Economic Development Unintentionally Causes Change Within CLS Flashcards
Where is economic development unintentionally causing change within CLS?
New Zealand
Where is the high quality sand resource?
Nearshore zone of the Mangawhai-Pakiri coastline
What type of sand is there?
White quartz
What are some of the uses of the sand? (4)
Construction
Concrete Making
Glass Manufacturing
Beach Replenishment
What are the two advantages of the sand?
Coarse (need a lot of energy to remove)
Looks clean (tourists)
How far from Auckland does the sand mining take place?
50km north
What is the population of Auckland?
1.5 million
What proportion of NZ total population does Auckland account for?
One third
How many foreign visitors did Auckland have in 2015?
2.3 million
How much of the country’s GDP does Auckland account for?
35%
How long is the Mangawhai - Pakiri coastline?
20km
How long has the sand dredging gone on for?
Over 70 years
How much sand was extracted between 1994 and 2004?
165,000 m cubed a year
1,650, 000 total
When did Mangawhai mining stop?
2005
What are the current extraction rates at Pakiri beach? (2020)
75,000 m cubed a year
How much sediment is input from rivers and offshore sources?
7,000 m cubed a year
Why is the sand a non-renewable resource?
Deposited during the Holocene (past 9000 years)
How much greater are extraction rates at Pakiri than the inputs?
Factor of 5
How much does the Pakiri sediment budget decrease by each year?
68,000 m cubed
How much sand is in the nearshore zone?
100,000,000 m cubed
How long will the nearshore store of sand last for?
1470 years
What is happening to the beach because of the mining?
Starved of sediment so wider and flatter, less effective in absorbing waves
The waves are high energy, what’s the effect?
Erosion of dunes and spits
What has happened to vegetation?
Loss of cover making landforms susceptible to aeolian erosion
Why did the harbor experience sedimentation?
A second breach of the Mangawhai spit altered tidal currents
What did shallow harbor water lead to?
Risk of flooding the waterfront Mangawhai community
What is the estimated long term retreat number for the end of the century?
35m
What is the width of the susceptible coastal zone and how does it compare to Auckland’s other regions?
Varies between 48 to 111m
Significantly higher
What is suggested about future erosion rates?
Increase with declining natural protection from storm events
How has some equilibrium been restored?
Dredging and groynes on the spit
