Coastal erosion is a natural process that is part of natural beach behaviour. Most shorelines vary between periods of sand erosion and accretion (building up). Unfortunately, much of our coastal development in the Waikato Region has occurred too close to the sea. Future global warming effects will cause a significant rise in sea level in our coastal marine area, which may drive a long term trend for shoreline erosion, worsening the problem. We need to manage this coastal hazard carefully so we can protect our coastline's future.
Short-term erosion can be caused by storms or climate cycles without causing a permanent change in the position of the shoreline. The area usually recovers, however a full erosion and recovery cycle can take several decades. The largest shoreline changes are usually seen near estuary and river entrances. Though periods of erosion can continue for years, in most cases it is not permanent. When viewed over a long period, such as a hundred years, the shoreline in the Waikato Region is simply shifting backwards and forwards. Learn more about shoreline change at Waikato beaches in our Shoreline change indicator.
Wide, well vegetated dunes provide a natural buffer that absorbs the effect of short-term coastal erosion during storms, allowing the dune area to repair itself naturally. Natural dunes are therefore essential for protecting properties from coastal hazards.
When natural coastal processes are interfered with, our coastline becomes more exposed to coastal hazards such as storms and flooding. People’s activities can put pressure on our coasts and in many cases increase the potential for coastal hazards. For instance, natural shoreline change processes can be affected by:
To order a copy of ‘Fragile: a guide to Waikato dunes’, see Publications.
At many beaches, most of the dune sand reserves now lie buried under houses and there's often not enough width and volume of dunes in front of houses to protect them from natural coastal erosion and flooding . Shoreline protection structures (such as seawalls) are then often added to protect threatened property. These structures degrade the natural and recreational values of beaches and often affect public access along the beach at high tide.
Also, high frontal dunes have been bulldozed to improve views, and have been capped with fill to develop lawns. This has altered the natural character of coastal dunes and affected natural dune binding and repair processes .(external link)
Protecting and enhancing the dunes we have left is critical to the future of beaches and existing beachfront properties. Walking or playing on the dunes can damage vegetation. Our dunes must be wide enough and covered with native vegetation to maintain their natural building and repair processes. This means we need to:
Waikato Regional Council:
Check out our risk mitigation plans, which aim to minimise the effect of natural hazards on the Waikato economy and community.
Waikato Regional Council’s Regional Coastal Plan also sets out methods of improving coastal hazard management. Our Regional Policy Statement includes significant resource management issues relating to our coastal resources.
National Institute of Water and Atmospheric Research (NIWA(external link)) – has information on natural hazards affecting our coasts.