Changing landscapes - Rivers Flashcards
What does the bradshaw model show
Changes that occur in a river as it flows from its source to its mouth
Name some physical factors that cause flooding
Prolonged/heavy rainfall, geology and relief
Name some human factors that influence flooding
Building/urbanisation and deforestation
How does geology effect flooding
Impermeable surfaces such as clay and granite do not allow water to go through them leading to greater surface run-off causing more water to reach the channel quickly
How does relief effect flooding
The steeper the slope the more rapid the flow of water into a river channel
How does building/urbanisation effect flooding
Creates impermeable surfaces increasing surface run-off therefore water reaching the channel faster and in higher volume
How does deforestation effect flooding
Vegetation (trees) intercept rainfall slowing its movement and some of the water is stored before evaporating back into the atmosphere. Trees also absorb water from the soil allowing more water to be able to go into the soil. When vegetation is removed surface run-off is increased
Define watershed
Area of high land forming the edge of a river basin
Define source
Where a river begins
Define mouth
Where a river meets the sea
Define confluence
The point at which two rivers meet
Define tributary
Small river or stream that joins a larger river
Define channel
Where the river flows
State 4 factors that lead to deposition in a river
- Shallow water
- At the end of the rivers journey
- When volume of water decreases
- When a river slows down.
Name two processes of mass movement
Landslides and soil creep
What is soil creep
Soil slowly moving down a slope due to wet soil particles increasing in size and weight, then when the soil dries out it contracts vertically
What is a landslide
Rapid movement of earth or rock sliding along a steep slope
Why do landslide occur
After periods of heavy rainfall when the water saturates overlying rock making it heavy and liable to slide
What happens at the lower course of a river
Final course, land is flatter and the rivers load is fine sediment. Channel is at its widest and deepest as it flows towards its mouth (creates large flood plains)
What happens at upper course in a river
Where river starts , usually upland area meaning it’s steep increasing velocity. River channel is narrow and shallow here and the rivers load is large
What is a way of remembering how to describe the course of a river
SuRreaL
Speed, Relief, Load
Describe the mid course of a river
In the middle of lower and uppers conditions. Small meanders and small flood plains can be found as well as more eroded areas
What is a long profile
A line representing the river from source to mouth
What is cross profile
Section of rivers valley and channel
