Coastal Management Methods

There are three broad approaches to managing our coastline, (1) living with natural processes, (2) natural defences or (3) building coastal structures. These options can be broken down into more specfic details.

Living with Natural Processes

National policy and international best practice is now directing councils to consider living with natural coastal processes whenever possible as a way of protecting natural values and improving long-term resilience of coastal communities in the face of future sea level rise and climate change (Whitianga Coastal Futures Report, May 2012). This means managing use and development of the land to lessen risks to human assets, rather than trying to manage the natural processes to prevent erosion of the land.


Enhancing Natural Defences

Dune Restoration:

This involves the proactive restoration of a frontal dune by replanting with native sand binding species (spinifex, knobby club rush, muehlenbeckia, native spinach and sand coprosma) then fencing to restrict access while plants re-establish. In some cases it’s necessary to reshape the dune before planting can occur.

Beach Scraping

Once a beach has recovered sufficiently following an erosion event, a shallow layer of sand is moved from the beach onto the upper beach face and dune to reform the dune shape. Sand binding plants are then used to prevent wind erosion. This method doesn’t prevent or reverse erosion but can accelerate natural dune and beach recovery. This method was very successful at Whangapoua Beach in 2008 following a severe storm.


Coastal Structures

Seawalls

These types of walls are constructed parallel to the coastline. The primary purpose of this type of seawall is to protect the land behind from wave action. These seawalls can either be constructed with rock or an engineered-structure (geotextile bags)

Groynes

These are narrow structures (usually made from rock or an engineered structure) and are constructed at right angles to the coastline.

Offshore Breakwaters

These structures are usually built parallel and offshore to the coast. Wave action is either dissipated, reflected, refracted or diffracted resulting in reduced wave energy. The breakwater can be built either submerged or emerging from a low tide. Both groynes and breakwaters hold sand in a certain area of the beach, but means other sections of beach get deprived of sand, causing erosion there.

Geotextile Walls

Often called “sand sausages,” these are containment bags made up of extremely robust geotextile designed to be filled with local sand or sandy gravel mix to form a durable container for the construction of seawalls or groynes. The coarse surface in combination with the beach sand provides long term resistance to UV damage as well as limiting local puncturing. 


Waikato Regional Council's role 

Waikato Regional Council is responsible for managing the region’s rivers and their catchments, including the effects of flooding and erosion. As part of the Peninsula Project, we’re working with local communities to better protect them from frequent flooding and erosion through river management, soil conservation and flood protection works, and animal pest control on private land. We’re also responsible for undertaking works and services in the coastal marine area (CMA).

For more information visit WRC's Peninsula Project page.