A flash flood is a rapid flooding of geomorphic low-lying areas – washes, rivers and streams. It is caused by heavy rain associated with a thunderstorm, hurricane, or tropical storm. Flash flooding occurs when the ground becomes saturated with water that has fallen too quickly to be absorbed. The runoff collects in low-lying areas and rapidly flows downhill. The weather bureau said that the 5 day rains in Q3 2009 were triggered by Typhoon Morakot, which was moving away from the Philippines toward Taiwan.

Flash floods in the Philippines recently have caused immense distress in the Gupaya region in Southern Philippines. Many people had lost their homes or had their homes significantly damaged. This has caused many problems one of which was access to food. Sacks of rice were procured and provided to feed hundreds of people in Gupaya.