P1A 03 Flood Hydrograph Interpretation: Study Guide

Front

What is a hydrograph?

Back

A graph showing the variation in river discharge over time, usually in response to a rainfall event.

Front

What is a storm/flood hydrograph?

Back

A specific type of hydrograph that illustrates the river's response to a particular rainstorm, showing rainfall and corresponding discharge.

Front

What is lag time in a hydrograph?

Back

The time difference between the peak rainfall event and the peak discharge of the river.

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What is peak flow/discharge?

Back

The highest rate of water discharge reached by the river during or after a storm event.

Front

What is storm flow?

Back

The portion of river discharge that comes from surface runoff and rapid through-flow after a rainstorm.

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What is baseflow?

Back

The portion of river discharge derived from groundwater flow, which sustains river levels during periods without rainfall.

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What is the rising limb of a hydrograph?

Back

The initial part of a hydrograph where river discharge is increasing. Its slope indicates the speed of the discharge increase.

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What is the recessional limb of a hydrograph?

Back

The part of a hydrograph where river discharge is decreasing, showing how quickly the floodwaters are receding.

Front

What is bankfull discharge?

Back

The discharge level at which the river is at the top of its banks. Exceeding this level leads to flooding.

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What is a catchment area/drainage basin?

Back

The area of land where precipitation collects and drains into a common outlet, such as a river.