EAE3311 Week 9 Flashcards

Question 1

Q

Definition

The shore

Answer

A

The zone that lies between the lowest tide level (LAT) and the highest elevation on land that is affected by storm waves.

<div>Width ranges from a few meters to hundreds of meters (tidal range, storm surge).</div>

_{EAE3311 9aa}

Question 2

Q

Definition

The coast

Answer

A

Extends inland from the shore as far as ocean related features can be found (this can be many 10s of km)

_{EAE3311 9ab}

Question 3

Q

Definition

The coastline

Answer

A

Marks the boundary between the shore and the coast (the landward limit of where ocean water reaches)

_{EAE3311 9ac}

Question 4

Q

Definition

Coastal areas

Answer

A

A definition used in social sciences, population studies and policy making. Usually defined as within 100 km of the coastline

_{EAE3311 9ad}

Question 5

Q

Definition

Low elevation coastal zone

Answer

A

<10 m elevation in the coastal area

_{EAE3311 9ae}

Question 6

Q

How is population distributed from the coast?

2 points.

Answer

A

Presently, 40% of the world’s population lives with 100 km of the coast

<ul> <li>Access to ocean navigation, coastal fisheries, tourism and recreation.</li> <li>Vulnerability to sea-level rise and other coastal hazards such as storm surges.</li></ul>

_{EAE3311 9af}

Question 7

Q

Describe

Sea Level

Answer

A

The interface between the sea and the atmosphere

_{EAE3311 9ag}

Question 8

Q

Describe

Landmass at the coast

Answer

A

The interface between the land and the atmosphere

_{EAE3311 9ah}

Question 9

Q

What is the relationship between Sea Level and Landmass at the coast?

Answer

A

Both move independently of each other relative to the centre of the Earth (Geoid)

_{EAE3311 9ai}

Question 10

Q

Definition

RSL

Answer

A

Relative Sea Level

_{EAE3311 9aj}

Question 11

Q

Definition

SL

Answer

A

Sea Level

<div>(mainly to do with the growth and decay of ice mass)</div>

_{EAE3311 9ak}

Question 12

Q

Definition

R

Answer

A

land motion

<div>R>0 uplift</div>

_{EAE3311 9al}

Question 13

Q

Describe

Waves in the coastal zone

4 points.

Answer

A

Waves are all important in the coastal zone

<ul> <li>Waves have equal amounts of kinetic and potential energy</li> <ul> <li>Potential energy (the energy acquired by resisting gravity)</li> <li>Kinetic energy (the energy acquired by a mass in motion)</li> </ul> <li>Energy carried by the wave is proportional to the height and speed of the wave</li></ul>

_{EAE3311 9am}

Question 14

Q

Describe

The flux of wave energy (Wave Power)

Answer

A

Each metre of wave crest delivers 36 kW of power

<div>NB Formula applies to 'deep water'</div>

_{EAE3311 9an}

Question 15

Q

Definition

Deep Water

Answer

A

Depth > ½ Wave Length

_{EAE3311 9ao}

Question 16

Q

The flux of wave energy (Wave Power) - Shallow Water

2 points.

Answer

A

<ul> <li>The shallower the water, the less power is left in the wave. </li> <li>More energy arriving at the cliff when the tide is high</li></ul>

_{EAE3311 9ap}

Question 17

Q

Describe

The dynamics of coastal systems: where is the work done

6 points.

Answer

A

Wave energy is deposited where the sea meets the land

<ul> <li>As the waves arrive to shore they transform and break when they get too steep.</li> <li>The plunging waves thrust water onto the shore-face (swash) which recedes as backwash</li> <li>High shoreward speed, 'wave setup' of water above SWL</li> <li>Conservation of Mass = runs back down</li> <ul> <li>Undertow</li> <li>Rip Currents (jets that intercept the breaker line)</li> </ul></ul>

_{EAE3311 9aq}

Question 18

Q

Describe

Constructive Waves vs Destructive Waves

<div>A very simplified way of looking at this</div>

Answer

A

<ul><li>Under calm wave conditions, sand moves onshore and the beach builds into a broad feature with a well-developed berm. Fair weather waves tend to be swells of low amplitude and long period. </li><li>Strong asymmetry in the associated bottom wave surge with the landward stroke beneath the wave crest (swash) being significantly more intense than the seaward stroke beneath the trough (backwash). </li><li>Differential velocity moves sand upslope and onshore (except in zones of rip currents).</li></ul>

_{EAE3311 9ar}

Question 19

Q

Describe

Constructive waves

4 points.

Answer

A

<ul> <li>Low amplitude (height)</li> <li>Long period: time for swash to run up the beach without being interrupted by backwash</li> <li>Swash >> Backwash</li> <li>Erosion leaves behind larger grains</li></ul>

<div>Opposite for Destructive waves</div>

_{EAE3311 9as}

Question 20

Q

The dynamics of coastal systems: where is the work done

Rocky Shores

3 points.

Answer

A

<ul><li>Active margins </li><li>Rocks uplifted faster than sea level </li><li>Result = rocky cliffs interspersed with pockets of sand</li></ul>

_{EAE3311 9at}

Question 21

Q

The dynamics of coastal systems: where is the work done

Sandy Shores

4 points.

Answer

A

<ul> <li>Passive margins</li> <li>Sea rises faster than the land surface</li> <li>Sand is spread out over the littoral zone through a range of processes</li> <li>30% of the world's ice free shorelines</li></ul>

_{EAE3311 9au}

Question 22

Q

Key points

Rocky coastline

6 points.

Answer

A

<ul> <li>Wave power leads to rock erosion</li> <ul> <li>Quarrying</li> <li>Plucking of rocks</li> <li>If the wave carries sand, abrasion</li> </ul> <li>A rock experiencing a typical ocean swell of 10-20 s experiences >1 million impacts/ year</li> <li>Impact can be measured seismically, cliff sways a few microns with every passing wave</li></ul>

_{EAE3311 9av}

Question 23

Q

Key points

Beaches

4 points.

Answer

A

<ul> <li>The beach is a 3D structure (practically a loose pile of sand in a high energy environment) that moves both in a cross shore and an along shore direction.</li> <li>When the material comes from the erosion of beach cliffs or nearby coastal mountains, beaches are composed of mineral particles that can be relatively coarse.</li> <li>When the material comes primarily from rivers that drain lowland areas, the grains are very fine (e.g. clay and silt) and mud flats develop.</li> <li>Some beaches have a significant biological component.</li></ul>

_{EAE3311 9aw}

Question 24

Q

Key points

Beaches - movement

4 points.

Answer

A

<ul> <li>Regardless of the composition, these material are in transit along the shoreline ('rivers of sand').</li> <li>The movement of sand is both</li> <ul> <li>parallel (alongshore) </li> </ul></ul>

<ul> <ul> <li>perpendicular (cross shore) to the shoreline</li> </ul></ul>

_{EAE3311 9ax}

Question 25

Q

How can we measure longshore drift?

Answer

A

Long term longshore drift rates can be measured as the accumulation of sediment behind natural or human-made structures

_{EAE3311 9ay}

Question 26

Q

Key points

Beach morphology

3 points.

Answer

A

<ul><li>Self-organisation vs. chaos </li><li>Landforms can have spatial order at a range of scales derived from internal forcings and dynamics (fractal pattern formation).</li><li>But coastal systems are non-linear dissipative systems where wind, currents and waves deposit energy (multiple elements with non-linear interactions)</li></ul>

_{EAE3311 9az}

Brainscape's Knowledge GenomeTM

EAE3311 Week 9 Flashcards

Brainscape's Knowledge Genome^TM