Watershed degradation abetted flooding, says scientists’ group | Inquirer News

Watershed degradation abetted flooding, says scientists’ group

/ 05:03 AM November 30, 2020

MANILA, Philippines — Unabated quarrying and logging in the Sierra Madre mountain range and other mountainous areas in Luzon have contributed to the disastrous flooding following the onslaught of Typhoon “Ulysses” (international name: Vamco), a scientists’ group said on Sunday.

A rapid research done by the Advocates of Science and Technology for the People (Agham) showed that aside from the excessive amount of rainfall dumped by the typhoon, the degraded condition of watersheds upstream the Marikina-Pasig and Cagayan rivers was also a critical factor in the floods that devastated communities in Marikina City and in the provinces of Rizal and Cagayan.


“If a watershed is no longer healthy, when there are no trees and no vegetation, runoff water can easily travel down from the mountains and toward the rivers and other channels,” Ana Celestial, Agham education and public information officer, said in a online forum.

Not protected

Land conversion and urban expansion also play a role in the worsening state of the country’s watersheds, she said. “Water running off toward the urban areas are blocked by structures, as well as garbage,” she said.


These destructive activities, Agham said, persist despite the protected status of some of the watersheds, such as the Upper Marikina Watershed Protected Landscape.

Three mining companies with mineral processing sharing agreements operate within the protected area in the towns of Baras and Tanay in Rizal province, Agham reported. Their permits were granted in the late 1990s, however, long before the Marikina river basin was declared a protected area in 2011.

Just outside the protected site, 10 quarries with a combined area of 50 hectares were reported to be operational, as of 2019, the group said.

Near Kasiglahan Village, a relocation site in Rodriguez, Rizal, that was heavily inundated during the height of Ulysses, at least six quarries operate in San Isidro, just north of the residential area.

Cagayan River Basin

In northern Luzon, watersheds in the Cagayan River Basin are also threatened by mining and logging, said Agham secretary general Feny Cosico.

While floods can be typical for communities near Cagayan River and its tributaries, deforestation in the Sierra Madre has greatly contributed to the watersheds’ inability to absorb and hold rainfall dumped by the typhoon.

Between 1965 and 1987, widespread deforestation by cronies of the late dictator Ferdinand Marcos have resulted in the loss of 27,000 square kilometers of forests due to timber license agreements.


More than 444,000 ha of forest land, according to Agham, remain under legal commercial, private and community use “under different grants” issued by the Department of Environment and Natural Resources.

Urgent gov’t probe

Following the devastation caused by Ulysses, the government must take urgent action to probe and put a stop to these disastrous activities, the group said.

“Flooding is a natural phenomenon, but with anthropogenic or man-made factors, the hazards become much greater,” Cosico said.

“Stop-gap solutions do not address coping capacity and rooted inequalities … Environmental and socioeconomic analyses must be incorporated in all of the governments’ projects,” she added.

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