A flash flood is usually caused by heavy, intense rainfall within a short period of time. They come very suddenly and are particularly dangerous for people, as they can sweep everything away and occur unexpectedly

How does a flash flood occur? Simply explained

A flash flood is the presence of too much water so that downstream water systems and the ground can no longer absorb any of it.

• Flash floods are usually caused by sudden heavy rainfall with high intensity within a very short period of time. This quickly becomes a danger, especially in normally dry regions.

• This is caused by heavy rainfall events that cause water levels to rise. The ground becomes saturated within a short period of time, causing the water to run off the surface and sweep everything away as rising flood waves.

• In contrast to other types of flood, flash floods can also occur far away from bodies of water. They usually occur locally and hit small bodies of water.

Floods and storm surges

A flood is a condition in which a certain threshold value of a body of water is exceeded.

• In river floods, it is not the torrential floods that cause damage, but the long periods of standing water and the pollution caused by contaminants. Large areas are usually affected. The duration of the floods ranges from a few days to several weeks. The cause is usually heavy rainfall, which can lead to flooding.

• In addition to these, the soil and vegetation also determine the effects. Saturated, frozen or even sealed soil, e.g. due to cement, cannot absorb the water, which means that too much water collects too quickly in the watercourse, which in turn overflows its banks. Humans also have an influence on flood potential. Settlements, for example, encourage flooding. Areas at risk are primarily those close to the river

• Storm surges, on the other hand, can be found on the coast. Here, strong winds or storms carry the water from the sea over high waves to the land, causing the water level to rise and the land to be flooded. In addition, the so-called spring tide can occur, in which high and low tides are stronger than usual due to the sun-earth-moon constellation.