What Causes Longshore Transport?

Is longshore drift erosion?

Longshore drift happens when waves moves towards the coast at an angle.

The swash (waves moving up the beach) carries material up and along the beach.

Longshore drift provides a link between erosion and deposition.

Material in one place is eroded, transported then deposited elsewhere..

What stops longshore drift?

Answer: Groynes were originally installed along the coastline in 1915. Groynes control beach material and prevent undermining of the promenade seawall. Groynes interrupt wave action and protect the beach from being washed away by longshore drift.

What is the movement of sand down the beach called quizlet?

Terms in this set (14) ~Sideways~ drift is the movement of sand down a beach.

What is Longshore transportation?

Longshore transport refers to the cumulative movement of beach and nearshore sand parallel to the shore by the combined action of tides, wind, and waves and the shore-parallel currents produced by them.

How is longshore current direction determined?

This occurs because most of the wave hit the beach at an angle. In the picture below notice how the waves are approaching the beach at an angle. The yellow line represents the angle of the approaching waves. The orange arrow shows the direction of the longshore current.

What is the difference between longshore current and longshore drift?

The movement of sand along the shoreline is known as beach drift. The thicker blue arrow represents the waves approaching the shoreline at an angle. The narrower blue arrows show the current that develops as a result of the waves hitting the coastline at an angle. The current is called longshore current.

What factors affect longshore drift?

The prevailing wind (the direction the wind ususally blows from) causes waves to approach the coast at an angle. The swash carries the sand and pebbles up the beach at the same angle (usually 45º).

How is longshore drift managed?

Barriers are long narrow strips of sand and gravel that are separated from the main shore by lagoons, marshes and mud flats. Sometimes people will build fences or walls to try and slow down longshore drift. The sand and gravel just ends up piled along the structures.

What is the most obvious difference between summertime and wintertime beaches quizlet?

What is the most obvious difference between summertime and wintertime beaches? During summertime, there is much more sand on the beach. Why does the beach shown in the video look the way that it does during summertime? Small waves move sand up the beach face and create a wide, sandy beach.

What are longshore currents caused by?

Longshore currents are generated when a “train” of waves reach the coastline and release bursts of energy. The speed at which waves approach the shore depends on sea floor and shoreline features and the depth of the water.

What do groins do?

Groins are shore perpendicular structures, used to maintain updrift beaches or to restrict longshore sediment transport. By design, these structures are meant to capture sand transported by the longshore current; this depletes the sand supply to the beach area immediately down-drift of the structure.

What is Longshore transport quizlet?

Longshore drift (LSD) is the movement of material along the beach (1). … It is comprised of swash – where breaking waves move material up a beach (in the direction of prevailing wind/waves (1), and backwash – where (due to gravity) material is dragged back towards the sea (1).

What does groyne mean?

A groyne (in the U.S. groin), built perpendicular to the shore, is a rigid hydraulic structure built from an ocean shore (in coastal engineering) or from a bank (in rivers) that interrupts water flow and limits the movement of sediment. It is usually made out of wood, concrete, or stone.

How do groynes work?

A groyne functions as a physical barrier by intercepting sand moving along the shore. Sand is gradually trapped against the updrift side of the structure, resulting in a wider beach on this “supply-side” of the structure. However the downdrift beach is deprived of the sand trapped by the groyne and therefore it erodes.

How do engineers decrease the amount of erosion caused by a groin quizlet?

How do engineers decrease the amount of erosion caused by a groin? They build more groins and place them parallel to each other along the beach. What causes longshore transport?