David Hare-Scott wrote:
songbird wrote:

I had to start a new thread for this as my news server kept rejecting my
reply (perhaps it is a laissez faire capitalist machine).

maybe the long references line...


....
for the longer term i think the ground water
situation would benefit from a higher percentage
of capture of rainfall. has anyone tried to
increase that percentage?

Your idea doesn't work because:

- Irrigation water is held in dams that don't leak (or shouldn't) so that
doesn't lead to groundwater recharge.

i'm not necessarily talking just irrigation water,
but ground water recharging, which can involve
methods as described by Yeomans and others.

would you be fined if you ripped your land deeply
to capture more rainfall and soak it in instead
of letting it run off?


- The more that is held in dams the more that is lost to evaporation which
is not useful to anybody including the downstream ecology.

that i agree with.

not all dams are water tight and so they do
contribute to ground water levels and thus
indirectly to stream and river flows.


- It is used for irrigation where most is lost to evapotranspiration not to
groundwater, if your irrigation is soaking down below the root level you are
doing it wrong and may be raising the water table and so contributing to
salination. This has happened in too many irrigation systems around the
world including the Murray-Darling.

arid climates are different, but they are
manageable. some folks use trees to lower the
water table (and increase shade, wind protection
and to provide food and habitat for critters).


- The figure was arrived at to allow sufficient flow in the rivers for
environmental, agricultural and domestic purposes downstream, many rivers
cease flowing none the less in dry times. If the figure was more it would
be favouring those where the rain falls at the expense of those users
downstream. And yes higher figures have been suggested by those who would
benefit at the expense of others.

yes, and true if the water is going to dams and
irrigation, but if alternative approaches are
used it can recharge aquifers even in an arid
climate.

likely nobody actually get audited until someone
complains or has a grudge or the entire watershed
has issues and they do a survey... or is your
area and administration somehow highly enlightened?


You must also take into account that the system must respond to el nino - la
nina cycles as well as any seasonal pattern. This is not a reliable annual
rainfall nor a reliable seasonal pattern such as annual snow-melt. It's a
hard land.

you have no reliable rainy season at all? i
thought you managed to grow a decent pasture on
a part of your property? you don't get that in
unreliable arid climates without sequestering a
significant amount of rainfall...


songbird