Economic Development Unintentionally Causes Change Within CLS

Question 1

Where is economic development unintentionally causing change within CLS?

Answer 1

New Zealand

Question 2

Where is the high quality sand resource?

Answer 2

Nearshore zone of the Mangawhai-Pakiri coastline

Question 3

What type of sand is there?

Answer 3

White quartz

Question 4

What are some of the uses of the sand? (4)

Answer 4

Construction
Concrete Making
Glass Manufacturing
Beach Replenishment

Question 5

What are the two advantages of the sand?

Answer 5

Coarse (need a lot of energy to remove)
Looks clean (tourists)

Question 6

How far from Auckland does the sand mining take place?

Answer 6

50km north

Question 7

What is the population of Auckland?

Answer 7

1.5 million

Question 8

What proportion of NZ total population does Auckland account for?

Answer 8

One third

Question 9

How many foreign visitors did Auckland have in 2015?

Answer 9

2.3 million

Question 10

How much of the country’s GDP does Auckland account for?

Answer 10

35%

Question 11

How long is the Mangawhai - Pakiri coastline?

Answer 11

20km

Question 12

How long has the sand dredging gone on for?

Answer 12

Over 70 years

Question 13

How much sand was extracted between 1994 and 2004?

Answer 13

165,000 m cubed a year
1,650, 000 total

Question 14

When did Mangawhai mining stop?

Answer 14

2005

Question 15

What are the current extraction rates at Pakiri beach? (2020)

Answer 15

75,000 m cubed a year

Question 16

How much sediment is input from rivers and offshore sources?

Answer 16

7,000 m cubed a year

Question 17

Why is the sand a non-renewable resource?

Answer 17

Deposited during the Holocene (past 9000 years)

Question 18

How much greater are extraction rates at Pakiri than the inputs?

Answer 18

Factor of 5

Question 19

How much does the Pakiri sediment budget decrease by each year?

Answer 19

68,000 m cubed

Question 20

How much sand is in the nearshore zone?

Answer 20

100,000,000 m cubed

Question 21

How long will the nearshore store of sand last for?

Answer 21

1470 years

Question 22

What is happening to the beach because of the mining?

Answer 22

Starved of sediment so wider and flatter, less effective in absorbing waves

Question 23

The waves are high energy, what’s the effect?

Answer 23

Erosion of dunes and spits

Question 24

What has happened to vegetation?

Answer 24

Loss of cover making landforms susceptible to aeolian erosion

Question 25

Why did the harbor experience sedimentation?

Answer 25

A second breach of the Mangawhai spit altered tidal currents

Question 26

What did shallow harbor water lead to?

Answer 26

Risk of flooding the waterfront Mangawhai community

Question 27

What is the estimated long term retreat number for the end of the century?

Answer 27

35m

Question 28

What is the width of the susceptible coastal zone and how does it compare to Auckland’s other regions?

Answer 28

Varies between 48 to 111m
Significantly higher

Question 29

What is suggested about future erosion rates?

Answer 29

Increase with declining natural protection from storm events

Question 30

How has some equilibrium been restored?

Answer 30

Dredging and groynes on the spit