Nelson City Council

Coast Care Tahunanui

Coast care has been underway at Tahunanui Beach since 2001, with encouraging results.

Coast care is a community based programme which aims to protect the natural coastal environment and enhance the beach and dunes. It consists of volunteer groups, made up of concerned beach users, schools and residents who wish to be actively involved in managing and protecting their coastal environment.

Nelson City Council supports the programme by providing advocacy and advice on reducing erosion and assisting with resources such as labour, native plants, fertiliser and materials for pedestrian walkways.

Trapping sand

Here at Tahunanui Beach we have undertaken a three pronged programme to help save our beach.

In September 2001 sand trapping barriers were constructed to help reduce the erosion at the base of the dunes. The barriers work in three ways:

1. to help trap and build up sand as wind blows it by. This has occurred, especially at the western end of the front beach where wind blown sand has built up, in some cases by over a metre.
2. to reduce the waves' energy when a high tide occurs together with a northwest wind. The barriers were particularly effective near the Lions Playground where storms have threatened to erode the dunes away. However, the sand trapping barriers have helped to reduce the force of the waves and the damage has been minimal. The force of the storms still affects progress: netting can be ripped open and posts pushed over and snapped off.
3. to encourage people to keep out of the fenced off areas. Erosion caused by people is surprisingly significant. Playing and walking over dunes can cause a lot of damage, both to the dunes and to plants growing in them.

Planting natives

In the ensuing months, numerous schools and community groups have taken part in planting native sand binding plants at the beach. Already Coast care are seeing some exciting results as pingao and spinifex start to build up the dunes.

Pingao was once a common plant all around NZ shores. It has a good root system that helps to stabilise the dunes, and coarse, grass-like leaves that trap wind blown sand.

Another native sand binding plant, spinifex (spinifex sericeus), has been planted as an experiment. The plants get regular doses of fertiliser to help with growth and rabbit repellent was applied to stop the rabbits eating the new shoots.

Signs were placed around the beach to encourage people to keep out of the fenced off areas. This is to give the new plants a chance to establish and to minimise the damage to dunes from people walking and playing on them. Fenced walkways encourage people to keep to the walkways rather than go onto the dunes.

Trials to achieve best results

As Coast care has developed over the past years, following an experimental path and different approaches to planting and placing the sand trapping barriers have been trialled to get the best results. It is an ongoing learning process but already there are good results. Coast care hope to be able to build on the knowledge that they already have, and with the Coast care initiatives and the natural changes of the beach, our Tahunanui Beach will slowly start to build itself up again.

How has the beach changed?

• the sand trapping barriers have helped the sand to build up - in some places almost a metre has been gained (look at the barriers in the dog exercise areas)
• the barriers have stopped high tides eating away at the base of the dunes, which has caused substantial damage in the past, even though the barriers themselves have been damaged
• .the pingao and spinifex have helped sand build up and has helped stabilise some dune areas
• .walkways have encouraged people to stop encroaching onto and eroding the dunes
• .beach renourishment (moving sand to eroded areas) has helped build up dunes
• the beach has naturally changed too. As the Waimea River pushes east, more sand is being dumped onto the front beach and areas that were eroding away are slowly building up again.