Coastal processses

Question 1

Wave formation

Answer 1

Made by friction between wind + sea surface
size depends on wave spped + fetch

Question 2

Formation of a wave - Fetch

Answer 2

Distance of open sea that wave travels before reaching the shore

Question 3

Formation of a wave - Shore

Answer 3

Area of beach exposed between high + low tide

Question 4

Parts of a wave - Crest

Answer 4

Top of a wave

Question 5

Parts of a wave - Trough

Answer 5

Bottom of a wave

Question 6

Parts of a wave - Wavelenght

Answer 6

Distance between 2 crests

Question 7

Parts of a wave -Breakin gwave

Answer 7

Friction slows down trougha of waves as they approach shore. Wave becomes steeper as fast crest catches up + collapses over the trough

Question 8

Parts of a wave -Swash

Answer 8

Beach material carried up the shore by a breaking wave

Question 9

Parts of a wave -Backwash

Answer 9

When the swash has no more energy, it drags lighter material with it as it flows back to the sea

Question 10

deposititing waves are

Answer 10

Constructive waves

Question 11

Eroding waves are called

Answer 11

Destructing waves

Question 12

Wave Refraction - def

Answer 12

Waves change direction as the approach the shore due to friction

Question 13

Erosion factors - List

Answer 13

Composition
Wave strength
Coastal shape
Shore gradient
Human activity
Rising sea levels
Climate change

Question 14

Erosion factors - composition

Answer 14

Hard coast (sandstone cliffs) erode slowly. Soft coasts (clay + sand) erode fast

Question 15

Erosion factors - Wave strength

Answer 15

destructive waves are strong + cause erosion - strongest in storms

Question 16

Erosion factors -Coastal shape

Answer 16

Determines the amount of wave refraction that occurs

Question 17

Erosion factors -Shore gradient

Answer 17

Steep slopes = more destructive waves becuase they break close to the shore

Question 18

Erosion factors -Human activity

Answer 18

Removal of beach material material increases erosiom. Sea walls + rock armour reduce erosion

Question 19

Erosion factors -Rising sea levels

Answer 19

Higher sea levels = higher flooding + erosion

Question 20

Erosion factors - climate change

Answer 20

Increased storm frequency + strength - increased erosion

Question 21

Compression

Answer 21

Coastal erosion. Waves wash over rocks. air is compressed within cracks + joints. As the waves retreat, air expands, weakening + shattering the rock

Question 22

Bays and headlands eg

Answer 22

Dublin Bay, Co Dublin

Question 23

Bays and headlands - description

Answer 23

Bays are curved indents on the coastline formed by destructive waves. A headland is a section of land that protrudes further into the sea than its surrounding coastline

Question 24

Bays and headlands - explanation

Answer 24

An area of soft rock along the coast has hard rock on either side of it. Due to differential erosion from hydraulic action and compression , the soft rock erodes much faster, creating an indent called a bay with the headlands jutting out on either side. This leads to wave refraction which causes deposition in the bay leading to beach formation

Question 25

Longshore drift

Answer 25

Waves approach the shore - friction causes them to slow + break. Swash carries material up the beach at an angle and the backwash flows back into the sea at a 90 degree angle. Deposited sediment is moved along the shoreline

Question 26

Beach example

Answer 26

Donabate beach, Co. Dublin

Question 27

Beach def

Answer 27

A build up of loose material deposited by constructive waves between the low + high tide mark

Question 28

Beach explanation

Answer 28

Form on gently sloping shore from loose material deposited by constructive waves. Has uppershore + lowershore sections. Powerful swash pushes materials on shore, pushing large materials to the upperbeach + weak backwash can only drag light small sand + mud to the foreshore, leaving large coarse material eg shingle at the backshore. Storm beaches develop at the very back of the beach where only powerful constructive storm waves can reach

Question 29

Storm beach

Answer 29

Constructive storm waves deposit ridges of large stones and heavy material out of reach of normal waves at the very back of the beach

Question 30

Beach - Berms

Answer 30

Small ridges of slightly coarse gravel deposited parallel to the shore. Mark the highest point reach by the swash during each tide

Question 31

Beach - runnels

Answer 31

Depressions separating berms

Question 32

Beach - sand dunes

Answer 32

small hills of sand that develop inland behind beaches. Formed with lots of fine beach sand with prevailing sea wind. Sand dries during low tide and is deposited by wind when it comes into contact with obstacles.

Question 33

Maram

Answer 33

coarse, strong grass that grows in sand. Its long roots act as an anchor which binds sand together.

Question 34

Coastal management - hard vs soft structures

Answer 34

Hard structures are permanent, prevent erosion + are usually made of reinforced steel or concrete Soft structures are eco friendly + repair wave damage

Question 35

Coastal management - Sea walls

Answer 35

protect coastlines from destructive waves, made from reinforced steel concrete. Curved walls to deflect breaking wave back into sea

Question 36

Coastal management -Gabions

Answer 36

Steel mesh cages filled with stones. Wave is broken as it hits gabions, spreading out its energy + erosive power

Question 37

Coastal management - Groynes

Answer 37

Low walls of cement/ wood at right angles to shore, trap sediment from being moved by longshore drift - prevents erosion

Question 38

Coastal management - Rock armour

Answer 38

Large boulders placed around coastline. Wave energy reduced as the crash off rocks

Question 39

human interferance w coast - Rosslare - sand trapping

Answer 39

1860s -Viaduct prevented sediment transport by longshore drift - sediment build up in harbour needed dredging 1987 - viaduct expanded - acted as groye trapping lots of sand.

Question 40

Human interferance w coasts - Rosslare - Effects of sand trapping

Answer 40

Balance between erosion + deposition changed - rapid coastal retreat

Question 41

Human interferance w coasts - Rosslare - coastal retreat countermeasures

Answer 41

Coastal defences to reduce rate of erosion - worked at Rosslare strand, but worsened other areas Largest beach nourishment scheme in Ireland - 275,00 cubic metres of sand added + marram grass planted