River Processes Flashcards
Why are streams called systems?
The stream system has both inpust and outputs of various types of materiaals.
Name 3 inputs and 3 outputs.
inputs: - precipitation.
- runoff
- undergroud flow.
output: - evapouration
- seepage
- flooding
- human consumption
What is a laminar flow?
Occurs when water flows smoothly in a stream. very rare.
what is turbulent flow?
it is caracterised by the horizontal eddies and small surface whirlpools that is caused by uneven shape of the bed of the stream.
name the ways in which material can be transported by a stream.
- suspention
- solution
- saltation
- traction
Describe suspention.
-suspention is when very fine particles of clay and silt are picked up by moving water and moved along without being dropped.
Describe solution.
- Solution is when salts and chemicals are dissolved into the water and carried along.
Describe saltation.
- Heavier particles like pebbles may be picked up by the stream and carried a short distance.
Describe traction.
- traction is when heavier stones and pebbles are rolled along the streembed.
Describe the meaning of the following words.
- Drainage basin.
- Watershed
- tributaries
- confluence
mouth
source
- it is the area drained by a river and its tributaries.
- high lying areas that separate drainage basins.
- Smaller streams that join the main river.
- Place where a smaller stream joins the main river.
Name the eroding processes of a river.
- hydralic action
- attrition
- abrasion/corration
Describe hydraulic action.
- sheer power of water in a turbulent stream pushes water into cracks and crevices in bed and banks of stream.
Describe abrasion.
- Stones and gravel carried by river, scour the banks and bed of river channel. like sandpaper.
Describe attrition.
- Material carried by river grinds down other materials also being carried along.
Describe headward erosion.
- occurs at the source of the river where the river extends its length upstream, caused by rainwash and soil creep.
