Which statement best describes a hydrograph?

Which statement best describes a hydrograph?

• A. A representation of runoff over time
• B. A measure of rainfall intensity
• C. A diagram of sediment deposition
• D. A chart of groundwater levels

Answer: (A)

A hydrograph shows how runoff from rainfall changes a stream’s flow over time. It plots time on the horizontal axis and discharge (the rate of water flowing in the stream) on the vertical axis, illustrating how quickly rainwater runs off and into the channel, reaches a peak, and then recedes as runoff diminishes and baseflow returns. This timing and shape—how fast the flow rises, how high the peak is, and how long it takes to return to normal—are key for understanding flood response and for sizing sediment and erosion-control measures. It’s different from a rainfall diagram (which shows rainfall intensity over time), a diagram of sediment deposition, or a chart of groundwater levels.

A hydrograph shows how runoff from rainfall changes a stream’s flow over time. It plots time on the horizontal axis and discharge (the rate of water flowing in the stream) on the vertical axis, illustrating how quickly rainwater runs off and into the channel, reaches a peak, and then recedes as runoff diminishes and baseflow returns. This timing and shape—how fast the flow rises, how high the peak is, and how long it takes to return to normal—are key for understanding flood response and for sizing sediment and erosion-control measures. It’s different from a rainfall diagram (which shows rainfall intensity over time), a diagram of sediment deposition, or a chart of groundwater levels.