DREDGING the lower part of the Cagayan River will save the province of Cagayan from severe floods, Department of Environment and Natural Resources (DENR) Secretary Roy Cimatu said, adding that this has already been approved by President Rodrigo Duterte.
Based on a study conducted by government geologists, according to Cimatu, at least 30 kilometers from the mouth of the Cagayan River in Aparri town or up to Lallo and Alcala towns would need dredging to mitigate a repeat of severe flooding brought by Typhoon “Ulysses” in the province last week.
Described as the “worst” flooding in Cagayan since 1972, Cagayan province was submerged in water late Friday night, killing more than a dozen people and affecting over 300,000 others and destroying more than P1 billion worth of crops, livestock and property and infrastructure.
Last Wednesday, continuous heavy downpour caused the Cagayan River to swell, failing to accommodate water flowing from its more than 20 tributaries that eventually resulted in massive flooding and landslides in Region 2 (Cagayan Valley), particularly in Isabela and Cagayan.
“When dredged, the Cagayan River will improve the volume of water that the river can accommodate,” Cimatu, who was with Duterte on Sunday in Tuguegarao City, said.
The Cagayan River, known as Rio Grande de Cagayan, is the longest river and largest river
by discharge volume of water in the Philippines with a total length of approximately 505 kilometers.
The river has a drainage basin covering 27,753 square kilometers and flows north to its mouth at the Babuyan Channel near the town of Aparri.
It traverses the provinces of Nueva Vizcaya, Quirino, Isabela and Cagayan.
If the river down to its bottleneck cannot be widened, Cimatu said, at least it should be dredged to deepen it.
He cited a 1987 Japan International Cooperation Agency report that recommended the widening of the river channel from the town of Alcala to Lallo.
The Mines and Geosciences Bureau (MGB), which had conducted a geo-hazard mapping study, also recommended the dredging of the “heavily silted” Cagayan River “to avoid further erosions.”
Felicitas Piligan, MGB senior geologist, years ago alerted concerned Cagayan local government units on the river’s siltation that prevented the flow of water when there were flash floods.
“During the mapping, we warned affected communities based on initial results of an assessment conducted in their areas which parts were vulnerable to landslides and floods,” she said.
Piligan added that every time there was a storm coming, the MGB repeatedly warned communities and local officials to relocate to higher grounds and set up evacuation centers.