River Landscapes and Processes Flashcards
Mouth?
Source?
Where the river flows into the sea
Starting point of a river
Tributary
A smaller river or stream that joins a large river
Confluence
Where two streams or rivers meet
Watershed
The boundary of the drainage basin
Drainage basin
The area of land that is drained by a river
Upper course characteristics
-Shallow and narrow river channel
-Steep
-Slowest
-V shaped valleys, rapids, waterfalls
-High bed load
-Vertical erosion
Middle course characteristics
-Deeper, wider river channel
-Flatter
-Faster
-Meanders and floodplains
-Lateral erosion
Lower course characteristics
-Widest, deepest river channel
-Flattest
-Fastest
-Deltas, levees
-Lateral erosion
-Deposition
Width?
In the Bradshaw model?
The size of the river from each side
Increases closer to mouth
Discharge?
In the Bradshaw model?
The volume of water flowing in a river
Increases closer to mouth
Gradient?
In the Bradshaw model?
The steepness of land
Decreases (flatter) closer to mouth
Channel roughness?
In the Bradshaw model?
The unevenness of the channel bed and banks
Decreases (gets smoother) closer to mouth
Sediment shape in the Bradshaw model?
Gets smaller closer to mouth due to increased erosion
Evaporation
The process of changing water to water vapour
Transpiration
The release of water through a plant’s leaves
Surface run off
The movement of water above land on the surface
Infiltration
The process of water soaking into the soil
Percolation
The process of water soaking into the rocks
Throughflow
The down slope movement of water through the soil
Groundwater flow
The movement of water stored underground in rocks and soil
Interception
Vegetation catching rainfall on branches and leaves
4 Upper course landforms
Interlocking spurs, waterfalls, gorges, v shaped valleys
Interlocking spurs def?
How is it formed?
A river winding around spurs.
River winds around resistant rocks, spurs form on each side and become interlocked.
V shaped valley def?
How is it formed?
A valley with steep sides sloping down to a river
Vertical erosion due to abrasion and hydraulic action creates a channel. Weathering (bio & mech) on sides and mass movement creates V shape
Waterfall def?
How is it formed?
A stream of water over resistant rock
Soft rock that lies under hard rock is eroded, creating a plunge pool. Sediment in the plunge pool widens it and creates an overhang. This collapses and waterfall retreats.
Gorge def?
How is it formed?
Narrow valley with steep sides
As a waterfall retreats overtime
2 Middle course landforms
Meander, oxbow lake
Meander def?
How is it formed?
A pronounced curve along a river’s course
Current moves to each side and erodes the bank when it hits it. Current is faster on the deeper outside bend due to less friction, more lateral erosion takes place forming river cliffs. Current is slower on the shallower inside bend due to more friction, more deposition takes place forming slip-off slopes.
Ox bow def?
How is it formed?
A crescent shaped lake isolated from the river by sedimentation
Lateral erosion causes outside bends to get closer, then river breaks through to flow in shortest course. Deposition cuts of meander.
3 Lower course landforms
Flood plains, levees, deltas
Flood plain def?
How is it formed?
Area of flat land next to a river
Meanders migrate across a valley floor
Levees def?
How is it formed?
Ridges of flood-deposited sediment on each side of a river bank
Large sediment is deposited on the banks first during floods due to a lack of energy. Fine sediment deposited further away.
Deltas def?
How is it formed?
Body of sediment deposited at the mouth of a river
A decrease in velocity
