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HOW DOES HUMAN ACTIVITY CAUSE CHANGE WITHIN COASTAL LANDSCAPE SYSTEMS -…
HOW DOES HUMAN ACTIVITY CAUSE CHANGE WITHIN COASTAL LANDSCAPE SYSTEMS
Sandbanks, Bournemouth- intentional
managment strategies
Sandbanks peninsula being managed by Poole Borough Council which organised the two bays shoreline management plan
Beach replenishment- in 2005 over 1/2 million tonnes of sand was pumped ashore and distributed along Poole's beaches via a pipeline
Groynes- 2000-2001, 4 new rock groynes were built, and the old ones were refurbished, they maintain a deep and wide beach by minimising sand movement and absorbing wave energy. Protects the harbour and prevents 1.6m of erosion per year
Sand dunes- 2000-2001 2,500m2 of sand dunes were constructed
why?
Sandbanks is the 4th most expensive residential area in the world, major tourist attraction, home to many water sports, Poole harbour is used for trade and transport
erosion on southeast end by offshore current in the deep channel of Poole harbour
fetch from Atlantic Ocean generates large erosional waves
sandstone cliffs vulnerable to hydraulic action when spring tides combine with stormy weather
intentional changes to flows, processes and sediment budget
minimised longshore drift towards the harbour
wave energy is absorbed
effect of these changes on landscape
less build-up of sediment in a particular place
sand and vegetation isn't as easily degraded by large waves
consequences of changes to the landscape
buildings are less vulnerable
harbour is protected
Mangawhai, New-Zealand- unintentional
what is the development taking place- why is it taking place
Seabed mining/suction dredging for the high quality sand used in construction projects in Auckland (glass and concrete) and beach replenishment in other areas like Mission Bay.
North of Auckland is the most economically active (35% of GDP) place in NZ 1/3 of the population lives there
Permits are being extended despite overwhelming evidence
76000 m3 sand per year
unintentional changes to flows, processes and sediment budget
System closed to inputs of sediment, no nearby rivers
Less effective at absorbing wave energy
Sediment transfer mostly occurs -25m below e sea level- extraction is mostly approved 18-25 but also 8m despite sediment being needed there for wave processes
effect of changes on landscape
Loss of sand dunes and vegetation
Fishery disturbed
Loss in the quality of the surf
At best stability of the coast, possible erosion no accretionary trend
consequences of changes to the landscape
Objections from residents , Auckland regional council don’t receive much revenue from mining company despite large investments
Spoiled natural coastline could deter tourists
Storms can exacerbate back shore erosion