4. How does human activity cause change with coastal landscape systems? Flashcards
(18 cards)
How does human activity intentionally change coastal landscapes?
Through coastal management, such as building defences (groynes, sea walls) or altering sediment flows (beach nourishment, dredging).
What are the main types of coastal management?
Hard engineering: sea walls, groynes, rock armour
Soft engineering: beach nourishment, dune regeneration
Managed realignment: allowing controlled flooding or retreat
How has Sandbanks been intentionally managed?
Groynes trap sediment to reduce longshore drift and maintain beaches.
Beach nourishment adds sand to widen the beach for protection and tourism.
Aim: protect high-value properties, maintain navigability of Poole Harbour, and reduce erosion
What are the impacts of management at Sandbanks?
Maintains beach width and protects land from erosion.
May reduce sediment supply to areas further along the coast.
Groynes may interrupt natural sediment flow, requiring ongoing maintenance.
How does human activity unintentionally change coastal landscapes?
Dredging, dam construction, urbanisation, and sand mining disrupt sediment supply or flows.
These actions can accelerate erosion, coastal retreat, or change landform development.
How has sand mining at Pakiri Bay altered the coastal system?
Sand extraction has lowered beach levels, reducing natural protection.
Disrupts sediment budget and longshore drift, increasing coastal retreat.
Makes the beach and dunes more vulnerable to storm damage and sea level rise.
How has the Aswan High Dam affected the Nile Delta?
Traps sediment upstream, reducing supply to the delta.
Erosion is now faster than deposition, causing delta retreat.
Saltwater intrusion and loss of land affect farming and settlement.
How can coastal defences unintentionally affect Saltburn to Flamborough Head?
Defences in places like Scarborough and Whitby interrupt longshore drift.
This reduces sediment supply to southern beaches (e.g. Filey), increasing erosion.
Can lead to narrow beaches and more wave energy reaching cliffs.
What are the wider impacts of human activity on coastal systems?
Alters sediment budgets, causing erosion in some areas and deposition in others.
Can change the shape and stability of landforms.
May increase flood risk or habitat loss (e.g. salt marshes, dunes).
What is one coastal landscape that is being managed, and why?
Sandbanks Peninsula, Dorset — managed due to:
High-value properties at risk of erosion and flooding
Narrow beaches caused by longshore drift removing sediment
Maintaining access to Poole Harbour for shipping and tourism
What management strategies are used at Sandbanks?
Groynes: to interrupt longshore drift and trap sand
Beach nourishment: to replace lost sediment and widen the beach
Sea wall and rock groynes: protect key infrastructure (e.g. roads, buildings)
What are the intentional impacts of these strategies on flows of material and energy?
Groynes trap sediment, reducing flow further along the coast
Beach nourishment increases beach volume, helping absorb wave energy
Alters sediment budget, preventing natural redistribution
Reduces erosion and wave impact in managed areas
How do these strategies change coastal landforms?
Wider, higher beaches protect dunes and cliffs
Groynes create steeper beach profiles on the updrift side
Sediment starved areas may suffer down-drift erosion
What are the long-term consequences for the coastal landscape?
Extension of the coastline seawards in managed areas
Creates artificial stability which requires ongoing maintenance
Ecosystem disruption if sediment isn’t allowed to move naturally
What coastal landscape is affected by economic development, and why?
Pakiri–Mangawhai, New Zealand — used for offshore sand mining to supply Auckland’s construction industry and tourist beaches
What are the unintentional impacts on sediment flows and energy?
Sand extraction disrupts sediment cell and reduces beach replenishment
Less sediment = less wave energy absorption, increasing erosion
System shifts out of dynamic equilibrium
How have landforms changed due to these impacts?
Narrower beaches and lowered dune ridges
Dune vegetation destabilised, allowing wind erosion
Loss of sediment = steeper beach profiles, faster retreat
What are the long-term consequences for the landscape?
increased coastal retreat and risk to housing/tourism
Disruption to natural coastal defences (dunes and beaches)
Irreversible erosion in some areas unless extraction is stopped
