Racing the King Tide

Islands adapting to sea level rise

In October 2013, a 7.2-magnitude earthquake struck the province of Bohol, Philippines, inducing about 1m land subsidence to some of its small island communities. Now, the islands of Batasan, Pangapasan, Ubay and Bilangbilangan of the Municipality of Tubigon experience partial or complete flooding even during normal spring tides. Coming face-to-face with a hundred years’ worth of sea level rise, the island communities show that they are far more resilient than we think.
 
The following films, shot in June 2017, present the own perception of the people living on the islands.
 
 
The Mother’s Story

Maria lives a peaceful life on Ubay Island with her family. In spite of tidal flooding, she does not want to leave her home in exchange for an uncertain life on the mainland. Maria cherishes the abundance of the sea, which provides for her family’s daily needs.

In response to tidal flooding, the Municipal Government of Tubigon launched a relocation program that would provide permanent houses for the island communities on the mainland. However, many island residents are reluctant to relocate because of livelihood concerns. Rather than permanently relocating, they negotiated with the government to maintain their houses on the islands for their fishing activities, while agreeing to diligently evacuate to the mainland whenever a potential natural hazard manifests itself. Due to this compromise, the residents instead began to view the relocation program as a temporary evacuation scheme. In any case, the program is severely delayed due to lack of financial resources.
 
 
Auntie’s Story

The island communities celebrate the feast of St. John the Baptist (San Juan) every 24th of June by going out to the sea with their families. Despite knowing that their home would also be flooded while they are away, Servillana’s family continue to cheerfully observe the long-standing tradition. They reveal their resilient spirit, assured by the thought that the tide will inevitably ebb at the end of the day.

Although the mass migration theory claims that communities living in low-lying islands will inevitably relocate away from their homes as a result of sea level rise, the communities of Tubigon so far continue living on their islands, striving to maintain their cultural practices and social relations despite the challenges of tidal flooding. This shows that, compared to sea level rise, the communities’ sense of identity and attachment to place could play a greater role in their final decision to relocate or not.
 
 
The Captain’s Story

Ricardo looks out for the safety of his people at Pangapasan Island, where he has been elected as the leader or “captain”. He ensures their prompt evacuation to the mainland, especially whenever weather disturbances such as tropical depression Queenie coincide with tidal flooding. Unable to grow mangroves, their island is so vulnerable to waves that even passing ferries could damage the coral piles on which they built their homes.

In 2014, Pangapasan suffered from heavy damages from Queenie, despite the fact that it was only a tropical depression with relatively weak winds. From this experience, the island communities learned that even weak weather disturbances can be destructive whenever they happen during high tides. Now, at the time of deciding whether to evacuate, people do not only consider typhoon strength and timing of land fall, but also the height and timing of peak tide.
 
 
The Fisherman’s Story

As the chairman of Batasan Island’s Marine Protected Area Management Council, Eduard is concerned about the health of the marine environment. Eduard appeals to the more fortunate members of his community to refrain from mining corals in fishing grounds, which has become rampant in response to tidal flooding. He encourages the community to build more stilted houses instead, as these are more environmentally sensitive, effective and economical.

Historically, as the community gradually grew, people have mined coral stones in order to reclaim land. After the earthquake, however, many households simultaneously resorted to coral mining to elevate their floors. Coral mining is actually expensive, although alternative materials for building stilted houses are also scarce on the island. Excessive coral mining does not only negatively impact fish population, but also endangers people’s lives. Corals serve as natural barriers against waves, protecting the island from typhoons and storm surges.

While NGOs have donated stilted houses to a good number of residents in response to damages caused by the earthquake, the rest of the communities are still exploring how to elevate their floors responsibly, using limited financial and natural resources.
 
 
The Teacher’s Story

Teacher Agnes worries about the learning environment and safety of the students of Bilangbilangan Elementary School, where she is also serving as school head. Tidal floods distract students from their lessons, bringing human waste and high waves into the classroom. Teacher Agnes dreams for classrooms to be elevated to reduce the impact of tidal floods on the children’s education.

Daytime flooding occurs during the southwest monsoon, which runs from April to September, and coincides with most of the school year. Thus, classes cannot simply be cancelled every time there is tidal flooding, as the students would then have a difficult time completing the required number of school days. Instead, classes are only cancelled whenever typhoons or strong monsoon winds occur together with high tides. In exchange, the school sometimes holds make-up classes in the weekends.
 
 
The Health Worker’s Story

As the community nutritionist, Amelita works hard to reduce the number of malnourished children in Pangapasan Island. However, the community’s water and vegetable intake is highly dependent on the surrounding environment. While drought can easily deplete their rainwater supply (there is no freshwater supply on the island), tidal floods pose a grave threat to all non-salt resistant plants and vegetables. To reduce their vulnerability, Amelita hopes to improve rainwater harvesting on the island, and to elevate roads to prevent waves from reaching vegetable gardens.

Island residents depend heavily on seashells and fish for nourishment, though they tend to often sell the latter as they can fetch higher prices in the market. Immediately after the earthquake, almost all of the vegetable gardens in the islands were washed away. During a prolonged dry spell in 2016, the rainwater supplies of the communities were completely exhausted. To address these problems, the residents began to plant vegetables in elevated pots, while the governments in each community procured several rainwater collectors.
 
 

Adaptation strategies for relative sea-level rise

A free, read-only version of a journal article containing the full details of tidal flooding and adaptation in the islands of Tubigon may be accessed here. The study was published by Nature Climate Change, and was featured on the cover of its August 2017 issue.

Rationale of the Study

The 5th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) projects that by the year 2100, the global mean sea-level will have risen by as much as 0.28m to 0.98m. This projection has sparked an intense debate amongst scholars and policy-makers about the possibility of climate-induced mass migration, especially in low-lying Small Island Developing States (SIDS).

However, due to the slow onset of sea-level rise, there is a lack of case studies that examine its actual impacts and potential adaptation strategies (currently, Atoll Island States are only experiencing complete inundation about once a year, during King tides). Furthermore, since climate projections are not yet available on the island-level, designing appropriate adaptation strategies, particularly engineering measures, is proving to be a difficult challenge.

To address the issue of data availability, the study drew an analogy between climate-induced sea-level rise and earthquake-induced land subsidence in terms of their tidal flooding effects. The study then examined the impacts of relative sea-level rise, and identified and evaluated various potential community-based adaptation strategies.

Key Findings

The study provides rare and real examples of adaptation strategies against sea-level rise, and challenges the mass migration theory.

Currently, the island communities of Tubigon become partially or completely inundated during spring tides that occur around the new and full moon phases of each month. In 2016, the islands were flooded across 44-135 days, with median flood heights reaching up to 0.2m-0.4m above ground level. Daytime flooding occurring during the southwest monsoon disrupts school activities, while nighttime flooding during the northeast monsoon increases disaster risk since it also coincides with the typhoon season.

Despite severe flooding conditions, none of the island communities have decided to relocate to the mainland through an available government-funded project, contradicting the prevailing mass migration theory. Instead, they have mainly pursued various accommodate (i.e. in-situ) adaptation strategies that include hard infrastructures, such as building stilted housing and raising floors, and soft measures, such as elevating belongings during floods and designing taller furniture. They have also implemented “no regrets” strategies that address both flooding and their pre-existing socio-economic problems, allowing the communities to continue their daily lives on the islands. Examples include the acquisition of rainwater collectors to solve water supply issues.

However, not all of these strategies were effective and thus adaptive. In particular, excessive coral mining for raising floors and reclaiming land inadvertently increases the islands’ vulnerability to storm surges and decreases its sediment supply. Coral reef assessment surveys of mined areas show live coral cover of less than 10%, indicating severe degradation.

Overall, the study shows that environmental factors (i.e. frequency and height of flooding) alone do not directly lead to mass migration, refuting the assumption of the mass migration theory. It therefore highlights the need to improve our understanding of the way humans adapt to climate change, avoiding simplistic scenarios and attempting to better appreciate how communities interact with their environment. Furthermore, the experience of the islands of Tubigon emphasizes the need to identify and improve potential in-situ adaptation strategies. As adaptation strategies ultimately tie back to the development agenda, holistic ways of looking at climate change adaptation are necessary for creating more sustainable development paths for small islands communities around the planet.