river landscapes 1 ✓ Flashcards
1
Q
what does the river valley look like in the upper course ?
A
- steep gradient
- v-shaped valley
- steep sides
- narrow, shallow channel
2
Q
what does the river valley look like in the middle course ?
A
- medium gradient
- gently sloping valley sides
- wider deeper channel
3
Q
what does the river valley look like in the lower course ?
A
- gentle gradient
- very wide
- almost flat valley
- very wide and deep channel
4
Q
how does the width of a river change from source to mouth ?
A
gets wider
5
Q
how does the depth of a river change from source to mouth ?
A
gets deeper
6
Q
how does the gradient of a river change from source to mouth ?
A
gets flatter
7
Q
how does the discharge of a river change from source to mouth ?
A
size of discharge gets larger
8
Q
how does the velocity of a river change from source to mouth ?
A
gets faster
9
Q
how does the sediment size of a river change from source to mouth ?
A
gets smaller
10
Q
how does the sediment shape of a river change from source to mouth ?
A
gets more rounded
11
Q
what is the structure of sedimentary rock ?
A
- in layers
- made from animals remains
- easily eroded
- soft rock
12
Q
how does the structure of sedimentary rock affect the way and speed it erodes ?
A
- more easily eroded
- layers are reasonably easy to erode
13
Q
how do storms affect the rate of erosion ?
A
- increase rate of erosion
- winds make waves stronger
- increased water increases velocity
14
Q
how does the rate of erosion differ in summer than in winter ?
A
- rains less in summer
- hotter in summer
- in winter rains more which means more water added into the rivers and the sea increasing velocity of water increasing rate of erosion
15
Q
how does erosion create interlocking spurs ?
A
- upper course there is more vertical erosion
- river cuts down into the valley
- if there are areas of hard rock which are harder to erode, the river will bend around it
- this creates interlocking spurs
16
Q
how does erosion create waterfalls ?
A
- layer of harder rock (whinstone) sits upon softer rock (carboniferous limestone)
- the limestone is easy to erode and is eroded away by hydraulic action creating a plunge pool
- as the notch grows the whinstone is left unsupported and falls into the water
- this constantly repeats creating a gorge and causing the waterfall to retread headwards
17
Q
how does erosion create gorges ?
A
- layer of harder rock (whinstone) sits upon softer rock (carboniferous limestone)
- the limestone is easy to erode and is eroded away by hydraulic action creating a plunge pool
- as the notch grows the whinstone is left unsupported and falls into the water
- this constantly repeats creating a gorge
18
Q
how does erosion create river cliffs ?
A
- a river goes around a bend, most of the water is pushed towards the outside
- causes increased speed and therefore increased erosion (through hydraulic action and abrasion).
- lateral erosion on the outside bend causes undercutting of the bank to form a river cliff
19
Q
how does deposition create meanders ?
A
- river makes its way to the middle course, it gains more water and therefore more energy
- lateral erosion starts to widen the river
- when the river flows over flatter land they develop large bends called meanders
20
Q
how does deposition create flood plains ?
A
- floodplains form due to both erosion and deposition
- erosion removes any interlocking spurs, creating a wide, flat area on either side of the river
- during a flood, material being carried by the river is deposited
- over time, the height of the floodplain increases as material is deposited on either side of the river
21
Q
how does deposition create levees ?
A
- levees occur in the lower course of a river when there is an increase in the volume of water flowing downstream and flooding occurs
- sediment that has been eroded further upstream is transported downstream
- when the river floods, the sediment spreads out across the floodplain
- when a flood occurs, the river loses energy. The largest material is deposited first on the sides of the river banks and smaller material further away
- after many floods, the sediment builds up to increase the height of the river banks, channel can carry more water (a greater discharge) and flooding is less likely to occur in the future
22
Q
how does deposition create a point bar (slip off slope) ?
A
the build up of deposited sediment in the inside of a meander bend is called a slip off slope
23
Q
how has urbanisation affect rivers and river processes ?
A
natural river processes can be reduced because of engineering that stops the rivers from flooding this an change the natural shape of the river
24
Q
how has agriculture affect rivers and river processes ?
A
- fertilisers and pesticides can contaminate the river
- land is taken up by agriculture and therefore protected by people to stop the river from flooding the area
25
how has urbanisation affect rivers and river processes ?
natural river processes can be reduced because of engineering that stops the rivers from flooding this an change the natural shape of the river
- concrete surfaces are impermeable
- water flows over them through storms drains and then back to river reducing lag time and causing water levels to rise and flood
26
how has agriculture affect rivers and river processes ?
- fertilisers and pesticides can contaminate the river
- land is taken up by agriculture and therefore protected by people to stop the river from flooding the area
- vegetation intercepts rainwater
- if vegetation is removed less rainwater is intercepted
- flows quickly over the land and back to the river causing rivers to rise and flood risk
27
what are the physical causes of river flooding ?
- heavy rainfall
- long periods of rain
- steep slopes
- impermeable rocks
- compacted or dry soil
- snow melts
28
how does river flooding impact people and animals lives ?
- loss of home
- loss of habitats
- loss of jobs
- loss of land
- loss of lives
29
what happens in channelisation and what are the advantages and disadvantages (hard engineering) ?
the river channel is made deeper wider and straighter
advantage:
- river channel can hold more water - less likely to flood
- long lasting
disadvantage:
- expensive
- water can travel faster to places downstream and possibly cause flooding there
30
what happens in dams and what are the advantages and disadvantages (hard engineering) ?
a large usually concrete structure built across a river valley to hold back water
advantages:
- effective for many years
- very visible so makes residents feel safe
- hydroelectric power can be produced as the water is released
disadvantages:
- looks ugly
- very expensive
31
what happens in reservoirs and what are the advantages and disadvantages (hard engineering) ?
large area of water which is created after the flow of a river has even controlled
advantage:
- can provide drinking water
- creates a large area of water which can be used for recreational activities
disadvantage:
- very expensive to control the flow of the river
- settlements and farmland can be lost
32
what happens in flood plain zoning and what are the advantages and disadvantages (soft engineering) ?
land that is close to a river is seen as low value because of flood risks so is uses for recreation
advantage:
- very cheap
- provides recreational facilities
- provides potential habitats for birds and animals
disadvantage:
- large areas of land cannot be built on
- flooding takes land out of action
33
what happens in washlands and what are the advantages and disadvantages (soft engineering) ?
an area where a river is allowed to flood
advantage:
- very cheap
- provided recreational activities
- provides potential habitats for birds and animals
disadvantage:
- large areas of land cannot be built on
- flooding takes land out of action
34
how can defences change river landscapes and processes ?
can protect one area of the coast however can then cause areas further down the coast to be effected by flooding and some areas of the coast cannot afford to be protected so are left vulnerable
35
what is the long profile of the river Tees ?
upper course - physical processes tend to dominant and create the distinctive landscape - although human factors like reservoirs can dramatically alter the landscape
lower course - human processes have tended to dominate as the river and its landscape is changed by faming, river management, industry and settlements
36
what are the characteristics of the River Tees ?
- rises on Cross Fell in the Pennines at a height of about 750m
- flows eastwards for about 137km before reaching the North Sea
- drains an area of 1834km2
- many tributaries
- it is an AONB and is a Global Geopark
37
what are the human factors changing the River Tees ?
- building reservoirs
- straightening river meanders
- Teers Barrage
38
what are the physical factors changing the River Tees ?
- rising sea levels
- geology
- river erosion ad deposition
39
how are people predicting the risk of flooding in the Tees catchment ?
- environmental agencies
| - met office
