Case Study- Mangawhai-Pakiri Coastline:
Unintentional consequences of economic development
Location =
East coast of New Zealand’s Northland Peninsula.
Reasons for economic development =
High quality sand for modern economy; glass, concrete, beach replenishment
Construction industry 50km N of Auckland (1/3 population, 35% country’s GDP).
Impacts =
Beaches starved of sediment (wider and flatter) less effective in absorbing waves
Dunes, spits and beaches more vulnerable to erosion
Fordune ridges undercut by wave action → steep, seaward-facing scarps
Loss of dune vegetation (wind erosion)
1978 28m breach at base of Mangawhai spit, 2nd breach altered tidal currents + led to
sedimentation of harbour. Weak recovery predicted consequence of sand mining
Long term retreat by 2100 estimated 35m
Sediment Budget =
Closed system and non-renewable (unsustainable)
