Flashcards in River Landscapes Deck (45):
What are the two physical processes that shape a river landscape
Weathering and Mass Movement
What are the three types of Weathering
Mechanical, Chemical and Biological
What is Mechanical weathering?
Freeze Thaw Action
What is chemical weathering?
What is biological weathering?
Roots grow into cracks and split rocks apart
What is mass movement?
Overtime the sides of a river valley become less steep as material is moved from the top to the bottom
Give two examples of Mass Movement
Sliding and Slumping
What is sliding?
Where rock, weathered or eroded material or earth moves down a slope. Gravity pulls the weakened material quickly downwards
What is slumping?
When the river erodes the bottom of the valley slope, making it steeper. Material above slides downwards, particularly if it is saturated with rainwater
What are the four types of erosion?
- Hydraulic Action
What is hydraulic action?
The force of the water on the bed and banks of the river removes material
What is attrition?
The load that is carried by the river bumps together and wear down into smaller, smoother pieces
What is solution?
Some rock materials dissolving in river water
What is abrasion?
Material carried by the river rubs against the bed and banks and wears the away
What is transport?
The way in which the river carries eroded material or load
What are the four main types of transportation?
What is traction?
Large boulders are rolled along the river bed
What is saltation?
Smaller pebbles are bounced along the river bed, picked up then dropped as the river flow changes
What is suspension?
Finer sand and slit particles are carried along in the flow, giving the river a brown appearance
What is Solution?
Some minerals are dissolved in the water and carried along in the flow
What is the gradient of a upper course, middle course and lower course?
Upper course - steep
Middle course - less steep
Lower course - shallow gradient
What is the discharge of the upper course, middle course and lower course?
Upper course - small
Middle course - large
Lower course - very large
What is the depth of the upper, middle and lower course?
What is the channel shape of upper, middle and lower course?
- narrow steep sides
- flat steep sides
- flat floor gently sloping sides
What is velocity in upper, middle and lower course?
- quite fast
- very fast
What is the valley profile of a upper, middle and lower course?
- steep sides
- flat with steep sides
- flat with gently sloping slides
What is features of a upper, middle and lower course?
- waterfalls, interlocking Spurs
- meanders, flood plains
- meanders, floodplain, levee and oxbow lakes
What are the impacts of climate on river on landforms and landscapes?
- Erosion rate
- Transport rate
- Amount of discharge
What can increase the risk of flooding?
- Increasing frequency of storms
- Increasing periods of hot, dry weather
- Soil becoming impermeable during cold conditions
What is a interlocking Spurs?
- The river at its source is small and has limited energy
- It flows naturally from side to side, around ridges in the valley sides called Spurs
- the spurs becoming interlocking with those on the other side of the valley
How is a waterfall formed?
- Increase in vertical erosion
- They form where there is a layer of hard, resistant rock overlying a softer, less resistant rock
What is a gorge?
Over a long time, the process of undercutting and collapse is repeated, and the waterfall retreats, forming a steep sided gorge
How is a floodplain formed?
The wide, flat area of land either side of a river and experiences floods when the river tops its banks
How does a levee develop?
The deposition process, which takes place during flooding, continues until eventually embankments, much of larger, heavier sediment, are created beside the river
How is a meander formed?
- The river erodes laterally and starts to form large bends
- the bends get bigger and wider, and eventually develop into a horseshoe shape
How does urbanisation affect the river landscape?
- causing towns to grow
- Increasing in demand for housing has led to new houses being built
- Rivers may be channelised or made to flow underground to make room for urban developments
Give four examples of physical causes
- Rainfall intensity
- Drainage basin
What is the physical effect of flooding?
Includes landslides, soil erosion, loss of natural habitats, contamination of water supplies
What is the human effects of flooding?
Includes depth, disease, damage to property, insurance claims, loss of livelihoods and loss of crops
What is hard engineering?
Dams and reservoirs and channelisation
What is dams and reservoirs?
Barriers constructed to hold back water in artificial lakes
What is channelisation?
Deepening or widening the river channel
Give two examples of soft engineering?
- Floodplain zoning
What is floodplain zoning?
Prevents development in areas most prone to flooding next to rivers