Managing coastal margins practice questions.

Rock groynes were built at Mappleton on the Holderness coast, England, in 1991 to hold sediment in front of the village. Sediment on this coast is transported southwards. What is the most likely effect on the coast immediately to the south?

• Erosion slows because wave energy is reflected offshore by the groynes
• The beach widens because transport is diverted around the groyne ends
• Cliff retreat stops because the groynes trap clay eroded from the cliffs
• Erosion speeds up because the beach there is starved of sediment

Answer: Erosion speeds up because the beach there is starved of sediment

A groyne field traps material updrift, so the same wave energy further along the coast now meets a thinner beach and reaches the cliff foot more often; the problem is exported rather than solved.

At Medmerry in West Sussex, England, the shingle bank was deliberately breached in 2013 and a new embankment was built further inland. What is the main coastal-process reason for that design?

• The breach increases alongshore transport towards the town's harbour
• New intertidal saltmarsh absorbs wave energy before it reaches the defence
• The inland embankment reflects storm waves straight back out to sea
• Removing the shingle bank lowers the local tidal range and surge height

Answer: New intertidal saltmarsh absorbs wave energy before it reaches the defence

Managed realignment buys protection by trading land for friction: waves cross a wide, shallow, vegetated surface and arrive at the set-back bank with much less energy.

At Happisburgh in Norfolk, England, the shoreline management plan sets a policy of no active intervention, and cliff-top homes have been lost to erosion. Which group carries the greatest uncompensated cost of that decision?

• Cliff-top residents, whose homes lose all market value
• The national government, which funds replacement housing
• Offshore aggregate dredging firms working in the North Sea
• Arable farmers several kilometres inland from the cliff line

Answer: Cliff-top residents, whose homes lose all market value

Cost-benefit rules concentrate public spending on high-value frontages, so the decision about who is defended is also a decision about who absorbs the loss, and in England there is no statutory right to compensation.

Which task requires synthesis and evaluation (AO3) rather than application and analysis (AO2)?

• To what extent is coastal management in one named area successful?
• Explain two reasons why river deltas often support dense populations
• Analyse the pattern of migration shown in the resource
• Suggest one reason for the anomaly identified in the graph

Answer: To what extent is coastal management in one named area successful?

'To what extent' demands a judgement supported by stated criteria and a counter-position. Explain, Analyse and Suggest all ask for reasoning about the material but stop short of an evaluative verdict.

At Medmerry in West Sussex the sea wall was breached deliberately and a new embankment was built two kilometres inland, creating an intertidal area in between. Which strategy is this?

• Managed retreat, creating a saltmarsh buffer in front of the new defence
• Hold the line, using a stronger structure at the original shoreline
• Advance the line, reclaiming land seaward of the old wall
• Do nothing, allowing the coast to erode without intervention

Answer: Managed retreat, creating a saltmarsh buffer in front of the new defence

Managed retreat moves the defended line landwards on purpose and lets the surrendered ground become intertidal, where the marsh absorbs wave energy. It is cheaper to maintain than an ever-taller wall and it creates habitat, but it requires giving up land, which is what makes it politically hard.

The Sand Motor on the Dutch coast placed a very large volume of sand in a single peninsula-shaped nourishment, letting waves and currents redistribute it over about twenty years. What is the advantage over repeated conventional nourishment?

• One large operation replaces frequent small ones, reducing repeated disturbance and cost
• It removes the need for any dune management behind the beach
• It stops longshore drift completely along that section of coast
• It converts a soft engineering scheme into a hard engineering one

Answer: One large operation replaces frequent small ones, reducing repeated disturbance and cost

The design works with longshore drift rather than against it, using natural transport to do the distribution that dredgers would otherwise repeat every few years. It is a good example of soft engineering scaled up rather than replaced by structures.