MANILA, Philippines — Many speculations surfaced as to the massive flooding that submerged portions of Marikina and Pasig during the onslaught of Typhoon Ulysses.
Department of Science and Technology (DOST) Undersecretary Renato Solidum explained in an interview with UNTV on Friday (November 29) what could have caused the deluge in Marikina and Pasig despite the fact that the volume of rains brought by Typhoon Ulysses was lesser than that of Typhoon Ondoy in 2009.
“Ang source ng tubig pagdating sa baha sa Marikina-Pasig river ay iyong ulan mismo na tatama sa Sierra Madre [The source of floodwater in Marikina-Pasig river would have been the rainfall that will hit the Sierra Madre],” said Solidum, who is also the Director of the Philippine Institute of Volcanology and Seismology (PHIVOLCS).
“Talagang hiwalay po ang rivers na nag-de-drain sa Marikina River at sa Angat. In fact, usapin na rin ito noong panahon ni Ondoy. Kung matatandaan ninyo, ganoon din ang mga usapin pero hiwalay po talaga sila,” he added.
[Marikina River and Angat drain into two separate directions. In fact, this was the same issue during Ondoy. If you recall, this was the same issue but they are separate.]
Solidum explained that the water that is being released from Angat Dam usually flows towards Bulacan specifically the towns of Norzagaray, Angat, Bustos, San Rafael, Baliwag, Plaridel, Calumpit, Hagonoy, and Paombong; not, and never will reach, Marikina City.
National Power Corporation (NAPOCOR) Dam Manager Engr. Conrado Sison Jr said they always make sure that the process of releasing excess water in dams is under careful control because they have to maintain a sufficient water supply for irrigation in view of the dry season.
“Hindi tayo basta-basta nagpapakawala ng tubig dahil iyan po ay mahalaga din po sa atin [We do not just release water considering its value],” he said.
“Kung nagkaroon tayo ng premature spilling din tapos wala ng darating na ulan parang tinapon lang natin yung tubig which is alam naman natin lalong lalo na dito sa area na ito eh kailangan din naman para sa domestic water supply at irrigation [If we there was premature spilling without expecting another rainfall, it’s like wasting water that could have been used for domestic supply and irrigation],” he added.
USec. Solidum believes that man-made activities could have worsened the situation like deforestation, uprooting of trees and quarrying that resulted in landslides and flash floods.
“Madami na pong mga subdivision o settlement sa taas ng Marikina for example sa Rodriguez Rizal, San Mateo na ang epekto po nito imbes na yung tubig ulan pumasok sa baba sa lupa. Ito po ay gagapang ng mabilis kasi sementado na, aspaltado na at didiretso nang mas mabilis sa ilog,” Solidum said.
[There are a lot of subdivisions or settlement areas right above Marikina. For example, in Rodriguez and San Mateo in Rizal, the soil could no longer absorb the rainwater because the roads are already cemented. The water would tend to rapidly flow to the river.]
“Ngayon iyong mga ilog hindi rin nababawasan ang lalim. Nagsi-silt po iyan dahil sa mga baha previously at mga basura. Sa mga factors pong iyan talagang bibilis po ang pagdating ng tubig sa ilog at biglang tataas ang tubig,” he added.
[Also, the depth of rivers do not change. The rivers silted up because of the previous floods and waste deposits. So from those factors, water will rapidly flow downstream and will cause a sudden increase in river water.]
Solidum added that the onslaught of Typhoon Ulysses also coincided with the high tide conditions.
The experts said it is still important at present to work on restoring the rivers into their original carrying capacity and encourage tree planting to help prevent much worse incidents associated with the overflowing of rivers. –MNP (with reports from Val Villaflor)
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