Economic Development Unintentional Change (Mangawhai-Pakiri)

• In the North of the North Island, 50km N of Auckland
• People use over 200kg of sand each year, taken from non-renewable sources
• Sand is used for glass, concrete, filling roads, building and renourishing beaches
• 1994 to 2004 - 165,000 m3 / yr extracted
• Stopped at Mangawhai in 2005 - 75,000 m3 / yr, extracting from nearshore
• Beaches starved of sediment are wider and flatter and less effective at absorbing waves
• Long term retreat by the end of the century estimated at 35m
• Auckland Regional Council say 2 years of monitoring should happen before mining occurs
• Dredging of harbour and groyne constitution at Mangawhai spit restored equilibrium
• During a storm in 1978 there was a 28m spit breach
• Loss of vegetation reduces resistance to erosion
• In 2006 Judge David Sheppard said that there was no link between extraction and environmental damage
• Solution - optimising existing infrastructure, or using wood to reduce consumption of sand
• Solution - taxes on sand and gravel extraction to create incentive for alternatives
• Solution - maintaining rate of extraction with rate of renewal