4a coastal changes and conflict

wave definition

the wind blowing over the ocean (friction with the surface water creates ripples which become waves)

what does the size of the wave depend on

• the strength of the wind blowing over the sea 

• how long the wind blows for (time)

• the length of water the wind blows over of fetch (distance)

fetch definition

the distance a wave has travelled towards coastline over open water

the stronger the wind and the longer the fetch, the bigger and more powerful the waves

swash and backwash definition

swash = the rush of seawater up the beach after the breaking of a wave

backwash = backward flow of water after the breaking of a wave

what are and what are the characteristic of contructive waves

small waves, low wave height, long wavelength

occurs in calm conditions, without much wind

strong swash, weak backwash

strong swash brings sediment to build up the beacj 

backwash not strong enough to remove sediment

low waves and further apart

what are and what are the characteristic of destructive waves

weaker swash and strong backwash 

occurs in stromy conditions with strong winds

strong backwash remove sediment from beach 

waves steep and close together 

tall waveswith short wavelength

arrive quickly and have high frequency - a ot come in short period of time

what are concordant coasts

bands of resistant and less resistant rock that run at right angles to the coastline. the rock is the same type

the hard rocks acts as a barrier but can be breached on lines of weaknesses such as faults and joints creating a cove, a circular area of water with a narrow entrance from the sea 

what are discordant coasts 

bands of resistant or less resistant rocks that run parrallel to the coastline. headlands are formed on discordant coast because the harder rock resists erosion for a longer time standing out as headlands. the softer rock erodes quicker forming bays

4 main types of erosion which can be affected by: (and explained)

seasons = low pressure in winter and strong winds leads to more erosion from high energy destructive waves

storm frequency = areas susceptable to stron storms are likely to suffer with more erosion

prevailing winds = mainly from the south - west bringing warm moist air and frquent rainfall, this leads to more wetahering and erosion

how an arch and stack are formed

large crack opened up by hyrdaulic action

the crack grows into a cave by hydraulic action and abrasion

the cave becomes larger

cave breaks through the headland forming natural arch

the arch is eroded and collapses 

this leaves a tall rock stack 

the stack is eroded forming a stump 

cliff and wave cut platform

• key areas of erosion

• climate change effect

• process

key areas of erosion : wave cut notch, base of cliff (occurs by undercutting)

climate change can make the process faster and the wave cut notch will be clearer and higher

the rock will overhang the notch. the overhang will collapse and the cliff will retreat. this will create a wave cut notch platform which is visible during low tide and submerged during high tide

what is longshore drift

the movement of material along a beach transported by wave direction

the pebble moves with the swash in the prevailing wind direction and comes back with the backwash by gravity

types of transportation in coasts 

suspension = sand grains floating

traction = large boulders rolling

saltation = small boulders bouncing

solution = calcium from limestone and chalk is dissolved and carried

the formation of a beach

destructive waves erode cliffs and beaches. eroded material is transported by longshore drift. constructive  waves deposit eroded material along the coastline. the largest waves deposit boulders and shingle at the top of the beach. the smallest material is deposited nearest the sea.

deposition definition

the laying down of sediment carried by wind, flowing water, the sea or ice

how are straight / curved beaches formed 

beaches can be straight or curved. curved beaches formed by waves refracting or bending as they enter a bay. they can be sandy or pebbly (shingle). shingle beaches are found where cliffs are being eroded. ridges in a beach parallel to the sea are called berns and the one highest up the beach shows where the highest tide reaches

how spits are formed

narrow projections of sand or shingle that are attached to the land at one end. they extend across a bay or where the coastline changes direction. they are formed by longshore drift powered by strong prevailing wind. the area behind the spit is sheltered where slt and mud is depositev creating a saltmarsh

how is a bar formed

form in the same way as spits, with longshore drift depositing material away from the coast until a long ridge is built up. however, bars grow right across the bay cutting off the water to form a lagoon. a bar is attached at both ends and a spit is at one

what are sub-aerial processes

land based processes that weaken cliffs and occur above the high tide line. they include weathering and mass movement

weathering definition

the wearing down or breaking of rocks while they are in place. weathering can be biologicak, chemical or physical 

different types of weathering definitions

physical / mechanicak (freeze thaw) = when temperature gets higher the snow melts and water gets in cracks of rock. when the temperature gets below 0.c the water in the crack freezes and expands about 9% making the crack larger. as the proccess is repeated the crack gets larger and pieces of the rock break 

chemical (acid rain) = slightly acidic rainfall reacts with weak minerals causing them to dissolve and decay

biologic = the roots of plants grow in cracks and split the rocks apart same as burrowing animals 

mass movement definition

the downhill movement of rock and soil under the force of gravity 

different mass movement processes

rock falls = pieces of rock fall from cliff, happens when the base of cliff has been undercut

slumping = happens after long periods of rainfall, rock slides down a steep slopem 

sliding = movement of material along flat surface, large amounts of soil and rock moving downslope rapidly 

what are the 4 types of erosion

abrasion = load is dragged by water wearing away the cliffs and sea bed (causing more erosion) 

attrition = load collides with loads and breaks up/wears down

solution = weak acid dissolves rock like limestone

hydraulic action = sheer force of water trapping air in crack fracturing the rock in cliffs and sea beds

positives and negatives of development, agriculture, industry, coastal management and tourisms on coasts 

development positiive = more interest in protecting coastal landscapes 

negative = weight of buildings on cliffs increases vulnerability. increased saturation due to changes in drainage 

agriculture positive = wildlife habitats may be created 

negatives = increased soil erosion

industry positive = brings jobs to an area

negative = increases soil, air and water pollution. destroys natural habitats 

coastal management positive = helps reduce risk of coastal flooding. can protect sand dunes, bars and spits

negative = can increase erosion further along the coast 

tourism = more money for an area. education about coastal landscapes 

negative = increased development, increased pollution

holderness case study basic info 

• erosion happening

• town names 

• popultion

• location

• holderness coast is the fastest eroding coastline in europe

• erodes at rate of 2m/year

• 4 main towns - mappleton, hornsea, skipsea, withernsea

• population of around 25,000 people

• north east cost of england in east yorkshire

what are the physical causes of erosion

1. rock type = cliffs made from less-resistant boulder clay (made from sand & clay)

2. powerful waves = waves at holderness travel long distances over the north sea so have long fetch - means that they will increase in energy

3. longshore drift (transportation process) = moves material away from cliffs leaving cliffs unprotected