Land and Water, River Diversity Flashcards
Catchments (othersise known as drainage basins and watersheds)
The drainage area of a river network
Drainage divides
Ridges and hills of high altitude and relief that separate neighbouring catchment areas
How is drainage density calculated?
DD = Total length of all streams/Area of drainage basin
What are the five key principles of catchments?
- Longitudinal profile
- Sediment movement
- Source zone
- Transfer zone
- Accumulation zone
Longitudinal profile
The changing charcateristics (slope, width, depth) of a river as it moves donwstream
Sediment movement
The origin, transportation, and accumulation of sediment
Source zone
An area where rate of erosion greatly exceeds the rate of deposition
Transfer zone
An area where the the rate of erosion and deposition are roughly balanced
Accumulation zone
An area where the rate of deposition exceeds the rate of erosion
What are the three controls of river diversity?
- Slope
- Energy
- Sediment type and size
What are the four confinements of river types?
- Confined
- Partly confined
- Laterally unconfined (continuous channel)
- Laterally unconfined (discontinuous channel)
What are the two broad types of rivers?
- Bedrock (supply limted)
- Alluvial (transport limited)
What are the four characteristics of bedrock rivers?
- Dominated by erosional processes (low sediment supply)
- Fixed channel boundaries due to bed and banks being composed of bedrock
- High transport capacity but low storage capacity (limited accomodation space)
- Input is roughly the same as output
What are the four characteristics of alluvial rivers?
- Dominated by depositional proccesses (low transport capacity)
- Erodible channel boundaries (both banks and bed)
- High storage capacity
- Input is larger than output
How do bedrock rivers form?
Bedrock rivers form very slowly by angular rocks abrading the river bed, forming a steep terrain
