Heavy rain and frequent landslides were not only caused by global warming but road and construction projects, Phivolcs (Philippine Institute of Volcanology and Seismology) executive director Renato Solidum said on Friday.

"Obviously with global warming, we are experiencing more rain. Unfortunately, it’s not rain that triggers landslides as well. We are also developing many areas. We are constructing roads and if you noticed many of the landslides in the Bicol area are along roads," Solidum told President Rodrigo Duterte in a command conference in Camarines Sur.

"Unfortunately many houses were built on road easements and also on the lower end of the roads. So with the development, we also have to make sure we employ slope protection and drainage on the roads we are constructing so that this will not be the site of future landslides," he added.

Thousands of people were affected by landslides and floods by Tropical Depression "Usman" which made landfall on December 29 in Borongan, Eastern Samar before leaving the country on Dec. 31. At least 122 persons were reported killed mostly in landslides in Bicol, the National Disaster Risk Reduction Management Council (NDRRMC) said.

Solidum explained that even "Usman" is only a tropical depression, it moved slowly to the Bicol area, causing more rain.

"First of all a tropical depression is the lowest category of tropical cyclone in terms of wind speed. However, it also moves very slow... it brings a lot of water and because it moves very slowly it taps a lot of rain in the area," he said.

"So in addition to the forecast moderate to heavy rainfall, more rains were experienced because it's stationary. And that is why Mr. President, there's a lot of rain," Solidum added.

Because many landslides started at roads, he told Duterte the government should make sure roads they develop have slope protection, drainage and no one should be living beside roads.

He said landslides and flashfloods were combination of extreme weather because of global warming.

"So we have extreme actions to cope up with the changing condition too," Solidum said.

Duterte reiterated his plan to make the NDRRMC a permanent government department to address these challenges.

"I have plans of making his (Executive Director Ricardo Jalad) agency a regular department. Solely to meet the challenges, everything is under his control," Duterte said.

"General Jalad has been there very much ahead than the others," he added. Ella Dionisio/DMS