Buffering saltwater waves for food and water security
Barges carrying equipment to Nanumaga arrive, with construction set to begin. © TCAP/UNDP.
On Tuvalu’s outer islands of Nanumea and Nanumaga, a novel approach is being implemented to significantly reduce the likelihood of wave overtopping and subsequent marine water flooding of village areas. These Berm Top Barriers raise the natural storm berm along the foreshore by an extra 1.5 meters, making storm waves far less likely to over top the shore, and penetrate further inland into village areas and farmland.
Marine water overtopping causes saltwater intrusion in groundwater and soils, with increased salinity potentially damaging or permanently destroying home and vegetable gardens, important tree crops like breadfruit, pawpaw, and banana. The local swap taro, an essential carbohydrate on the island, has also been affected. The Berm Top Barriers will therefore help to protect food and water security on the island, and in outer islands like Nanumaga and Nanumea, groundwater is also a valuable resource for home use.
In Nanumaga, the barriers will stretch 665 meters along the coast, consisting of 20-meter-long Geotextile mega bags filled with local sand and water, and revegetated. They will be built along the western coast of the island, to protect it from large storm events, with a new concrete boat ramp built over the top of the berm into the village center.
On Nanumea to the north, a 1,330-meter barrier will also be built along the western coast, replacing previous infrastructure destroyed during tropical cyclone Pam in 2015. The waves damaged and flooded buildings, roads, property, and crops, and more than 300 people – mostly women, children, and the elderly – were displaced.
Building a better future
Taking the construction materials to the island on barges has been a challenge for Hall Contracting, Australia’s largest privately-owned dredging, civil and marine construction company, which was selected to undertake construction on the three project islands. Several attempts have been postponed due to storm events and large waves. But the team has already transported the infrastructure to the capital Funafuti, where it is awaiting deployment imminently.
Alan Resture, Tuvalu Coastal Adaptation Project Manager, said: “I am so relieved that finally, after more than five years, the community are now finally going to see what they have been longing to see happening before their very own eyes. This is the cyclone season and there are already storm surges and waves crashing onto the island berms. Hopefully as soon as the construction finishes, the people of Nanumea and Nanumaga will no longer see water overtopping and flooding into their backyard.”
Alan noted that the storms are disruptive to daily life, preventing daily activities and communal gatherings. “In recent cyclones, all the crops have been destroyed, and a lot of water tanks have also been smashed and thrown around. A whole new village is being built – every time infrastructure is destroyed, it takes months for families to get back to normal. In the last decade, the tide seems to have changed its pattern, and cyclones can come at any time. Now, the waves are five to ten meters high, and storm surges are becoming more intense, hammering the island with a longer duration of between three to four days,” he added.
Revegetation will take place on the island to stabilize the shore and provide natural habitats and shade for wildlife. © TCAP/UNDP.
Protecting water and food resources on the islands
Disturbed areas along the shore will be rehabilitated, including revegetation in some areas to stabilize the shore and provide natural habitats and shade for wildlife. The community will be encouraged to take part in the revegetation activities, providing plants through nurseries to grow enough to cover the shore.
Chief Technical Advisor Arthur Webb, who supported the design of the barriers, said: “The berm is the raised area of sand dune before the shore found on tropical beaches. It can be anywhere up to 30 meters high, and it is well behind the beach but acts as a natural storm barrier. They are a critical part of the natural ecosystem and prevent erosion. You would not want to replace them, as they are natural active buffers, protecting the land and community for free.”
He added: “But now, the waves are of such a height that they are not only overwhelming beaches, but topping over the raised berm areas, taking salt water into the villages. To protect these areas, we have raised the berms artificially,” he explained, noting that the barriers are placed in locations along the beach that are safe from the most intense energy of the sea swell, ensuring that it stays intact.
With the backing of the Green Climate Fund, already 7.3 hectares of new, raised land has been installed in Funafuti, providing flood-free areas for island communities. Now, plans are underway to safeguard the long-term future of the island, through state-of-the-art technology. The vision is not only to protect the small island from physical climate threats, but also to protect the precious culture and heritage of the whole community on the island: something that once lost, can never be replaced.
About the Tuvalu Coastal Adaptation Project
With US$36 million financing from the Green Climate Fund and US$2.9 million co-financing from the Government of Tuvalu, the 7-year Tuvalu Coastal Adaptation Project is contributing to strengthening the resilience of one of the world’s most vulnerable countries to climate change and sea-level rise. Implemented by the UN Development Programme in partnership with the Government, the project is improving coastal protection in key locations on the islands of Funafuti, Nanumea and Nanumaga. While new measures will act as a buffer during storms, the project also strives to build the capacity of national and island governments and local communities in adapting to climate change in the longer term. Learn more at TCAP.tv Follow the project on Twitter @TCAP4Tuvalu or on Facebook
About the United Nations Development Programme
UNDP is the leading United Nations organisation fighting to end the injustice of poverty, inequality, and climate change. Working with our broad network of experts and partners in 170 countries, we help nations to build integrated, lasting solutions for people and planet. Learn more at undp.org
About the Pacific Community (SPC)
The Pacific Community (SPC) is the principal scientific and technical organisation in the Pacific region, proudly supporting development since 1947. It is an international development organisation owned and governed by 27 country and territory members.
SPC is a key project partner to TCAP, undertaking Environmental and Social Impact, Geotechnical, Sea Level Measurement and Wave Inundation Assessments in support of TCAP’s work programme. SPC will also deliver a hands-on training programme for Tuvalu government officers and other interested parties in 2023. Among various subjects the training will cover use and improvement of the hazards dashboard.
Additional photos from the Tuvalu Coastal Adaptation Project also available on Flickr: https://flic.kr/s/aHsm6S2Zkw *Please credit as indicated