Physical Landscape Flashcards
Where is Lyme Regis?
Lyme Regis is a small coastal town in Dorset, on England’s south coast
What are the issues in Lyme Regis? (4)
Unstable cliffs, powerful waves from the south west cause rapid erosion, foreshore erosion has destroyed/damaged properties, sea walls have been breached many times
What was the Lyme Regis scheme called and when did it start?
Lyme Regis Environmental Improvement Scheme was set up in early 1990s and completed in 2015
What was the phase 1 and 2 of the scheme?
- new sea walls and promenades
- cliffs stabilised
- creation of wide sand and shingle beach to absorb wave energy
- extension of rock armour to absorb wave energy and retain beach
What was phase 3 of the scheme?
It didn’t go ahead as costs outweighed the benefits
What was phase 4 of the scheme?
- new sea wall for extra protection
- cliffs stabilised to protect homes
What was the cost of the Lyme Regis Scheme?
£43 million
What were the positive outcomes of Lyme Regis scheme?
- new beaches have increased visitor numbers and seafront businesses are doing well
- new defences have withstood stormy winters
- harbour is better protected
What were the negative outcomes of Lyme Regis scheme?
- increased visitor numbers has caused conflict due to traffic congestion and litter
- some think the new defences spoil the landscape
- the new sea wall might interfere with natural processes and cause problems elsewhere
Where is the River Tees?
In the North East England and its source is in the Pennine Hills. It flows roughly east to reach the North Sea at Middlesbrough
What is a landform of erosion on the River Tees?
High Force - in the upper course, the waterfall drops 20m and continues through a gorge
Describe the rock type on High Force
- A resistant band of igneous rock (dolerite) cuts across the valley. Its resistance has led to the development of a waterfall
- Underlying weaker rock (limestone) is undercut
- Waterfall retreats upstream to form a gorge
What are examples of depositional landforms in the River Tees?
- meanders
- levees
- floodplains
Where is Banbury?
- 50km north of Oxford in the Cotswold Hills
- population of 45 000
- much of the town is on the floodplain of the River Cherwell
Why was the Banbury scheme needed?
- in 1998 flooding closed the railway station, shut roads and caused £12.5 million of damage
- in 2007, it was flood again (along with much of central and western England)
What has been done for the Banbury scheme?
- the embankment created a flood storage area mainly on the floodplain of the River Cherwell
- the A361 in the flood storage area has been raised
- flow control structures control the rate of flow towards Banbury. Excess water builds up in the storage area
What are the social benefits of the Banbury Scheme?
- the raised A361 stays open during a flood avoiding disruption
- quality of life improved with new footpaths and green areas
- less anxiety about flooding
What are the economic benefits and costs of the Banbury Scheme?
- the scheme cost £18.5 million, paid for partly by the Environment Agency and Cherwell District Council
- Over 400 houses and 70 businesses protected at a value of over £100 million
What are the environmental benefits and costs of the Banbury Scheme?
- Earth needed to build embankment was extracted locally, creating a small reservoir
- A new habitat has been created with ponds, trees and hedges
What are the 3 levels of flood warnings?
- Flood watch: flooding of low-lying land and roads expected
- Flood warning: threat to homes and businesses
- Severe flood warning: extreme danger to life and property. Stay upstairs or leave him
What makes a low, flat hydrograph?
Basin size, drainage density, rock type, land use, relief, rainfall intensity, soil moisture
Basin size: large basins result in a relatively slow water transfer
Drainage density: low density leads to slower transfer
Rock type: permeable rocks encourage slow transfer
Land use: forests slow down water trasnfer
Relief: gentle slopes slow down water transfer
Rainfall intensity: light rain will transfer slowly and most will soak into the soil
Soil moisture - dry soil soaks up water and slows down its transfer
Explain longshore drift
where waves approach the beach at an angle, sediment moves along the beach in a zig zag pattern where the swash carries material up along the beach and the backwash carries material back down the beach at right angles which is a result of gravity
Define transportation and what are the 4 types
the movement of eroded material
1) solution
2) suspension
3) traction
4) saltation
Describe the 4 methods of transportation
Solution - dissolved chemicals often derived from limestone or chalk
Suspension - particles carried within the water
Traction - large pebbles rolled along the seabed
Saltation - a ‘hopping’ or ‘bouncing’ motion of particles too heavy to be suspended
What is the lag time?
time in hours between the highest rainfall and the highest discharge
What affects the shape of a hydrograph?
affected by the rainfall and by drainage basin characteristics
What makes a flashy hydrograph?
Basin size, drainage density, rock type, land use, relief, rainfall intensity, soil moisture
Rainfall intensity: heavy rain exceed infiltration capacity of vegetation
Basin size: small basins often lead to rapid water transfer
Drainage density: high density speeds up water transfer
Rock type: impermeable rocks encourage rapid overland flow
Land use: urbanisation encourages rapid water transfer
Relief: steep slopes lead to rapid water transfer
Soil moisture: saturated soil results in rapid overland flow
The size and energy of waves depends on 3 things, what are they?
1) Fetch of wind - distance wind travels, longer the fetch, the bigger the wave
2) Power of wind
3) Duration of wind
Describe biological weathering
- plant roots grow in cracks in rocks
- animals burrow into weak rocks
Describe salt cracking
- seawater contains salt
- water evaporates, leaves sea crystals in cracks and holes, these salt crystals grown and expand
- puts pressure on the rocks and flaks may eventually break off
Describe freeze-thaw weathering
- water collects in crack
- at night, water freezes and expands and makes crack in the rock bigger
- when the temp rises, water will seep deeper into the rock
- after repeated freezing and thawing, fragments of rock may break off and fall to the foot of the cliff
Describe chemical weathering
Carbonation
- rainwater absorbs carbon dioxide from the air becoming slightly acidic
- contact with alkaline rocks e.g limestone produces a chemical reaction causing rocks to slowly dissolved
Define erosion
wearing away and removal of material by a moving force such as a breaking wave
What are the 4 types of erosion and explain them?
Hydraulic action - powerful waves hit cliffs
Abrasion - fragments of rock are picked up and hurled at the cliff
Attrition - rock fragments collide with each other -> rounder, soft pebbles
Solution - chemicals in the rocks are dissolved and are often derived from limestone and chalk
Define deposition
occurs when material being transported by the sea is dropped due to the sea losing energy
What is longshore dirft?
A process of transportation that shifts eroded material along the coastline
What landforms occur in rivers?
Upper - erosional landforms e.g waterfalls
Middle - most erosional and deposition landforms e.g meanders + transportation
Lower - depositional landforms e.g levees
What are interlocking spurs?
- a mountain stream erodes vertically creating a V-shaped valley
- it winds around areas of resistant rock to create interlocking spurs
