DAVAO ORIENTAL— To ensure the structural integrity of the Aragon Dam in Cateel town that is known to be Mindanao’s biggest irrigation system, the Office of the Provincial Engineer Office reminds the public and the nearby communities to be vigilant over illegal quarrying downstream and protect the surrounding forests and watershed.
Engineer John Christopher Algallar of the PEO recently presented to the media the technical data on the Aragon Dam during the “Kapihan sang Kapitolyo” at the Capitol’s Grand Conference Room
“Every year, during rainy season, Aragon Dam always cause an alarm in the nearby communities in Cateel town. So, it is very important to make the people aware of the status of the dam so that it will not cause unnecessary panic and alarm,” he said.
NO TO QUARRYING DOWNSTREAM
Despite that there have been no reports of quarrying downstream, he appealed to the concerned authorities not to allow quarrying downstream of the Aragon Dam. He also called on the people to always be aware and vigilant against those who illegally quarry gravel.
Although the structural integrity of the dam strengthens overtime, he reminded that quarrying downstream poses a huge threat that could cause the dam to fail. Algallar explained that the scouring of gravel downstream will eventually cause the degrading of the riverbed resulting in the eventual breakdown of the structure which is built atop the riverbed.
“Quarrying downstream will likely cause the failure of the dam especially when there is an uncontrolled rising of water levels,” he said. “If there is constant quarrying downstream, the riverbed will not be replenished. We can only allow it upstream,” Algallar added.
CLOSING THE FLOOD GATES IN TIMES OF FLOOD
Meanwhile, contrary to the popular belief that flood gates are ought to be opened when the water level rises, Algallar explained that in times of flooding, the floodgates should remain closed. “Opening of the gate will just create a vacuum and turbulence. Also, we need to close the gate so that debris from upstream will not be carried downstream which often causes the damage to the structure,” he explained.
However, the PEO assures the strength and durability of the dam. Known as the biggest irrigation system in Mindanao in terms of its impounding capacity, the Aragon dam consists of five ogee-type gates that overflows on both sides with a spill-over in between. The Aragon Dam was designed to withstand an elevation of 21.6 meters. Also, the weight of the dam is what makes the entire structure more solid, Algallar explained.
“Also, the fact that it is an ogee dam with a draining wall, water will just flow smoothly as there will be no sudden change in elevation and the pressure is constant,” he said.
Algallar further called on the nearby communities to preserve the watershed upstream so that water discharge is minimal.
“The drainage coefficient is reliant on the vegetation. That’s why it is very important preserve the watershed upstream to prevent high water levels,” he added.
The Dam, which has been operating for five years has been serving large swathes of rice fields of Cateel. However, based on the PEO’s flood susceptibility map, the areas that benefits from it are also susceptible to floods. These are Barangays Aragon, San Alfonso, Taytayan, San Miguel, and San Vicente.
Meanwhile, Algallar is advising communities living nearby Aragon Dam not to panic over possible water overflow. Instead, they are reminded to raise their awareness for their safety.
In times of heavy rain and flooding, the PEO advises the residents to follow evacuation protocols as per advised by the authorities.
Based on the Aragon Dam Emergency Information, Alert Level is raised at 19 meters. When the water level reaches 20 meters, a Warning Level is raised. At 21 meters, nearby communities are advised to evacuate. With reports from Riza M. Golez /Photos by Eden Jhan Licayan
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