Retired vice admiral Alexander Pama, chief of the National Disaster Risk Reduction and Management Council (NDRRMC), on Monday noted a rise in water levels of three of Luzon’s major dams because of continuous rains. He, however, allayed fears that rising water levels would result in an overflow.
Pama said water in Ambuklao and Binga dams in Benguet and Magat dam in Ifugao and Isabela are released occasionally.
“The good news is that none [of the dams]is in danger,” he added.
As a result of heavy rains brought by Typhoon Lando (international name: Koppu), the water level in Angat dam has risen to 201.5 meters, or 8.5 meters short of its normal high water level of 210 meters.
Metro Manila gets 90 percent of its water supply from Angat dam.
Water level in the dam can further rise early this week after surging by almost seven meters during the weekend.
“We expect Angat’s water level to rise by one to two meters more around Tuesday [October 20],” said hydrologist Jun Paat from state weather agency Philippine Atmospheric, Geophysical and Astronomical Services Administration (Pagasa).
He added that the typhoon was already moving away from Angat watershed but traces of rain from this typhoon and runoff from its downpour this week will still feed the dam, raising water level there.
The rise will bring Angat’s water even closer to the desired 210 meters flood season high water level (FSHWL) there, Paat noted.
What is ideal is for Angat water to reach at least such FSHWL by year-end to help ensure availability of this dam’s water for use the following year, he said.
Paagasa reported Angat’s 6 a.m. water level on Monday surged to 201.58 meters, up 6.98 meters from the 194.60-meter elevation the agency monitored there 24 hours earlier.
“Angat watershed received an estimated 230 millimeters of rain from [the typhoon]during the weekend so water in the dam rose considerably,” Paat said.
Data from Pagasa indicate that Angat dam still needs 320 mm of rainfall so water there can further rise from its level on Monday morning and reach the FSHWL.
Despite increase in Angat’s water reserve, Paat said water conservation must continue as the strong drought-driving El Nino phenomenon is still in progress and forecast to last until mid-2016 aside from possibly intensifying further.
“What happened in Angat is just a temporary reprieve so we must use water wisely,” he added.
Paat noted that Angat loses water because of evaporation, which can intensify during El Niño.
The water level in Pantabangan dam has increased to 199.84 meters, which is still below the 216-meter target level.
Three of Magat dam’s seven gates were opened as the river continued to overflow on Sunday.
As a result, the Cagayan River swelled, causing flooding.
As of 5 p.m. on Sunday, Magat dam reservoir elevation reached its critical and spilling level of 193.47, which is 17.47 meters higher that its normal water level of 175 meters.
According to the National Irrigation Administration-Magat River Integrated Irrigation System (NIA-MRIIS), the water inflow was at 2,238 cubic meters per second and it had to release the same amount of water per second, opening five units of the spillway (radial) gates with a total opening of nine meters.
The Office of the Civil Defense in Region 2 said there are 10 barangay (villages) that have been submerged in Tuguegarao City on Monday as a result of the water releases from the Magat dam.
Wilfredo Gloria, department manager of NIA-MRIIS, said the swelling of the dam’s major sources like the Ibulao River in Ifugao and the Magat River in Nueva Vizcaya was caused by heavy downpour brought about by Typhoon Lando.
Gloria added that as of Monday midnight, Magat dam’s reservoir elevation has reached 193.45 meters slightly above its critical and spilling level with an inflow of water at 2,272 cubic meters per second.
“This level necessitated a big volume of water release at 4,206 cubic meters per second by opening seven units of spillway [radial]gates with a total opening of 16 meters,” he said.
Civil Defense regional officer Dan Villamin said the continued release of water from the Magat dam contributed to the swelling of the Cagayan River, which has now reached its critical level, flooding low-lying communities along the river in Cagayan province.
According to Villamin, there are 1,729 families or 6,678 persons who are affected by floods in the province of Cagayan as a result of the release of water from the Magat dam.
He said that the number will still increase because of continued rising of the water level at the Cagayan River, which has already reached its critical level particularly at the Buntun Bridge in Tuguegarao.
“Thousands are still stranded in Cagayan and Isabela provinces due to the closure of overflow bridges,” Villamin added.
He said only one lane is open from Cadcadir to Cabugao as well as the Cagayan-Apayao road because of landslides.
Villamin added that on Monday, the Nagtipunan, Quirino-Aurora Province road is still closed,also because of landslides.
In Apayao province, provincial administrator Vincent Talatag said there because of flooding.
Talatag added that the Calanasan-Claveria, Cagayan road is also close, also because of landslides.