The UK Landscape - NW v SE

P1 Section C: UK Landscapes

Topography/Relief means the height and shape of the landscape. The Uk is made of uplands/highlands and lowlands which are scattered but mainly follow a NW to SE distribution (The highlands are in the NW and lowlands in the SE

The Cotswolds: low hills, rolling, agricultural, woodland/fields, gentle slopes soft sedimentary rock that is easily eroded.

Isle of Arran: steep, mountainous, rugged, exposed rock, weathered, erosion, high resistant igneous and metamorphic rock.

Constructive waves are created by a short fetch (distance) and build up the beach by depositing sediment.

Destructive waves are created by a long fetch (distance) and break down the beach by eroding sediment.

P1 Section C: Coasts

A coastline is where the land meets the sea

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Our coastline is shaped by the sea and the power of the waves.

Waves are controlled by the fetch this is the strength of the wind, the distance it has travelled and how long it has been blowing for.

Short weak fetch = constructive waves

Strong long fetch = Destructive

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Corrosion/Solution: Chemicals in the water dissolving the rock

Attrition: When rocks knock into each other and get worn into smaller and rounder pieces.

Hydraulic Action: When the energy of the waves forces air into cracks making them wider

Abrasion: When rocks are thrown at the cliff and break it down

The UK weather can affect erosion. Cold temperatures lead to freeze-thaw weathering in cliffs. Prevailing winds come from the SW bringing frequent rainfall causing weathering and mass movement. The UK is stormy with strong winds creating large waves.

Mass movement: Slumping [pictured below]

Rockfalls, Rockslides,

Geology can also affect erosion. Hard rocks like chalk are more resistant to erosion whereas softer rocks like clay are less resistant and so erode more quickly.

Hard Rock: Chalk

Soft Rock: Boulder Clay

Geomorphological processes:

Erosion: HAAC

Headlands and Bays – erosional feature [sequence Q]

A discordant coastline has bands of different types of rock that run perpendicular to the coastline.

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A concordant coastline has bands of rock that run parallel to the coastline

I have studied the Holderness Coastline

• Headlands and bays are formed on a discordant line made up of hard rock like chalk found at Flamborough Head and soft boulder clay like at Mappleton
• Destructive waves erode the coastline through processes like hydraulic action and abrasion
• The hard rock erodes slowly, sticking out to sea, creating a headland
• The soft rock erodes quickly, heading inland creating a curved bay
• Over time the headlands stick so far out that wave refraction takes place
• This causes the waves to collide in the bay, causing deposition
• This creates a sandy beach within the bay.

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Look at Swanage Bay on this map. It has retreated further inland as it is clay, a soft rock and so eroded quicker.

Headlands features– erosional feature [sequence Q]

I have studied Flamborough Head on the Holderness Coast .

• Destructive waves and hydraulic action creates a crack in the headland
• Over time these processes repeat to create a cave
• A blowhole might appear above the cave where hydraulic action has forced air to the surface of the cliff
• Eventually destructive waves will erode through the headland to create an arch
• Subaerial processes of weathering like freeze that, biological and chemical weathering weaken the arch
• Hydraulic action and abrasion continues to make the arch wider
• It eventually collapses due to gravity leaving behind a stack
• The sea erodes a wave cut notch at either side of the stack until it collapses, leaving behind a stump.
• This is eroded away leaving behind a wave cut platform can the cliff retreats.

Headland features

Cliff Recession

Erosional features on the Holderness coast are mainly located at Flamborough Head [chalk]

Bays beaches and sand dunes are found in boulder clay arreas around Withernsea and Mappleton. Spurn Head is the main depositional feature on the Humber Estuary, it is a Spit.

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4. Colonising pioneer plants like marram grass grow on the dune and stabilise it with their roots and trap more sand

SEA

1. Obstacles such as drift wood get dropped on the beach

3. This creates an embryo dune

5. As the plants die they add organic matter to the soil improving it for other plants to move in.

2. The wind blows sand up the beach, which gets trapped on the obstacle

Sand dunes need a lot of room between the sea and the back of the beach to form. There also needs to be plenty of wind and of course sand.

Depositional features – Sand dunes[sequence Q]

As you move away from the beach, sand dunes progressively become more brown as more organic matter is added and decomposes creating soil.

Depositional features – Spits and bars[sequence Q]

Longshore drift is controlled by the prevailing wind. The waves hit the beach at the same angle transporting material up the beach. Once they run out of energy they wash off the beach at a 90’ angle.

SAME AS A SPIT BUT HEADLAND TO HEADLAND.

Spits form across a river estuarty

I have studied Spurn Head on the Holderness Coast. .

• The prevailing wind causes longshore drift along a beach
• The swash of constructive waves transports materials through saltation and suspension
• The beach meets the Humber estuary and longshore drift continues across because of the prevailing wind
• Larger sediment is dropped first as the sea loses energy.
• The prevailing wind changes travelling across the estuary, creating a hook shape to the spit
• Alluvium is deposited behind the spit creating salt marshes and mud flats.
• The increasing velocity of the river prevents the spit from travelling all the way across
• Sand dunes might form on the spit but can easily be destroyed by destructive waves.

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Do nothing

Managed Retreat

Hold the line

Hard Engineering = Man-made structures built to control the flow of the sea and reduce flooding e.g. building a sea wall.

Soft Engineering = Schemes that use our knowledge of the sea and its processes e.g. erosion. For example, adding sand to the beach to stop erosion.

Holderness Coast:

Coastal Management:

• Hard engineering coastal management strategies are the most effective at protecting the coastline, how far do you agree? [6marks]
• Explain how hard and soft engineering strategies can be used to protect the coastline [6marks]

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V-shaped valley

Rivers:

The upper course has a steep v-shaped valley, a small channel and large angular boulders

The middle course has a less steep valley, a larger channel with round pebbles and floodplains

The lower course has no valley and it is flat land, a wide channel and mud/silt - no stones

Middle course

Upper course

Lower course

Meanders

Flatter valley

Large sediment

Flat floodplain

Mud flats

Deposition

Is when sediment is dropped when the water loses the energy to transport it

Erosion: HAAC

Transportation: SSST

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Erosional River Landforms

In the upper course the river begins to bend around layers of hard rock creating a V-shaped valley with interlocking spurs

I have studied High Force on the River Tees

• A water fall forms when a river flows over an area of hard rock followed by soft rock
• Hydraulic and abrasion erodes the soft rock quicker creating rapids
• This process continues until an overhang is created causing the water to fall vertically
• The vertical erosion creates a plunge pool at the bottom of the water fall and begins to undercut the hard rock overhang
• The overhang continues to be undercut by hydraulic action until it collapses due to gravity
• The waterfall retreats, overtime creating a steep sided gorge.

Waterfalls and Rapids in the upper course

Meanders and oxbow lakes

I have studied the Meander that goes around Yarm on the River Tees

• The thalweg of the river hits the outside bend of a meander as it turns
• This erodes the outside bend through hydraulic action creating a river cliff
• The rivers flow is slow on the inside bend so deposition takes place creating a slip off slope
• Over time the river continues to erode the outside bend making it more exaggerated
• Eventually the neck of the meander is eroded through and the river takes the path of least resistance, causing deposition to take place on the meander
• Over time the meander is completely cut off from the river creating an Ox bow Lake
• The process repeats – this is called meander migration and supports with the formation of floodplains.

Floodplains and levees

The flat land next to the river consists of silt transported downstream. Everytime the river floods further material is deposited, causing the floodplain to rise a little. The river meanders a lot, widening the floodplain. Heaviest sediment is deposited first meaning levees form on the river banks

• Levees form when a river busts its banks
• The fastest flow is in the river channel, the water that leaves the channel loses energy quickly
• It deposits larger materials first as these need more energy to carry
• As the floodwater travels across the flood plain, it deposits fine fertile sediment called alluvium
• When the river returns to normal flow, the sediment is left behind.
• This process repeats overtime creating large natural embankments called levees on either side of the river.

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A storm hydrograph shows us how a river reacts to a rainfall event.

Rain takes time to reach a river because most falls on the valley sides (not directly into the river) and reaches a river as surface run-off or groundwater flow

Factors affecting flooding:

The lag time

Short = urban, high chance of flood

Long = rural, lower chance of a flood.

High flood risk

Low flood risk

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Hard engineering

Man-made structures built to control the flow of rivers and reduce flooding;

Dams & reservoirs

Straightening

Flood relief channels

Embankments / Flood Walls

Soft engineering

Works with a river’s natural processes

Flood warnings & preparation

Floodplain zoning

Planting Trees (afforestation)

River restoration

New £21 million flood wall, 500 businesses and all their jobs protected. Instead of in 2007, 2 deaths, 2,200 properties flooded, £400 million damage. Aesthetically less attractive.

Sheffield: Example of flood management

River Defences/flood managment:

Controls the flow of a river, reducing flooding downstream.

Opportunity to prepare and evacuate… but doesn’t stop flooding

Cheap land near the river to be sacrificed first, more valuable land further away from the river.

Puts the meanders back into the river, slowing the flow and encouraging the flooding of low value areas.

Increases velocity, moving the water out of the area quicker

Increases river carrying capacity, devastating if they fail.

Additional channel to increase carrying capacity.

Increase interception and storage of water, reduce saturation of land and surface runoff.

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