Manage the Coast

The village that was saved, and the farm that was not

In 1991 the village of Mappleton on the Holderness coast was running out of land. The cliffs were retreating, the B1242 coast road linking Hornsea and Withernsea was close to going over the edge, and roughly fifty properties were at risk. The response cost around two million pounds: two rock groynes and a revetment along the cliff foot, built from some 61,000 tonnes of granite shipped in from Norway. It worked. The cliff at Mappleton stabilised and the road is still there. But groynes work by trapping material that would otherwise keep moving along the coast, and on Holderness that material travels south. A short distance beyond the new defences the beach was starved of the sediment that had been feeding it, and with less beach to absorb wave energy the cliffs there began to retreat faster than before. At Great Cowden, just down the coast, land and farm buildings were lost. That is the shape of almost every coastal management question. The engineering usually works where it is put. The difficulty is that a coast is a system, and sediment held in one place is sediment missing from another, so protecting one settlement can transfer the problem to a neighbour who was not consulted and is not being compensated. AQA asks you to match named strategies to what a particular stretch of coast actually needs and to weigh what they cost against what they achieve. This module gives you the defences, the prices and the argument.

Five management terms

The first three are the families of approach, the fourth is what happens next door, and the fifth is the framework that decides who gets protected at all.

Trace the consequence

These six stages follow one defence scheme along the coast. Put them in the order they happened.

• A village and the coast road serving it are threatened by retreating cliffs
• Rock groynes and a revetment are built to hold the line at that settlement
• The groynes hold back material that had been travelling along the coast
• Beaches further along receive less sediment than before and become thinner
• With less beach to absorb it, more wave energy reaches the cliffs behind
• Retreat there speeds up, and land and buildings are lost at a farm down the coast

Why did the neighbours lose out?

Defending Mappleton made erosion worse a short distance down the coast. Which answer explains that properly?

• Groynes work precisely by interrupting the movement of material along the shore, holding it on their updrift side so a beach builds up there. That beach is what absorbs wave energy at Mappleton. But the sediment held back is sediment that no longer arrives further along, so beaches beyond the scheme thin, less energy is absorbed before the waves reach the cliff, and retreat accelerates. The defence did not fail; it moved the cost onto a stretch of coast that received no protection and no compensation.
• The rock used in the groynes was too weak and broke up, releasing debris that damaged the coast nearby.
• The defences made the waves themselves more powerful further down the coast.
• The faster erosion to the south was a coincidence unrelated to the scheme.

Three approaches, with prices attached

The mark scheme asks for cost weighed against benefit, so learn these with their figures. The bottom row of each column is the honest drawback, which is where a judgement actually comes from.

Match each measure to what it does

Best for whom, and worth what

The specification note for this element asks for named strategies matched to the specific needs of a coastline, with cost and benefit reasoning. That rules out the two answers examiners see most often: a list of defences with their advantages and disadvantages, and a verdict that soft engineering is simply better because it is natural. Ask three questions instead. What is being protected, and what is it worth? A stretch with a town, a main road and a railway justifies expenditure that open farmland does not, and saying so is not callousness but the actual basis on which these decisions are made. How long does it need to last? A scheme that must hold for decades points towards hard engineering; one that buys time while something else is arranged may not. And what happens next door? Any defence that interrupts the movement of material along the shore has consequences further on, and an answer that notices them is doing the evaluation the question asked for. The framework that makes this concrete is the set of four shoreline policies: hold the line, advance the line, realign, or do nothing. Notice that two of the four involve not defending, which tells you the real question is not which engineering to use but which stretches are worth engineering at all. For a judgement question, the criterion that works best here is whose interests you are measuring by. A scheme can be excellent value nationally and a disaster for one farm, and the strongest conclusions say which view they are taking and why, rather than declaring one approach the winner everywhere.

Complete the coastal management facts

The scheme at Mappleton, built in _____, cost around two million pounds and used some 61,000 tonnes of granite to protect the village and the coast road. It worked where it was built, but the rock _____ trapped material travelling along the shore, so beaches further south were starved of sediment and the cliffs behind them retreated faster. Hard engineering such as a sea wall, at roughly 5,000 to 6,000 pounds a _____, is effective but costly. Soft engineering such as beach _____ is cheaper and looks natural, but the added material is carried away in its turn and the work must be repeated. A third option is managed retreat, as at _____ in West Sussex, where a shingle bank was deliberately breached in 2013 to create salt marsh.

Spot the three accurate management claims

Select the THREE statements that are true.

• A defence has to be judged along the whole coast rather than at the site alone, because material held back by a groyne is material that no longer reaches the beaches beyond it.
• Two of the four shoreline management policies involve not defending a stretch of coast, which shows the underlying question is which places are worth protecting rather than which engineering is best.
• Beach nourishment is cheaper to begin than a sea wall but is not permanent, because the same longshore movement that stripped the original beach carries the replacement away too, so the cost recurs.
• The Mappleton scheme is regarded as a failure because the cliffs there continued to retreat.
• Soft engineering is always the better choice because it works with nature.
• Managed retreat has no costs, since nothing is built.

A 9-mark evaluation, marked

"Hard engineering is the most effective way of managing a stretch of coastline." Using a named example, assess this view. [9 marks] At Mappleton on the Holderness coast, hard engineering was chosen in 1991 because the value at risk was concentrated and immediate: roughly fifty properties and the B1242 coast road linking Hornsea and Withernsea were close to being lost to a cliff retreating faster than anywhere else in Europe. Around two million pounds bought two rock groynes and a revetment built from some 61,000 tonnes of granite, and judged at the site it has been entirely effective, since the cliff stabilised and the road is still in use more than thirty years later. No soft option would have delivered that, because nourished sand at roughly 3,000 pounds a metre would have had to be replaced continually against the same drift, and dune regeneration is no answer to a clay cliff. However, effectiveness at the site is not the same as effectiveness along the coast. Groynes work by trapping material moving along the shore, so beaches to the south received less sediment, absorbed less wave energy, and the cliffs behind them retreated faster than before, with land and farm buildings lost at Great Cowden. The scheme therefore transferred part of its cost onto people who received neither protection nor compensation. Managed retreat offers a different balance again: at Medmerry in West Sussex, around 28 million pounds in 2013 created 183 hectares of salt marsh that absorbs wave energy permanently and improved protection for about 350 properties, at the price of giving up land deliberately. I partly agree with the statement. Hard engineering is the most effective option where high-value assets are concentrated and the protection must be certain, which is exactly the Mappleton situation. It is the least effective when judged across a whole coastal system, because it moves the problem rather than removing it, and the honest conclusion is that the best approach depends on whose interests the assessment is measuring by. What earned the marks: a named scheme with its date, cost, materials and purpose; the alternatives costed rather than merely mentioned; the downdrift consequence treated as central to the evaluation rather than as an afterthought; and a conclusion that answers the question on a stated criterion, distinguishing effectiveness at a site from effectiveness across a system.

Find the two soft engineering measures

Five things done to defend a coastline. Two of them are soft engineering, meaning they work with natural processes rather than building a structure to resist the sea. Tap those TWO.

• Marram grass is planted across the dunes and boardwalks are laid so that walkers no longer break up the surface.
• Boulders of imported granite are piled along the foot of the cliff to break up the waves.
• Sand dredged from offshore is pumped onto the beach each spring to widen it again.
• A curved concrete barrier is built along the seafront to throw the waves back.
• Timber barriers are driven into the beach at intervals to hold the drifting shingle in place.

Four stretches, four decisions

You advise on a shoreline management plan. Each stretch has different assets and a different budget.

• A seaside town with a promenade, a railway terminus and several thousand homes sits behind a cliff that is being undercut. The protection must be certain and must last decades.
• A resort depends on its beach for tourism. The beach is thinning each year. A sea wall would protect the buildings but would do nothing for the sand, and visitors come for the sand.
• A stretch of low-lying farmland behind an ageing shingle bank floods more often each decade. Maintaining the bank costs more each year than the land produces, but a village and a treatment works lie further inland.
• A scheme you have approved will hold the line at a village by trapping drifting sediment. The parish to the south has written to object that their beach will thin as a result.

Assess a management scheme

Using a named example, assess the costs and benefits of a coastal management scheme. [9 marks]

• Value of what was protected: the basis on which the decision was made
• Evidence that the scheme did what it was built to do
• Effects further along the coast on people who received no protection
• Effectiveness at the site versus across the whole coastal system