Hard engineering methods are often viewed as unsustainable as the defences are expensive to set up and maintain. Nevertheless, these costs are justified by the expense saved from preventing the loss of infrastructure to cliff collapse. Saving infrastructure can be considered as sustainable as jobs and homes are being protected for future generations. The Isle of Wight is recognised for using a wide variety of hard engineering techniques, but the main structure is the sea wall. Sea walls are highly effective defences as they’re commonly made from thick concrete allowing them to withstand erosion over long periods of time. Furthermore, they may have a recurved top aiding them to deflect waves. On the contrary, in December 2012, adverse weather led to a landslide that destroyed the sea wall resulting in £2 million worth of repairs. Cases such as this lead to the consideration of whether the cost of repair is worth the protection the wall will provide.As climate change leads to a global increase in sea level, the Isle of Wight is continually looking to increase its coastal defences against flooding. Like most other islands, flooding is becoming increasingly worse as tides creep inland, leading the government to want to use mostly hard engineering techniques as they’re more effective. Soft engineering defences are a very short-term solution against a very long-term issue. However, some fear increased defences will impact the coastal environment and ecosystems.Pevensey bay uses a variety of hard and soft engineering techniques, but the latter is now the dominant strategy used. Traditionally the bay was maintained through the use of 150 groynes. These were slowly reduced to 10 groynes and the focus moved to more sustainable strategies such as beach reprofiling. Beach reprofiling is very sustainable as it’s cheap to set up, also it can be undertaken at key points throughout the year when the impact on tourism or bird migration is at a minimum. This means income to the area remains consistent and ecosystems are impacted very little by coastal defences. When assessed on a long-term basis, beach reprofiling is less sustainable as it has to be regularly maintained and relative costs increase the longer the reprofiling takes. Initially, this strategy is effective as the beach is steeper creating a more frictional impact on approaching waves reducing the amount of material they will erode. If waves become stronger the technique becomes ineffective as the waves are able to adjust the gradient of the beach, hence the constant need to maintain it. Managed retreat (a soft engineering technique) at Abbotts Hall Farm was used after the sea wall (an example of hard-engineering) caused a coastal squeeze as the salt marsh was fixed between the sea and the sea wall was being eroded away. This case study demonstrates how a soft engineering strategy has replaced a hard engineering one, as managed retreat was considered a more effective and sustainable plan in this situation. Whether this is the case is yet to be discovered as a monitoring programme is being carried out to assess the effect of the realignment and provide guidance for future similar schemes.In summary, coastal management schemes are unlikely to be labelled as both effective and sustainable, due to sturdy, effective defences requiring materials such as concrete and rocks. These stronger materials are more expensive resulting in them being a less sustainable approach, not forgetting the fact they disrupt the natural environment. As hard engineering techniques are generally more costly, areas receiving a lower income may turn to sustainable strategies to protect their coastlines, whereas areas taking in a high income will simply focus on protecting industry and turn to durable defences for insurance. As well as considering cost, time also needs to be considered. The current sea level rise is 3.2mm a year, producing more frequent coastal floods. Soft-engineering schemes such as beach replenishment will not be economically beneficial as floods will wash away the fresh sediment resulting in regular maintenance. Sea walls act as flood and erosion protection so it is likely that more hard-engineering structures will be seen again along coastlines.
Hard beach reprofiling. Beach reprofiling is very sustainable as
September 10, 2019September 10, 2019| | 0 Comment