Coastal Protection

Question 1

when are they used

Answer 1

-implemented when erosion is in opposition to human interests
-alternatives are retreat or do nothing

Question 2

hard solutions

Answer 2

-decrease exposure to waves
-structure that create sheltered zones and block sediment transport
-efficient but high environmental impact
*by reducing water circulation
*visual impact
-problem not solved
*transported downstream or to unprotected areas
- Eg. groins, detached BW, revetments and seaswalls

Question 3

soft solutions

Answer 3

-return sediments or flux of sediments
-Eg. beach nourishment, sand by-passing and vegetation

Question 4

seawalls/revetments

Answer 4

-protects without stopping sand loss
-can lead to erosion in adjacent beach sections

Question 5

groins/jetties

Answer 5

-perpendicular to the shoreline and block sediment transport
-dont stop cross shore transport
-promotes erosion down stream
-diffracts waves

Jetties are at harbour entrances and stabilise river mouths

Question 6

Detached BW

Answer 6

-// to the shore
-creates a protected zone between the structure and the shore
-traps longitudinal sediment transport
-reduces cross shore transport
-modify the propagation pattern around them and the diffraction pattern

salients dont touch the BW but can develop into tombolos that do
-increasing the breaker length increases salient/tombolo
-reducing the distance between the shore and the breaker increases the salient/tombolo
-reducing he crest height reduces the salient/tombolo

can also just hault the change in the shoreline

Question 7

beach nourishment

Answer 7

replacement of eroded sediments with offshore/onshore sources
-increase the stability by using larger sediments
-storm protection by increasing the energy dissipation and having sacrificial material
-creates environmental habitat and recreation

Question 8

sand bypassing

Answer 8

artificial restoration of blocked natural sediment fluxes
-not commonly used
-expensive but very effective