MANILA – Residents along the Tullahan River in Luzon are facing the possibility of being flooded again if the La Mesa Dam overflows due to the onslaught of typhoon "Rolly" (international name Goni).
"Downpour from Rolly can raise La Mesa's water to the spilling level so those communities must prepare for this eventuality," said Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) hydrologist Edgar dela Cruz on Friday.
If La Mesa reaches such a level, he said its water will just overflow and spill into the Tullahan River and the surrounding communities.
"Such happens because La Mesa has no gate to control its water flow," he said.
Dela Cruz said if inclement weather looms, La Mesa can request to receive less water from Ipo Dam.
"That'll somehow control (the) flow of water into La Mesa," he said.
Even with such precaution, however, he said tropical cyclones like Rolly can still bring rain that will raise La Mesa Dam's water to the spilling level.
He said rain during 2009's storm "Ondoy" (Ketsana) did so and caused La Mesa Dam to overflow.
Such overflow resulted in the flooding of communities along the Tullahan River, he noted.
The Tullahan River is among the major waterways in Metro Manila.
The river begins in Quezon City and flows down to Valenzuela and Malabon cities before discharging into Manila Bay.
The government is cleaning up the Tullahan River to declog this waterway, improve water quality, and facilitate the flow of water.
As of 6 a.m. Friday, PAGASA reported La Mesa's water level at 79.20 meters, just 0.95 meters below the 80.15 meters spilling or normal high water level.
"Too much rainfall from Rolly can cause La Mesa to overflow," said dela Cruz.
He urged communities along the Tullahan River to monitor government reports about Rolly and La Mesa Dam.
In its 11 a.m. severe weather bulletin on Friday, PAGASA located Rolly at 1,100 km east of Central Luzon. It was moving westwards at 15 kph with maximum sustained winds of 165 kph near its center and gustiness of up to 205 kph.
PAGASA expects Rolly to make landfall in the Aurora province-Quezon province area on either Sunday evening (Nov. 1) or early Monday morning (Nov. 2) at an estimated peak intensity of 175 kph to 185 kph. (PNA)
