Fluvial floods

A fluvial flood, or river flood, occurs when the water level in a river, lake or stream rises and overflows onto the surrounding banks, shores and neighbouring land. The reasons of the water level rise may be due to the excessive rain or snowmelt. The damages can be significant because the overflow affects small rivers downstream, which can lead to the breaking of dams and dikes; moreover, this brings also swamping of nearby area. The determination of the severity of the fluvial flood is determined by the volume of rainfall in an area; it’s determined in function of the intensity and the duration of the precipitation. Another important factor is the terrain surrounding the river system. Where the terrain is flat, the floodwater tends to rise more slowly and be shallower and it often remains for days. In areas with hills or mountains, floods can occur in very few minutes after a heavy rain; floods drains very quickly and it causes damage due to debris flow. The models used to determine the probability of river flooding, take into account soil and terrain conditions as well as river levels and past and forecasted precipitation (Four Common Types of Flood Explained, s. d.).

Representation of a fluvial flood (Four Common Types of Flood Explained, s.d.)