ILOILO City – The Department of Tourism (DOT) in Western Visayas vowed to take the necessary steps once there is already an assessment from experts regarding the risks that sinkholes pose in the world-famous Boracay Island.
Newly-installed DOT Region 6 director Crisanta Marlene Rodriguez said the tourism regional office is yet to receive the result of the study conducted by the Mines and Geosciences Bureau (MGB) of the Department of Environment and Natural Resources (MGB-DENR).
She noted, however, that she already had a courtesy call with DENR regional executive director Livino Duran and the latter vowed to share data once they get a go-signal from their central office.
“Ang importante sa atin is transparency and information dissemination, especially for tourists. We expect that once we receive the report, there will be an assessment from experts such as geological engineers. DENR could also provide us with the technical analysis of the situation,” said Rodriguez.
Information dissemination is key and risk assessment will also help DOT decide what steps to take to make sure the tourists are safe, she added.
“We defer to the expertise of the DENR because we don’t even know how big the sinkholes are. I think we all know that the whole island is a limestone. There’s a natural occurrence of sinkholes for an island like Boracay,” she added.
In December 2022, MGB-6 disclosed that 815 sinkholes have so far been counted.
To minimize the risk of collapse, MGB recommended lessening the weight of the structures in Boracay such as by having one-storey buildings only.
“Kung sobrang bigat ng structure, nag-a-add ng weight, plus the fact na natutunaw ‘yung ilalim. Only time can tell, ma-collapse gid na siya,” said Mae Magarzo, chief of MGB Region 6’s Geosciences Division, in an interview last December 2022.
A sinkhole is a hole in the ground that forms when water dissolves surface rock, often limestone, which is easily eroded, or worn away, by the movement of water, according to the National Geographic.
In a landscape where limestone sits underneath the soil, water from rainfall collects in cracks in the stone. Slowly, as the limestone dissolves and is carried away, the cracks widen until the ground above them becomes unstable and collapses, it explained.
The collapse often happens very suddenly and without very much warning.
“Wala na siya indication, gulpi lang siya,” said Magarzo.
In Boracay which is entirely limestone, the number of sinkholes has been increasing in recent years, according to MGB-6.
Its Karst Subsidence Hazard Mapping showed 789 sinkholes in 2018. These increased to 801 in 2019, 814 in 2020, and 815 from 2021 to 2022.
“That’s because ang chemical composition ng limestone is calcium carbonate. When it comes in contact with acid, unti-unti siyang matutunaw. Basta may water, lalo na acid rain,” said Magarzo.
Boracay’s Barangay Manoc-manoc has the most number of sinkholes at 293. The rest are in barangays Balabag and Yapak, MGB-6 said.
“That is why we want the carrying capacity of Boracay observed. As you could see in our geo-hazard map, almost all parts of the island are highly susceptible,” said Magarzo.
MGB-6 stressed the importance of constant monitoring of the ground and structures in Boracay.
“Since ara na siya, i-monitor lang nila kung may mapansin sila. Delikado eh. Ang problema lang namon, wala masyado mitigating measures kay iya na property ka limestone,” she said.
Boracay has a total land area of 10.32 square kilometers. It is approximately seven kilometers long, dog-bone shaped, with the narrowest spot being less than one kilometer wide.
Based on the study conducted by DENR-Ecosystems Research and Development Bureau in 2018 yet, the tourist carrying capacity of Boracay is 19,215 persons at any given time, or equivalent to 6,405 arrivals a day for a three-day stay. The ideal tourist arrival per day should be 6,085.
Meanwhile, the island’s population carrying capacity is 54,945 including the tourism carrying capacity. The existing population when the study was conducted in 2018 was 70,781 or an excess of 15,836 a day.
According to Duran, they are yet to release an updated carrying capacity for Boracay.
“We respect the decision of the DENR in the conduct of the new study in the carrying capacity and we shall wait for their decision to release such. I believe our secretary and the DENR secretary had talks already regarding the uncompleted activities in Boracay. So we will know more in the coming days as Boracay is still a concern, a priority,” Rodriguez commented./PN
