Coastal Processes and Morphology Questions and Answers

Answer: C

The first pair describes change over a season and the second a persistent character of the site. Sediment size and wave climate together decide which state a beach occupies. Wave climate and grain size act together on the profile.

Answer: D

Wave energy is spread over a broad zone and released gradually as spilling breakers. Reflective beaches at the other extreme concentrate the energy into a narrow steep face. The two ends of the range behave very differently.

Answer: A

Both are true and the reason gives the mechanism, and the weakened backwash leaves more sediment high on the face. Shingle beaches are consequently among the steepest natural profiles found. Percolation is the controlling difference between them.

Answer: B

Coarse material drains quickly and supports a much steeper face than sand. Fine sand beaches by contrast are typically nearer one in fifty to one in a hundred. Grain size is the strongest single control on beach slope.

Answer: C

The part of a crest in shallower water travels more slowly and the crest swings round. This is why waves arrive nearly shore parallel even when generated far offshore. Refraction is the reason the drift angle is usually small.

Answer: D

Both are true and the reason gives the mechanism, and this is why headlands erode while bays accumulate sediment. The process tends over time to straighten an irregular coastline. Erosion and deposition are distributed by the wave field.

Answer: A

Correct answer: 1 and 2 only

Statements 1 and 2 describe refraction correctly: the crest slows first where the water is shallow, so it bends and the orthogonals converge on headlands and diverge into bays. Statement 3 is the reverse of the consequence - that concentration of energy is precisely what erodes the headlands and the divergence is what lets sediment settle in the bays, so refraction is one of the principal agents shaping a coast.

Answer: B

Correct answer: in the lee of a breakwater or headland

Diffraction is the lateral spreading of wave energy into a region the wave could not reach directly, so it matters wherever there is a sheltering obstruction - behind a breakwater arm, round a headland, through a harbour entrance. It is what determines how much wave energy penetrates a sheltered basin, and it is why the shelter behind a structure is partial rather than complete.

Answer: C

Correct answer: A-2, B-4, C-1, D-3

Four transformations with four distinct causes. Shoaling is the change in height and speed as the depth decreases beneath the wave. Refraction is the bending that follows when different parts of one crest travel at different speeds in different depths. Diffraction is energy spreading laterally past an obstruction. Reflection is energy returned from a steep boundary such as a wall or a cliff.

Answer: D

Correct answer: waves approaching the shore at an oblique angle

Oblique waves run up the beach at an angle and the backwash returns straight down the slope under gravity, so each swash cycle moves a grain a little way along the shore - and the breaking waves also drive a longshore current in the surf zone. Waves arriving exactly perpendicular produce no along-shore component at all, which is why the drift rate depends so strongly on the wave approach direction.