Hydrographs & Drainage Basins Hydrograph

Hydrographs:

• Hydrographs are graphical representations of river discharge (flow) over a period of time.
• They help us understand how rivers respond to rainfall and snowmelt events.

Hydrographs of Drainage Basins:

Components of a Hydrograph:

• Hydrographs show river discharge (usually in cubic meters per second, m³/s) on the vertical axis and time (hours or days) on the horizontal axis.
• They typically have two main components: rising limb and falling limb.

Rising Limb:

• The rising limb shows how quickly a river's discharge increases in response to rainfall.
• It is steep if the rain is heavy or gentle if it's light.

Peak Discharge:

• The highest point on the hydrograph is the peak discharge, which indicates the maximum flow during the event.

Falling Limb:

• The falling limb shows how quickly the river's discharge returns to its baseflow (normal flow) after the rainfall stops.

Lag Time:

• The lag time is the delay between the peak rainfall and the peak discharge.
• It depends on factors like drainage basin size and shape.

Uses of Hydrographs:

• Hydrographs help predict and manage river flooding, assess the impact of land use changes, and study the response of rivers to climate change.

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Hydrographs & Hydrographs of Drainage Basins

Summary

• Hydrographs represent river discharge over time.
• Components include the rising limb, peak discharge, falling limb, and lag time.
• Hydrographs are valuable for flood prediction and understanding river behaviour.