabions and what are the advantages and disadvantages?

Answer 40

Rock filled cages build at cliff bases
Absorb wave energy and reduce erosion
Visually obtrusive

Question 41

What are breakwaters and what are the advantages and disadvantages?

Answer 41

Concrete barriers out at sea
Force waves to break offshore so material is deposited
Expensive, can be damaged

Question 42

What is beach engineering and what are the advantages and disadvantages?

Answer 42

Sand and shingle is added to beaches so they are wider and slow waves
Protects against flooding and erosion
Taking material can harm organisms elsewhere, expensive, lots of maintenance required

Question 43

What is managed retreat and what are the advantages and disadvantages?

Answer 43

Removing existing defences and allowing the land to flood
Marshlands are created to protect land behind
Can have social impacts on people living on the coast