P2 - Rivers Flashcards
What is a river?
a flow of water from upland to lowland
What are the main parts of a river? e.g source
Source, mouth , tributary , confluence
What is a drainage basin?
an area that is drained by a river
What are the 3 courses found in a river?
Upper,middle,lower
What is the long course of the river
river from source to mouth
What landforms can be found in the upper course
waterfalls, interlocking spurs, v shape valley
What landforms can be found in the middle course
meanders, ox-bow lakes
What landforms can be found in the lower course
meanders , floodplains , levees
How are rivers formed?
Rain falling on the ground anc creating a river channel (precipitation)
What are the 4 types of erosion? What do they do?
Hydraulic action - sheer pressure of the water
Attrition- makes sediment smoother , smaller rounder
Abrasion - acts like sandpaper
Solution - acidity of the water
Which process does not affect the landform of the river
attrition
What is erosion?
the breaking down and wearing away of rock
What other processes are found in a river?
deposition, transportation
What are the 4 ways sediment can be carried?
traction ,suspension ,solution ,saltation
What is traction ?
heavy rocks rolling along the bottom of the ocean
What is supension?
the sediment floats in the water
What is saltation?
rocks bouncing along the bottom of the seabed
What is solution?
sediment dissolves in the water and gets carried
What happens to sediment when it gets further down the river?
It gets smaller ,smoother and rounder
What are the shapes of the 3 courses?
upper- v shape
middle - u shape
lower - wide u shape
What are the two different types of erosion?
Lateral and vertical
How do we manage rivers?
Hard and soft engineering
Give 4 examples of soft engineering methods for managing flood risks
Aforestaion, washland, restoration and floodplain retention
Give 4 examples of hard engineering methods for managing flood risks
Walls, levees, flood relief channel, dredging
Give pros of soft engineering
cheaper, sustainable, attractive, long term
Give cons of soft engineering
trees take long time to grow
Give pros of hard engineering
lasts long time, more effective
Give cons of hard engineering
really expensive
What is a confluence?
a point where multiple rivers meet
What is a tributary
a smaller river that joins the main river stream
Meanders: on the outside of the bend the current is faster/slower
faster
Meanders: on the inside of the bend the current is faster/slower
slower
Meanders: on the outside of the bend what occurs?
erosion (lateral)
Meander: on the outside of the bend what occurs?
deposition
How do waterfalls form?
- more resistant rock over less resistant rock
- less resistant rock erodes creating a step
- overhang is created
- overhang cannot withstand pressure, it breaks and rocks fall down
- a plunge pool is created, hydraulic action and from falling rocks.
What are the physical factors that affect hydrographs
Geology of the land - more resistant rock will absorb less rock than less resistant rock, run-off will be greater and faster
Soil type - impermeable and permeable soils, more run-off
Vegetation - more water absorbs if more vegetation planted
Slope - steeper causes more runoff reaches water more quickly
What are the human factors that can affect hydrographs
land use change
deforestation
urbanisation
building on floodplains
not dredging
