Beach Erosion and Protection Questions and Answers

Answer: A

Correct answer: the cliff was a source of sediment to the littoral cell

An eroding cliff is not only losing land; it is feeding the beaches downdrift with the material it releases. Protecting it stops that supply, and the beaches that depended on it begin to thin - often some kilometres away and some years later, so the connection is easily missed. This is why cliff protection is assessed at the scale of the whole littoral cell rather than the frontage alone.

Answer: B

Correct answer: Both A and R are true, and R is the correct explanation of A

Both are true and the reason gives the mechanism. The sediment budget of a cell counts cliff recession as an input, so removing it creates a deficit that appears as erosion elsewhere. The effect is delayed and displaced, which makes it politically awkward: the benefit is local and immediate, the cost distant and later, and the two are rarely borne by the same community.

Answer: C

A revetment stops the cliff supplying material and is therefore a loss to the cell. The other three each deliver sediment into the system where it can be redistributed. A revetment converts a source into no source at all.

Answer: D

Correct answer: forms a steeper and more stable protective ridge

Shingle stands at a much steeper angle than sand and is far harder for waves to move, so a recharged shingle ridge is a compact and durable defence that occupies little width. It is also transported less readily than sand by the drift, not more, and it can be obtained from licensed marine sources. Its drawback is that what does move accumulates against the groynes and must be recycled.

Answer: A

Correct answer: Both A and R are true, and R is the correct explanation of A

Both are true and the reason is the mechanism. The large voids between shingle particles let the uprush sink into the beach rather than run back down the face, so much of the wave energy is spent in that percolation and the backwash is greatly weakened. The result is a steep beach that dissipates energy in a narrow width - which is why shingle frontages need much less room than sand ones for the same protection.

Answer: B

Correct answer: one to a few years

Shingle moves alongshore under oblique waves and accumulates against the updrift face of each groyne, leaving the downdrift compartments thin. Restoring the distribution by lorry or by loading shovel is a routine maintenance operation carried out every year or two, and the cost of it is part of the whole-life cost of the scheme rather than a sign that the scheme has failed.