River regimes and their controls

Overview

River regime, river with a simple regime and state its control and typical regime of a British lowland river.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   Define a river regime.

   Model answer

   A river regime is the pattern of a river's discharge through the year, normally shown as mean monthly flow.

2. 2

   What distinguishes a simple regime from a complex one?

   Model answer

   A simple regime has one clear high-flow period produced by a single dominant control, while a complex regime has several peaks because different controls act on different parts of the basin.

3. 3

   Give an example of a river with a simple regime and state its control.

   Model answer

   An Alpine headwater fed mainly by snowmelt has a single sharp peak in late spring and early summer as the snowpack melts.

4. 4

   Why do large rivers crossing several climate zones usually have complex regimes?

   Model answer

   Their tributaries reach peak flow at different times of year, and these peaks combine to give more than one high-flow period.

5. 5

   Describe the typical regime of a British lowland river.

   Model answer

   Discharge is highest in winter, when rainfall is high and evapotranspiration low, and lowest in late summer, when plants are drawing heavily on soil water.

6. 6

   Explain why UK river discharge falls in summer even when rainfall totals are similar.

   Model answer

   High temperatures and full leaf cover raise evapotranspiration, so a far greater share of the rainfall returns to the atmosphere before it can reach the channel.

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