Once the amount of rainfall reaches 10 mm, flood and landslide warnings will be issued to avoid accidents and damage in Cebu, the Mactan office of the state weather bureau Pagasa said yesterday.
Mactan Pagasa weather bureau chief Oscar Tabada said they have set up an early warning system following the unusual volume of rainfall experienced in Cebu and Central Visayas last Tuesday and Saturday.
“If our rain gauge records at least 10 millimeters (mm) of water with continuous rains in 30 minutes, we will issue warnings on possible flooding and landslide for everybody’s awareness,” Tabada said.
The warning will be issued to different media outlets and government agencies, Tabada added.
A “threshold or risk value” of 23.7 mm of rainfall was established as the ceiling, he said.
“At this rate, flooding or landslide would have already occurred. So our warnings will be given as early as recording of 10 mm of rainfall for people to have time to prepare,” Tabada said.
Based on Pagasa’s climatological normals from the year 1981 to 2010, the heaviest rainfall recorded in one day for September is 97.3 mm.
But Tabada said last Saturday’s heavy rains that caused drainage overflow at the Mactan Cebu International airport domestic arrival baggage counter set a new record at 100.1 mm.
Tabada clarified this wasn’t the first time the airport experienced above normal rainfall causing floods.
Mactan Pagasa’s complex station climatological extremes chart of 2010 said rainfall that occurred in Jan. 8, 1999 registered a volume of 126.2 mm which caused knee-deep flooding within the airport. “I cannot forget that time because we were also affected since our office was still inside the airport then,” Tabada said.
The Pagasa office is still located within the airport property but in a separate parcel right before reaching the first airport security checkpoint.
That same chart registered the all-time largest volume of rainfall ever recorded back in November 12, 1990 when rainwaters reached 276.1 mm.
Tabada said Metro Cebu officials should re-design their drainage systems to cope with the ever rising volume of rainfall.