How hard and soft engineering, ICZM, Shoreline Management Plans and the views of different players are used to manage coastal flooding and erosion.

What this dot point is asking

Edexcel wants you to explain how coastal flooding and erosion are managed. You need hard and soft engineering strategies, the integrated approaches of ICZM and Shoreline Management Plans (SMPs), the appraisal tools of cost-benefit analysis and EIA, and the conflicting views of the different players involved.

Hard and soft engineering

Hard engineering includes sea walls that reflect waves, groynes that trap longshore drift to fatten the beach, rock armour (rip-rap) that absorbs energy in a permeable barrier, revetments that slope to dissipate waves, breakwaters offshore that create calm water, and gabions of wired rock. These protect high-value coasts but are expensive and can cause terminal groyne syndrome, where trapping sediment starves the coast downdrift and accelerates erosion there.

Soft engineering includes beach nourishment (importing sand to widen the beach), dune stabilisation (planting marram and fencing to fix dunes), managed retreat or realignment (deliberately letting the sea flood low land to create energy-absorbing salt marsh), and cliff regrading and drainage (reducing the slope angle and removing water to prevent slumping). Soft methods are cheaper and more sustainable but provide less certain short-term protection.

ICZM and Shoreline Management Plans

Integrated approaches replace piecemeal defence with whole-coast planning.

Choosing a policy for each stretch rests on appraisal. Cost-benefit analysis (CBA) compares the cost of defence with the value of the land and assets protected; defending low-value farmland rarely passes, while defending a town does. Environmental impact assessment (EIA) weighs the ecological consequences, for instance the loss or gain of salt marsh and bird habitat. These tools explain why SMPs assign different policies to neighbouring stretches.

Players, conflict and appraisal

Coastal management is contested because the costs and benefits fall on different groups.

The players include residents (who want their property protected), local councils and national government (who balance budgets and votes), conservation bodies such as the RSPB and National Trust (who value habitats and sediment supply), and insurers (who price flood risk). ICZM aims to reconcile these views, but managed realignment in particular generates conflict because it asks some communities to accept loss for the wider benefit of the cell.

Examples in context

Example 1: Mappleton, Holderness. In 1991 two rock groynes and a revetment were built to protect Mappleton and its coast road, costing around 2 million pounds. The groynes trapped longshore drift and held the beach, but starved the cliffs immediately south, where recession accelerated sharply, the textbook case of terminal groyne syndrome shifting erosion downdrift.

Example 2: Medmerry and the Delta Works. At Medmerry, West Sussex, the Environment Agency completed the UK's largest open-coast managed realignment in 2013, breaching the shingle bank to flood farmland and create 183 hectares of salt marsh that absorbs surge energy and protects Selsey. By contrast the Netherlands Delta Works, built after the 1953 floods, is a vast hard-engineering system of dams and barriers, highly effective but costly and less adaptive than soft approaches.

Try this

Q1. Explain why groynes can cause increased erosion elsewhere on a coast. [4 marks]

• Cue. Groynes trap longshore drift to fatten the local beach, but starve the coast downdrift of sediment, accelerating recession there, known as terminal groyne syndrome.

Q2. Outline why managed realignment is often a sustainable option for low-value coasts. [4 marks]

• Cue. It works with natural processes, creates energy-absorbing salt marsh, is cheaper long-term and adapts to rising sea level, though it requires relocating affected residents.