4B Unintentional Change In A Coastal Environment New Zealand Flashcards
What type of resource is sand classified as?
Sand is a nonrenewable resource
Where is most sand thought to be derived from?
Most sand is thought to be derived from offshore
What is the coastal sediment budget described as?
The coastal sediment budget is potentially a closed system
What happens to the outputs of sand through nearshore geologic processes?
Outputs of sand are not replaced by inputs from rivers and waves from offshore
By what factor do the extraction rates at Pakiri Beach exceed the inputs?
Extraction rates exceed the inputs by a factor of 5
What is the effect of mining on sand storage in coastal areas?
Mining depletes the total sand stored in dunes, beaches, and on the seabed
What natural process undercuts foredune ridges?
Wave action undercuts foredune ridges
What effect does loss of vegetation cover have on foredune ridges?
Loss of vegetation cover makes them susceptible to wind erosion
What significant event occurred in 1978 at the base of the Mangawhai spit?
Storms caused a 28m breach at the base of the Mangawhai spit
What was the consequence of the breaches at Mangawhai?
Breaches altered tidal currents, leading to the sedimentation of Mangawhai’s harbour
What threat did shallower water in Mangawhai’s harbour pose?
Threatened Mangawhai’s waterfront community with flooding
What measures have been taken to help restore equilibrium in Mangawhai’s harbour?
Dredging of the harbour and groyne construction on the spit
How long has nearshore sand dredging operated on the coastline?
Over 70 years
What was the annual extraction rate of sand between 1994 and 2004?
165,000m3/year
When did mining end at Mangawhai?
2005
What is the current extraction rate at Pakiri beach until 2020?
75,000m3/year
What are the primary uses of the sand extracted from Pakiri beach?
- Replenishing Auckland’s tourist beaches
- Construction industry
Is sand a renewable or nonrenewable resource?
Nonrenewable resource
Where is most sand thought to have been derived from?
Offshore
What type of system is the coastal sediment budget described as?
Closed system
How do the outputs of sand through nearshore mining compare to inputs from rivers and waves?
Outputs are not replaced by inputs
By what factor do extraction rates at Pakiri beach exceed the inputs?
Factor of 5
What is the overall effect of sand mining on total sand supply?
Depletes the total sand supply stored in dunes, beaches, and on the seabed
What is sand used for in a modern economy?
Construction, concrete making, glass manufacture, beach replenishment
Sand is considered an essential mineral resource.
Where is a high-quality sand resource located?
Nearshore area zone at Mangawhai to Pakiri
This sand is suitable for the construction industry.
How far is the high-quality sand resource from Auckland?
50km north of Auckland
What is the population of the Auckland region?
Over 1.5 million
What percentage of the country’s GDP does the Auckland region account for?
35%
What types of industries are prominent in the Auckland region?
Businesses and high-tech industries
True or False: The Auckland region is known for its outstanding coastal amenities.
True
What is the current status of sand extraction in the sediment cell at Mangawhai to Pakiri?
Current rates of sand extraction are unsustainable.
What impact is the depletion of sand having?
It is impacting landforms and landscapes.
What happens to beaches due to higher energy waves?
Beaches are eroded.
What landforms become vulnerable due to beach erosion?
Dunes and spits become vulnerable.
What is the effect of wave action on foredune ridges?
Foredune ridges are undercut, developing steep seaward facing scarps.
Fill in the blank: Higher energy waves erode _______.
beaches
True or False: The depletion of sand does not affect landforms.
False
