case study - sand mining

Question 1

where is the area of study?

Answer 1

mangawhai-pakiri coastline, 50km north of auckland on the east coast of NZs northland peninsula

Question 2

why is sand in central mineral resource in a modern economy?

Answer 2

used for:
-Construction
-concrete making
-Glass manufacturing
-Beach replenishment

Question 3

Where is the high-quality sand found?

Answer 3

-nearshore zone at mangawhai-pakiri

Question 4

what is Auckland?

Answer 4

New Zealand’s largest and economically most dynamic metropolitan region

Question 5

What is Auckland’s population?

Answer 5

Over 1.5 million

Question 6

What does Auckland’s regional account for?

Answer 6

over one third of New Zealand’s, total population, and 35% of the countries GDP

Question 7

how is the region rapidly growing?

Answer 7

-Finance and high-tech industries are growing
-Tourism is a large part- in 2015, 2.3 million tourist were recorded

Question 8

where is nearshore sand dredging done?

Answer 8

-On the 20 Km coastline between mangawhai and pakiri, which has operated for over 70 years

Question 9

how much material was extracted between 1994 and 2004

Answer 9

165000 m³ per year

Question 10

when did mining end and where?

Answer 10

It ended in mangawhai in 2005, but continued at pakiri beach

Question 11

what are current rates of extraction?

Answer 11

75,000 m queued per year until 2020

Question 12

What is a large proportion of sand used for?

Answer 12

replenishing Aucklands tourist beaches and in construction industry with many holiday homes and hotels being built

Question 13

what is sand and When was it deposited onto the beach?

Answer 13

sand is a non renewable resource and is deposited during the Holocene (past 9000)

Question 14

What are the inputs of sediment?

Answer 14

-Few rivers in the area, but most sand comes from offshore

Question 15

what is the area viewed as?

Answer 15

a closed system

Question 16

how does the sediment budget in the area work?

Answer 16

outputs of sand through nearshore mining may not replaced by inputs from rivers and offshore waves

Question 17

what are extraction rates at pakiri beach

Answer 17

they Exceeded inputs by 5X

Question 18

What is the effect of mining on the sediment budget?

Answer 18

it depletes the total sand supply, stored in dunes, beaches and the seabed(up to 2km offshore)

Question 19

what happens to the beaches as they starved of sediment

Answer 19

-become wider and flatter and less effective at absorbing waves, so higher energy waves erode beaches and landforms such as dunes, and spits become vulnerable

Question 20

what do fordune ridges develop?

Answer 20

they are undercut by wave action, and develop a steep seaward facing scarp

Question 21

what does loss of vegetation cover mean?

Answer 21

It makes him susceptible to wind erosion

Question 22

when was the storm and what happened?

Answer 22

1978 storms caused a 28 meter breach at the base of mangawhai spit
-this altered title currents and led to sedimentation of mangawhais harbour this shallow water made waterfront susceptible to flooding .

Question 23

what helps restore equilibrium?

Answer 23

dredging of harbour and groynes

Question 24

What did studies by Auckland regional Council suggest?

Answer 24

increased amounts of erosion are likely in the future with declining natural protection from increased storm events

Question 25

What is the long-term retreat estimated at?

Answer 25

36 m and width of coastal zone susceptible to erosion varies from 48 to 111 m
-higher than any of aucklands 123 beaches