Floods can be categorized into slow-onset floods, rapid-onset floods, and flash floods. The categorization is made based on the time period for which the flood lasts. Therefore, the difference too is essentially in the time period for which these floods last. A slow onset flood usually builds over a period of time, and is caused usually by water overflowing from a dam, etc. This kind of flood takes its time to arrive, and also stays on for a long period of time. People have time usually to evacuate, and this means that there is more damage to property than to life. A slow-onset flood can stay on for at least a week, and the flooding can remain for even months at a time, sometimes.
A rapid-onset flood comes in more rapidly than a slow-onset flood. It lasts for a shorter time period, usually a day or two. Sometimes the flooding may continue for a week. Since it sets in rapidly, the damage to people, livestock, and property is more as people do not have enough notice to be able to prepare for evacuation. Of the three types, flash floods cause the most damage, as they arrive, literally, in a flash, sometimes in as short a time period as a mere few minutes, and can last for a maximum for a few hours. It happens usually after a dam bursts, or due to excessive rainfall, a storm, etc. The damage is caused as people do not get time to evacuate, usually.
A rapid-onset flood comes in more rapidly than a slow-onset flood. It lasts for a shorter time period, usually a day or two. Sometimes the flooding may continue for a week. Since it sets in rapidly, the damage to people, livestock, and property is more as people do not have enough notice to be able to prepare for evacuation. Of the three types, flash floods cause the most damage, as they arrive, literally, in a flash, sometimes in as short a time period as a mere few minutes, and can last for a maximum for a few hours. It happens usually after a dam bursts, or due to excessive rainfall, a storm, etc. The damage is caused as people do not get time to evacuate, usually.
