The coastal questions in the 2021 AQA Assessment materials

Seems appropriate for my first Substack piece....

Coastal systems - sample answers

Outline the processes which lead to the development of barrier beaches. (4)

Barrier beaches can be formed in a number of ways. Where a spit has developed right across a bay because there are no strong currents to disturb the process, it creates a bar which then dams the water behind it forming a lagoon. This is one form of barrier beach. Offshore bars are deposits of sand and shingle situated some distance from a coastline. They usually lie below the level of the sea, only appearing above the level of the water at low tide. They form in shallow seas where the waves break some distance from the shore. When a bar begins to appear above the level of the sea for most of the time, it also becomes barrier beach.

Figure 5 shows data related to the distribution of beach erosion and accretion from 1984 to 2016. Accretion occurs when more sand is accumulated on beaches than is lost to erosion.

Analyse the data shown in Figure 5.  (6)

There is significant variation in the rates of accretion and erosion of sandy beaches across the world. Overall, across the continents, beaches are experiencing net gains, most notably in south-east Asia. This area is experiencing accretion rates over 1m/yr greater than any other continent.

In some areas where rates are high for erosion, there is some evidence that rates are also high for accretion and vice versa. However, an anomaly is at 30oW for example, where the erosion is running at over 50% with accretion at only around 5–10%.

There are some distinct bands where erosion is dominant (e.g. India or the band stretching from the Mediterranean to east coast of Africa). There are some bands of significant accretion e.g. south east Asia and northern Canada.

Finally, the resource is difficult to use, and therefore may not be that useful. There are areas where it is very hard to tell which process is dominant and how much erosion or accretion is taking place e.g. Middle East.

Figure 6 is a photograph of a coastal feature, taken in Malta in 2017. Using Figure 6 and your own knowledge, assess the view that rock type is the most important factor in the development of this landscape. (6)

The photo shows a coastal erosional landscape, with a cliff coastline, together with a pronounced arch which is becoming very thin at the top. The rock type of this landscape (possible limestone) will have greatly influenced its development. Firstly, it is clearly a resistant rock to create such a cliff coastline, but a weakness within it has been exploited by the sea to create at first a cave on either side of the headland, then a large arch, and eventually the roof of this arch will collapse.

Weathering and mass movement processes are also active here with salt weathering, where the water spray sends saline water into the cracks which then leaves behind expanding salt crystals as the rock dries out in the sunshine (clear blue sky shown for this area of Malta – a hot country). Rock falls will have been common. There is also a distinct horizontal weathered notch on the left of the photo – this can’t be due to the sea as it is too high up. A weakness such as this in this horizontal layer is also due to the rock type.

So, despite the area being a choppy sea area, with big waves – a high energy coastline – I think that rock type is indeed the main factor in the development of this landscape.

‘Shoreline management/integrated coastal zone management can effectively tackle the expected eustatic sea-level change and associated threat to coastal landscapes in the coming decades.’

To what extent do you agree with this view?  (20)

On the one hand, shoreline management can provide sustainable plans for coastlines, to effectively tackle eustatic sea level change and associated threats. For example, along the Holderness coast, the shoreline management plan (SMP) adopts a hold the line approach in places like Hornsea. 11.4km of this stretch of coastline is protected by coastal defenses such as sea walls and groynes. SMPs are effective because they outline the plan for beyond 50 years, and they are continually updated to take into account any dangers. For example, erosional levels are as high as 10m along the Holderness coast, such as at Hornsea. This is projected to be exacerbated by sea level rise. Therefore, the SMP here suggests higher sea walls to deal with this.

However, its effectiveness is limited by disparities. Less populated areas are relatively neglected. This can be seen in a small town in West Somerset which has been assigned a ‘no active intervention policy’ whereas Minehead a more economically viable area has a hold the line policy. Therefore, the effectiveness of shoreline management plans in tackling sea level rise and associated hazards here is more limited.

On the other hand, community action can also be effective tackling sea level change. For example, in the Sundarbans, a coastal zone in Bangladesh, mangrove forests act as a defense against eustatic sea level change. Mangrove forests dissipate wave energy, as a density of 30 trees per 0/01ha can reduce the destructive of a tsunami by 90%. This reflects the effectiveness of natural deforestation protecting the coastline. Over 30,000 people in the Sundarbans have received training by USAID on sustainable agricultural techniques to mitigate and prepare for sea level rise. In this aspect, community action and natural defenses can act effectively where there is no management plan.

LICs are most at risk from flooding. Relatively weak and sometimes corrupt governments mean that strategies like SMPs are not applicable. Therefore, it can be argued that the projected impacts of eustatic sea level rise cannot be tackled effectively everywhere. Thermal expansion is a central cause of eustatic sea level rise. A 10c increase in temperatures can result in sea levels rising by up to 0.7m. In the last 30 years 7,000 people in the Sundarbans have been displaced due to sea level rise and erosion. Therefore, it can be argued that cohesive strategies such as SMPs may not be applicable to LICs, who lack the infrastructure to adopt such practices. In this aspect, SMPs cannot effectively tackle eustatic sea level change and associated hazards such as erosion.

In conclusion, while shoreline management plans may provide effective plans for life in the UK, LICs are most at risk. The lack of infrastructure and funding therefore means that shoreline management plans are very difficult to adopt. Therefore, the effectiveness of shoreline management plans in tackling sea level rise and associated risks like erosion is limited. SMPs are not widely applicable and other forms of community preparation can be highly effective, as these make up localized responses, that can be applied to that specific place.

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