What is a 'flood hydrograph'?

A flood hydrograph is specifically defined as a graph showing how river discharge or flow changes over time, particularly in response to precipitation events such as rainfall. It illustrates the relationship between rainfall (input) and river discharge (output), emphasizing how quickly water enters the river system and how this affects flow levels. The hydrograph typically displays time on the horizontal axis and discharge on the vertical axis, allowing one to see the rise and fall of river levels following rainfall, including peak flow and the duration of a flood event.

The other options may relate to hydrological studies but do not capture the specific focus and purpose of a flood hydrograph. For example, charts depicting seasonal rainfall changes focus on precipitation patterns rather than river discharge. Methods for measuring flood risks pertain to assessing potential hazards rather than visualizing actual river flow changes over time. Templates for predicting flood damage involve estimating impacts and are unrelated to the graphical representation of discharge. Thus, option B accurately encapsulates the essence of what a flood hydrograph represents in the context of river management and flood studies.