River landscapes + processes [Part 2] 🌊 Flashcards
Explain two ways in which climate has an influence on river landscapes in the UK.
Hint: rainy climate, wetter climate + higher discharge, rate of erosion.
- one way in which climate has an influence on river landscapes in the UK, is chemical weathering.
- This is because, chemical weathering occurs more in places with a rainy climate.
- and Both carbonation + dissolution weathering can happen when rainwater comes into contact with minerals that make up rocks in river valley + this can affect the river landscape by making valleys less stable.
- rivers in wetter climates have a higher discharge + a higher discharge increases the rate of erosion [Because if a river has a high volume of water, its has more power to erode river bands and bed ———-> adds material to river’s load.
What’s one way how temperature in the UK, can influence river processes ? [2]
- during winter, temperature can drop below freezing [especially at night], and this leads to freeze-thaw weathering.
- and because of weathering, mass movement suck as rockfalls becomes more likely- since it loosens material on the valley side,
Explain two ways how storms can impact river processes [2]
- storms bring heavy rainfall, which causes the ground to become saturated and this makes it heavier and less stable.
- mass movement will then be more likely- (because river banks may slide or slump into river channel).
- ; floods caused by storms can also build up the floodplain, and form levees.
Explain two ways in which droughts can impact river processes [2]
- mass movement more likely to take place because ground is dry.
- less erosion occurs because of lower discharge, which means the river has less energy and is less able or pick up and transport material.
Explain two ways in which urbanisation can affect river processes and landscapes [2]
- the volume of water in the river rapidly increases because urban areas have lots of impermeable surfaces (e.g- concrete).
- and because water can’t infiltrate into these surfaces, more water flows quickly overland when it rains, gutters and drains will quickly take water runoff to rivers.
- this means the amount of transportation will also increase because, more rainwater gets into a river at a shorter time (in urban areas), therefore, the river has more energy,
Explain two ways in which agriculture can affect river processes and landscapes [2]
- irrigation (supplying crops with water) can involve taking water from a river, which causes a reduction in the amount of water in a river, decreases a river’s ability to erode and transport material, so it may deposit material instead.
- ploughing of farmland exposed soil, which allows it to be washed away into rivers when it rains- gives rivers a large sediment load + leads to more deposition occurring downstream.
Explain two how industry can affect river processes and landscapes [4]
- air pollution from factories + vehicles can make rainwater more acidic- this results in more chemical weathering of the river landscape.
- dredging- creates deeper channels which allow large boats to fit. However, it means the river has a faster flow + has more energy for erosion.
What does river discharge mean?
- river discharge, is the volume of water that flows in a river per second
Explain how prolonged rainfall can influence river flooding
- After a long period of rain, soil becomes saturated which means that any further rainfall cannot infiltrate the soil.
- This increases runoff into rivers, quickly increasing discharge- so flooding is more likely to happen.
How can heavy rainfall influence river flooding?
- Heavy rainfall means that the water arrives too rapidly for infiltration- this means that there’s a lot of runoff.
- This them increases discharge quickly, which increases the risk of a flood [happening].
Explain how geology can affect river flooding
- clay soil - some rocks (such as granite + shale are impermeable) so runoff is increased. When it rains, discharge quickly increases, which can cause a flood
RECAP: What does the term ‘impermeable’ mean?
Impermeable means that infiltration is not allowed.
What does the term ‘relief’ mean?
- relief, is the change in the height of the land.
Explain how relief can influence river flooding.
- If a river is in a steep-sided valley, water reaches the river channel much faster, because water flows more quickly on steeper slopes.
- Discharge rapidly increases, which therefore increases the risk of a flood
Explain how building (s) can cause river flooding. [2]
- Because buildings are often made from impermeable materials, + they’re surrounded by rocks made from tarmac, this increases runoff, and drains quickly take runoff to rivers.
- [discharge increases quickly, so there’s a greater risk of flooding].
