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:
- damage or loss of sand dunes
- damage to sand dune vegetation
- shoreline structures to prevent erosion
- the removal of coastal plants and trees to preserve views
- sea level rise
- removal of sands and aggregate from rivers or beaches.
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.
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:
- build future coastal developments further back from the shoreline
- keep to beach access ways
- avoid trampling over dune sand grasses and removing dune vegetation
- keep cycle, motorbike and horse riding off the dunes (wait until low tide and use the hard, flat sand near the water)
- observe the Dune Care Code.
Waikato Regional Council:
- provides advice to territorial authorities on coastal erosion and flooding risks
- identifies hazard risk areas for inclusion in district plans
- works with these agencies to develop region-wide strategies for sustainable management of coastal erosion and flooding
- encourages the use of building and development controls for hazard risk areas
- works with coastal territorial authorities and local communities on hazard management strategies
- takes part in a national project co-ordinated by the National Institute of Water and Atmospheric Research (NIWA) to develop video monitoring techniques for measuring beach changes
- pilots a storm surge warning system in the Firth of Thames to improve coastal flood warning systems
- works with Beachcare groups, helping preserve the natural character of beaches and dunes through building accessways, fences and protective planting. A good example of a hazard management strategy in action with a beachcare group can be seen at Whiritoa Beach (on the eastern Coromandel Coast).
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.
- Waikato Regional Council - Natural Hazards
- Waikato Regional Council - Civil Defence and Emergency Management
- Waikato Regional Council- Our Coast - Dunes
- Waikato Regional Council- Coastal Pressures
- Waikato Regional Council - Hazards - Coastal Hazards
- Waikato Regional Council - Coastal indicators
National Institute of Water and Atmospheric Research (NIWA) – has information on natural hazards affecting our coasts.