Hard and soft engineering

Hard engineering

Hard engineering builds structures to resist or alter marine processes. It is costly to build and maintain and has a limited lifespan (Getting Started Guide).

• Sea walls: concrete walls that reflect wave energy; can cause scouring of the beach in front.
• Revetments: sloping structures (concrete, timber or rock) that absorb wave energy.
• Rip rap (rock armour): large boulders piled at the cliff foot or in front of walls to absorb energy.
• Groynes: barriers at right angles to the beach that trap sediment moving by longshore drift, building a wider beach.
• Offshore breakwaters: structures parallel to the coast that make waves break before reaching the shore.

Because they directly alter processes, hard defences often increase erosion downdrift (the terminal groyne effect).

Case study: Mappleton, Holderness

In 1991, almost 2 million pounds was spent protecting Mappleton village and its coastal road: two rock groynes to trap sediment, a rock revetment at the cliff base between them, and reprofiled, vegetated cliffs. The rock was granite imported from Norway (Internet Geography).

The scheme worked locally, but at Cowden, about 1 km south, erosion at one farm rose from an average of about 1 m to 3 m per year after the defences were built, and the farm was eventually lost. Data across Holderness show faster erosion just south of the sea walls at Hornsea and Withernsea too (urbanrim.org.uk).

Soft engineering

Soft engineering works with physical systems:

• Beach nourishment: adding sand or shingle (often dredged offshore) to widen a beach, which absorbs wave energy. Needs repeating.
• Beach profiling (reprofiling): reshaping the beach with machines, for example pushing sand up the beach before winter.
• Cliff regrading and drainage: lowering the cliff angle and draining water out to reduce slumping.
• Dune stabilisation: planting marram grass, fencing and boardwalks to trap sand and reduce trampling.

Soft engineering is usually cheaper and less visually intrusive, but it needs constant maintenance and gives less certain protection.

Worked example

Explain why the Mappleton groynes increased erosion at Cowden.

1. Longshore drift on Holderness moves sediment southwards.
2. The groynes trapped sediment at Mappleton, widening its beach.
3. Less sediment reached Cowden downdrift, so its beach narrowed and gave less protection, and waves attacked the cliff more often: erosion rose from about 1 to 3 m per year at one farm.

Answer: The groynes starved the downdrift beach of sediment: the terminal groyne effect.

Check yourself

1. What is the main purpose of groynes?
   • To reflect waves back out to sea
   • To drain water from cliffs
   • To trap sediment moved by longshore drift
   • To create new land offshore
   Show answer

   To trap sediment moved by longshore drift. They build up a wider beach.

2. An offshore breakwater protects the coast by
   • making waves break before they reach the shore
   • trapping sand at right angles to the beach
   • adding sand to the beach
   • lowering the cliff angle
   Show answer

   making waves break before they reach the shore. Energy is lost offshore.

3. Which of these is soft engineering?
   • Rip rap
   • A concrete sea wall
   • Cliff regrading and drainage
   • A revetment
   Show answer

   Cliff regrading and drainage. It reduces mass movement by working with slope processes.

4. At one Cowden farm, erosion rose from about 1 m to 3 m per year after the Mappleton scheme. By what factor did it increase?
   Show answer

   3 times. 3 / 1 = 3.

5. Over 10 years, how many more metres would be lost at 3 m per year than at 1 m per year?
   Show answer

   20 m. (3 - 1) x 10 = 20 m.

6. A disadvantage of a vertical sea wall is that
   • it traps too much sediment
   • reflected waves can scour the beach in front of it
   • it needs replanting each year
   • it increases dune growth
   Show answer

   reflected waves can scour the beach in front of it. Reflection removes beach material, undermining the wall.

7. Explain how beach nourishment reduces coastal erosion.
   Show answer

   Adding sand or shingle makes the beach wider and higher, so waves break and lose their energy on the beach before reaching the cliff or sea wall, reducing erosion.. Add sediment, wider beach, energy absorbed.

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Sources

• Pearson Edexcel International Advanced Subsidiary/Advanced Level in Geography specification, Issue 3 (September 2025)
• Pearson IAL Geography Getting Started Guide
• Internet Geography: Mappleton case study
• Holderness coast data (urbanrim.org.uk): erosion 2003 to 2025, geology and defences
• Pearson Edexcel International Advanced Subsidiary/Advanced Level in Geography specification, Issue 3 (September 2025)

Last updated 8 November 2026. Spotted a mistake? Tell us.