1a River Environments

Question 1

List characteristics of the drainage basin

Answer 1

Source
Watershed
Confluence
Tributary
Mouth

Question 2

What is an open system and give an example

Answer 2

The amount of water can vary, as it has inputs and outputs
Eg: Drainage basin

Question 3

List inputs

Answer 3

Precipitation

Question 4

List stores

Answer 4

Interception
Soil moisture
Surface storage
Ground water

Question 5

List flows/transfers

Answer 5

Infiltration
Percolation
Groundwater flow
Through flow
Surface run off

Question 6

List outputs

Answer 6

Evaporation
Evapotranspiration
River carrying water to a lake or sea

Question 7

Upper course: channel characteristics

Answer 7

Narrow, shallow channel with a steep gradient and uneven bank

Question 8

Middle course: channel characteristics

Answer 8

Channel widens due to lateral erosion

Question 9

Lower course: channel characteristics

Answer 9

Wide and deep channel with a shallow gradient and smooth banks

Question 10

Upper course: type of erosion

Answer 10

Vertical erosion

Question 11

Middle course: type of erosion

Answer 11

Lateral erosion
And deposition seen on meanders

Question 12

Lower course: type of erosion

Answer 12

Lateral erosion but deposition is more common here

Question 13

Upper course: type of transport

Answer 13

By saltation and traction

Question 14

Middle course: type of transport

Answer 14

All methods of transport can be seen but most common is suspension

Question 15

Lower course: type of transport

Answer 15

Load moved by suspension

Question 16

Upper course: size of load

Answer 16

Large angular boulders

Question 17

Middle course: side of load

Answer 17

Load becomes smaller and more rounded

Question 18

Lower course: size of load

Answer 18

Small rounded pebbles

Question 19

List the conditions when deposition is likely to occur

Answer 19

• river enters a lake or the sea slowing its flow
• there is an area of shallow water slowing the river flow
• the load increased suddenly eg after a landslide
• the river floods onto its floodplain, where it flows very slowly

Question 20

How does deposition work

Answer 20

When the velocity of the river is reduced, the energy of the water decreases, and so the water can no longer erode or transport material. Instead, the load is dropped, starting with the largest (and heaviest) particles.

Question 21

What’s the Bradshaw model

Answer 21

A theoretical geographical model that helps describe how a rivers characteristics vary between upper and lower course of a river

Question 22

How are water falls formed

Answer 22

-There is a layer of hard rock over a layer of softer rock
-the softer rock is more easily eroded, so the hard rock is undercut
-a step is formed but the process of abrasion and hydraulic action
-the river falls into a plunge pool and eventually the overhanging hard rock will collapse due to this undercutting
-finally the waterfall retreats backwards/upstream forming a gorge

Question 23

How are levees formed

Answer 23

-a river overflows its banks, the velocity decreases
- this causes energy to decrease and the river must depositor much of its load into the floodplain
- the largest load is deposited first
-over time after repeated floods, layers of deposited material builds up to form natural embankments called levees
- levees can be artificially strengthened and raised to protect floodplain from flooding

Question 24

What are the positive impacts of flooding on people

Answer 24

-Replenishes drinking water supply
-can encourage innovative solutions in future building design
-provides sediment that naturally fertilisers the soil of the floodplain
-countries such as Bangladesh and Egypt rely on floods to help crops (like rice) grow

Question 25

What are the positive impacts of flooding on the environment

Answer 25

-fish benefit as they can breed in the standing water -in dry areas, floods bring relief from drought, providing drinking water for wild animals

Question 26

What are the negative impacts of flooding on people

Answer 26

-buildings and infrastructure can be damaged or destroyed -crops grow on fertile floodplains can be washed away in a flash flood -can increase house insurance costs for house holders -animals and people can be made homeless or even drown -spreads waterborne diseases such as cholera

Question 27

What are the negative impacts of flooding on the environment

Answer 27

-Flooding can wash chemicals or sewage into the local rivers and pollute them -wild animals may drown or lose their habitat during a flood

Question 28

What is the point of methods used to prevent flooding and to manage rivers

Answer 28

Flood management schemes aim to control rivers and reduce the risk of unwanted flooding. Planners can respond to flood hazards by changing the river through hard or soft engineering methods.

Question 29

What are hard engineering methods

Answer 29

Hard engineering flood controls often involve making large artificial structure to control the river, breaking its natural cycle of flood and subsidence. These measures are not sustainable in the long term

Question 30

List types of hard engineering methods

Answer 30

Dams Levees Flood walls Straightening a river Storage areas

Question 31

What are soft engineering methods

Answer 31

Is more economically sensitive than hard engineering. It will work with natural processes to reduce the potential for floods to occur

Question 32

List soft engineering methods

Answer 32

Afforestation Washlands Land-use zoning

Question 33

What are physical causes of flooding

Answer 33

-Heavy rainfall - especially thunderstorms -Prolonged rainfall as in a monsoon climate -Melting of a glacier or snow -Underlying rock is impermeable or clay soil -Ground is frozen

Question 34

Consequence and elaboration of heavy rainfall

Answer 34

Consequence: excessive surface runoff Elaboration: flash flood

Question 35

Consequence and elaboration of Prolonged rainfall as in a monsoon climate

Answer 35

Consequence: Saturates the ground Elaboration: Slow, long flood

Question 36

Consequence and elaboration of melting of glacier or snow

Answer 36

Consequence: creates high river discharge Elaboration: river overflows

Question 37

Consequence and elaboration of underlying rock is impermeable or clay soil

Answer 37

Consequence: reduces infiltration into the ground meaning precipitation is more likely to be taken to the river as surface run off Elaboration: high risk area for regular flooding

Question 38

Consequence and elaboration of ground is frozen

Answer 38

Consequence: reduces infiltration into the ground meaning precipitation is more likely to be taken to the river as surface run off Elaboration: high risk area for regular flooding

Question 39

What are the human causes of flooding

Answer 39

Deforestation Urbanisation Narrowing a river channel Building of levees

Question 40

Consequence and elaboration of deforestation

Answer 40

Consequences: -Less root support for soil -Less water used by plants -Big raindrops no longer broken up by leaves elaboration: more surface runoff = more flooding

Question 41

Consequence and elaboration of urbanisation

Answer 41

Consequence: More tarmac and concrete creates impermeable surfaces elaboration: more surface runoff = more flooding

Question 42

Consequence and elaboration of narrowing a river channel (eg by building a bridge)

Answer 42

Consequence: river has a reduces capacity to hold water elaboration: more surface runoff = more flooding

Question 43

Consequence and elaboration of building levees

Answer 43

Consequence: provide short term protection Elaboration: more surface runoff = more flooding