Dipping water in San Roque Dam may hit the 225 meters critical low elevation this week.
Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) hydrologist Adel Duran is not discounting such possibility, noting San Roque Dam has not been receiving much water and is unlikely to immediately do so.
“With insufficient inflow, water in San Roque will likely dip to the low elevation there this week,” she said Monday.
PAGASA reported San Roque Dam’s 6 a.m. water level at 227 meters on Monday, just 2.00 meters above the critical low level.
Duran noted San Roque’s water level has been dipping at an average 0.40-meter recently and expected inflow will unlikely increase dramatically soon so there is possibility for water in the dam to already reach the critical low.
“In the next three days, the watershed where San Roque is may receive rain totaling 25 mm to 30 mm only — that’s not a lot of inflow for the dam,” she said, noting PAGASA forecast below-normal rainfall there this July.
Water levels in Ambuklao and Binga dams are fluctuating so these sister-facilities of San Roque may not yet significantly increase such inflow soon, she continued.
Ambuklao, Binga and San Roque dams comprise the series of cascading dams supporting irrigation and power generation in Luzon.
Water in Ambuklao discharges into Binga which, in turn, releases water to San Roque.
San Roque Dam’s water level is generally low in July but begins rising either later this month or in August, noted Duran.
“That trend in San Roque indicates possibility for water level there to be above its critical low elevation by the end of July this year,” she said.
Forecasting mean rainfall of some 446 millimeters this July over San Roque’s watershed, and assuming a 34 cubic meters per second water allocation there, PAGASA earlier said water level in the dam can rise to nearly 239 meters by this month’s end.
PAGASA also forecast near-normal rainfall over San Roque watershed this August and September.