UK landscapes
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Solution, When the sediment is dissolved into the water
Abrasion, when sediment bashes against the river or seam bed
Hydraulic action, when water enters a crack, compressing the air causing the rock to expand and contract.
Attrition, Rocks that bash together and become smoother and smaller
waves are formed by the wind blowing over the water which causes friction which in return causes the water to swell. waves break by reaching the beach, which causes them to slow down the bottom of the wave causing the top to continue and causing the wave to break. A constructive wave has a strong swash which pushes sediment up the beach and a weak backwash. Destructive waves have a string backwash which draws sediment into the sea and a weak swash.
Hard Engineering
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Suspension, sediment carried along by the flow of the water
Saltation, pebbles that bounce along the river, sea bed
Solution, when the sediment is dissolved into the water
Traction, when bigger rocks, roll along the river, sea bed
Our UK river case study was on the river Severn. They have built temporary and permiment defences along the river to prevent it flooding in extreme conditions ever again. The temporary sea defences allow tourists to see the city in the summer. In addition to this, the rivers banks had been raised and re-enfirced to hold more water.
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Mass movement is the movement of weathered material and rocks under the influence of gravity. These include rockfalls, landslides, mudflow and rotational slip.
types of weathering: Mechanical is the disintegration of rock (freeze thaw) , chemical which is caused by chemical changes (carbnation), biological is when a plant and animals.
Bays are formed due to coastal erosion. AS the waves hit against the hard and soft rick, the soft rock erodes a lot quicker than the hard rock causing the formation of a 'u' shaped beach which is called a bay. The harder rock is left jutting out into the sea. This is a headland and is now more vulnerable to erosion.
How stacks are formed in steps
- Hydraulic action widens cracks in the cliff face over time.
- Abrasion forms a wave cut notch between HT and LT.
- Further abrasion widens the wave cut notch to from a cave.
- Caves from both sides of the headland break through to form an arch.
- Weather above/erosion below –arch collapses leaving stack.
- Further weathering and erosion eaves a stump.
Soft Engineering
Deposition = When the sea or river loses energy, it drops the sand, rock particles and pebbles it has been carrying. This is called deposition.
Sea walls are concrete walls to break up the energy of the waves hitting the mainland.
Groynes are wooden barriers to sea which are designed to stop long shore drift
Gabions are cages full of rocks and boulders designed to break up the waves energy and to protect the cliffs.
Beach nourishment is when beaches build up with sand and grass is planted to hold the sand down.
Managed retreat is when poor land quality areas are designed to be flooded.
UK coast case study is on Bognor Regis, the sea defences have been owrking there because all the groynes on the east side had a lot more build up of sediment on them. It had a ses wall to prevent waves from damaging the sea walk. So hard engineering is working there
Formation of an oxbow lake
Water cycle terms
Soft Engineering for rivers
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Afforestation – plant trees to soak up rainwater, reduces flood risk.
Demountable Flood Barriers put in place when warning raised.
Managed Flooding – naturally let areas flood, protect settlements.
Hard Engineering for rivers
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Straightening Channel – increases velocity to remove flood water.
Artificial Levees – heightens river so flood water is contained.
Deepening or widening river to increase capacity for a flood.
Causes of flooding
Physical: Prolong & heavy rainfall
Long periods of rain causes soil to become saturated leading runoff.
Physical: Geology
Impermeable rocks causes surface runoff to increase river discharge.
Physical: Relief
Steep-sided valleys channels water to flow quickly into rivers causing greater discharge.
Human: Land Use
Tarmac and concrete are impermeable. This prevents infiltration & causes surface runoff.
Precipitation is when water falls from clouds, snow, rain and hail
Interception is when vegetation stops water from hitting the ground
Surface run off is when water runs into rivers off the surface
Infiltration is when water is absorbed by the ground
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The water reodes the outsides of the river bank anf forms a river cliff. Hydraulic action and abrasion erode it further. Erosion breaks through the neck and flows in the fastest and easiest direction. main channel is cut off creating an oxbow lake.
Waterfalls are formed by the water falling over the hard rock and falling on soft rock. The water erodes the soft rock which puts the hard rock under a lot of pressure, eventually, the hard rock will give way. Over a long period of time. the waterfall will retreat causing a gorge.