Mangawhai Pakiriiii Flashcards
1
Q
LOCATION:
A
- East coast of New Zealand’s Northland Peninsula
- 20km long stretch
- 50km north of Auckland (population of over 1.5 million)
- Region home to a third of the population and 35% of its GDP
2
Q
IMPORTANCE:
A
- Region home to a third of the population and 35% of its GDP
- Region is growing rapidly economically
- Tourism booming, with a record 2.3 million foreign visitors in 2015 coming to see Auckland’s outstanding coastline
- Due to its proximity to New Zealand’s largest and most economically dynamic region
3
Q
DREDGING:
A
- Operated for over 70 years, (over 165,000 m3/year extracted from 1994 to 2004)
- Although mining ended at Mangawhai in 2005, it has continued at Pakiri Beach
- Current rates of extraction are 75,000 m3/year
4
Q
WHY DREDGING IS HAPPENING:
A
- Large proportion of sand used for replenishing the tourist beaches of Auckland
- Wide range of uses in industry including construction, concrete making, glass etc.
- High quality sand used predominantly in construction
5
Q
SEDIMENT BUDGET:
A
- Deposited during the Holocene period (past 9000 years) and is a non-renewable resource
- Few sizeable rivers, with most sand coming from offshore
- Sediment budget essentially a closed system, so sand removed by nearshore mining not replaced
- Extraction rates at Pakiri exceed input by a factor of five
6
Q
IMPACTS:
A
- Beaches starved of sediment have become wider and flatter, therefore less effective in absorbing wave energy meaning beaches are eroded and landforms eg. Spits, dunes etc. become vulnerable
- 1978 storm caused breach at the base of Mangawhai spit, affecting currents and leading to sedimentation of harbour
- Shallower water in the harbour also threatened waterfront community with flooding
- Subsequent dredging of the harbour and groyne construction helping to restore equilibrium
- Coastal retreat estimated to be 35m by end of the century
- Estimate is higher than any of the region’s other 123 beaches
7
Q
A
