Practices in disaster mitigation in the case of the 2015 Typhoon Koppu debris flows in Nueva Ecija, Philippines

In October 2015, heavy rains brought by Typhoon Koppu generated landslides and debris flows in the municipalities of Bongabon, Laur, and Gabaldon in Nueva Ecija province. Satellite images and clusters of landslides show that most of the rain fell in the Sierra Madre mountains in Nueva Ecija and Aurora provinces. Landslides of rock, soil, and debris then converged in the mountain stream networks where they were remobilized into debris flows that destroyed numerous houses and structures. Approximately 42 million cubic meters of materials were mobilized into debris flows. Accurate forecasts enabled the municipal governments to warn residents to prepare for flooding and landslides. The debris flows occurred during the day, which may have helped to prevent deaths, unlike the 2004 Aurora debris flows which occurred at night, or the 2012 New Bataan disaster that happened very early in the morning. Here, we explain why the Typhoon Koppu debris flows caused no casualties due to mitigation mechanisms that were in place. We feature the people-centered early-warning system embedded in the Pre-Disaster Risk Assessment protocol of the Office of Civil Defense after the 2004 and 2012 debris flow disasters killed 1440 people.