Rivers

Question 1

Define:

• Drainage Basin
• Source
• Tributary

Answer 1

Drainage Basin = Area drained by river

Source = Start of river (spring/lake)

Tributary = Small river joining on to big river

Question 2

Define:

• Confluence
• Mouth/Estuary
• Watershed

Answer 2

Confluence = Where 2 rivers meet

Mouth/Estuary = Where rivers meet sea

Watershed = Boundary between drainage basins

Question 3

What is the difference between lateral and vertical erosion?

Answer 3

Lateral Erosion = channel widening

Vertical Erosion = channel deepening

Question 4

Name the 3 main types of weathering

Answer 4

Physical - Freeze thaw

Chemical - Acid rain

Biological - Roots cracking rocks

Question 5

Name the 3 main types of mass movement

Answer 5

Slumping

Rockfall

Soil Creep = soil particles move down slope due to gravity

Question 6

Describe what happens to each of these river characteristics as the river goes downstream

Width, Depth, Velocity, Discharge, Gradient, Valley Shape

Answer 6

• Widens
• Deepens
• Velocity increases
• Discharge increases
• Flattens
• V shape -> U shape -> flat

Question 7

Name 3 characteristics of an upper course river

Answer 7

Vertical erosion

Steep

Narrow

Question 8

Name 2 landforms found in the upper course of a river, and how they form

Answer 8

Interlocking Spurs - low energy river floes around valley sides (spurs) -> interlocking

Waterfalls - Vertical erosion where hard, resistant rock is over less resistant rock

Question 9

Name 2 landforms found in the middle course of a river, and how they form

Answer 9

Meanders:

• River erodes laterally -> large bends
• Bends get bigger -> meander
• Inner bend - slow current, high disposition -> slip-off slope
• Outer bend - fast current, high erosion -> river cliff

Oxbow Lakes:

• Erosion -> meander neck to narrow
• Outer bends meet, river cuts through
• Meander cut off by main river -> oxbow lake

Question 10

Name 2 landforms found in the lower course of a river, and how they form

Answer 10

Flood plains:

• River carried lots of sediment
• Floods -> excess water spills over surrounding area
• Deposits sediment -> flood plain
• Floodplain shaped by lateral erosion of meanders

Levees:
- River floods -> sediment deposited on bank (heaviest first)
-

Question 11

Name 4 physical causes of river flooding, and how they lead to flooding

Answer 11

Rainfall Intensity:
- Lots of rainfall in short time -> soil infiltration

Geology:
- Impermeable rocks can’t absorb water

Snow Melt:
- Snow melts in spring -> more water

Drainage Basin:
- Steep valleys and tributaries collect water

All causes lead to:
Excess water -> surface runoff -> more water than channel can hold -> flooding

Question 12

Name 3 human causes of river flooding, and how they lead to flooding

Answer 12

Deforestation:
- Less plants to absorb water

Climate change:
- Melting ice sheets and glaciers -> more water in glaciers

Urbanisation:

• Rain forced to flow quickly into sewers
• Man made surfaces = impermeable

All causes lead to:
Excess water -> surface runoff -> more water than channel can hold -> flooding

Question 13

Give 2 social impacts of the 2011 mississippi flooding

Answer 13

Outbreak of water borne diseases

Homes flooded

Question 14

Give 2 economic impacts of the 2011 mississippi flooding

Answer 14

Insurance, fuel and food prices increase

Expensive fertilisers needed to replace washed away nutrients

Question 15

Give 1 environmental impact of the 2011 mississippi flooding

Answer 15

Crops and farmland are destroyed

Question 16

Explain 3 hard engineering methods used to manage the mississippi river

Answer 16

Levees built since 1700s

River straightened

Floodways and cut offs divert water

Question 17

Explain 4 soft engineering methods used to manage the mississippi river

Answer 17

Insurance scheme regulates land use on floodplain

Flooded agricultural land bought to store excess water

Resorting upriver wetland areas - soak up extra rainwater

Government funding for farmers. Land -> wildlife conservation reserved & water storage areas

Question 18

Give 1 reason how planning and 2 reasons how prediction can reduce the impact of flooding

Answer 18

Planning: Land use zoning

Prediction: Environment Agency monitors rivers

• forecast potential floods
• give advanced warnings of flooding

Question 19

Give 4 reasons how prevention and 4 reasons hoe education can reduce the impact of flooding

Answer 19

Prevention - Reduce water damage to homes:

• Use ceramic tiles
• Raise height of electrical sockets on walls
• Install heating systems on upper floors
• LICS build homes on stilts above water levels

Education - spread information:

• Leaflets and advertising
• Posting information on website
• Phone helplines
• Organising flood drills

Question 20

Explain the advantages and disadvantages of 3 methods of soft engineering

Answer 20

Afforestation - planting trees in drainage basin:
Ads - Vegetation soaks up water
- Provides habitats
Dis - Could use land for other purposes

Land Use Zoning:
Ads - Homes and expensive projects can be
located in low risk areas
- Less important located in high risk areas
Dis - Public access may be difficult
- May cause planning problems elsewhere

Washlands - areas allowed to flood:
Ads - Cheap
- Less visual pollution
Dis - Floodplain can’t be used for other purposes

Question 21

Explain the advantages and disadvantages of 3 methods of hard engineering

Answer 21

Flood relief channels - extra channels to carry extra water:
Ads - Excess water taken away, stopping it from
flooding nearby land
Dis - Visually unattractive
- Only needed during flood risk
- Expensive to build and maintain

Channelisation - depeening/widening river channel:
Ads - Allows water to quickly flow away from
flood risk areas
Dis - Visually unattractive
- More water taken downstream, increasing
flood risk to other settlements

Embankments - levees built along river banks:
Ads - Use natural materials, so blend in
- Prevent water moving into flood risk areas
Dis - Flood water can spill in extreme conditions
- Can burst under pressure -> widespread
damage