Coastal Systems and Landscapes

Definition: System

A set of interrelated components working together towards a type of process.

What is an input?

Addition of matter and/or energy into a system.

What is a flow/transfer?

Movement of energy or matter between the link of 2 stores/components.

What is a store/component?

A part of the system where energy/matter is stored or transformed.

What is an output?

When matter/energy leaves the system.

Matter and energy examples:

Matter = living things and physical substances

Energy = solar or wind energy

Definition: Open system + example

Systems where matter and energy can be transferred from the system across the boundary into the surrounding environment: local drainage basin.

Definition: Closed system + example

Systems where energy can be transferred/flowed both into and out of the system but NOT the transfer/flow of matter. These cycle matter in a closed loop: global hydrological system.

Definition: Isolated system + example

These systems have no interactions with anything outside the system boundary. NO input or output of matter or energy: a laboratory experiment.

Definition: Dynamic equilibrium + example

Inputs and outputs in a system are equal and balanced, stores stay the same: a glacier, as the rate of snow falling (input) is equal to the rate of ice melting (output).

What is positive feedback? Give an example.

Positive feedback: effects are AMPLIFIED

1) Global temperature rise

2) Sea temperatures increase

3) Dissolved carbon dioxide in oceans are released

4) More carbon dioxide added to the atmosphere

What is negative feedback? Give an example.

Negative feedback: effects are REDUCED/NULLIFIED/CANCELLED

1) Humans burn fossil fuels

2) Increase in atmospheric carbon dioxide levels

3) More plants grow

4) Reduction in atmospheric carbon dioxide levels

Positive feedback features… (2)

• Effects amplified

• Moves system away from previous state

Negative feedback features… (3)

• Effects are reduced/nullified/cancelled

• Moves system towards previous state

• Changes are counteracted by a response to the change

Waves can be formed by… (3)

• Wind

• Tectonic activity

• Underwater landslides

Definition: Wind

The movement of air from one place to another - moving from high to low pressure.

How do pressure gradients work and how do they affect wind strength?

1) Pressure gradients are the difference in air pressure of 2 different places.

2) The higher the difference, the steeper the pressure gradient.

3) The steeper the pressure gradient, the stronger the wind.

What are the factors affecting wave energy? (3)

1) Strength (from pressure gradient)

2) Duration of wind

3) Fetch (distance of open water the wind blows across)

How does a wave form? (4)

1) Water becomes shallower so the orbital particle motion becomes more elliptical.

2) Wavelength and velocity decreases, however waveheight increases, steepening the crest of the wave.

3) Water backs up from behind and topples over.

4) Water rushes up the beach as a swash and flows back as a backwash.

Explain how beaches can be examples of negative feedback- how do they maintain dynamic equilibrium? Is it realistic?

1) Constructive waves surge up gently sloping beaches

2) These deposit material on the beach

3) This steepens the beach

4) Constructive waves decrease, destructive waves increase

5) Destructive waves plunge onto beach and remove material with backwash

6) Beach slopes more gently again, constructive waves return

UNREALISTIC as WIND STRENGTH and DIRECTION changes so balance cannot always be reached.

Constructive waves characteristics (5)

Formation: Distant weather systems generate these in open oceans

Form: Short, long wavelength, surging

Break: Strong wash, weak backwash

Beach: Gains material, gentle slope but will steepen

Destructive wave characteristics (5)

Formation: Local storms

Form: Tall, short wavelength, plunging

Break: Weak swash, strong backwash

Beach: Loses material, steep slope but will flatten

Definition: Tides

Change in water level of seas and oceans due to gravitational pull of the moon (and little from sun).

Definition: Tidal range and what affects it

The difference in height between a high tide and low tide, this is affected by the relative position of the sun and moon.

What does strong tidal range indicate?

High-energy coastline characteristics

• Rocky coasts found here

• Atlantic facing coasts with powerful waves

• Rate of erosion > rate of deposition

• Find headlands, cliffs and wave-cut platforms

Low-energy coastline characteristics

• Sandy, estuarine coasts found here

• Sheltered coasts, weak waves

• Rate of deposition > rate of erosion

• Beaches, spits and coastal plains

Explain steps of wave refraction (NEGATIVE FEEDBACK)

1) Waves approach indented shorelines (headlands and bays)

2) Wavefronts distort (bend)

3) Wave refraction occurs

4) Wave energy is concentrated at headlands, and dissipates at bays

NEGATIVE FEEDBACK because reduction of erosion of soft rock at bays and increase of erosion of hard rock at headlands.