Coastal erosion

Coastal erosionCoastal erosion is evident in all of our region's coastal areas, the eastern Coromandel Peninsula, the Firth of Thames and the West Coast. 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). However, when these natural processes are interfered with, the 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. Natural dune repair is more likely to happen on dunes with good cover of native sand binding grasses.
  • Long-term erosion - This is a permanent change in the position of the shoreline, for example, through erosion caused by sea-level rise.

Coastal development in the Waikato region has seen many subdivisions placed too close to the shoreline. Sand dunes, plants and trees provide a natural buffer to coastal hazards and are essential to keep enough sand reserves in place to maintain the beach. In some coastal settlements, plants and trees have been removed to ‘enhance the view’ for property owners. In others where sand dunes have been lost, property owners have built seawalls or other structures along the front of their land.

These activities change the natural vegetation of the beach, affecting natural erosion and recovery processes and exposing the shoreline to the effects of global warming.