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Author Topic: How long without rain would it take for the UK to become a desert?  (Read 8884 times)

paul.fr

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or would it be a desert? if not what would it be like?
« Last Edit: 25/03/2008 05:47:32 by Karen W. »


 

Offline Andrew K Fletcher

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The UK rainfall total for 1997 is 1057 mm, 98% of the 1961-90 average; mainland regional totals all fell within the 90-110% range The lowest actual rainfall totals were registered in a zone from the Thames estuary extending well into East Anglia Generally, the lowest percentage rainfall totals were also found in this region, several areas recording less than 75% of the 1961-90 average. By contrast, localities exceeding 115% showed a wide distribution. Within-region rainfall variability was generally substantial and the distribution of rainfall throughout the year was very uneven. January was remarkably dry; Britain registered its lowest precipitation, for the month, in a 138-year record. As significant, from a water resources perspective, the combined December 1996 and January 1997 rainfall total was the second lowest since 1879/80. This intensely dry episode provided fresh impetus to the long term drought. At the beginning of February extreme rainfall deficiencies, in the 22-month timeframe, characterised north-west England and parts of the Pennines; over wide areas the deficiencies were the equivalent of 5-6 months average rainfall. http://www.nwl.ac.uk/ih/nrfa/yb/yb97/review_rainfall.htm
Wising up to water shortages at Hyde Hall
Matthew Wilson, curator, RHS Garden Hyde Hall, spares the hosepipe to produce a sea of drought-tolerant plants.
RHS Garden Hyde Hall is situated in one of the driest areas of the British Isles, with an average annual rainfall of just 600mm (24in). In 1996 only 451mm (17.7in) fell. This is a lower annual rainfall than Beirut and Jerusalem. If the rain didn’t fall so evenly throughout the year, Essex would look like a desert.
Add to this heavy, unstable Essex clay soil and the picture of a ‘challenging site’ is complete. All the work that has been done at Hyde Hall, and will be done in the future, is carried out with climate very much in mind.
The Dry Garden
Even during the devastating floods that submerged many parts of the UK in 2000, East Anglian gardeners knew that come summer, only a few days of hot, drying winds beneath clear blue skies would cause any amount of rain to evaporate, leaving plants wilting in the cracked and blanched soil.
http://www.rhs.org.uk/Learning/Research/Climate_Change/casestudies.htm
 

Offline Andrew K Fletcher

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The problem with desertification is that it requires water based soil erosion, usually in the form of flash floods. These happen when the trees have been removed and grass crops and overgrazing practice degrades the soil sufficiently so that it no longer binds together as good soil does. Once sufficient organic material has been leeched from the soil and blown away in the wind, then the real desertification begins to spread like wildfire as demonstrated to perfection in the 1930's American Dustbowl.

So the question should not be how long without rain but how long without a common sense approach to land management and soil husbandry.

There are many areas in East Anglia, Snakes Pass, and Kent that are becoming borderline semi desert. Rainfall is sparse in these areas compared to the rest of the country and the soils by nature are already fragile before monoculture cash cereal crops arrived there.

We already have real problems in the U.K. But still a long way from becoming a full blown desert like Australia has.

Believe it or not there are huge areas where the soils are so poor it has been abandoned by farmers and is now viewed as moor land, yet the stone dwellings found in these harsh terains bare wittness to the folly of over exploiting the soils.
 

Offline JimBob

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Desertification can tale place with any ground cover. A lack of rain causes the soil to dry out, the vegetation to die and be stripped away, the soil becomes exposed and then is eroded by aeolian processes.

Moorland in the UK is not going to become desert unless there is no fog. Rainfall isn't necessary when fog is involved as it provides enough moisture for soil cover to grow.

When can you last remember a full year without any fog?
 

Offline Andrew K Fletcher

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Jim, I was not saying the moors would become a desert, but stating the soil is so bad on the moors that only grazing animals are farmed there now. The moors are moors because humans continually burn them and grazing animals help to prevent self seeding from trees.
There is a lot of peat on the moors now and boggy areas in the troughs. Peat was used to heat the homes of the local villages. Trees are no longer available.

Fog happens in deserts too and plastic nets are used to harness this valuable resource by milking the fog and collecting it in storage tanks for irrigation and potable water.

My other thread titled Project OASIS is based upon utilizing moisture in the air to establish forestry along the arid coastlines by irrigating with waste domestic water from Europe, possible and economical by utilising the balast capacity of super crude oil tankers.

Fog is very interesting from my point of view, particularly when you observe it on one side of the coastal road so thick you can cut it with a knife, yet on the other side of the hot black tarmac road the sun is shining, clear skies and soaring temperatures. The fog only crosses on to the land where trees are present and stretch inland fropm the coast. I have a fascinating video of this occuring.

Desertification can tale place with any ground cover. A lack of rain causes the soil to dry out, the vegetation to die and be stripped away, the soil becomes exposed and then is eroded by aeolian processes.

Moorland in the UK is not going to become desert unless there is no fog. Rainfall isn't necessary when fog is involved as it provides enough moisture for soil cover to grow.

When can you last remember a full year without any fog?
 

Offline Bored chemist

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According to this
http://en.wikipedia.org/wiki/Desert
a desert is anywhere with a total of less than 250mm of precipitation in a year (though I'm not sure how fog counts).
The idea that vegetation or ground cover has much to do with deserts is countered by the fact that the much of Antarctic counts as desert even though it's covered with ice.
I guess that a year with less than 250mm of rain etc would make the UK a desert by that definition but I have no doubt there are other definitions too.
 

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