✅🟢Rivers Landscapes in the UK Flashcards
Source meaning
The start of a river, often a spring
Drainage basin meaning
Area of land drained by a river and its tributaries
Tributary meaning
A small stream that joins a larger river
Confluence meaning
Where 2 rivers join
Eg. A tributary joining a larger river
Watershed meaning
The edge of a river basin
Mouth of a river meaning
End of a river where it joins the sea
What’s an estuary?
Transitional area between river and sea
Delta meaning
Material laid down in the mouth of a river
Meander meaning
River course bends
Flood plain meaning
Flat area near the mouth of a river where depositing dominates
How does the shape of the river + valley change as the river flows downstream?
Source - usually an upland area + flows over steep slopes with uneven surfaces.
It flows over a series of water falls.
As a river flows down steep slopes, the water performs vertical erosion. Forming V-shaped valleys.
As the river flows towards the mouth the rivers gradient becomes less steep, it eventually flows over flat land as it approaches the sea.
The load of the river also changes as it’s transported + eroded along the rivers profile.
The discharge increases as river approaches the sea
Whats the altitude in relation to sea level in the:
Upper course
Lower course
Altitude - source of potential energy stored / height above sea level
Upper course : High
Lower course : Low
Whats the weight / mass of the water in the:
Upper course
Lower course
Volume of water increases as river flows
Upper course : Low
Lower course : High
Whats the steepness of the long profile in the:
Upper course
Lower course
The gradient gets less steep as the river flows
Upper course : Steep
Lower course : Gentle
Whats the velocity in the:
Upper course
Lower course
The velocity increases as the river flows
Upper course : Low
Lower course : High
What are channel processes and what do they all
depend on?
The amount of energy available
Channel processes - erosion / transportation/ deposition
What’s erosion?
Wearing away and removal of soil + rock
Hydraulic action
Abrasion
Solution
Attrition
What’s Difference between lateral and vertical erosion?
Vertical :
- downwards
- steep v-shaped valley
- river narrow + shallow
- cutting down into the river bed
Lateral:
- side to side erosion (across valley)
- flat valley floor
- deeper + wider channel
Describe hydraulic action + what type of erosion is it?
Sheer force of the moving water against the banks can cause air to be trapped in the cracks and crevices, the pressure weakens the banks and it gradually wears away.
- vertical erosion
Describe abrasion + what type of erosion is it?
Rocks carried along be river scraps + scour + rub along the river bed and banks and wear down the river like sandpaper.
- lateral erosion
Describe solution + what type of erosion is it?
Minerals in the rocks are dissolved by weak acids in the river water. Particularly in ricks like chalk+limestone, soluble particles are dissolved into the water.
- lateral erosion
What is attrition?
Rocks being carried by the river s,ash together + break into smaller, smoother and rounded particles.
Compare the upper + lower course
Uppercourse :
Shallow + narrow channel
High GPE = height above sea level - high
Volume of water + velocity + kinetic energy = low
Loads of friction as water volume is low = higher % of water touches the valley
Lowercorise:
Board + deep river channel
Low GPE = height above sea level = low
Volume of water + velocity + kinetic energy = high
Less friction as water volume is high = lower % of water touches the valley
GPE = gravitational potential energy
What’s transportation?
The movement of particles in the river
- solution
- suspension
- saltation
- traction
What’s traction?
Large Boulders and rocks being rolled along the river bed
What’s solution?
Minerals dissolved in water eg. Calcium carbonate found in limestone and chalk dissolves in a weak acid like rainfall witch fills rovers. This is called solute load
What’s suspension?
Fine and light material is help up by floating in the water eg. Alluvium. This is called suspended load
What’s salutation?
Small pebbles and stones are bounces along
Lifter and dropped depending on the velocity
What do deposition + transportation rely on?
Energy:
- how steep the gradient is
- water volume
- velocity of the water
What’s deposition + why does it occur
Occurs when the velocity decrease and doesn’t have the energy to transport material
It’s the laying down of sediment carried by wind, flowing water, the sea or ice
Why are larger rocks deposited in the upper course?
Because there’s the least amount of energy, and it’s unable to carry large rocks
When will finer sediment be deposited?
Near the lower course as the river ends, when the sea meets the river it slows the velocity of the river as the water is pushing in a different direction causing decrease in velocity causing deposition of materials.
Why does so much deposition occur at the mouth of the river
Because the river slows down as it has a loss of energy due to the :
- Incoming tide which opposed the direction of the flow of the river
- it has a gentle gradient
- at sea level
What is ,want by the long profile of the river?
Change in gradient of a river from source to mouth
Landforms at the 3 stages of the river
Source / upper course:
- v-snapped valleys
- waterfalls
Middle reaches:
- meanders
Mouth / lower course:
- deltas
- salt marshes
Landforms of deposition (mouth has the most deposition):
- levees - elongated ridge, prevents flooding by raising river banks
What are waterfalls a result of?
Erosion
How are waterfalls formed
Occurs When a band of hard rock (eg. Granite) overlies a soft rock (eg. Sandstone).
Erosion processes such as hydraulic action (force of water) and abrasion (where river rubs stones that are being transported against the bed - eroding it down) dominate.
The softer rock erodes faster than the hard rock and gradually washed downstream, creating a plunge pool where water is swilled around, corrosion occurs deepening it further.
Overtime softer rocks eroded further creating an overhand of hard rock, Thsi overhand = unstable as its unsupported. It eventually collapses and waterfall retreats.
This creates gorges which are steep sided river valleys. This process repeats
What’s a gorge?
Narrow deep + steep sided valley
Formed by waterfall retreats
What’s a meander a result of?
Erosion + deposition
What can meanders form?
Oxbow lakes
How do meanders form
As the river erodes laterally it forms large bends and them horseshoe like loops called meanders.
The formation of meanders is due to deposition and erosion and meanders gradually migrate downstream.
The force of the water erodes and undercuts the river bank on the outside of the bend where water flow has most energy due to decreased friction. This will form a river cliff.
On the inside of the bend, where the river flow is slower, material is deposited, as there is more friction. This will form a slip-off slope.
Water flows faster on the outside of the bend, where it’s deeper and there’s less friction, causing greater erosion which depends channel - this creates a steep sided river bank.
Overtime the horseshoe becomes tighter until it becomes straight, creating oxbow lakes
Describe what flood warnings + preparations are and how it works
Signals sent out saying how severe the flood will be
Flood watch / flood warning / severe flood warning
Warnings are sent from satellites / social media to wan people what type of flooding there will be / when the flooding will be
Positives of flood warnings + preperations
Protects property to a certain point
Cheap
Makes people feel secure
People are in control of what they do
Negatives of flood warnings + preparations
Not everyone has social media
Based on forecast - not always accurate, situations change fast
Doesn’t take direct action / people don’t always listen / doesn’t prevent flooding
House values drop
Describe what flood plain zoning is + how it works
Zoning the land for different uses
Restricts different land uses to different locations (close to river = farmland / woodland, far from river = high value property and land uses / housing)
Planning land use to minimise flood impacts
Positives of flood plain zoning
Restricting impermeable surfaces
Low cosy
Environmental benefit = promoting green space
Negatives of floodplain zoning
Doesn’t stop flooding
Cant move building in areas which have been built on / difficult to implement to places which have been built on
Describe how planting trees as a management strategy for flooding is positive
Soaks up water / Slows water flow / Intercepts water
Cheap
Environmentally friendly + promotes woodland + wildlife
Meeting environmental charter / rules (carbon sink)
Describe how planting trees as a management strategy for flooding is negative
Loss of farmland
Could take a long time
Might note fit in with the environment around it (use of different trees)
What’s river restoration + describe how it works
Where a course of the river has been artificially changed, can restore it to its original course.
River restoration uses the natural processes and features of a river such as meanders + wetlands to slow down river flow + reduce likelihood of major flooding downstream
What’s soft engineering?
where the natural environment is used to help reduce coastal erosion and river flooding
River restoration positives
Prevents flooding downstream Improve ecology + biodiversity - by reducing floods Little / no maintenance Low cost solution Increases capacity of river
River restoration negatives
Can look intrusive + out of place
Can be quite loud to build - intrusive to those around while building
