River and Coastal Management
Why Manage Rivers and Coasts?
Rivers and coastlines constantly change through natural processes, but where people live, farm and work alongside them, the consequences of flooding or erosion can be devastating. Management aims to reduce flood risk (rivers) and coastal erosion/flooding (coasts), while balancing economic cost, environmental impact and social equity.
River Flood Management
Hard Engineering
Hard engineering uses artificial structures to control the river:
| Structure | How it works | Pros | Cons |
|---|---|---|---|
| Dam and reservoir | Stores water upstream; releases it in a controlled way | Effective flood control; water supply; HEP | Expensive; displaces communities; traps sediment; alters downstream ecology |
| Embankments/levées | Raised earth or concrete banks alongside the river | Cheap; increases channel capacity | Unattractive; if they fail, flooding is severe; raises flood risk downstream |
| Straightening (channelisation) | Removing meanders; lining channel | Faster water movement; reduces local flood risk | Increases flood speed downstream; destroys aquatic habitat |
| Flood walls | Concrete walls in urban areas | Protects built-up areas effectively | Expensive; can be aesthetically intrusive |
UK case study — River Severn / Bewdley: The River Severn is prone to extreme flooding — the November 2000 and January 2014 floods caused £0.5 billion in damage. Hard engineering schemes include: raised flood embankments in Shrewsbury, Ironbridge and Bewdley; temporary barrier systems (Demountable Flood Barriers) erected when flooding threatens. A proposed major reservoir at Clywedog in mid-Wales (built 1967) regulates the Severn's upper flow.
Soft Engineering
Soft engineering works with natural processes rather than against them:
| Approach | How it works | Benefits |
|---|---|---|
| Flood plain zoning | Restricting development in the floodplain | No new buildings at risk; low cost |
| River restoration | Re-meandering straightened channels; removing concrete lining | Slows flow; improves ecology; amenity value |
| Afforestation | Planting trees in the catchment | Trees intercept and absorb rainfall; reduce peak discharge |
| Washlands | Deliberately flooding low-value agricultural land | Acts as a storage basin; protects settlements downstream |
Welsh case study — Pontypridd / Taff Flood Alleviation Scheme: The River Taff regularly flooded Pontypridd town centre. The £48 million scheme (completed 2020) used a combination of raised walls, embankments and a flood storage area at Treforest to protect 1,500 homes. The scheme is considered one of the most effective in Wales.
Coastal Flood and Erosion Management
Hard Engineering at the Coast
| Structure | Function | Issues |
|---|---|---|
| Sea walls | Concrete/rock wall reflects wave energy | Expensive (£2,000/m+); increases wave scour at base; ugly |
| Groynes | Timber/rock structures perpendicular to shore; trap longshore drift | Starve beaches further along the coast of sediment |
| Rock armour (rip-rap) | Large boulders absorb wave energy | Cheap; effective; can look unnatural |
| Revetments | Sloping wooden or concrete structures absorb wave energy | Less effective than sea walls; cheaper |
Soft Engineering at the Coast
| Approach | How it works |
|---|---|
| Beach nourishment | Pumping sand from offshore to widen the beach — a natural wave energy absorber |
| Managed retreat | Allowing the coastline to erode/flood in low-value areas; compensating landowners |
| Dune stabilisation | Planting marram grass to bind dune sand; reduces erosion |
| Cliff drainage | Removing groundwater from cliff to reduce slumping/landsliding |
Coastal Management Strategy: Shoreline Management Plans (SMPs)
The UK government uses SMPs to decide the long-term future of every stretch of coastline:
- Hold the line — maintain existing defences
- Managed realignment — allow the coast to move inland in a controlled way (e.g., Medmerry, West Sussex — 183 ha of farmland sacrificed to create a saltmarsh buffer, protecting 348 homes)
- No active intervention — allow natural erosion; typically for uninhabited coasts
Welsh case study — Towyn/Kinmel Bay, North Wales: The 1990 Towyn flood (caused by a North Wales coastal storm surge) flooded 2,800 homes when the sea wall failed. Since then, major hard engineering investments have been made along the North Wales coast. More recently, managed retreat has been considered for some sections of the Cardigan Bay coastline to create saltmarsh habitats.
Evaluating Management Approaches
- Cost vs benefit: Hard engineering is usually most expensive; benefit is most direct. Managed retreat is cheap but politically very difficult.
- Environmental impact: Hard engineering can disrupt sediment supply; soft engineering enhances habitat.
- Inequality: Richer areas tend to receive more protection. Communities facing managed retreat often feel abandoned.
- Climate change: Rising sea levels and more intense rainfall increase the urgency and cost of management — a key factor for WJEC evaluation questions.
WJEC Exam Tips
- Use the phrase "hard vs soft engineering" — examiners look for this
- Evaluation questions (8 marks) require both sides + a conclusion: which approach is better overall and why?
- Welsh case studies (Taff, Towyn) will be rewarded; also know one UK-wide case study (e.g., the Thames Barrier for tidal flooding)
- "Coastal management conflict" is a common exam theme — not everyone benefits equally
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