WEEK#13 RISK OF COASTAL EROSION

WEEK#13 RISK OF COASTAL EROSION

The impact of climate change in Tonga is most readily apparent when examining the land loss at the coastlines. Sea level rise, damage from inundation, inundation, flooding to properties and infrastructures, groundwater contamination, and plant and crops in the coastal zone have been experienced. Additionally, increases in air temperatures and changes in rainfall patterns have reduced soil moisture levels which have altered runoff to the coast. An increase in the intensity of extremes events such as tropical cyclones, storms and heat spells, coupled with other impacts of climate change has put the sustainability of many existing coastal communities and natural resources at risk. Along the coastlines of Northeastern and Northwestern Tongatapu, where many communities are located, wave-induced erosion has put houses, coastal infrastructure, and the emergency evacuation road at risk.

Tonga’s coasts provide communities with an abundance of natural resources to sustain them while

providing natural harbors for commerce, trade, and transportation. These coastal ecosystems serve critical functions to cycle and move nutrients, store carbon, detoxify wastes, and purify air and water. Additionally, these coasts mitigate floods and buffer against coastal storms that bring high winds and salt water inland and erode the shore. The many benefits and opportunities provided in coastal areas have strengthened Tonga's economic reliance on coastal resources. Consequently, the high demands placed on the coastal environment will increase commensurately with human activity.

                                     

Aerial photography indicates the coast has been subject to coastal erosion of up to 25 m since 196848. Coastal erosion has been arrested by the coastal road, which acts as a sea wall. Despite upgrading in

2011, the road is under threat in many places and recent cyclones have uprooted trees & undermined their root systems. The coast road is a critical access, and the only route available for the villages of Nukuleka, Talafo’ou, Navutoka and Manuka to access the capital Nuku’alofa and to escape the area in an extreme storm or tsunami event. 

Previous actions to arrest erosion along the coastline have not been successful. Currently trials of groynes and semi-emergent breakwaters are in place as temporary initiatives. The Climate Resilience Sector Project (CRSP) is in the process of completing design of coastal protection works for this coast, but available funds means that construction of the coastal protection will be done over only a small section of the coast (approximately 1 km). This will leave the majority of the Hahake Peninsula unprotected against future erosion, and increased frequency and damage with sea level rise and larger storm events.

Sea level rise is a clear and present danger to the Pacific Island nation of Tonga. Since the record-breaking volcanic eruption a year ago, which triggered up to 15m tsunami waves that gutted entire villages, the Government is building higher and higher sea walls to keep the ocean out.

Meanwhile, small island developing states (SIDS) in the region suffer an estimated US$1.1 billion in total average losses each year from natural disasters. This is the current reality faced by SIDS in the Pacific, and beyond.

Devastating impacts of sea level rise

Tonga was ranked as the third most at-risk country for natural hazards (cyclones, flooding) and Sea Level Rise in the 2021 World Risk Report. Any sharp rise in sea levels could be devastating to the public infrastructure in Tonga and a total collapse of the promenade and tourism at the waterfront capital of Nuku’alofa.

The world saw what this could look like when the January 2022 volcanic eruption and tsunami resulted in an estimated US $90 million in damages (18.5 percent of GDP), affecting properties, infrastructure, communication, tourism and the productive sectors of agriculture and fishing.

Early data from the January tsunami indicates that Tonga needs to add another metre to its sea walls to be safe from future tsunamis.

Tonga, like many SIDS in the region, is particularly vulnerable as it is located along the Pacific tectonic plate called the Ring of Fire. This part of the world accounts for 75 percent of the world’s volcanoes and high variability in sea level over space and time. The factors affecting extreme ocean levels in the Pacific islands are related to the high frequency of tropical storms, the high frequency of storm surges, an ongoing trend in seismic uplift, and glacial adjustments. 

The fight to save coastlines

According to the Intergovernmental Panel on Climate Change (IPCC), the high variability of sea level rise can shift from region to region - meaning Tonga’s reality today could be another SIDS nightmare tomorrow.

The Government is responding robustly and the fight is ongoing to save the coastlines. One of Tonga’s top priorities in the climate crisis is strengthening coastal resilience written within the Joint National Action Plan 2 on Climate Change and Disaster Risk Management (JNAP2 2018 – 2018).

The country’s pipeline of project proposals is targeting strengthening existing and building new coastal defence infrastructure. Its second Nationally Determined Contribution (NDC) of 2020 aims to plant one million trees by 2023, most of which are coastal species such as mangroves.

Strengthening Tonga's ability to recover from climate change impacts is also a key focal area. Tonga continues to be grateful to committed partners, such as the Government of New Zealand, who recently announced an additional 8 million New Zealand dollars of funding to Tonga to combat the threat of climate change. 

SOURCES:

Coastal Resilience Project – TongaUnited Nations Development Programmehttps://pims.undp.org › attachments

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