Tonga is one of the most disaster-prone countries in the world, ranking 2nd of 181 countries on the World Disaster Risk Index. To better understand and prepare for disaster risks and the impacts of climate change, the Government of Tonga and the Asian Development Bank commissioned a Multi Hazard Climate and Disaster Risk Assessment in 2020 that analyzed thousands of buildings, roads, power and water assets in the island of Tongatapu. A risk index was developed from the assessment, which showed areas in Tongatapu that are at high risk to the impacts of climate change and will be subject to frequent or permanent flooding. The report also showed relatively safe areas that can be developed into resilient communities.


The Kingdom of Tonga, a country with over 3,000 years of history is positioned at the southernmost group in the Polynesian Islands. Because of its position in the South Pacific, and its low-lying geography, Tonga is one of the most disaster-prone countries in the world, ranking 2nd of 181 countries on the World Disaster Risk Index in 2020. Earthquakes, tsunamis, floods and cyclones are a constant threat in Tonga and with climate change cyclones and flooding are becoming less predictable and more intense.

In 2020, the Government of Tonga and ADB commissioned a Multi Hazard Climate and Disaster Risk Assessment covering the island of Tongatapu in order to identify both high and low risk areas and communities.

Paula Ma’u


Ministry of Meteorology, Energy, Information, Disaster Management, Environment, Climate Change and Communications (MEIDECC)

Kingdom of Tonga

And this study, providing the opportunity of this important assessment of where we are, the situations and giving us some solid scientific evidence of these impacts of climate change. Our database was developed of course, to quantify the distribution and characteristics of assets and the population across the island.

Based on international, regional, national datasets and field observation, the assessment analyzed 28,000 buildings, 1,200 kilometers of roads, 26,000 power and 500 water assets across the entire island including the Capital.

These assets were plotted against earthquakes, windstorms, tsunamis, rainfed and coastal flooding hazards to model the impact of natural hazards with and without climate change. The assessment, finalised in May 2021, identified climate and disaster risks to assets and population across Tongatapu expressed as annual average losses.

Taaniela Kula

Deputy CEO, Ministry of Lands and Natural Resources

Kingdom of Tonga

Nuku’alofa is the most densely populated area of Tongatapu and it's situated between 2 bodies of water. It’s also the 5th lowest lying city in the world, at only 1.5 metres above sea level. When you combine these factors plus underlying poor drainage and continual development, it is very important for us to understand how to manage low risk planning for the future.

The assessment applied various climate change scenarios, namely sea level rise and extreme rainfall events, against different levels and likelihoods of flooding. Results were broken down at the level of individual "towns" which are the basic administrative units in Tonga.

A risk index was established ranking these towns against individual and combined hazard threats. And this way, the assessment gained an understanding of areas in Tongatapu that will be at high risk from climate change and subject to frequent or even permanent flooding. The assessment also identifies relatively safe areas on the island for future investments and adaptation. As Asia and the Pacific's climate bank, ADB is bringing new ideas and technologies to take meaningful action against the threat of climate change.

Rosamond Carter Bing

CEO, Ministry of Lands and Natural Resources (MLNR)

Kingdom of Tonga

The Multi Hazard Risk Assessment Report is of great value to Tonga. By helping us plan with low risk, we can ensure the long-term security of our assets and the safety of our populations, by identifying the high risk, we are able to look at a new way as to when and where to locate our future assets so that we can ensure that we plan for the sustainable development and future growth of the Kingdom of Tonga.

The information allows to design the gradual development of safer areas and steering investments away from the highest risks areas while ensuring that all investments are designed and operated to withstand multiple hazards.

This includes using post disaster situations and recovery to not only "build back better" in a manner resilient to natural hazards but to promote rebuilding away from high risk locations for a safer and resilient Tonga in the 21st century.