Avana coastal protection – it’s in the bag

Saturday 28 November 2020 | Written by Te Ipukarea Society | Published in Editorials, Opinion

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Avana coastal  protection – it’s in the bag
Geo-textile sandbags, each weighing over one ton, are being placed along the Avana coast to help protect against erosion caused by sea-level rise and climate change impacts. (PHOTO: TIS) 20112729.

Local environment group Te Ipukarea Society is trying to prevent the Avana lagoon claiming back what was taken. By Kelvin Passfield.

The northern end of Avana harbour is undergoing another physical transformation. If my memory is correct, the area was originally transformed significantly back in 1992 when land was reclaimed from the lagoon back at the time of the Festival of Pacific Arts. This was to accommodate the events related to the arrival of the traditional voyaging canoes, including the Hokule’a. This was back in the days before Environmental Impact Assessments were required. 

Twenty-three years later, in 2015, another substantial change occurred with the construction of a jetty and a boat ramp, with a pile of rocks either side, funded by the Japan Fund. Now, nearly 30 years later, a pilot project implemented by Te Ipukarea Society is trying to prevent the lagoon claiming back what was taken!

The project involves placing geo-textile sandbags, each weighing over one ton, for approximately 45 metres along the coast to help protect against erosion caused by sea-level rise and climate change impacts. These bags are placed on top of a geo-textile matting, which helps prevent the bags being undermined by wave action.  The stack starts at four bags high at the northern end and decreases to a single bag as it approaches the Avana stream.  It has the additional benefit of providing a much more stable platform for the fishermen to access their small fishing boats that are moored in the area.

This intervention is what could be termed a hybrid “nature-based solution”.  This is a combination of an engineered wall of man-made geo-textile bags, filled with natural sand dredged from the site, and backed up with the planting of beach vines, vetiver grass and native trees behind the geo bags to provide a second level of natural defence. When eventually the wall fails, as all walls will in the event of a severe cyclone, the damaged bags can be easily removed, and we will only be left with sand on the beach, rather than a chaotic shamble of scattered rocks.


(PHOTO: TIS)

Te Ipukarea Society has been suggesting the use of these geo-bags for several years as an alternative to the rock walls commonly used in Rarotonga. However, until now, nobody seemed willing to give them a try.  We were extremely fortunate to be able to find this funding so we could do this trial at no cost to the country and bring in external revenue to help bolster the Cook Islands economy.

This work requires a lot of attention to detail, as it is a demonstration project, and we must do our very best to do it right. So, a huge shout out to Koko and the team at S&T contractors who are doing a very professional job. They have been very quick to learn how to install this new technology. The project has been a learning by doing process and has involved a lot of extra man hours on the job.  The engineering oversight is being kindly provided by Paul Maoate, Matt Blacka and Ata Herman. Funding is from the GEF Small Grants Global Grant for Community Based Adaptation to Climate Change, funded by the Australian Government. Lunch was generously supplied on several days by Iro Maroroa and the Matavera and Avana fishing clubs! Also, an acknowledgement and appreciation of the cooperation and support of Manavaroa Mataiapo Philip Nicholas.

We hope this is the start of something new in coastal protection for our island, leaving a reduced environmental footprint, and helping conserve our beaches.