Flood refers to flood of water moving in the land area that is normally not under water. As a result of flooding, many areas can become flooded where water is anything but hoped for. For example flooding of a river may bring so much water onto a road that it becomes impossible to drive on the road with a car. Flood water can also move to basements of buildings.
Flooding is generated in several ways. The most common reason is melting snow in the spring. Melting water brings the surface of the water higher in rivers and causes problems. Ice dams are another cause of problems as they can rise the water levels much higher than normal, locally. There have been many different ways of trying to explode or dig open ice dams, but the solutions are usually not easy.
Rivers can also flood after long and heavy rain and floods can be either fast or slow. There are many places in the world where volcanoes can melt snow very quickly and therefore cause flooding, not to forget severe wind that can push water from the sea to inland.