UP geologist: Residents warned of ‘Sendong’ disaster in 2009

by Xianne Arcangel

Photo on the left shows a Google map image of Hinaplanon area in Iligan City before "Sendong." Photo on the right shows the change in the town's landscape after the typhoon hit. (Courtesy of UP-NIGS)

A geologist from the University of the Philippines said Friday that residents of Iligan City were warned as early as 2009 to relocate their homes to higher areas because of the high probability of flooding like what was experienced in Marikina during typhoon “Ondoy.”

Two years after that first warning, tropical storm “Sendong” washed away entire communities in the city and left more than 1,400 people dead and several missing in northwestern Mindanao.

Alfredo Mahar Lagmay of the UP National Institute of Geological Sciences said in a press conference that national and local government officials constantly reminded residents about the flooding risks in Iligan City.

“In 2009, we actually gave them some advice to move to higher ground certain areas. Apart from that, I think the local government, as well as the national government, [were] not remiss in their duties. With their geohazard maps, they also warned the government of Cagayan de Oro,” he said.

Lagmay was part of the UP Padayon Disaster Response team sent by the university to evaluate the damage brought by Sendong to Iligan City. The 22-man team composed of doctors, geologists and forensic experts chose to focus their efforts on Iligan City because their assessment showed that the destruction there is “worse than in Cagayan de Oro.”

The geologist said the red flags were raised in 2009 “because the scientists knew the lay of the land.” Iligan City is is located downstream of Mandulog River, a 50 kilometer-long river which flows from the mountains of Lanao del Sur.

“They knew that there’s a mountainous area and the city was a delta or a flood plain. The natural cycle of the delta is that it gets flooded. The advice was given way before Sendong hit.”

Lagmay explained that their findings showed that water from the mountain cascaded down the river, taking with it logs, mud, sand and other debris at the height of the storm.

Photo on top shows the clean roads of Orchids Home Subdivision in Iligan City. Bottom photo shows the devastation after "Sendong" hit the area. (Courtesy of Firm Builders Realty Development Corporation and UP-NIGS)

He said that the rush of water laden with debris from the mountains did not take the course of the river but instead spilled over and took over the flood plain where the city was.

Lagmay called the flash flood that devastated Iligan City a “hyperconcentrated flood” that was not only high velocity, but also high in volume. The surge of water coupled with erosion caused the massive destruction in the city.

The flash flood, Lagmay said, was “like a tsunami, but with more debris.”

However, the geologist added that while logging might have worsened the damage, the primary reason for the flash floods was the heavy rains.

“Logging—may it be legal or illegal—may have aggravated the floods, but the primary reason for this was the extreme rainfall brought about by Sendong,” Lagmay said.

Data from Iligan City’s Social Welfare and Development office showed that as of Dec. 28, 456 were reported to have died and 466 still missing in Iligan City alone, with 863 injured, according to Lagmay.

Lagmay showed a picture of Orchids Home subdivision in Santiago town during his presentation to highlight the destruction caused by Sendong. The subdivision was a village with concrete houses until the flash floods reduced everything to rubble.

He warned that after this disaster, Santiago and other affected areas should not be occupied again.

“If the same thing were to happen 10, 20 years from now, the damage will be much bigger,” he said.

Lagmay’s team identified the town of Sta. Elena as a possible resettlement area because of its geographic location. The town lies south of Iligan City and was not damaged during the storm.

“It appears to be all right, although we still recommend that geohazard mapping still be made regarding the area,” he added.

However, the geologist also said the Iligan City government has already chosen another yet undisclosed relocation site.