Summary of the GCCA+ SUPA project in Tonga

The project used a consultative and people centred approach to (i) conduct an impact analysis of past coastal protection measures on the north coast of Tongatapu; and (ii) plan and implement hard and soft coastal engineering protection measures for the communities on the northern coast of Tongatapu.

Project Focus: Coastal Protection

Direct benefit: 12,268 persons
Indirect benefit: 62,343 persons

  • Geographic coordinates: Lat. 15° – 23°S, Long. 173°- 177°E
  • Total land area 747 km²
  • Exclusive economic zone (EEZ) 700,000 km²
  • Population (2019 mid-year) 104,494
    • Temperatures have warmed and will continue to warm with more very hot days in the future.
    • Rainfall shows no clear trend since the 1940s. Projections of annual rainfall are unclear with some models suggesting a slight increase by the end of the century. Extreme rainfall events are projected to become more frequent and more intense. Drought frequency is projected to decrease slightly by the end of the century.
    • December to March wave heights and periods are projected to decrease slightly.
    • Ocean acidification has been increasing in Tonga’s waters. It will continue to increase and threaten coral reef ecosystems.
    • Sea level near Tonga has risen and will continue to rise throughout this century.

Source: BOM, CSIRO, 2014, Climate Variability, Extremes and Change in the Western Tropical Pacific: New Science and Updated Country Reports

How does this project address climate change adaptation in Tonga?

Tonga consists of four main island groups of which Tongatapu is the biggest. Tongatapu is flat and low-lying and the highest elevation is 70 meters above sea level. Most of the urban area of Nuku’alofa, the capital city, is only 1–2 meters above sea level and is subject to periodic flooding during heavy rain. Accelerated sea level rise, a result of climate change, is contributing to beach erosion. This is, in turn, resulting in the wave overtopping being experienced on coastal roads and by coastal communities in Tongatapu.

Focusing on selected vulnerable communities in Tongatapu, the project will adopt a participatory and inclusive approach that addresses the vulnerabilities and the rights of these residents. Skills in climate resilience will be enhanced, particularly for town officers and community representatives.

Recognising the continuing and increasing challenges posed by climate change, the project is scaling up small-scale coastal protection and ecosystem-based measures for selected communities in northern Tongatapu. These will complement existing medium-scale coastal protection works – revetments, groynes and offshore breakwaters – that have been constructed along the north and north east coasts of Tongatapu. To assist with the Government of Tonga’s strategic planning for the north coast, the project will prepare a feasibility and conceptual design study to guide the protection of coastal communities up to the 2030 and 2050 planning horizons.

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Key Highlights

  • Conducting a coastal assessment for the entire north coast of Tongatapu and developing costed designs for coastal protection measures to inform Government’s 2030 and 2050 planning.
  • Assessing the impacts of previous coastal protection measures and applying the findings to the design of new measures.
  • Implementing small-scale coastal protection and ecosystem-based measures.
  • Delivering maintenance training for the small-scale coastal protection and ecosystem-based measures.
  • Strengthening community governance to address coastal issues in an equitable manner.
  • Engaging youth groups in northwest Tongatapu to undertake climate change adaptation measures and facilitating the sharing of traditional knowledge between elders and youths.
  • Conducting a needs analysis and raising awareness about climate resilience for local area stakeholders.
  • Building the capacity of community leaders and district officers in climate resilience through accredited training.
  • Integrating climate change and disaster risk into local area sustainable development plans.
  • Assessing the impacts of past climate change adaptation projects and applying the results to national strategic planning.
  • Testing an impact assessment methodology on completed climate change interventions.

Activities meet the following SDGs:


Enhancing coastal protection

Concept Note

Climate Change Profile

Consultation Reports – June 2019

Consultation Reports – Aug 2019

Project Design Document – Amended January 2021

Situation Brief Post-Tsunami – February 2022

Situation Brief Post-Tsunami – February 2022

Assessment and conceptual design

Desktop Assessment and Community Priority Issues- Report 1 (Jan 2020)

Coastal Protection Feasibility Study, Northern Tongatapu- Report 2 (Feb 2021)

Community-based impact assessment in Western Tongatapu- Nov 2020

Community-based impact assessment in Eastern Tongatapu- Dec 2020

Conceptual design and preliminary costing for coastal protection, northern Tongatapu, 2023

Web Story: Communities highlight flooding and inundation as major issues for northern Tongatapu

Installation of coastal protection measures

Detailed Design of Small-Scale Coastal Protection and Ecosystem-Based Measures for Northwest Tongatapu- Aug 2021

Youth Training- Re-establishment of Mangroves (June 2021)

Additional Detailed Design of Small-scale Coastal Protection and Ecosystem-based Measures for Northwest Tongatapu – Nov 2021

Training and awareness

2020 Coastal clean-up and tree planting report

2020 Video competition report

Vava’u Youth Consultation report

Web Story: Women lead coastal planting and clean-up activities in Hihifo, Tongatapu

Community Leadership Training Report

2021 Video Competition report

2021 Coastal clean-up and tree planting report

Building community resilience