THE recent flooding in several communities in Metro Cebu may lead one to assume that rainfall has been unusually heavy, but weather bureau monitoring shows that levels remain below normal.
The Philippine Atmospheric, Geophysical and Astronomical Services Administration (Pagasa) has a 30-year historical data that monitors rainfall levels and patterns in the Visayas.
In an interview on SunStar Cebu’s “Beyond the Headlines,” a news and public affairs digital program, engineer Al Quiblat of Pagasa Visayas explained that heavy rainfall patterns are not unusual and recur almost every year.
He noted that the real change lies in the condition of the environment, particularly inadequate drainage systems and the reduced ability of upland areas to absorb water, which has lessened the capacity of waterways.
“Flooding has become more frequent not because of record-high rainfall, but because our waterways and drainage systems have lost capacity. Our uplands no longer hold water as they used to,” Quiblat said in Cebuano.
Why floods hit Cebu despite low rain
Even with rainfall levels below historical averages, Cebu is experiencing frequent and severe flooding. This is not due to a change in weather patterns, but rather a weakening of
Cebu’s infrastructure and environment, Quiblat said.
Breaking down the problem
For two consecutive months, July and August, rainfall in Cebu has been below normal. According to Quiblat, the amount of rain is 50 percent lower than the 30-year historical average. In climatological standards, rainfall is considered “normal” when it reaches 80 percent of the monthly average.
The role of infrastructure and the environment
Quiblat stressed that while rainfall levels are not unusual, the environment’s ability to handle that rain has been significantly reduced.
Weakened drainage systems: The capacity of waterways and drainage systems has decreased, making them more prone to overflowing. This means that even a typical amount of rain, like the 10 mm per hour seen during thunderstorms, can overwhelm the system.
Reduced water absorption: Upland areas that once absorbed large amounts of rainwater have lost that ability with more developments and paving of roads and walkways. This leads to more runoff flowing into lower-lying areas, contributing to floods.
Recent flood events
Recent rains, influenced by the southwest monsoon, have caused significant disruptions across Metro Cebu.