Rivers Flashcards
Give two characteristic features of a meander on the cross-section (2)
Fastest flow River Cliff Slip-off slope Area of Erosion Area of deposition
Explain the formation of a meander.
You may use a diagram in your answer (4)
Channel flow is directed towards one side of the river (1) - erosion occurs forming river cliff (1). Slower flowing
water passes around the inside of the channel (1) and
deposition occurs forming a slip-off slope(1).
Which landform can meanders develop into?
(1)
Ox-bow lakes/river scars
Outline the main effects of a flood (3)
Damage to property Loss of land Subsidence Breached levee Disruption to life
Explain how flooding can be caused by physical factors (4)
Steep sided relief
Impermeable surfaces
Heavy/persistent rainfall, snowmelt,
Deforestation
Explain how planning and building design can reduce the effects of flooding (4)
Planning:
Reference to local authority and planning
permission – floodplain zoning
Building Design: Buildings on stilts Moving electrical sockets up walls Concrete floors instead of wooden Waterproof plaster
Explain how a river has been managed (6)
Reference to examples
Management techniques include:
Embankments; floodplain zoning; warning systems; flood walls
Clear explanation of points
Range of specific facts and explained points about how the river has been managed
Explain how erosion will cause a waterfall to retreat (3)
Erosion of softer rock leading to the overhang of harder rock ledge (1)
Attrition of collapsed material in plunge pool (1)
Hydraulic pressure on the plunge pool floor (1)
Erosion over time leading to waterfall recession and gorge formation (1)
Compare the characteristic features of a river in its upper and lower stages (4)
Watershed is the boundary of the drainage
basin usually an area of highland, often found in the
upper stage (1), whereas the mouth where the river
meets the sea is in the lower stage (1).
Near the source the velocity is slower (1), compared to the mouth where it has increased (1)
Explain the formation of levees.
Use a diagram(s) in your answer (4)
Formed during flood events when the river breaches its banks
Water loses energy as it leaves the channel therefore deposition occurs
Larger material is deposited first nearest bank.
Sequential deposition. Over time this material builds up to form levees.
Explain how the effects of river flooding can be reduced. Use examples in your answer (6)
- Forecasting systems
- Building design
- Land-use planning
- Education
Explicit answer with a range of specific and explained points which could be from different examples
Define the following drainage basin terms: (2)
- Confluence
- Watershed
Confluence – the point at which two rivers
meet/tributary joins the main channel.
Watershed – the
boundary/edge/outside/circumference/perimeter/periphery of a drainage basin OR A ridge of land surrounding the drainage basin.
Explain the advantages of different engineering methods used to manage rivers in the UK (6)
Advantages may relate to:
- effectiveness
- cost
- ease of construction/use
- impact on the environment.
Outline why discharge changes downstream (2)
- Increases downstream (1)
- Increased input from tributaries (1)
- More water from ground water / bank sides / ground water (1) which increases volume (1)
- Changes in land use affect discharge (1) e.g. urbanisation means more water entering channel (1)
- Water entering from surface run-off (1) and direct precipitation (1)
- Greater energy in channel therefore more erosive power (1) provides greater width therefore more capacity (1)
Use an annotated diagram to explain the formation of an oxbow lake (4)
- Increased erosion on the outside of the meander leading to elongation of meander neck
- Thinning of meander neck caused by erosion on outside bend.
- Increased discharge event leading to breach of meander neck
- Deposition in the old meander to separate the new channel and old meander
- Meander scar develops as the water drains over time
