The Coast 1. The Sea 2 Wind Waves The Sea 3 TidesCurrents 1.Long-Shore 2.Cross-Shore.

1

The Coast

2

The Sea

Wind Waves

3

The Sea

Tides Currents1. Long-Shore 2. Cross-Shore

4

The Sea

Currents

5

Shore protection structures

GroinsA groin is a shore protection

structure designed to

build a protective beach

or to retard erosion of an

existing beach by

trapping littoral drift

Groins are usually

perpendicular to the

shore and extend from a

point landward into the

water far enough to

accomplish their

purpose

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The effect of groins on the coastGroins interrupt the longshore transport. As a result accretion occurs

at the updrift side and erosion at the downdrift side

The re-orientation of the shoreline between the groins results in local

retreat of the shoreline relative to the original position. This can be

restored by applying some sand nourishment between the groins.

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GroinsA system of groins may be an effective coastal protection scheme, and it can be considered as a proven technology for which the effects on the coast can be reasonably well predicted.

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JettiesJetties are structures used at

inlets to stabilize the

position of the

navigation channel, to

shield vessels from

wave forces, and to

control the movement of

sand along the adjacent

beaches so as to

minimize the movement

of sand into the channel.

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Jetties

The sand transport into an inlet

will interfere with navigation and

will usually necessitate more

frequent dredging to maintain the

navigation depth.

Because of the longshore

transport reversals common at

many sites, jetties are often

required on both sides of the inlet

to achieve complete channel

protection

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Breakwaters1. Shore Connected2. Offshore

Shore Connected BreakwatersShore connected breakwaters are used to shelter commercial harbors and small craft marinas by creating calm water in a harbor area, and provide protection for safe mooring, operating and handling of ships, and for harbor facilities

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Breakwaters1. Shore Connected2. Offshore

Offshore BreakwatersAn offshore breakwater is a structure that is designed to provide protection from wave action to an area or shoreline located on the leeward side of the structure.

This system is usually built approximately parallel to the shore or to the predominant wave train.

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Offshore BreakwatersDetached Breakwaters have many advantages over other conventional forms of shore protection.

Unlike groins, they allow sand to be transported alongshore, protecting the local beach, but not depriving downdrift beaches of sand.

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Shore protection structuresNourishment (Beach fill)Beach fill is a traditional and increasingly popular method of shore protection and flood control, and nourished beaches also have value for recreational, commercial, and environmental purposes.

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Shore protection structuresNourishment (Beach fill)

Nourishment is a process of feeding a beach periodically with the amount of sand that was lost during this period. Fill is commonly placed together with the building of coastal structures such as groin fields and detached breakwaters

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Shore protection structuresNourishment (Beach fill)When the natural protection system fails during large storms, the first solutions frequently chosen are quasi-natural methods such as beach nourishment or artificial sand-dune building.

Such solutions retain the beach as a very effective wave energy dissipater and the dune as a flexible last line of defense.

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Seawalls and RevetmentsSeawalls and revetments are structures placed parallel or nearly parallel to the shoreline to separate a land area from a water area.

They do not attract the sand or prevent longshore transport, but they only hinder the transport and protect the backshore.

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Seawalls and RevetmentsSeawalls are simply retaining the beach material behind them, so they can be assumed as a retaining wall that should be maintained stable.

They can be built so high that no water would overtop the crest of the structure and wing walls must be designed to prevent progressive failure that may be found at the ends of the structure

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Seawalls and Revetments

If they are permeable, they absorb part of the energy of the incoming waves and reflect the other part back to the sea.

The Coast 1. The Sea 2 Wind Waves The Sea 3 TidesCurrents 1.Long-Shore 2.Cross-Shore.

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Transcript of The Coast 1. The Sea 2 Wind Waves The Sea 3 TidesCurrents 1.Long-Shore 2.Cross-Shore.