Component 2 : River pressures Flashcards
What are the features of the upper course of a river?
The features of the upper course of a river include:
- Its steep
- Its narrow
- Waterfalls are formed here from vertical erosoin
How are waterfalls formed?
Waterfalls are formed by:
1) . Less resistant rock is eroded by hydraulic action
2) . The hard, resistant rock overhangs
3) . Plunge pool is formed when boulders form hard resistant rock
4) . The waterfall retreats
What are the features of the middle course of a river?
The features of the middle course of a river include:
- Flatter
- Wider
- Meanders form from lateral erosion
Where does deposition occur in meanders?
Deposition occurs on the inside of meanders where there is a slower flow and less energy
Where does erosion occur in meanders?
Erosion occurs on the outside of means where there is a faster flow and more energy
How are oxbow lakes formed?
Oxbow lakes are formed by:
1) . Erosion makes the neck of meanders narrow
2) . During floods, the river takes the shortest course through the neck
3) . This creates a new straighter river course that cuts off a section creating an oxbow lake
What are four hard engineering managements of rivers?
Four hard engineering managements of rivers include :
- Embankments
- Flood walls
- Demountable barriers
- Floodgates
What are the positives and negatives of embankments?
Embankments:
+ = Stops water from spreading
- = Water can go over the top
What are the positives and negatives of flood walls?
Flood walls:
+ = Prevents water from spreading
- = Expensive to build
What are the positives and negatives of demountable barriers?
Demountable barriers:
+ = Puts in place when flood expected
- = Risk not installed in time
What are the positives and negatives of floodgates?
Floodgates:
+ = Gates closed during high tide
- = Construction costs are high
What the soft engineering river management?
Soft engineering of river management include floodplain retention and river restoration
What are the positives and negatives of floodplain retention?
Floodplain retention:
+ = Slows water and recovers sediment
- = May mean a change in land use
What are the positives and negatives of river restoration?
River restoration:
+ = Slows the velocity of the river
- = Flood banks are often still needed
What is the role of the environment agency for rivers?
Environment agency works out where flood defences would be most effective and not cause environmental damage. They make an environmental impact assessment to see the effects of a scheme
