Cyclone Gita Recovery Project

Introduction

Severe Tropical Cyclone Gita was the most intense storm to ever hit the Pacific Island nation of Tonga. Making landfall on 12 February 2018, it caused severe damage to the islands of Tongatapu and ‘Eua. Widespread destruction of the power network disrupted communities and led to energy sector reconstruction costs of about $46 million. In 2018, the Asian Development Bank (ADB) and Government of New Zealand approved separate grants to help reconstruct and improve disaster resilience of the Nuku’alofa electricity network, in partnership with the Government of Tonga and Tonga Power Limited. 

The power network recovery was informed by an existing 10-year Energy Roadmap and building back better lessons from the Cyclone Ian Recovery Project in 2014. Some 5% of power grid segments upgraded in Tongatapu and ‘Eua through earlier support were found to be damaged following Cyclone Gita, compared to a damage of about 45% in other areas. ADB is continuing its support for national energy resilience through the 2019 Tonga Renewable Energy Project.  

Maintenance activities of energy infrastructure in Tonga

About the Initiative

Tropical Cyclone Gita hit Tonga on 12 and 13 February 2018. It caused widespread destruction on Tongatapu, including Nuku'alofa, and the neighboring island of Eua. With average wind speeds of 130 kilometers per hour, and gusts of up to 195 kilometers per hour, it was the strongest cyclone to directly hit Tongatapu and Eua since severe Cyclone Isaac in March 1982.  

An accompanying storm surge reached 1 meter above normal high-tide levels, and 200 millimeters of rain fell within 24 hours, resulting in localized flooding. It is estimated that more than 80,000 people (or about 80% of the population of Tonga) were directly affected. The destructive winds, storm surges, and flooding brought down power lines; damaged and destroyed schools, resulting in closures; destroyed crops and fruit trees; and damaged public buildings, including the domestic airport, the Parliament building, and Tonga meteorological services. Nearly 5,000 houses were either destroyed or damaged. The government declared a state of emergency for the whole of Tonga on 12 February 2018. The project was expected to deliver impacts toward more reliable and safe energy services, reduced energy consumption, increased resilience to disasters, and more reliable and safer buildings and structures to improve services and maintenance. Its intended outcome was to restore reliable electricity supply in priority areas of Nuku’alofa. The project’s target output was to rehabilitate and upgrade priority sections of the Nuku'alofa electricity network. 

Installation of electric conduits on building walls

Learning & Impact

The Asian Development Bank’s Operational Priority 3: Tackling Climate Change, Building Climate and Disaster Resilience, and Enhancing Environmental Sustainability sets out an approach to enhance the physical, eco-based, financial, social, and institutional resilience of Developing Member Countries. ADB projects seek to build resilience in one or multiple areas.

The project enhanced the physical resilience of Tonga’s power system by building a more decentralized network with strengthened distribution assets. Specific measures included moving service connections underground, changing distribution system aerial conductors from individual to bundled lines, upgrading the capacity of the distribution network, providing high voltage underground supply to critical locations, such as hospitals, network reconfiguration to support rollout of renewable energy, and applying the latest technical standards from Australia and New Zealand. 

The project set high targets for capacity development and gender inclusion in order to develop a more diverse workforce that is better equipped to respond to future disasters. Capacity building included training and coaching for Tonga Power Limited to meet gender and social targets and strengthen implementation and coordination capacity for future emergencies. As a result of gender diversity efforts, TPL’s line crew is made up of 33% females. 

At project completion, 2,184 customers were connected to the network, with sufficient provision to cater to any new connection requests arising from new developments in the area. A total of 256 customers were also able to connect to the grid energy for the first time and 71 new three-phase power connections were provided. A total of 24 transformers, and 35 km of high-voltage and 103 km of low voltage lines were used.  

It is noted that 19 km more of the high-voltage and 45 km more of the low-voltage cables were used over the estimated lengths. This is attributed to the completion of the entire Area 2 upgrade work against a target of 90% at appraisal and to the extension of cables to vacant locations earmarked for upcoming development. In addition, a total of 830, 11-meter length poles for high voltage cabling and 2,214, 9-meter length poles for low voltage cabling were installed. Overall, the project met its expected impact and outcome targets and exceeded the output targets within the original budget and implementation timeline. 

Additional Information

Tonga

Implementing Agencies & Partners:
  • Asian Development Bank
  • Government of New Zealand

Acknowledgement:

This case study has been contributed by Asian Development Bank 

Disclaimer:

The compendium of good practices on Disaster Resilient Infrastructure (DRI) has been compiled through content contributions from G20 member countries, invited countries and international organizations. This content and views expressed in this website publications reflect the opinions of contributing agencies and not necessarily the official views of CDRI.