Beach Erosion and Protection Questions and Answers

Answer: A

Correct answer: 2 - 4 - 1 - 3

The order is diagnosis before prescription. First establish whether the reported erosion is a genuine trend or a storm event that will recover. Then determine the sediment budget and what is causing the deficit, since the cause dictates which family of measure can work. Only then appraise the options against their benefits and costs, and finally implement and monitor. Reversing any of these steps is how schemes come to address the wrong problem.

Answer: B

A measure aimed at the wrong cause will not work however well it is built. Diagnosis before treatment is as true in coastal engineering as it is in any other branch of the discipline. Cause and remedy must be matched to one another.

Answer: C

A vertical step often develops in the first weeks as the placed material redistributes. It usually resolves itself, though it can present a temporary hazard to beach users while it persists. Grading it flat is sometimes done for safety reasons.

Answer: D

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

Both are true and the reason gives the hazard. Newly placed sand stands at a slope steeper than equilibrium, and the waves cut a vertical face into it that may be a metre or more high, unstable and liable to collapse when stood on or undercut. On a public beach this is a real risk, particularly to children, so scarps are graded off or fenced until the profile has adjusted.

Answer: A

It creates an immediate defensive ridge before a forecast storm without importing material. Since it adds nothing to the beach it can weaken the lower profile it drew from. The benefit is short lived and strictly local.

Answer: B

Correct answer: 1 and 2 only

Statements 1 and 2 are correct: scraping takes sand from the lower beach and pushes it up to form a temporary ridge, which can be done in hours ahead of a forecast storm. Statement 3 is wrong and is the limitation of the method - nothing is added, so the lower beach is left thinner, and where the practice is repeated the whole profile is progressively depleted.

Answer: C

The material buys time and absorbs the wave attack that would otherwise reach the asset. Its loss is the intended outcome rather than a sign that the scheme has failed. Performance is judged on what the fill protected.

Answer: D

Both are true and the reason gives the intent, and performance is judged on the protection achieved. Judging it on the volume remaining misunderstands what the scheme was for. The asset behind is the measure of success.

Answer: A

The bay between the headlands adjusts towards a stable planform and then holds it. The approach requires an initial fill to establish the bay shape it is intended to retain. Without fill the bay erodes to reach that shape itself.

Answer: B

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

Both are true and the reason explains the necessity. A bay between two headlands adjusts towards a stable planform determined by the wave approach, and if it is not filled to that shape at construction it will fill itself - by drawing material out of the beach the scheme was built to protect. Supplying the fill at the outset avoids that transitional erosion, which would otherwise be blamed on the scheme.