Sand dunes
Why are dunes important?
Dunes are narrow but important areas of sand that lie between the sea and the land.
In many places, our sand dunes are the first line of defence against the sea, providing an effective buffer absorbing the energy of waves.
Dunes protect properties against coastal erosion and flooding from waves. They:
- provide a physical barrier against storm waves, reducing the risk of flooding for nearby properties; and
- work as a dynamic buffer, and are eroded and then built up again as part of natural physical processes.
However, when these natural processes are interfered with, our coastline becomes more exposed to coastal hazards such as storms and flooding. There are two types of coastal erosion:
Short-term erosion
This can be caused by storms or climate cycles without causing a permanent change in the position of the shoreline. While the area usually recovers, a full erosion and recovery cycle can take several decades.
Long-term erosion
This is when there is a permanent change to the position of the shoreline, for example, through erosion caused by sea-level rise.
Dunes on the move
The movement of sand dunes is a natural process. During stormy conditions, sand is taken from the beach and dunes, and deposited on an off-shore bar. The sand bar then works to protect the beach from further erosion by reducing the impact of the waves.
.jpg)
Pingao is a native plant that helps rebuild sand dunes.
During calmer conditions, the sand returns to the beach and is blown onto the dunes by onshore winds. The native sand binding plants then trap the sand, restoring the dunes and allowing them to build up again before the process is repeated during another period of high wave activity.
Without sand dune plants, the sand blows away. Without sand, the dunes disappear. With no dune protection, the land behind is at risk of flooding and erosion during storms and heavy seas.
Dune care code
Dunes are adapted to natural coastal processes, but are fragile and easily damaged by human activities. We can all help protect our dunes and the plants and animals that live there by following the Dune Care Code.
Keep your vehicle off the dunes
Important plants, birds, insects and lizards live in sand dunes. Drive on existing access tracks and below the high tide mark. Respect archaeological sites.
Protect plants – keep to the tracks
Coastal native plants hold the sand dunes together. By keeping to designated accessways and tracks, you reduce the risk of damaging fragile dune vegetation. Keep away from fenced areas and respect signage.
Horsing about is definitely out
Riding horses through dunes can damage plants and wildlife. Use designated accessways to reach the beach, and ride your horses on the hard sand.
Ride the waves, not the dunes
Sandboarding on the dunes destroys plants and loosens the sand, causing wind erosion.
Leave our beaches litter-free
Litter is unattractive and can be harmful to people and to wildlife. Always take your rubbish home with you.
Don’t let our beaches go to the dogs
Ask your local district council which beaches you can exercise your dog on. Always keep your dog under control and pick up its waste.
Keep stock in the paddocks
Farm stock can trample sand dunes and eat dune plants. Fence off coastal margins and keep stock off dunes.
Get rid of pests and weeds
Rabbits and possums eat dune plants and shrubs, while garden plants and weeds smother native vegetation. Destroy animal pests and compost your garden waste – don’t use dunes as dumping grounds.
Leave sand and pebbles for future generations
It is illegal to remove sand, pebbles or rocks from our beaches. These materials are the building blocks of our coastline and take thousands of years to accumulate.
Take action – get involved
Join your local CoastCare group. Contact the CoastCare co-ordinator at the Northland Regional Council – phone 0800 002 004 or email mailroom@nrc.govt.nz
.jpg)
Establishing accessways, fencing off dunes and replanting with natives has been successful in restoring the dunes at Matapouri beach.