coasts as a system 1.1.1

what is the coast effected by

physical factors and human activity

examples of physical factors

• climate

• fetch

• geology

• erosion

examples of human activity

• groynes

• sea wall

• dredging

• jetties

what makes the coast a system

it has inputs, outputs, transfers and stores

dynamic open system

there is a lot going on due to sediment entering and leaving the system

cliff sub system

a transfer of sediment due to mass movement from cliffs e.g. slumping

beach sub system

the input of sediment from long shore drift

sediment budget

the amount of sediment available

how much sediment comes from land (terrestrial)

90%

how much sediment comes from off shore

10%

examples of inputs

• LSD

• waves, wind

• geology of coast

• beach nourishment

examples of erosion features

• stump

• wave cute platform

• blow hole

• arch

examples of depositional features

• beaches

• tombolo

• sand dunes

• cuspate foreland

examples of outputs

• LSD

• dissipation of wave energy

• sediment above tidal limit

• dredging

what is a sediment cell also known as

littoral cell

sediment cell

a length of coastline and its associated nearshore area where the movement of sediment is self contained

how many sediment cells are there in england and wales

11

dynamic equilibrium

the sediment moving in and out is always equal

how can humans disturb the equilibrium - river dams

river dams: stop fluvial sediment carried by currents from reaching the coast which means natural inputs are interrupted

how can humans disturb the equilibrium - groynes

trap sediment transferred by LSD so the cell is thrown out of balance

key characteristics of sediment cells

• bounded by things like headlands

• sediment isnt exchanged between cells

an example of a sediment cell

South Downs

how does human activity affect the south downs cell

• 8km of beach is protected by manmade features stopping the movement of sediment

• dredging increases outputs from the cell