Freshwater in Average Year

Runoff is closely linked to rainfall and soil moisture since rainfall onto saturated soil leads to high runoff. Similarly rainfall onto an impervious surface (such as paved roads) also leads to runoff and urbanisation is often seen as increasing runoff.

Runoff is important to consider because it is linked to where water is flowing. Rainfall or melting snow/ice flows downwards either over the land surface or into the soil. The timing of rainfall or snowmelt is also important because a heavy rain shower occurring over a short period of time causes high runoff which can lead to flooding.

Also it is important for habitat development because changes in soil moisture means a particular region will not be able to sustain its habitat. By comparing a given month over a number of years extreme events can be detected, if the frequency of extremes events increases (such as floods or droughts) then changes in habitat are to be expected.

  1. Average freshwater for Jan
  2. Average freshwater for Feb
  3. Average freshwater for Mar
  4. Average freshwater for Apr
  5. Average freshwater for May
  6. Average freshwater for Jun
  7. Average freshwater for Jul
  8. Average freshwater for Aug
  9. Average freshwater for Sep
  10. Average freshwater for Oct
  11. Average freshwater for Nov
  12. Average freshwater for Dec
  1. Map of average freshwater for January 1985 - 1999

    Runoff is lower in high latitudes due to frozen soil water, and high in equatorial regions.

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  2. Map of average freshwater for February 1985 - 1999

    Equatorial regions experience highest runoff.

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  3. Map of average freshwater for March 1985 - 1999

    Equatorial regions experience highest runoff

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  4. Map of average freshwater for April 1985 - 1999

    Start of Asian Monsoon period bringing rain to China, SE Asia & India.

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  5. Map of average freshwater for May 1985 - 1999

    End of rainy season in South America.

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  6. Map of average freshwater for June 1985 - 1999

    Higher runoff in high latitude regions because of Snowmelt & thawing.

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  7. Map of average freshwater for July 1985 - 1999

    Glacier melt and monsoon rains cause high runoff in Indian subcontinent region.

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  8. Map of average freshwater for August 1985 - 1999

    Runoff in Himalayan region high due to rainfall and snowmelt.

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  9. Map of average freshwater for September 1985 - 1999

    Central and Western Africa start of wet season.

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  10. Map of average freshwater for October 1985 - 1999

    start of rainy season in South America see Amazon basin

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  11. Map of average freshwater for November 1985 - 1999

    Period of transition, localised regions of high runoff

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  12. Map of average freshwater for December 1985 - 1999

    Indonesian region experiences high runoff from wet season.

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Google Earth View

Freshwater Legend (mm/month)

Bargraph referencing the colours on the evaporation maps.

Other Maps

Freshwater Maps