Geography PAPER1 rivers Flashcards
define hydraulic action
water smashing against river banks, air becomes trapped in the cracks this causes rocks to break apart
define abrasion
pebbles that grind along the river bed
define attrition
when rocks know against eachother becoming smaller
define
solution
when water dissolves certain types of rocks
what is erosion?
erosion is the process that wears away the river bed and banks
What is upland
Land high above sea level
What is a lowland
Land close to sea levels
What is the gradient of a land
The steepness
What is the relief of the land
The shape of the land
What is a drainage basin
An area of land that is drained by a river and its tributaries
What is the source of a river
The start of a river usually in a plant areas
What is the mouth of a river
The end of the river with it meets the sea
What is a tributary
A small stream or river which joins the main river
What is a confluence
The point where tributary meets the main river
What is a watershed
An imaginary line showing the boundary of the drainage basin
What is long profile
Shows how the river gradient changes as the river moves from upper to lower course
What are the gradients like in the upper middle and lower course
Upper – steep gradient
middle – gentle gradient so less deep lower – very gentle gradient
What is the cross-section like in an upper middle and lower course river
Upper course – V shaped valleys
middle course – wider valley floor
lower- very wide valley floors so basically flat land
What is the river like in upper middle and lower course
Upper – shallow, narrow and turbulent middle – wider and deeper river
lower – wide and deep
What is the size of load like in upper middle and lower course
Upper – large bedload so rocks and boulders
middle – smaller and smoother material lower – very fine sediment
What is the process like in upper middle and lower course
Upper – mostly erosion
middle – erosion and deposition
lower- deposition
What is solution
When soluble particles are dissolved into the River
What is suspension
When material is carried along by the river
What is saltation
When small pebbles and stones are bounced along the river bed
What is traction
When large boulders and rocks are rolled along the river bed
What is vertical erosion
Intense downwards erosion that deepens a river valley and channel making it the shape shed
What is lateral erosion
Erosion which widens the River Valley and channel
What is deposition
When river drops the material is transporting
What are reasons for why with a slowdown and deposit material
Material increases, the water shallow, the river reaches The mouth
How do waterfalls form
River flows over area of hard rock followed by softer rock
Softer rock is eroded by hydraulic action and abrasion and more than hard rock creating a step
The water erodes more softer rock
A steep drop is created which is called a waterfall
Hard Rock is eventually undercut and is unsupported and collapses this creates a deep plunge pool.
What is a gorge
A narrow steep sided valley formed as a waterfall retreats
What are interlocking spurs
Hillsides that stick out into their paths on each side
What are meanders
Large bends in a river which consistently change shape
Where does the river flow the fastest
On the outer bends
What happens after the river is wore away
Little by little the water old is the bank
The slowest flowing part of the river is on the
Inner bend
What happens at the inner bend of the river
This is where it deposit it’s a load of mud and shingle
What happens on the outside of the River bend
The river continues to cut the bank and results in the river eroding more and more
How is an oxbow lake formed
Erosion causes the outside bend to narrow
Until there’s only a tiny bit of land between the bends
River breaks through this land usually during a flood
The river flows along the shortest course
Deposition cut off the meander forming an oxbow lake
What shape is an oxbow lake
a (c) crescent shape
What are floodplains
Flat areas of land that flood
How are floodplains formed
Rivers flood the water slows down a deposit material that builds of the floodplain, me and has widened and migrate across floodplains overtime me and has also migrate downstream
What are levees
Levees are raised embankments at the side of a river channel
How are levees created
During a flood eroded material is deposited over the floodplain,
Material is deposited closest to the river channel over time the deposit material buildup creating levees
Describe the levee
A calm steel river short grasses and flat grassland
Where is an Estuary found
Estuaries are found at rivermouths
What do contour lines tell you
The direction a river flows
(Human factors that affect flood risk) why are urban areas more likely to be at flood risk
They are more likely to flood because water will not infiltrate into the ground – impermeable surfaces
(Human factors that affect flood risk)
Why are Rural areas less likely to be at flood risk
They are less likely to flood because there is vegetation that intercept rainfall – permeable surfaces
(Physical factors that affect flood risk)
How does heavy rainfall affect flood risk
water may not infiltrate in the ground quick enough
-more land flow
-more river discharge
(Physical factors that affect flood risk)
How does prolonged rainfall affect flood risk
Excessive amount of rain over a long period of time can cause
-Overland flow
-increase of river discharge
(Physical factors that affect flood risk)
How do you impermeable rocks affect flood risk
A place with an impermeable surface are more likely to flood because impermeable rock doesn’t allow water to infiltrate over the ground
What is the river discharge
The volume of water flowing through a river channel
What are hydrographs used for
Recording the discharge of a river before during and after a rain storm
What is hard engineering
Man-made structures built to control the flow of rivers
What is soft engineering
Schemes set up using knowledge of rivers and its processes to reduce effects of flooding
Describe the characteristics of an estuary
It has mudflats
It has deposited sediment
Mudflats are exposed at low tides
