Flooding occurs most commonly from heavy rainfall when natural
watercourses do not have the capacity to convey excess water. However,
floods are not always caused by heavy rainfall. They can result from
other phenomenon, particularly in coastal areas where inundation can be
caused by a storm surge associated with a tropical cyclone, a tsunami or
a high tide coinciding with higher than normal river levels. Dam
failure, triggered for example by an earthquake, will result in flooding
of the downstream area, even in dry weather conditions. |