Water On The Land Knowledge Flashcards
Describe three features of the middle course
Medium sized valley
Lateral erosion
Transports its load
Describe two features of the lower course
Large valley
Flood plain
Describe hydraulic action
Sheer force of the water
Describe abrasion
Rivers load brushing on river bed and sides
Describe attrition
The load brushing against each other
Describe solution (erosion)
Water dissolving particles of the river and its load
Describe traction
Large boulders on river bed
Describe saltation
Pebbles bouncing along the river bed
Describe suspension
Small particles of mud in water
Describe solution
Minerals being dissolved in the water
Describe four features of the upper course
Small valley
Vertical erosion
Lots of energy
Erodes down
Describe the formation of a water fall (four marks)
Water runs over a strand of more resistant rock that is on top of a less resistant strand of rock. The less resistant rock erodes and forms an overhang. The overhang eventually becomes to big and collapses under its own weight. This process occurs repetitively
What occurs on the outside of a meander
River cliffs
Lateral erosion
Fast flowing
Why are meanders formed
Because the river wants to get the easiest route from A to B
Describe the inside of a meander
Slower current
Deposition occurs
Slip off slopes
What occurs at the outside of a meander
Current is faster
Erosion occurs
River banks form
Describe the formation of an ox bow lake
Starts with a tight meander
This becomes tighter (swan neck meander)
A straight channel is formed
Deposition occurs at the edges of where the old channel was isolating it
What happens to the water after it breaks the rivers banks, and what does this lead to
It slows down and it leads to deposition
Does a levee take many or few floods to form
Many
What does lag time mean
The difference between peak rainfall and peak discharge
The shorter the ….. And the longer the …. The greater the…. Will be
Lag time
Rising limb
Chance of flooding
Name all five factors effecting discharge
Impermeable surfaces Temperature Precipitation Relief Previous weather conditions
How do dams work to prevent floods
They allow human control over the discharge of a river by ta-ra point and releasing water
Describe the positives of dams
Effective
Can be a tourist attraction
Can be used to produce HEP
What are the disadvantages of dams and resevoirs
Extremely expensive
Traps sediment
River straightening works by…
Increases the speed of the water
Describe the advantages and disadvantages of river straightening
Water moves out of the area more quickly reducing the likelihood of a flood however this leads to increase in flooding down stream
Dredging and forming artificial levees work by increasing the rivers capacity but what are their advantages and disadvantages
Cheap
Works well
Has to be Redon annually
Block nice views
Warnings are methods of soft engineering describe a positive and a negative
Doesn’t prevent the flood
Allows people to prepare
State three soft engineering strategies
Warnings
Sand bags
Flood plain zoning
Doing nothing
Areas of surplus = ?
An area with more than enough water
An area with less than enough water is called…
An area of deficit
When an area has not enough water it is undergoing
Water stress
What is meant by the term hydrological cycle
The cycling of water through the sea land and atmosphere
What is meant by interception (WOTL)
Where vegetation catches precipitation
What is meant by transpiration
Plants give off water vapour via the pores in their leaves
Corrosion is another word for the term
Abrasion
Once material is eroded it is…
Transported
What are the processes of transportation
Traction
Saltation
Suspension
Solution
What is traction
Large boulders roll along the river bed
What is saltation
Smaller pebbles bounced along the river bed
What is Suspension
Small particles being carried along the flow
What is abrasion
Silt and pebbles rubbing against the river bank
What is attrition
The rivers load rubbing against itself
What is hydraulic action
The sheer force of the water
Where would a meander be found
The middle course (prehaps the lower)
The cross section of a meander is
Asymmetrical
Describe a flood plain
Wide and flat
What forms a flood plain
Erosion and deposition
What river conditions forms a levee
Slow flowing but with common floods
