Nepal flood was a debris flow, says expert; similar disaster hit Philippines in 2012

The tragedy in Nepal is believed to have been caused by a “debris flow” — an incident that has happened in the Philippines and may happen here again, an expert said on Thursday.

According to Maki Pulido's report on "24 Oras," scientists are still figuring out the massive flood that devastated the border of Nepal and Tibet.

But Mahar Lagmay, the Executive Director of the University of the Philippines Resilience Institute, it would appear that the incident was a debris flow.

He said it was akin to a flood but with chunks of rock, gravel, sand, and more, giving it the appearance of wet concrete.

This hazard has already occurred in the Philippines before. In 2012, there was a debris flow in Compostella Valley. At least 500 people were killed.

Then in 2015, large rocks hit several barangays in Baco, Oriental Mindoro in a debris flow.

In the Philippines, a debris flow could be triggered by heavy rainfall on a mountainside that could cause a landslide.

“We have a lot of mountains… If there is a landslide because of a storm, there are thousands of landslides in the mountains; there is source material, and then when they remobilize. They turn into what we call a debris flow; they exit at the drainage network,” Lagmay said in a mix of English and Filipino.

A debris flow would hit communities by the river, Lagmay said.

“There are more than a thousand places we’ve identified where there are communities there…and we need to put them out of harm's way if we can’t make them leave or at least get them prepared,” Lagmay said.

This is the relevance of Project NOAH (Nationwide Operational Assessment of Hazards), which recently received P1 billion in funding.

The money will fund hazard mapping to better prepare for natural hazards. —Jean Mangaluz/NB, GMA News