Building a Resilient City in the Pacific

Workers lay water pipes in Nuku'alofa. Improving the water supply infrastructure is a priority project in the city. Photo credit: ADB.

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Nuku'alofa, the capital of Tonga, is transforming into a resilient, disaster-ready urban center designed to withstand the impacts of climate change.


Nuku'alofa will not be left behind. Urban development in the Tongan capital is picking up its pace with the Asian Development Bank-supported Integrated Urban Resilience Sector Project. Approved in 2019, the project aims to improve the living standards of residents and increase the capital’s resilience to natural hazards and the impacts of climate change.

A technical assistance project, which was cofinanced by ADB and the Government of Australia, ensured that lessons from relevant past projects were incorporated into the design of the new one, helped improve coordination among agencies and stakeholders to prevent project overlaps, and took a new and more strategic approach to address climate change adaptation, considering it the core of the equation for building a more resilient Nuku'alofa.

Project Snapshot

  • June 2017 : Approval of Project
  • May 2019 : Project Completed

  • $900,000.00 : Total Technical Assistance
  • $675,000.00 : ADB
  • $225,000.00 : Government of Australia

  • Financing :
  • Financing :
    • Government of Australia
  • Executing agency :
    • Tonga Ministry of Finance
  • Implementing agency :
    • Tonga Ministry of Lands and Natural Resources
  • Others :
    • Tonga Water Board
  • Others :
    • Waste Authority Limited

Urban development in Nuku’alofa needs to keep up with population growth. The city is on the island of Tongatapu and home to about one-third of Tonga’s total population of 100,651. With continuous migration from the outer islands, the population of the capital is expected to reach 40% of total population by 2030.

However, urban development is often stymied by natural hazards, such as earthquakes and tropical cyclones that cause widespread destruction. Climate change is expected to make matters worse. A more strategic approach to urban development that puts climate change adaptation measures at centerstage is needed to increase Nuku'alofa’s resilience.


Nuku’alofa needs better urban infrastructure and public services—such as water supply, sanitation, and waste management—to sustain urban growth. However, Tonga has very limited land to build on. Many of the areas surrounding Nuku’alofa are below tide levels, and therefore prone to frequent coastal flooding, especially since natural hazards, such as tropical cyclones, storm surges, and tsunamis, are common. Sea-level rise brought by climate change is expected to be the greatest long-term threat to the capital and could lead to permanent flooding, especially in poor and low-lying communities, such as Sopu and Popua.

Since 2008, ADB has been a major supporter of urban development in Nuku’alofa. The Integrated Urban Development Sector Project (Phases I and II; 2008–2010) and the Nuku'alofa Urban Development Sector Project (cofinanced with the Government of Australia; 2011–2020) aimed to upgrade the living standards of Nuku'alofa’s residents with better urban infrastructure and services. They also prioritized the most urgent urban necessities such as water supply, sanitation, and waste management.

The Integrated Urban Resilience Sector Project, the third in the series, will focus on the long-term impacts of climate change in the design and upgrading of urban infrastructure and associated services in the capital. To plan and prepare for this project, ADB and, once again, the Government of Australia cofinanced a technical assistance project.


This latest technical assistance supported the Ministry of Finance and the Ministry of Lands and Natural Resources, as executing and implementing agencies, respectively, in planning, designing, and prioritizing investments to improve urban infrastructure and resilience to floods and climate change in Nuku’alofa.

Comprehensive feasibility studies and due diligence. The project conducted reviews of previous relevant projects in Tonga and other Pacific Island countries, especially those that covered disaster resilience and climate change. It also conducted a preliminary study of climate and disaster risks for Nuku’alofa and prepared a climate change and flood management assessment based on past flooding events, projected climate change impacts, and condition of existing drainage infrastructure. It covered the necessary feasibility and due diligence investigations (including economic and financial viability), environmental and social investigations, applicable resettlement framework and plan, gender analysis and action plan, project risks and mitigation measures, and stakeholder engagement and communication plan.

Flood Management Master Plan and other concept designs. A Flood Management Master Plan was prepared for Nuku’alofa, which was informed by the climate change and flood management assessment and feasibility studies. The project also assessed proposals for improving drainage infrastructure and other flood management measures.

The master plan identified potential infrastructure solutions that would reduce depth and duration of floods. However, the appraisal considered a range of constraints that could limit the capacity and effectiveness of this infrastructure. The study discovered how extensive these constraints were, thus limiting the options available to substantially mitigate future flooding through infrastructure solutions.

The project also designed the following:

  • a community-based disaster risk management program, including an awareness-raising campaign strategy, to be run by identified civil society organizations;
  • a strategic plan to improve the water management skills of the Tonga Water Board, which provides water supply services to Tongatapu and other areas in Tonga, including in reducing nonrevenue water and providing better water supply services, and also incorporated with climate change adaptation and mitigation considerations; and
  • a concept design for the improvement of sewage treatment and for enhancing the waste management capacities of the Waste Authority Limited, which oversees waste management in Tongatapu.

Adjustment in project scope. Because of the constraints discovered in the appraisal, the technical assistance project abandoned traditional infrastructure solutions and adopted a more strategic vision for flood management in Nuku’alofa that would include a transition plan to implement a phased approach to dealing with sea level rise. The strategic approach would involve long-term land use planning and progressive relocation of communities in the lowest areas to higher ground while providing interim infrastructure solutions.

These findings forced major changes in the plans for the ensuing Integrated Urban Resilience Sector Project. Aside from a reduced scope for major flood management infrastructure, the project design now also included the preparation of a climate and disaster resilient urban development strategy and investment plan, which would assess and design longer-term development options for Nuku’alofa.


The technical assistance project redefined the scope of the Integrated Urban Resilience Sector Project and provided a more solid blueprint to transform Nuku’alofa into a resilient city, replete with climate-ready urban infrastructure. It provided clearly defined project outputs to guide project implementation:

Output 1: Effective flood risk management infrastructure implemented. The rehabilitation of old and construction of new flood management and drainage infrastructure throughout Nuku’alofa will address inundation in low-lying areas in the short and mid-term, avoiding high risk areas where further investments could result into maladaptation.

Output 2: Water supply service in Nuku’alofa improved. The rehabilitation and upgrading of the piped water distribution network and an institutionally stronger Tonga Water Board, which is responsible for the provision of water on Tongatapu and other parts of Tonga, will help reduce nonrevenue water and provide better water services.

Output 3: Public and environmental health enhanced. Enhancing septage and solid-waste management and collection in Tongatapu and setting up a new sanitary landfill cell, among other initiatives, will help improve the environment and public health.

Output 4: Urban resilience strengthened. A gender-sensitive climate- and disaster-resilient urban development strategy and investment plan for the greater Nuku’alofa area will improve resilience and guide further government urban planning and investments. A pilot gender-sensitive, community-based disaster risk management program will also be implemented and will involve Nuku’alofa communities, including women and girls, in the preparation of disaster risk management plans.


Flexibility in scope. It is important to allow a degree of flexibility within the scope of the technical assistance to adapt the feasibility studies, economic analysis, and concept designs to an evolving project scope. The initial studies conducted through the technical assistance concluded with the need to take a different investment approach and modify the original project scope. Fortunately, the way the technical assistance was written allowed this flexibility. But this is not always the case.

Climate change projections. Climate change projections should be considered as much upstream as possible when assessing possible solutions and investments for a certain issue. If climate change projections are only considered at the end, this usually involves the climate proofing of the selected infrastructure only. By considering potential climate change impacts as early as possible, the preparatory work could find a more holistic and long-term solution.

Partners’ support and communications. The support of financing partners throughout the technical assistance and their openness to changes in scope are crucial. Communication and sharing of information with financiers are key to facilitate changes and keep their support.

Maria Vicedo Ferrer
Urban Development Specialist, Pacific Department, Asian Development Bank

Maria Vicedo Ferrer has more than 10 years of experience working for the private sector, government, and development institutions on infrastructure, urban planning, disaster risk reduction, and climate change adaptation. She joined ADB in 2016 to support Pacific island countries to enhance urban resilience and reduce disaster risk and has also worked in the operationalization of ADB’s Healthy Oceans Action Plan. She holds a double masters’ degree in Civil Engineering by the Polytechnic University of Valencia and the ESTP Paris.

Asian Development Bank (ADB)

The Asian Development Bank is committed to achieving a prosperous, inclusive, resilient, and sustainable Asia and the Pacific, while sustaining its efforts to eradicate extreme poverty. Established in 1966, it is owned by 68 members—49 from the region. Its main instruments for helping its developing member countries are policy dialogue, loans, equity investments, guarantees, grants, and technical assistance.

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