IB Geography • Section 3
Managing Coastal Margins
The varying power of different stakeholders in relation to coastal-margin management
Restored from the original AdornGeo Weebly page • syllabus order preserved
Coastal Erosion & Flooding Management
Coastal erosion and flooding management strategies, including cliff-line stabilization and managed retreat
Begin by diagnosing the coastal process and the assets at risk. Students then compare hard engineering, soft engineering, nature-based protection and managed retreat, judging each option by effectiveness, cost, lifespan, environmental impact and who gains or loses.
- Cliff stabilization reduces mass movement through drainage, regrading, vegetation, netting or retaining structures.
- Sea walls, revetments and groynes can protect selected places but may transfer erosion or alter sediment movement down-drift.
- Beach nourishment and restored dunes, marshes, reefs or mangroves work with natural processes but need space and maintenance.
- Managed retreat moves development away from the hazard zone; it can lower long-term risk while creating difficult compensation and ownership decisions.
Watch: Wave tank: how coastal defences change flood risk
Watch: Norfolk: clifftop homes, erosion and competing management choices
Coastal Stakeholders
The varying power of different stakeholders in relation to coastal margin management
Coasts are contested spaces. A strong geographical evaluation identifies stakeholders, maps their interests and influence, and explains why a technically effective scheme may still be socially or politically unacceptable.
- Residents, fishers, tourism businesses, developers, conservation groups and governments value the same coast differently.
- Power comes from legal authority, land ownership, finance, expertise, political access and the ability to shape public opinion.
- Participation is meaningful only when affected groups can influence choices, not merely receive information after decisions are made.
- Use an influence–interest grid, then identify conflicts, alliances, trade-offs and possible compensation.
Samut Chin, Upper Gulf of Thailand
One coastal-management case study focused on the decision-making process and perspectives of different actors
Use Samut Chin as the decision-making case study. The low-lying muddy coast of the Upper Gulf is exposed to erosion and relative sea-level rise, while subsidence, altered sediment supply, mangrove loss and development intensify risk. Students should compare the evidence and perspectives before recommending a management pathway.
- Locate the case study on the Upper Gulf of Thailand and distinguish the physical drivers of erosion from human pressures.
- Compare protection, accommodation and retreat, including barriers, sediment management and mangrove restoration.
- Identify the priorities of local residents and monks, fishers, planners, engineers, businesses and environmental groups.
- Evaluate who pays, who benefits, what happens down-coast and whether the strategy remains viable as conditions change.
Watch: Ban Khun Samut Chin: coastal erosion threatens a community near Bangkok
Watch: Ban Khun Samut Chin: a coastal school adapting to a changing shoreline
Maritime Sovereign Rights
Sovereignty rights of nations in relation to territorial limits along coastal margins and exclusive economic zones (EEZs)
Move from management on the shoreline to control at sea. Students apply UNCLOS zones to resources, navigation and overlapping claims, then use the Arctic to examine how environmental change creates new strategic opportunities and disputes.
- A state exercises sovereignty in its territorial sea, normally extending 12 nautical miles from its baseline.
- The contiguous zone may extend to 24 nautical miles; an EEZ may extend to 200 nautical miles.
- Within an EEZ, a coastal state has rights over living and non-living resources, while other states retain navigation and overflight freedoms.
- Overlapping claims, continental shelves and newly accessible Arctic routes reveal the difference between legal rights and geopolitical power.
Mangroves: Natural Coastal Protection
Coastal ecosystem values and the role of natural coastal protection in managing changing coastal margins
Mangroves connect protection, livelihoods and biodiversity. Treat them as living infrastructure: their success depends on suitable tidal conditions, sediment supply, space for landward migration and local stewardship—not simply planting seedlings.
- Roots trap sediment and reduce wave energy while stabilising sheltered tropical shorelines.
- Mangroves provide nursery habitat, fisheries support, carbon storage and livelihood benefits alongside hazard reduction.
- Aquaculture, reclamation, pollution and coastal infrastructure can remove forests or block their landward migration.
- Restoration must repair hydrology and reduce the original pressure; protection, regeneration and community management may outperform mass planting.
Watch: Mangrove forests: how the ecosystem works
Watch: Mangroves for the Future: investing in coastal ecosystems
Coral Reefs: Value, Threats & Management
Coastal ecosystem values, threats and management, including coral reefs
Build from ecosystem value to threat and then management. Students should distinguish global stressors—especially ocean warming and acidification—from pressures that can be reduced locally, such as pollution, destructive use and unmanaged tourism.
- Reefs dissipate wave energy, support fisheries and tourism, and contain exceptionally high biodiversity.
- Marine heatwaves cause bleaching; acidification makes calcification harder, while pollution and physical damage reduce resilience.
- Local responses include marine protected areas, zoning, mooring buoys, wastewater control, visitor limits and community monitoring.
- Reef restoration can assist recovery at selected sites, but it cannot substitute for reducing greenhouse-gas emissions and chronic local pressures.
Watch: Coral Reefs 101 — National Geographic
Watch: Coral reefs: ecosystem processes and pressures
Watch: Coral spawning: reproduction on the reef
Watch: How coral atolls form
Coastal Management Synthesis
Synthesis of coastal-management futures and the value of global cooperation
Finish by designing an adaptive coastal pathway rather than selecting one permanent structure. Combine risk evidence, ecosystem processes, stakeholder participation and periodic review so the strategy can change as sea level, exposure and community priorities change.
- Integrated coastal-zone management links land, water, ecosystems and sectors instead of treating each project in isolation.
- A robust strategy can combine grey engineering, nature-based protection, planning controls, warning systems and selective retreat.
- Set measurable thresholds and review dates so communities know when to maintain, upgrade, change or withdraw a measure.
- Global cooperation matters because climate change, biodiversity loss, pollution, fisheries and maritime governance cross national boundaries.