A NEW scientific study has found that the devastating floods during Typhoon Tino were caused by record-breaking rainfall and "soaked" ground, rather than a single land development. The research, conducted by experts at the University of the Philippines (UP), used advanced computer modeling to understand why Metro Cebu went underwater during the 2025 storm.
The study by the UP Institute of Environmental Science and Meteorology (IESM) labeled Typhoon Tino an "extreme rainfall event." To put it in perspective, the storm dumped 428 millimeters of rain in just 24 hours.
This shattered previous records for the region:
Typhoon Tino (2025): 428 mm
Typhoon Ruping (1990): 276.10 mm
Typhoon Amy (1951): 195.33 mm
When that much water falls in one day, it overwhelms the soil, the rivers, and the city’s drainage systems.
The researchers addressed a common belief: that open grassland always prevents flooding. While soil acts like a sponge, it has a limit.
During Typhoon Tino, the ground became "saturated." This means the earth was so full of water that it couldn't hold any more. At that point, rain falls on grass but behaves exactly like it’s hitting concrete—it just slides off and rushes toward the city.
The study focused on the Monterrazas de Cebu development and how it affects the Guadalupe and Kinalumsan river basins. A "watershed" is like a giant basin where all rain drains into one specific river.
Key Findings on Development:
Localized Impact: Water from the Monterrazas site stays within its own watershed. It cannot flow into other flooded areas like the Butuanon or Mananga rivers.
The Role of Ponds: The development uses detention ponds—large basins that catch rainwater and release it slowly.
Surprising Result: The model showed that these ponds actually reduced peak water runoff by 70 percent to nearly 100 percent. In fact, the flooding in that specific area was two percent less than it would have been if the land were still just open grassland.
While one project isn't to blame, the study did warn about long-term changes across the city. Between 1994 and 2019, Metro Cebu lost about 3.21 square kilometers of greenery every year. Meanwhile, "built-up" urban areas (concrete and buildings) grew by 17.77 square kilometers.
More concrete means water moves faster and has nowhere to sink in, making the entire city more vulnerable to storms.
The UP study concludes that Typhoon Tino’s floods were a "basin-wide" problem driven by nature's intensity. It highlights that while individual developments need to manage their water with tools like detention ponds, the real challenge for Cebu is managing entire river systems as the climate changes and the city continues to grow.