Geography - Rivers

Front 1

What are the 5 key characteristics of a river?

Back 1

- Width
- Depth
- Velocity
- Discharge
- Gradient

Front 2

Define Width:

Back 2

the distance from one bank to the other (rivers get wider downstream)

Front 3

Define Depth:

Back 3

the distance from the surface of the water to the bed (rivers get deeper downstream)

Front 4

Define Velocity:

Back 4

how fast the water is flowing (flows faster further downstream)

Front 5

Define Discharge:

Back 5

the volume of water moving through the river channel in any given time (lower volumes at the upper course)

Front 6

Define Gradient:

Back 6

the steepness of the river bed (steeper nearer the upper course)

Front 7

What are the 4 main types of erosion in rivers?

Back 7

- Hydraulic Action
- Abrasion
- Attrition
- Solution

Front 8

Describe Hydraulic Action:

Back 8

- the force and pressure of water weakens the banks of the river and erodes the rock
- it also creates cracks which air gets trapped into and pops, causing rocks to fall away

Front 9

Describe Abrasion:

Back 9

- water pushes rocks along the sides and bottom of the river - like sandpaper - so erodes it

Front 10

Describe Attrition:

Back 10

- water causes rocks to hit each other which creates smaller rocks

Front 11

Describe Solution:

Back 11

- chemicals in water dissolve the rock

Front 12

What is Transportation?

Back 12

- rivers use the energy of the water to transport material such as sand and pebbles
- rocks are known as 'load' and have to be moved, but it depends on the size because of the energy needed.

Front 13

What are the 4 main types of Transportation?

Back 13

- Traction
- Suspension
- Saltation
- Solution

Front 14

Describe Traction:

Back 14

- the energy of the river rolls large rocks and boulders along the river bed
- requires lots of energy as rocks are heavy - are transported only when there is enough energy
- energy levels are high near the source of the river, where this type of transportation occurs

Front 15

Describe Suspension:

Back 15

- small fine particles such as clay and silt are transported by the flow of the river
- they are too light to sink so are suspended
- this process needs low energy so found in the middle and lower courses

Front 16

Describe Saltation:

Back 16

- it is the transportation of small rocks and pebbles
- the river's current lifts and bounces material along the river bed
- this type of transportation takes less energy than traction, but more than suspension

Front 17

Describe Solution:

Back 17

- sodium and calcium etc. have been dissolved by by acids in water and carried in solution
- this type of transportation cannot be seen by the naked eye

Front 18

What is Deposition?

Back 18

- the river drops its load because of less energy and velocity
- when a river loses energy, the heavier load will be dropped or deposited and the lighter load will be carried further

Front 19

What is a Drainage Basin?

Back 19

- the area that is drained by a river and its tributaries

Front 20

What are the source and mouth of a river?

Back 20

- source - the beginning of a river (often found in mountains)
- mouth - where the river ends

Front 21

What is a confluence, tributary and watershed?

Back 21

- a confluence is where a tributary meets a river - the point at which two rivers meet
- a tributary is a smaller stream that joins up with a larger river - small streams leading into a river
- a watershed is the invisible boundary between drainage basins

Front 22

What are the characteristics and features of the Upper course of a river?

Back 22

Characteristics:
- Steep/V-shaped Valley
- Narrow/Shallow Channel
- High Bedload
Features:
- 'V' shaped valleys
- interlocking spurs
- waterfall
- gorges

Front 23

What are the characteristics and features of the Middle course of a river?

Back 23

Characteristics:
- Open/gentle sloping valley with floodplain
- Wider/deeper channel
- More suspended sediment
Features:
- Meanders
- River Cliffs
- Slip off slopes

Front 24

What are the characteristics and features of the Lower course of a river?

Back 24

Characteristics:
- Open/gentle sloping valley with floodplain
- Flat and Wide floodplain
- Wide, open valley
- Very wide and very deep channel
Features:
- Ox-bow lakes
- Flood Plains
- levees

Front 25

What does the long profile of a river look like?

Back 25

See diagram above:

Front 26

Describe how the landform of Interlocking Spurs is formed and which part of the river it is found in:

Back 26

- They are an Upper Course Landform
- They are formed when a river cuts into a valley as this produces steep sides whilst the river winds gently around areas of more resistant rock
- the ridges of land jut into the river valley, looking as though they're interlocking
- they are steeper on one side - where the river cuts into the side - and gentler on the other
- Buckden Beck is the case study

Front 27

Describe how the landform of Waterfalls is formed and which part of the river it is found in:

Back 27

- Upper Course landform
- there is a layer of hard rock on top of soft rock which water flows over
- the ledge then undercuts and the soft rock underneath is worn away to form a plunge pool
- the waterfall then takes up a new position, leaving a steep valley, or gorge and large rocks break off to the bottom
- rock is eroded by abrasion and hydraulic action and smaller rocks tumble to the bottom and the waterfall is created
- Case studies are Bridal Veil Falls, New Zealand or Buckden Beck

Front 28

Describe how a Meander is formed and what part of the river it is in:

Back 28

- Middle Course Landform
- The river forms a natural corkscrew pattern - helical flow - which forms a meander
- this is a completely natural process as river flow is rarely straight and is usually turning - causes energy to move laterally
- the meander is eventually formed by erosion - the fastest current is forced against one of the banks which undercuts it and produces a rivercliff steep edge - the narrow neck is gradually eroded
- there is erosion on the outside of the bend as fast flowing water with lots of energy is directed to the outside bank
- there is deposition on the inside bend as where there is less water on the inside there is more friction and slower flowing water
- Case Study - downstream from Buckden Beck - Starbottom to Kettlemill

Front 29

Describe how an Ox-bow lake is formed and what part of the river it is found in:

Back 29

- Middle Course landform
- rivers produce a wide range of landforms
- the narrow neck of the meander is gradually eroded
- water takes the quickest route and deposition takes place, sealing off the old meander - the meander neck is cut through completely
- an ox-bow lake is left behind when the meander is completely cut off
- Case study - River Mississippi

Front 30

What is the thalweg, pointbar and rivercliff?

Back 30

- the thalweg is the fastest point in the river
- a rivercliff is on the outside bend where there is erosion
- a pointbar is on the inside bend where there is deposition

Front 31

Describe how flood plains and what part of the river they are found in:

Back 31

- the floodplain is formed by both erosion and deposition
- the lateral (sideways) erosion is caused by meanders eroding on the outside of their bends which creates a flat land form known as a floodplain
- it is very fertile for crops as when the river floods it leaves behind fine silt and alluvium
- The terrace is the bumpy light green bit
- Case study - River Don floodplain on 25th June - 2 people killed and hundreds relocated

Front 32

Describe how levees are formed and what part of the river they are found in:

Back 32

- in times of floods, water and sediment come out of the channel as the river overflows its bank
- the water immediately loses velocity and as it leaves the channel the largest sediment is deposited first, on the banks
- repeated flooding causes these banks to get high, forming levees
- Case Study - River Wharfe

Front 33

Describe where the Afon Nant Peris river is and what surrounds it at its different parts:

Back 33

- in Wales
- more mountains near the source - contour lines
- flatter near the mouth where there is more towns and cities

Front 34

Describe the characteristics of the Afon Nant Peris river at its different sections:

Back 34

- at the source (pen-y pass) it is a narrow valley with mainly vertical erosion
- in the middle course (parking lay-by) there is less vertical erosion and more lateral erosion, and also more deposition
- the valley widens and the velocity is quite high and there is a broad flood plain with gently sloping sides
- at the mouth (Nant Peris village - Menai Strait) there is little vertical erosion and mainly lateral erosion
- there is a lot of deposition and a broad flood plain

Front 35

Give a statistic of the area of which the river Afon Nant Peris is in:

Back 35

- this whole area receives 2500mm of rain each year and 80% flows out along the river

Front 36

Give 12 physical causes of flooding:

Back 36

- heavy rainfall in an area with little vegetation
- heavy rainfall in an area with impermeable bedrock and thin soil
- rivers silting up - often because of soil erosion upstream
- heavy rainfall in an area with steep valley sides
- a dam bursting or a levee breaking
- a sudden increase in temperature that rapidly melts snow and ice - water flows over the frozen ground
- a cloudburst in a thunderstorm - the ground can't cope with the sheer volume of water landing on it
- a long, continuous period of rain which has saturated the ground
- where the underlying rock is impermeable - the water can't infiltrate
- steep valley sides
- a period of heavy rainfall on the confluence of 2 or more rivers, causing a backlog of water
- when the soil is saturated from previous rainfall

Front 37

Give 6 human causes of flooding:

Back 37

- a flood control dam being opened in a country upstream
- building new houses - making more surfaces impermeable and letting water travel quickly through sewers
- deforestation - reducing interception
- farm animals and machinery compacting the soil - making it more imeprmeable
- a sudden increase in temperature that rapidly melts snow and ice - water flows over the frozen ground
- urbanised areas - water can't infiltrate man made surfaces such as tarmac and concrete

Front 38

Describe the characteristics of a forested slope:

Back 38

- there is a layer of saturated rock with a groundwater table on top - this helps preserve a high water table and there is slow movement of water through the drainage basin
- on a forested slope there is less flooding
- trees and leaves increase the amount of water evaporated
- soil, roots and leaflitter catch water and allow it to infiltrate into soil
- forest soil is deep and can hold more water
- rainfall is intercepted by trees, undergrowth or leaf litter, it drips to the ground slowly
- Water seeps slowly from soil water, groundwater and into the river - the water level is lower but clearer

Front 39

Describe the characteristics of a deforested slope:

Back 39

- on a deforested slope there is more flooding
- there is a layer of saturated rock and a groundwater table above it and the fast movement of water through the drainage basin causes floods
- Grazing animals compact the soil making it less porous
- rainwater moves more quickly over the surface into the river (surface runoff increases)
- soil is thin or eroded and therefore stores less water, rain water does not soak into the ground
- loose soil and rock wash downhill into the rivers, channels become more blocked and flood more easily

Front 40

What are the characteristics of an area before urbanisation?

Back 40

- precipitation is intercepted by the tops of trees
- there is overland flow over the surface of the ground, infiltration into the ground and throughflow in the ground

Front 41

What are the characteristics after urbasnisation?

Back 41

- less vegetation so less interception
- many impermeable surfaces so increases the overland flow
- the water moves rapidly through drains

Front 42

Describe what a hydrograph shows and where:

Back 42

- y-axis - increased rainfall and discharge
- x-axis - Time (hours, from the start of the rainfall)
- dotted line near the bottom shows base flow
- top of the blocks shows peak rainfall
- line going upwards is the rising limb
- line going downwards is the recession (falling) limb
- the top of the line is peak flow (discharge)
- the time between the peak rainfall and the peak flow/discharge is the basin log time

Front 43

What does a hydrograph show?

Back 43

shows how a river responds to a period of rainfall

Front 44

What were the 3 main causes of the Carlisle floods and when were the Carlisle floods?

Back 44

- January 2005
- heavy rainfall - 200mm in 36 hours
- land already saturated due to to snowfall in the previous week
- deep depression tracked east across southern Scotland

Front 45

What were the 3 main effects of the Carlisle floods?

Back 45

- 3 people died - 2 from drowning and 1 from a falling wall
- 2700 homes were affected
- £400 million damage

Front 46

What were the 3 main responses to the Carlisle floods?

Back 46

- installing a pumping station
- building flood walls along the river
- re-opening the natural floodplain downstream of Carlisle

Front 47

What were the 4 main causes of the Sheffield floods, where is Sheffield and when were the floods?

Back 47

- 2007
- prolonged rain - 15th June 90mm fell - more than 1 month's amount
- on 25th June 100mm fell in 24 hours - most received in a day
- soil saturation - after the 15th and 16th of June the soil was saturated and the ground had not dried out by 25th June so all extra rain ran into rivers as surface run-off
- the confluence of several rivers - rivers Rivelin and Loxley join so the volume of water increased and flooding was an immediate risk
- river Don joined the river Loxley and caused a backlog of water which overflowed the banks
- the physical landscape - sheffield is situated where 3 rivers meet and the several storage reservoirs filled rapidly and overflowed
- steep slopes near Sheffield mean that water runs off rapidly filling the river - river levels were also raised, blocking drains in the city

Front 48

What were the 4 main effects of the Sheffield floods?

Back 48

- 2 people drowned
- over 1200 homes were flooded and more than 1000 businesses were affected
- roads were damaged and a bridge collapsed, blocking roads and affecting travel for several days
- 13,000 people were without power for 2 days

Front 49

What were the 3 main responses to the Sheffield floods?

Back 49

- Meadowhall Shopping Centre has its own defences - an embankment around it to hold off water
- the river Sheaf has an enlarged concrete-lined channel where it joins the river Don in central Sheffield and aims to speed up the flow of water away from the city - in June 2007 it worked and there was no flooding in this part of the city
- in Rother Valley Country Park, east of Sheffield, lakes have been shaped from old quarries along the River Rother to take floodwater
- they hold it until it is released into the River Don a few miles away and prevented this area flooding in 2007 (also used for boating and pleasure)

Front 50

What are the 4 ways that governments try to prevent flooding?

Back 50

forecasting, building design, planning and education

Front 51

How do governments prevent flooding by forecasting?

Back 51

rivers with a history of flooding are monitored by the environment agency
maps have been produced that shows areas at levels of risk
computer simulation models were used by Rice university in texas to evacuate texas medical centre in 2001

Front 52

How does building design prevent flooding?

Back 52

ceramic tiles are put on floors as they are impermeable
use rugs instead of fitted carpets
electrical sockets 1.5m above the ground
in poorer areas, houses are built on stilts
drains fitted with one way valves to decrease backflow

Front 53

How is flooding prevented by planning?

Back 53

now in at risk areas buildings have to have sufficient protection measures against floods
land use zoning is often used so that buildings aren't built in flood risk areas

Front 54

How does education help to prevent flooding?

Back 54

governments educate the local people about prevention and recovery
leaflets, TV and newspaper adverts, information websites, security drills and the exercises
give advice to store food without refrigeration in case of electricity loss, store water, keep first aid kits and disaster relief kits handy

Front 55

What are the six ways to manage floods?

Back 55

flood walls, channel straightening, flood relief channel, embankments, deepening the river, dams

Front 56

How do flood walls manage floods?

Back 56

built around factories - made out of concrete
they protect homes but are very expensive and don't look natural

Front 57

How does channel straightening manage floods?

Back 57

straightens the river channel so water can run through more quickly
they take water away from places at risk of flooding but this can lead to more flooding downstream as water is carried there faster
it also doesn't look natural and changes ecosystems affecting plant and animal species

Front 58

How do flood relief channels manage flooding?

Back 58

digs extra channels on the river to divert it
water doesn't overflow as it goes to a relief channel and the river discharge is reduced
however it doesn't natural, it's not needed very often and it's a high cost for infrequent use

Front 59

How do embankments manage flooding?

Back 59

they raise the heights of riverbanks and aim to stop water spreading to other areas
they are made out of earth, grass and concrete
they protect land but are expensive and burst under pressure

Front 60

How does deepening the river manage flooding?

Back 60

the river is deepened to store more water to increase its flow
the water is likely to build up and cause flooding and can lead to more flooding further downstream as the water is carried there faster
it also doesn't look very natural and can affect your ecosystems

Front 61

How do dams manage flooding?

Back 61

they can trap and store water to control flow and are built upstream to regulate flow
they hold back water at times of rain or heavy snow melt, supply water and HEP and are also used for recreation
however they can be an eyesore, are expensive to build, can damage natural ecosystems, when made the land behind is flooded, if it bursts the damage is devastating and they trap sediment that would normally go downstream, leading to further erosion

Front 62

What are the 4 types of soft engineering methods?

Back 62

washlands, afforestation, land use zoning and flood warning systems

Front 63

What are the 4 hard engineering methods?

Back 63

embankments (levees), channelisation, dams and floof relief channels

Front 64

How do washlands manage flooding?

Back 64

these are areas on the flood plain that are allowed to flood which gives a safe place for floodwater to go, it is also cheap and leaves the natural environment unspoilt, however the flood plain can't be used for other things

Front 65

How does afforestation manage flooding?

Back 65

- trees are planted in the drainage basin as trees intercept rainfall and take water out of the soil which reduces the amount reaching rivers

- wooded areas look attractive and provide wildlife habitats but then land then can't be used for other activities, such as farming

Front 66

How does land use zoning manage flooding?

Back 66

- governments allocate areas of land to different uses, according to their level of flood risk

- major building projects are allocated to low risk areas

- open space for leisure and recreation is placed in high-risk areas because flooding would be less costly for them

- these may not be the best places in terms of public accessibility

Front 67

How do flood warning systems manage flooding?

Back 67

- rivers are carefully watched and if the levels are rising, places downstream can be warned

- people living in towns or villages downstream have a chance to prepare or evacuate

- sometimes it isn't possible to give very much warning and so it is hard to save possessions

Front 68

Describe the case study of the River Skerne,how it tried to prevent flooding and how successful it was:

Back 68

- in Darlington, and flooded in June 2007

- in the 19th century the meanders were straightened to allow industries to build on the flood plain, though this decreased its length by 13% which increased the flood risk

- the Environment Agency restored 2km or river

- some meanders were rebuilt, lengthening the river and slowing water down

- banks were lowered to make the river flood the park instead of Darlington

- the flood plain was lowered to increase its ability to store floodwater

- it did flood in 2007, but rainfall was high so despite the damage it was better than the floods in 2000, which was before the work was done

- 50 homes were flooded due to the backlog of rainwater entering the city's drains

- there was a large increase in species with a 30% increase in birds and insects, within one year

- locals liked the changes - in a survey 82% of people liked it either 'mostly' or 'strongly'

Front 69

Name the soft engineering case study and its location:

Back 69

- on the River Skerne

- near Darlington

Front 70

What is the background information on the Soft Engineering River Skerne case study?

Back 70

- on River Skerne, NE England

- river meandered across a flood plain, but over the 200 years before 1998 the river was straightened and deepened

- flood plain used as a tip for industrial waste

- was a straight urban drain - carried flood waters through a built-up area

Front 71

What was done on the River Skerne, using soft engineering to prevent flooding?

Back 71

- from 1998 was restored to its natural meandering by using earthmoving equipment to create large bends which enables the river to flow from side to side and for water to run off on to the flood plain during floods

- wide range of wetland habitats created alongside the river

- banks of meanders protected with coconut fibre rolls and willow stakes to prevent excessive erosion until tree roots become established

- over 20,000m cubed of industrial spoil was removed from the flood plain so the river can overflow its banks but still protect surrounding housing - spoil used to reshape and raise the valley sides

- 20,000 trees and shrubs planted, as well as wildflowers and bulbs, improving water quality, reducing flooding and increasing wildlife such as swans, fish, dragonfly and water voles

Front 72

What were the benefits of using soft engineering on the River Skerne?

Back 72

- cheaper

- more environmentally friendly way of protecting houses and buildings in the area rather than traditional hard engineering methods

Front 73

Name the hard engineering case study, its location and its background information:

Back 73

- Hard Engineering in York

- York

- prone to flooding by River Ouse and Foss

Front 74

What has been put in place, using hard engineering, to prevent flooding in York?

Back 74

- over last 20 years hard engineering was put in place to protect homes and families

- mostly raised embankments - some earth, some concrete (supported by steel sheeting)

- natural floodplain upstream of York, called Clifton Ings stores 2.3 million cubic litres of water and lowers the city's peak flood level by 150mm

- banks around the Ings were raised in 1982 and sluice controls were built for letting flood water in and out of the Ings

Front 75

What were the disadvantages of using hard engineering in York?

Back 75

- very expensive

- not benefited wildlife

- water still overflows the embankments causing damage to homes, offices and factories; happened in 2000 and left the city with a clean-up bill of £1.3 million not including cost of damage to people's homes and businesses

Front 76

What was introduced in York in 2008 and what are they?

Back 76

- new system introduced for a trial

- temporary hollow plastic barriers called 'Aquabarriers'

- have holes in one side, allowing flood water in and increasing flood stability

- when the flood recedes, the water drains out or the holes

Front 77

What are the advantages of Aquabarriers?

Back 77

- cheaper than traditional hard engineering solutions

- can be easily moved

Front 78

What are the characteristics of a hydrograph in a rural area?

Back 78

e.g. River Severn

- lag time is longer

- flows through coniferous woodland which absorbs the water and delays it in reaching the river

- peak flow of the river is less high and more delayed

- less rapid falling limb due to less rapid runoff

Front 79

What are the characteristics of a hydrograph in an urban area?

Back 79

e.g. River Wye

- lag time is very short

- water runs over moorland which doesn't have much vegetation to absorb it

- discharge reaches a higher amount, increasing the risk of flooding

Front 80

What were Sheffield's drains and culverts designed to do and what were their two problems in 2007?

Back 80

- they carry away rainwater and were designed to deal with rainfall amounts that might only occur once in 30 years

- but the 2007 floods were a 1 in 400 year event and people wonder whether anything could have protected them

Problems:

- couldn't cope with the rain, so streets flooded

- where drains met the rivers, water couldn't escape as the rivers were already high

Front 81

Define Hard Solutions and Soft Solutions:

Back 81

Hard - structures built to defend areas from floodwater

Soft - adapt to flood risks and allow natural processes to deal with rainwater

Front 82

What 3 things does the UK's Environment Agency believe?

Back 82

- hard defences are not the solution

- buildings at risk must be flood-proofed (e.g. on raised sites or protected by walls), or companies relocated to safe locations

- councils should increase maintenance - streams and drains block easily with debris or tree branches

Front 83

What was most of Sheffield's flooding caused by and what other natural things added to the flooding?

Back 83

- drains, river channels and flood defences being overwhelmed by extreme flows of water

- sudden downpours of rain made everything happen so quickly and made it difficult to predict where flooding might occur

- fallen trees along the rivers Sheaf, Loxley and Don quickly blocked river channels

- as surface run-off raced down Sheffield's hills, drains were blocked and overflowed

Front 84

What were the impacts of Sheffield's floods on Hillsborough and North-West Sheffield?

Back 84

- Hillsborough Football Stadium was flooded up to 8 metres deep and it cost several million pounds to repair the damage

- of 300 homes on on estate, 128 (43%) were flooded and though all council tenants returned home within 9 months some owner-occupiers had to wait much longer as builders were so inundated with work

- displaced people suffered stress and some families were moved into caravans for the winter

- there were several health risks from raw sewage escaping into floodwater

Front 85

What were the impacts of Sheffield's floods on the city centre and the River Don floodplain?

Back 85

- in the city centre on 25th June, motorists had to abandon their vehicles as roads flooded and traffic gridlocked

- as floodwaters rose, many people were caught unaware and had to be evacuated from flooded buildings

- so many trains and buses were cancelled that many people were unable to get home and some were trapped overnight, with over 900 people spending the night in their offices

- 20 people were airlifted to safety from one building and a further 3 from the roof of another

- 200 people were stranded on the first floor of a Royal Mail distribution centre

Front 86

What were the impacts of Sheffield's floods on the Lower Don Valley?

Back 86

- deepest flooding occurred in areas near the River Don, where some industries were badly affected

- the tool-making company Clark-Osborn suffered £15 million in flood damage with equal damage to Sheffield Forgemasters International and Cadbury Trebor Bassett

- Meadowhall shopping centre was flooded causing millions of pounds work of stock losses and damage and closing the centre for a week; its flood defences, built to withstand a '1 in 100-years' flood event, were overwhelmed

Front 87

What were the impacts of Sheffield's floods on the Ulley Reservoir Area?

Back 87

- on 26th June, there were fears that the Ulley dam might collapse, following the rains and damage to its structure

- 700 residents were evacuated from the villages of Whiston, Canklow, Catcliffe and Treeton with some being allowed back 2 days later but some being allowed back 2 weeks later

- 100 people took shelter at Dinnington Comprehensive School, where the Salvation Army provided clothes, food and bedding

- about 100 people had to be rehoused for up to a year where flood damage was severe

- the M1 motorway was closed for 2 days between junctions 32 and 36 because of the risk of the dam bursting