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Coastal environments

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Question 5

Threats to Coastal Ecosystems

Study Figures 1a, 1b, and 1c, which show information about human threats to salt marsh ecosystems in temperate coastal zones.

Figure 1a - Diagram: Impact of sea defences on salt marsh migration under sea-level rise Two cross-sections of a coast. Section A (Natural Coastline) shows salt marsh migrating landwards over low-lying fields as sea levels rise, preserving the ecosystem. Section B (With Sea Wall) shows a concrete sea wall built behind the salt marsh. As sea levels rise, the high-water mark rises against the concrete wall, squeezing the salt marsh. This prevents landward migration and drowns the pioneer and middle marsh zones, reducing the total marsh area.

Figure 1b - Map: Spatial development plan in the Blackwater Estuary An aerial map of an estuary showing areas of salt marsh. Red hatched areas indicate areas designated for salt marsh reclamation to build a new 250-berth luxury marina, holiday lodge park, and car parks. Drainage channels from nearby agricultural land are highlighted with arrows showing runoff emptying directly into the remaining marsh creeks. Public footpaths are shown running directly through the sensitive upper marsh areas.

Figure 1c - Table: Coastal marshland loss and human environmental indicators (1990-2020)

Estuary LocationSalt Marsh Loss 1990-2020 (%)Primary Human Driver of LossAnnual Nitrogen Runoff (tonnes/yr)
Blackwater Estuary18%Coastal squeeze (sea walls) & tourism142
Ribble Estuary28%Agricultural reclamation & urban sprawl315
Solent Estuary22%Marina construction & leisure infrastructure198

Using the figures and your own geographical understanding, analyse how human activities and coastal management strategies pose threats to coastal marshland ecosystems.

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Coastal environments Questions

  1. IGCSE
  2. /Geography
  3. /Coastal environments