A recent study by scientists from the University of the Philippines (UP) in Diliman, Quezon City, identified extreme rainfall as the main trigger of the flash floods during typhoon Tino on Nov. 4, 2025.
The study is useful, but it also raises more questions, particularly on policy, infrastructure and governance. What the study does accomplish is to introduce science into a conversation that has often been emotional and political. But once the science is presented, other important questions remain.
The analysis by the UP Institute of Environmental Science and Meteorology (IESM) showed that the Cebu flash floods were not caused by a single factor. They were a result of several factors: an unusually intense rainfall, rapid water runoff from the uplands, urbanization that reduces the land’s ability to absorb water and the limited capacity of drainage systems and river channels.
The science part said typhoon Tino dumped 428 millimeters of rain within 24 hours. By comparison, typhoon Ruping in 1990 brought about 276 millimeters of rain. Also, during Tino, the soil quickly became saturated. Once that happened, the ground could no longer absorb additional rainfall and the water rushed downstream. This led to rapid runoff into the Guadalupe and Kinalumsan river basins. In other words, the study concludes that the trigger was extreme rainfall across the watershed, not a single land development.
Using advanced computer modeling, the researchers also simulated the effect of specific upland developments. In particular, the study examined the Monterrazas de Cebu development and its relationship to the Guadalupe and Kinalumsan watersheds. It found that water from the Monterrazas site remains within its watershed. The project also uses detention ponds or large basins designed to collect rainwater and release it slowly. According to the model, these ponds reduced peak runoff by 70 percent to nearly 100 percent.
These findings help explain why the flash floods happened. But they also open new questions.
For one, did the flood control projects work? Between 2016 and 2025, Cebu received about P17.4 billion for flood control projects. Whether those projects actually performed as intended during typhoon Tino is a question entirely separate from whether rainfall was extreme.
How about the other areas and rivers affected by the flash floods? How about the Butuanon River?
Extreme rainfall does not automatically make a disaster inevitable. Cities around the world experience intense storms. The difference is that some places have infrastructure, planning and preparedness that reduce the damage. Others only begin discussing these after the disaster has already happened.
The real question, then, is this: How resilient are Cebu’s watershed and urban systems? If typhoon Tino represents the new normal, Cebu must rethink how it manages water from upland forests to urban drainage.
Scientific findings can easily be misused in public debate. The danger now is that the phrase “extreme rainfall” becomes a convenient explanation that ends the conversation about who failed Cebu during typhoon Tino.
That conversation should continue.