003 - River Processes
Geographic Knowledge and Understanding
River processes of erosion, transportation and deposition and spatial and temporal factors influencing their operation, including channel characteristics and seasonality.
Physical processes of fluvial erosion, transportation and deposition interact within a drainage basin system.
To be have knowledge and understanding of the river processes of erosion, transportation and deposition, specifically:
Erosion - attrition, hydraulic action, solution, abrasion and vertical erosion
To have knowledge and understanding of the spatial and temporal factors associated with river processes:
Channel characteristics - The inside of a meander vs. the outside
Seasonality - summer meltwater from glacial environments / seasonal differences in deltas
- Flood Plain
- Natural Flood Defence
Define the words above using your Freshwater text book by Codrington.
Activity One - Explain
Image One - River Processes
Rivers help create a range of landforms due to its very specific processes. We can not begin to look at the landforms found in the different areas of the river without knowing what the processes are and how they move the sediment and bedload. Using the slide show below explain how the following processes work:
- Hydraulic Action
- Vertical Erosion
- Horizontal Erosion
Activity Two - Transportation
You have already learnt how a river transports its material so this should just be a review (hence the distinct lack of resources). On a A4 white board draw a diagram to show the four ways in which a river transports is material (bedload and sediment). Remember that using the correct terminology is crucial!
Activity Three - Draw
Below is a digram which represents Hjulstrom's theory. Hjulstrom's theory illustrates how fast the water needs to be to carry a certain size of sediment. If the velocity of the river falls then heavier material will be deposited. If the velocity increases then more sediment can be transported and the greater chance that erosion will take place. For us in Switzerland we have seen the impact that snow melt has on the velocity of our rivers and the large boulders the rivers can then carry.
- Copy out the diagram below.
- Describe what the image represents.
Image Two - Hjulstrom's Theory
Activity Four - Channel Characteristics
When we discuss a channel's characteristics we think about its shape and size. The discharge and velocity of a river can impact those characteristics. A bend in a river is called a meander and this helps to show how a channels shape can change due to erosion and deposition.
- Looking at image three describe how the meander has changed its location in the valley.
- Draw out image four and explain how a meander impacts a channels shape.
Image Three - Changing Channel Flow
Taken From -
Image Four - Meander
Taken From -
Activity Five - Seasons
Seasons can have a huge impact on the discharge of river depending on the precipitation rates and temperature. By reading the article below and using your Freshwater text book by Codrington write down how the different seasons can impact discharge.
Exam Style Questions
State two river transport processes and outline how each process operates. [2 +2]
Explain how stream discharge is related to channel size and shape. 
Describe two processes involved in the transport of a river’s load. [2 + 2]