Explain why hard engineering approaches are still used to protect some coastal areas?

Cost benefit analysis if often used to establish whether hard engineering strategies should be used to protect an area of coastline. The general equation used is the following: Cost Benefit= Value of land protected/ Cost of Defence x years. Hard engineering strategies are necessary to protect vital infrastructure and vulnerable urbanised areas. For example, the Thames Barrier protecting London from flooding cost £534 million to implement, yet as the financial capital of the UK it generates around 23% of the country’s GDP, which is around £649715 million. This evidences the economic gains and the predicted longevity of the strategy (no new implementation needed until 2070) outweighs the initial investment making it a useful approach. This approach is also necessary because of the multiple threats London faces, from sea level rise and more extreme precipitation (due to climate change), isostatic rebound and a large tidal range. Hard engineering strategies also tend to be more reliable and effective in stopping the rates of erosion and flooding, whereas soft engineering strategies such as dune replenishment is less certain to effectively protect a certain spatial extent. In this case study and in others such as the Easington Gas terminal, damage to even a small spatial extent of the area that needs to be protected could have severe economic, political and even environmental consequences. For example, the Gas terminal on the Holderness coastline deals with 25% of the oil from the North Sea, if this terminal stopped it would present a severe threat to energy security. These benefits are considered to outweigh the damaging consequences for the rest of the littoral cell, for example the groynes implemented here will limit the longshore drift to the coast southward.