Case Study: Hard Engineering (AQA A-Level Geography): Revision Notes

Case Study: Hard Engineering

Introduction to Heysham and Morecambe

Morecambe in Lancashire provides a detailed example of how hard engineering strategies are used to protect coastal settlements. The local authority, Lancashire County Council, has implemented a range of coastal defence techniques along this 8.5 km stretch of coastline. This case study demonstrates the practical application of different hard engineering methods and how they can be combined to create an effective coastal management scheme.

• Hold the line means maintaining the current position of the coastline by keeping existing defences in good condition or constructing new structures where the old ones are no longer effective enough

• Do nothing but monitor is chosen for stretches where building or maintaining defences is not practical, either because the cost is too high or because there are few properties or important features to protect

• Retreat the line involves allowing the coast to erode in a controlled and managed way, rather than trying to stop it completely

• Advance the line means constructing new defences further out to sea than the existing coastline, effectively pushing the defensive boundary seaward

Background to the coastal defence scheme

The current protection along Morecambe's coastline resulted from a major improvement programme that took place between 1989 and 2018. This comprehensive scheme cost £30 million and transformed the coastal defences through a multi-phase approach. The project combined traditional hard engineering methods with more contemporary techniques, creating a sustainable management solution that would last for many years.

The scheme was carefully designed to balance the need for strong coastal protection with environmental concerns and aesthetic considerations. As the area includes important natural habitats, the engineers had to ensure that the defences would not damage the local ecosystem.

Strategy 1 – Rock armour/rip rap to enhance and protect the existing sea wall

This strategy involved placing large boulders of locally sourced limestone along the majority of the promenade and sea walls. The placement extended from the western end of the promenade to approximately one kilometre east of the town centre, creating a robust barrier against wave action.

The individual stones used in this rock armour varied considerably in size, ranging from 0.77 tonnes to 7 tonnes, with an average weight of 3.5 tonnes. In total, an enormous 436,000 tonnes of rock armour was installed along this section of coast. This massive quantity of material provides substantial protection by absorbing and dissipating wave energy before it can reach the sea wall behind. The irregular shape and size of the boulders means that waves break up as they pass through the rock armour, significantly reducing their erosive power.

Strategy 2 – Breakwaters or rock groynes

Around ten breakwaters were constructed at regular intervals along the coastline in front of the town. These structures included several fish-tail shaped breakwaters, which have a distinctive curved design. Just under 1 million tonnes of locally sourced limestone boulders were used to build these offshore structures.

Breakwaters are built perpendicular to the coastline and extend out into the sea. Their purpose is to reduce wave energy before waves reach the shore, creating a calmer area of water between the breakwater and the beach. This reduction in wave energy helps to protect the shoreline from erosion and encourages sediment deposition in the sheltered areas. The fish-tail design is particularly effective at dissipating wave energy while also helping to trap sediment and build up the beach.

Strategy 3 – Repaired and replaced sea walls

The traditional recurved sea wall that runs along the promenade received significant attention during the improvement programme. Between 2015 and 2018, four kilometres of 30-year-old sea wall that ran along the promenade was completely replaced with a modern, state-of-the-art design featuring a decorative wave reflection wall and flood wall.

This major replacement project cost £11 million and provides protection for 11,400 homes and 2,246 commercial properties in the area. The new wall was designed with a lifespan of 100 years, ensuring long-term protection for the community. The wave reflection feature at the top of the wall helps to throw wave energy back towards the sea, reducing the amount of water that can overtop the defences during storms.

Strategy 4 – Gabions

More than 500 gabion cages were installed at various locations along the coast to reinforce the defences. Each cage measured 2 metres × 1 metre × 1 metre and was filled with small limestone boulders.

Gabions are particularly useful in coastal defence because they are permeable, allowing water to drain through them, which reduces the build-up of pressure behind the structure. They are also relatively quick and easy to install compared to solid concrete structures, and they can be stacked to create walls of different heights depending on the level of protection required.

Strategy 5 – Concrete revetment and sea wall

To the west of Heysham Head, extending towards the port and power station, the existing sea wall and large concrete revetments were carefully repaired and kept in place rather than being replaced.

Revetments are sloping structures built on the face of a cliff or embankment to protect it from erosion. Concrete revetments are particularly durable and can withstand significant wave energy over many years. By repairing rather than replacing these structures, the project saved money while still maintaining effective coastal protection in this area.

Summary and additional features

Although the scheme relied heavily on traditional hard engineering strategies, the designers made sure that the work was carried out in a way that respected the environmental importance of Morecambe Bay. The bay is classified as both a Site of Special Scientific Interest (SSSI) and a Special Area of Conservation (SAC), which means it contains rare habitats and species that need protection.

Several sustainable practices were incorporated into the design. For example, sourcing the limestone locally for the rock armour and rock groynes meant that the material came from the same geological origin as the rocks forming the natural coastline. This created a more natural appearance and reduced environmental impact. Most of the quarries used were located less than 10 km away, which significantly reduced the carbon footprint associated with transporting the materials.

To further enhance this natural protection, the project included a substantial beach nourishment programme. Between Heysham and the eastern end of the promenade, 89,000 tonnes of sand and 19,000 tonnes of shingle were added to the beach. This increased the beach volume, providing a natural buffer against wave action and complementing the hard engineering defences.

The entire project was designed not just for protection, but also to improve the area for residents and visitors. The scheme includes combined cycle and walking paths along the promenade, playgrounds, and various artistic elements that make the seafront more attractive and enjoyable. This demonstrates how coastal management schemes can serve multiple purposes, providing both defence and social benefits.