Coastal Engineering Solutions for Remote Island Communities

 Stuart H Bettington1 and William Blank2

1 Royal HaskoningDHV, Brisbane, Australia,

2 Hall Construction, Buderim, AUSTRALIA.

Keywords: reef, atoll, climate change coastal erosion, seawall, nourishment, groyne, dredge.

The nation of Tuvalu is made up of a series of low lying inhabited islands, which are highly vulnerable to inundation and coastal erosion; issues that will worsen with climate change. The likely impact of climate change on the communities of Tuvalu is not fully understood, though their very existence is threatened. These threats were highlighted when Tropical Cyclone Pam passed hundreds of kilometres to the west of Tuvalu in March 2015.  The large swells caused high water and waves over the reefs and islands, which led to extensive damage to infrastructure, coastal erosion, destruction of crops, and loss of amenity.

The Government of Tuvalu (GoT), supported by the World Bank and UNDP, recently undertook coastal works on two islands to improve resilience to severe weather and improve amenity for the community. GoT engaged Hall Pacific, a dredging and civil contractor, supported by AECOM, to develop affordable solutions that included seawall construction and beach nourishment with groynes to benefit the communities on Funafuti and Nukufetau.

Being atolls, the islands lack rock or other suitable construction materials for coastal armouring. Historically armour has been imported at great cost or won by mining the coral reef to obtain coral boulders. The only environmentally sustainable construction material that can be exploited on these islands is sand found in deeper waters. Recognising the logistical issues and budget limitations, and considering the uncertain future, large geobags are seen as a suitable quasi-permanent solution, which will provide protection while longer term climate change adaptation strategies are developed. The use of this method allowed works to be completed just six months after being proposed, affordably delivering more resilient and attractive communities in areas lacking the resources for more conventional coastal engineering solutions. This paper looks at these specific projects along with recent examples where more conventional armour solutions were used to discuss the application of these technologies on remote islands.