What is a flood hydrograph?

A flood hydrograph is a graphical representation of the discharge of a river over time. It shows the rate at which water flows past a specific point in the river and is used to understand the characteristics of a flood.

When it rains heavily or there is another significant input of water into a river, the discharge increases and a flood event begins. This increased discharge is represented by the rising limb of the flood hydrograph. The peak discharge is the highest point on the hydrograph and represents the maximum rate of flow during the flood event. After the peak discharge, the discharge decreases and this recession limb represents the end of the flood event.

Flood hydrographs are important because they provide information about the timing and severity of flood events. This information can be used to identify flood-prone areas, determine the appropriate level of flood protection, and develop flood management strategies.