lesson 10- hard and soft engineering Flashcards
what is hard engineering
controlled disruption of natural processes by using man made structures
what is soft engineering
the use of ecological principles to protect coastlines while enhancing habitats, looks and money efficiency
how do sea walls/ recurved sea walls work
-the recurved section throws back the wave into the path of the incoming wave to reduce the impact
-physical barrier
-hold the line
-any gap will be exploited by hydraulic from the wave and destroy the structure
how does rock armour/rip rap work
-large boulders are dumped infront of the cliff or sea wall to absorb the force of the wave
-boulders are angled to present a large face.The holes created by stacking the rocks help dissipate the wave energy
-boulders are not secured so boulders slightly move
how do gabions work
-operate as rip raps
-small stones are encased in a wire cage which act as a large boulder
how do revetments work
-concrete or wooden structures placed across a beach
-the gaps allow the wave energy
to be dissipated preventing erosion and supporting deposition
how do groynes work
-wooden, stone or steel breakwaters built at right angles to the waves
-control longshore drift
-halting longshore drift in one area could have a serious consequence to other areas
how does cliff fixing work
driving iron bars into the cliff face to stabilise the ground
how do offshore reefs work
-large boulders are pilled parallel to the coast
-cause wave refraction, absorb energy and deposition occurs behind them
how do barrages work
-large structures built to prevent flooding on major estuaries or sea inlets
-acts as a dam across the estuary preventing water entering the river
-generate electricity
how does beach nourishment work
-attempt to replace material lost to longshore drift
-sometimes sand is moved back up the beach when it has previously been moved by longshore drift
how does beach replenishment work
sand is taken from seabed and pumped into beach
how does beach profiling work
-beach is eroded by a storm - steep and irregular
-it is then flattened for tourism
how does dune regeneration work
-fragile dune environments can easily be disrupted
-removal of vegetation can damage
-can:
replant areas with marram grass
stabilise surface with wire
restrict human access
boardwalks
how does managed retreat work
-abandoning the current sea defence and then developing the exposed land in a way e.g. salt marsh to reduce wave energy
-old sea wall is abandoned, sea floods the area, the marsh will be reclaimed by plants, which act as a defence
how does land use management work
-planning for the future to encourage people to think about land at risk usage
-e.g. caravan sites or grazing
how does do nothing work
funding given up due to high cost and low cost of land
