Is the Philippines at risk of a 'debris flow' disaster like Nepal's?
A geologist said a debris flow similar to the one along the Nepal-Tibet border, which claimed more than 400 lives, could also occur in the Philippines.
According to UP Resilience Institute Executive Director and geologist Mahar Lagmay, what happened in Nepal was a debris flow—a mixture of water, rocks, gravel, and sand that can flow like wet concrete as it moves downhill.
"Parang baha pero may laman na mga bato, graba, buhangin. Kapag umagos ay parang wet concrete. Debris flow ang tawag diyan," he said, according to a report by 24 Oras. "Boulders na tangay-tangay ng baha na more than 50% ang bato, ang graba, mas marami pa sa tubig."
Similar incidents have also occurred in the Philippines. In 2012, a debris flow in Compostela Valley (now named Davao de Oro) claimed more than 500 lives following Super Typhoon Bopha (locally known as Pablo).
In 2015, parts of several barangays in Baco, Oriental Mindoro, were also buried under large rocks from a debris flow.
Lagmay explained that debris flows in the Philippines are triggered by heavy rainfall in mountainous areas, which can cause landslides and can affect communities located along riverbanks.
"Marami tayong bundok. Pag nagkaroon ng landslide because of a storm, na thousands of landslides sa mountains, meron tayong source material. And when they get remobilized, they turn into what we call as debris flows and they exit at the mouth of the drainage network," he said.
Project NOAH (Nationwide Operational Assessment of Hazards) studied the Mayo River debris flow before its resources and attention were redirected to Super Typhoon Haiyan (locally known as Yolanda) in December 2013.
According to Lagmay, the institute has already identified 1,000 areas at risk of debris flows.
"There are more than 1,000 places that we've identified na merong communities na nandun and we need to put them out of harm's way. And if we cannot get them to leave that place, at least we need to get them prepared," he said.
This year, the UP Resilience Institute received one billion pesos in funding to purchase equipment for hazard mapping across the country.
“The P1 billion allocation for UPRI will be measured by better information, transparency, evidence-based governance and decision-making, effective flood management, and reduced disaster risks and losses,” Lagmay stated.
Lagmay said the UPRI budget will fund high-resolution hazard mapping, land-use planning, and flood-control initiatives in partnership with government agencies, local governments, and the private sector. It will also support LiDAR drone surveys, capacity-building, environmental assessments, mapping of hidden waterways, nature-based solutions, and the use of artificial intelligence for disaster risk management.
On Aug. 26, a huge wall of mud and rock collapsed into a river on the Himalayan border of Nepal and China's Tibet, triggering catastrophic flooding on the Nepali side that killed 496 people as of writing and left more than a thousand people missing.
