permaculture

["Wesley Trotman" <trotmanw@bigpond.com>]

In my area the public water system is supplied from underground aquafiers.
However the draw down is exceeding the intake and levels are down to
dangerous point. If they get too low sea water will contaminate them and
destroy them. One sloution suggested is to clear 200 square kilometers of
trees from the catchment area.  It saddens me that we have to contemplate
this sort of action. The loss of animal and bird habitat and at this scale
it could even reduce the rainfall.
In most other places in Oz removal of trees has increased to level of
aquafiers, they have risen up through layers of salt to be close to the
surface. Ground evaporation then concerntrates these salts in the top soil.
It has been estimated that we will loose one third of productive land in the
next twent years unless drastic action is taken to lower the water tables.
Just to explain further, trees absorb perhaps 80percent of rain fall,
drainage into aquifiers could be as low as 5 percent,
Grass land only absorbs 15 percent of rainfall with aquifier recharge of
perhaps 70 percent, the figures will vary depending upon climate and species
and topography etc but I guess you can get the picture.

Wes

> Kirby Wrote:
>
> I recently flipped through an old National Geographic where they were
> covering a Mojave Desert restoration project where one of their main
> activities was going around and pulling up non-native tamaresk trees
because
> they were "thirsty" and concentrated salts in their leaf litter.
>
>
> Claude replies:
> Kirby, I once saw a show about South Africa where the "solution" to the
> problem of lack of water was to uproot "thirsty" pine trees - he logic was
> that by doing so, more water would make its way to the
> dams/ponds/lakes/rivers/streams.... This seemed to me to be a short term
> solution in that, yes water is not being "drunk" by the trees, but in the
> longer term, the trees are not there to pump water up, keep the water
table
> high, transpire, catch, hold and otherwise "make" rain....
>
>
> > From: "Kirby Fry" <peace@totalaccess.net>
> > Reply-To: permaculture@lists.ibiblio.org
> > Date: Sat, 31 Aug 2002 10:37:55 -0500
> > To: <permaculture@lists.ibiblio.org>
> > Subject: [permaculture] Turning Deserts into Woodlands
> >
> >
> > I recently flipped through an old National Geographic where they were
> > covering a Mojave Desert restoration project where one of their main
> > activities was going around and pulling up non-native tamaresk trees
because
> > they were "thirsty" and concentrated salts in their leaf litter.
>
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