Flood

A phenomenon in which the river water level rises high for a certain period of time, then falls, in which: a) Historical flood is a flood with a peak rarely seen during the observation period or obtained through surveys; b) Exceptionally large flood is a flood with a peak rarely seen during the observation period; c) Abnormal flood is a flood occurring before or after the flood season or a flood formed due to heavy rain occurring in a small area, reservoir discharge, dam failure, dam overflow, dike failure, or dike overflow.