Rivers fluctuating

AQA Water on land 5.3... from the AQA Geography A textbook GCSE. 

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How and why does the water in a river fluctuate?

Discharge - The volume of Water in a river and the speed it is flowing. It is measure in cumens m^3 per sec.

The River System

The River System is part of the Hydrological cycle operating on land, it is made up of 4 key parts:

1) Input - Water entering the system through precipitation 

2) Stores - water stored in lakes trees rocks soil or vegetation. Storage can be temperary and is linkewd to the amount of precipitation.

3) Transfers - Processes that move the water through the system such as, surface runoff, infiltration and undergroung flow.

4) outputs - Where the water is lost to the system either to the sea or through evaporation. 

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How and why does the water in a river fluctuate?

A Hydrograph shows how a river responds to a period of rainfall.

A High peak and a short lag time show the river responds to precipitation quickly 


A lower peak and a short lag time shows a delayed hydrograph.

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How and why does the water in a river fluctuate?

Hydrograph - Precipitation (mm) and run-off/discharge (cumecs) over time (http://www.bbc.co.uk/scotland/learning/bitesize/higher/geography/images/hydro_01hydrograph.gif)

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How and why does the water in a river fluctuate?

Factors affecting Discharge 

  • The amount of precipitation 
  • Temperatures affect the lose of water due to evaporation 
  • The rock in the river depends how much water infiltrates.
  • The Discharge increases a couple of days after it has rained because it takes time for the water to reach the river
  • Previous weather conditions affect it due to the ground absorbing the water if it has been dry and therefore not much water getting to river, but if it has been raining and the ground is saturated then the water will run off to the river. 
  • Objects that restrict the water getting to the river eg buildings and trees (deforestation and urbanisation) 

Key Words: Deforestation and urbanisation 

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