Mangawhai Pakiri

Question 1

About

Answer 1

High quality sand along coastline. Perfect for construction industry.
Region rapidly growing. Coastal amenities booming (3.5 million foreign visitors)

Question 2

On average how much do people use?

Answer 2

On average people use over 200kg of sand per person per year (essentially non renewable)

Question 3

What sand mining used for?

Answer 3

Glass manufacture, beach replenishment, concrete manufacture, construction industry

Question 4

How much sand was extracted between 1994-2004?

Answer 4

165.000m^3/ year extracted

Question 5

Impacts of sand mining

Answer 5

Has an effect on marine creatures’ ecosystems
Beaches starved of sand become wider and flatter so less effective in absorbing wave energy so more erosion. Dunes and spits vulnerable

Question 6

Where is the sediment budget from

Answer 6

Most sand in sediment budget from offshore sources minimal from fluvial sources and is not replaced through inputs from rivers or offshore

Question 7

The impact of sand mining

Answer 7

The depletion of the total sand supply on the sea bed beaches and sand dunes. As a result movements of sand between the major stores have diminished

Question 8

Future?

Answer 8

Studies suggest that increased rates of erosion are likely in the future w/ declining natural protection from extreme storm events
Long term coastal retreat by the end of the century is estimated at 35m.

Question 9

How long is the Mangawhai-Pakiri coastline?

Answer 9

20km

Question 10

The sand on the Mangawhai-Pakiri coastline is…

Answer 10

…high quality and therefore suitable for construction

Question 11

Tourism on Mangawhai-Pakiri coastline

Answer 11

2.3 million foreign visitors in 2015; over 1 billion USD made from this industry since 2004

Question 12

Auckland

Answer 12

50km south of the Mangawhai-Pakirii coastline, so accounts for 1.5 million people (1/3 of population) and 35% of New Zealand GDP

Question 13

Sediment budget on the Mangawhai-Pakiri coastline

Answer 13

• 165,000 m³/year of sand extracted from this coastline between 1994 and 2004; now 75,000 m³/year of sand extracted from Pakiri beach until 2020 (Mining ended on Mangawhai beach); most of this sand is used for replenishing tourist beaches in and around Auckland
• Most sand in the area thought to have been derived from offshore, therefore not much of the sand that is being removed from the beaches is being re-deposited- 5 times more sand being taken that deposited

Question 14

Impacts of sand mining on coastal landforms (e.g. Mangawhai-Pakiri coastline)

Answer 14

• Beaches have become wider and flatter due to the removal of sediment- they are now much less effective at absorbing waves
• Landforms such as dunes and spits have become more vulnerable due to higher energy waves being able to further erode beaches

Question 15

Economic development

Answer 15

High quality sand resource is found in nearshore zone at Mangawhau-Pakiri on east coast of Northland peninsula. Used in construction industry

Question 16

Statistics

Answer 16

Population: 1.5 million people, 1/3 is Auckland and 35% of country’s GDP. 2015: 2.3 million foreign visitors going to Auckland

Question 17

Offshore sand mining and the sediment budget

Answer 17

Extraction of Pakiri beach is being mined at 75000m3/ year until 2020. And the sand is being used to replenish Aucklands tourist beaches

Question 18

Coastal sediment budget

Answer 18

Is a closed system since outputs of sand through nearshore mining are not replaced by inputs from rivers or offshore waves

Question 19

Impact of coastal landforms

Answer 19

Sand extraction at Pakiri beach has been starved of sediments and have become wider and flatter and less effective in absorbing waves which meant high energy waves erode the beaches and increases vulnerability to dunes and spits