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.
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.
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!
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.
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.
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.
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.