What structure usually occurring in pairs shown below is bui

What structure, usually occurring in pairs, shown below is built to protect the sides of a shipping channel? Select one: A. Jetty B. breakwater C. Seawall D. groin

Solution

SEAWALLS: when the coastal structures or roads are under threaten due to coastal erosion, usually seawalls are built which are made up of steel, concrete, wood or boulders that run parallel to the beach at the land/ water interface.

GROINS: These are built perpendicular to the beach, it is usally have large boulders and also made up of concrete, wood or steel. Groins are built to build sands on one side of the groin for sand deposition.

BREAKWATERS: These are built parallel to the shore, designed to block the waves and the surf. use to provide calm waters for harbours and artificial marinas.

JETTIES: These are man made piles of concrete and boulders that are built on either side of coastal inlet, to change the effects of beach eroison, jetties are built so that a channel to the ocean will stay open for navigation purpose.

THE ANSWER IS JETTIES AS THEY ARE BUILT PERPENDICULAR TO THE OCEAN REDUCE THE AFFECT OF LONGSHORE CURRENTS, ON EITHER SIDE OF THE LAND TO PROVIDE PASSAGE INTO THE HARBOUR, WHEREAS THE BREAKWATER ARE BUILT PARALLEL TO THE OCEAN NEAR THE HARBOUR TO REDUCE THE OCEAN WAVES AFFECT, AND GROINS ARE USED ONLY AT CERTAIN POINTS OF OCEAN WHERE THE SEA EROSION IS MORE EG: BUILDING ETC.

SO, THE ANSWER IS \"JETTIES\"