The narrow, shallow Pantal River cause flooding in city–DPWH
THE government’s engineering office offered a more plausible explanation for the unusual and frequent flooding in Dagupan City these days.
Engineer Rodolfo Dion of the Second Highway District of the Department of Public Works and Highways (DPWH) explained that the incessant flooding in Dagupan City is caused by spillover of water from the now heavily silted and narrower Pantal River during typhoons.
His explanation debunked the claim of Mayor Benjamin Lim and City Administrator Vladimir Mata that the flooding is a result of the construction of the Jose R. De Venecia Expressway Extension and the back-filling of fishponds in Lucao.
Dion, speaking at the first outside session of the Sangguniang Panlungsod (SP) in the island Barangay of Salapingao on October 24, said the Pantal River is now too shallow and narrow to carry the water flowing from upstream when it rains.
The Pantal River is connected to the Sinocalan River where all the water of the Toboy and Tagamusing Rivers in San Manuel and Binalonan, and the Mitura River in Urdaneta flow before exiting to the Lingayen Gulf.
Dion accompanied the SP led by Vice Mayor Belen Fernandez on an ocular inspection of the Pantal River from Barangay Pugaro and Salapingao all the way up to the Dagupan-Calasiao boundary by motorboat and pointed out how narrower the river has become when compared to the length of span of the Magsaysay Bridge.
The Magsaysay Bridge, spanning across the Pantal River at 193 meters from abutment to abutment, was constructed by the Italian company Foundation Specialists in 1992 after the 1991 earthquake that devastated Dagupan.
“Look how wide the river is now. It is not even one-third of 193 meters,” Dion said.
SILTATION & ACCRETION
Dion also cited the structures that sprouted over the years in the eastern and western banks of the river.
The DPWH official also revealed that the river did not go through any dredging for the past 50 years to clear the bottom of mud and garbage that have accumulated from upstream that resulted in heavy siltation in the area.
He also pointed out that as the mud gathers in the riverbanks, many have taken advantage of the accretion and applied for foreshore lease agreements with government agencies.
“Consequently, the accreted areas were annexed by private individuals from where they built permanent structures like buildings and warehouses,” Dion said.
He said that since river can no longer carry the heavy volume of water cascading through it, the excess volume will have to find its way in other tributaries and shallow area.
“This is what’s happening to the recurring floods in Lasip, Caranglaan, Malued, Lucao, Tebeng, Mangin, Salisay and many other areas in southern Dagupan,” he added.
The city council likewise noted that the river is now only less than seven feet deep in the area of Barangay Pantal and only three feet deep in Barangay Banaoang, Calasiao.
LONG-TERM SOLUTION
Dion told the SP that the long-term solution to the flooding is an intensive dredging of the Pantal River from its mouth to the boundary of Calasiao, while a parallel dredging should also be done from Sta. Barbara to Calasiao which is under the DPWH Third Engineering District.
The dredging, he said, should be done for six hours daily and continuously for about one year.
Dion admitted that this solution will entail huge resources and time.
The DPWH already has a dredging machine stationed in the Calmay River that will need about 200 liters of fuel per hour at a cost of about P10,000.
The recovery for one hour work is at least 1,000 cubic meters which is equivalent to 40 to 50 dump trucks.
At the same time, Dion suggested the creation of an inter-agency body that will address the retrieval of portions of the Pantal River illegally annexed by private individuals.
Asked if the drainage canals can help abate the flooding, Dion said these structures can only address the outflow of rainwater but not the flood spawned by the overflow of water from the Pantal River.
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