waves and the coast

waves and coast

definitions

coast

waves

the transition zonebetween the land and the sea

factors affecting the coast can be

human activity

sea

weather and climate

land

a long body of water curling into an arched form and breaking on the shore. They erode, transport and deposit materials

waves are created by winds, the wind makes friction with the sea creating a wave, this is why the power of the wave is the power of the wind, it as well depends on the length and time it has been affected by the wind, this factors are called fetch

terminology of waves

wave length

wave height

wave frequency

velocity

fetch

swash

backwash

the distance between 2 successive waves

distance between the through and the crest

crest

through

lowest point of the wave

highest point of the wave

the movement of water down the beach

the amount of water over which a wave has passed

number of waves per minute

the speed of the traveling wave

the movement of water up the beach

constructive and destructive waves

destructive waves

steep gradients

wind strendth, rainfall

settlement, development

water depth, ecosystem

ecosystem, river sediment

there are 4 main processes happening along the coast

erosion

the wearing away of rocks by wind and rain

types of costal erosion

hydrolic action ( wave hit wall)

attrition (rock hit rock)

abrasion(Rock scratch rock)

solution (dissolve rock)

the sheer power of the waves repeatedly forcing water and air bubbles into cracks in the rock

longshore drift

when a rock becomes eroded off a cliff or a rock the waves can move it along the beach, this is called longshore drift. (the smaller the material the faster it will move)

diagram in comments

when the sand particles and stones hit against each other and are broken into smaller particles

weathering

mass movement

when the salt and chemicals in the seawater dissolve away the rocks that the shoreline is made up of

when the stones in breaking waves wear against rocks

types of weathering

physical

biological

chemical

onion skin weathering

when a rock repeatedly gets heated and cooled causing it to break down

freeze thaw weathering

happens when rainfall gets acumulated inside rock cracks, this water then freezes and makes the crack expand. This repeated process will cause the rock to break down.

weathering that is caused by plants or animals, for example a seed falling into a crack expanding the crack as the plant grows

physical and biological weathering are types of mechanical weathering

a chemical reaction that changes the nature of the rock causing it to break down

the removal of cliff based materials by gravity

landslide

mudslide

rock fall

slumping

the downslope movement of discrete blocks of rock down a flat/linear slip plane, maintaining contact with the cliff surface throughout

a rock fall involves fragments of rock breaking away from the cliff face, often due to freeze-thaw weathering

occur when saturated soil and weak rock flow down a slope.

Slumping is a rapid movement of a mass of earth or rock sliding along a concave surface.

constructive waves

elliptical orbit

the movement of material along a coast by waves which approach at an angle to the shore but recede directly away from it.

Process of transportation

Suspension

Solution

Saltation

Traction

prevailing wind

a wind from the direction that is predominant or most usual at a particular place or season.

large heavy material dragged along the coast

small material bounces along the sea

small material bounces along the coast

Dissolved material carried in water

Wave action

waves will

transport

deposit

erode

Hight and strenght of the wave is determined by

strength of wind

amount of time with wind

fetch

low wave height

shallow gradients

long wavelength

deposits sediment

strong swash

weak backswash

carries a lot f sediment

removes very little material

remove sediment from the beach. They have a short wave length, normally occur on steep gradients and have a circular orbit. High wave height. Weak swash, brings little material, strong backswash which removes a lot of sediment.

circular orbit

high wave height

short wave length

Removes sediment from the beach

weak swash

strong backswash

Carries little material

Removes a lot of sediment

Process of a wave

Why do waves deposit material

wave looses energy

little/ no wind

shallow waters

wave aporaches the coast and enters shallow water

friction with the sea bed makes the wave lean forward

The wave crests and break onto the beach

Rates of erosion

eriosion is affected by 3 things

material

Shore geometry

energy

More energy in the wave means more material will get eroded

More energy is available when

destructive waves

waves break onshore

steep gradients

strong tidal currents

rip currents

Narrow fast moving currents

more wind

The type and mount of material affects the rate of erosion

More erosion happens when

large amounts of material increase abrasion

less resistance rocks (soft rock) erode more easily

Less erosion happens

Large beaches absorb wave energy, reducing erosion

More resistant rocks erode more slowly

If more material goes into the wave the system deposits more material, leading to larger beaches

Steeper gradients lead to destructive waves

destructive waves cause more erosion

shallow gradients lead to constructiv waves

Constructive deposit more material

Eroded material comes from

Longshore drift

Constructive waves

Eroded cliffs

RIvers discharge

Longshore drift

Main process of deposition and transportation in the coast

Process

the prevailing wind pushes the waves at an angle

The waves break and the swash carries the material up the beach

The backwash carries the sediment back to the sea at a 90º angle

The process repeats, resulting in the sediment moving with a zigzag motion

Deposition happens when

increased friction between water and seabed

large amounts of sediment is being carried by the water

wave energy decreases

the water encounters an obstacle which means the wave breaks, depositing the sediment it is carring

Does not shape the coastline, it only changes the shape of the rocks

more fetch

Sediment being transported in the coast

Deposition

COstal deposition is when sediment is deposited in the coast

This happens when the flow of water flow slows down

This happens because there is a decrease in energy so sediment can't be carried by the waves

Wave refraction

When a line of waves changes shape due to the change of the shaoe of the coast

Happens comonly in headlands and bays

In bays

In headlnads

The energy converges on headlands to have more energy

There is more friction and the wave diverges