Jonno wrote:
Re Dams. Of course you cant make it rain more, but you can spread the
catchment areas. The spin doctors who tell you "dams don't increase
rainfall" are using dams that catch the available rainfall. Using the
stupid argument that dams don't increase rain is correct but wrong in
reality. We need them where the rain IS falling. That can be anywhere.
So you spread your catchment areas...In our case South Gippsland. I'm
particularly concerned about Victoria. They have decided to go hand in
hand in having a increased population and at the same time not providing
dams in catchments that ARE having rainfalls. Instead, they're putting
in a desalination plant. Putting up the cost of water....


.... and ... umm... you can predict how damming 'newer' catchments will
affect things like stream flow, velocity, the water table, salination
levels and availability of potable water for wildlife (oh - and
people!), can you?

In 200 years of drought and aridity, don't you think there have always
been reasons why 'new dams' haven't been employed in the places where
you think they should?

Just because rain falls in an area doesn't mean it's safe to dam and
collect it! What about the Bonanza Dilemma (first saw it on 'Bonanaza'
in about 1962): if you dam the headwaters of a stream and enjoy the
benefits of its water for your purposes, what about the poor bloke
immmediately downstream? What about the even poorer bloke half-way to
the sea? The distraught bloke in the tidal zone?

Not only that, but the ways in which streams form and runoff contributes
to creeks and rivers is not only determined by precipitation. Other
factors, such as soil porosity, the existence of bedrock or otherwise,
the integrity of the substrates etc etc etc all come into play. Some
areas where rain falls plentifully may not be suitable for damming, even
though there *appears* to be a plethora of water. Porous soils, for
example, often mean that the majority of the rainfall disappears almost
immediately into the ground. In the opposite case, the rain may run off
(often beneath the soil and vegetation cover, but above a non-porous
bedrock such as granite or basalt) to wind up in a completely different
catchment area. Damming the existent stream may cause untold damage to
an already delicate habitat (which includes you and your water needs!).

Hydrology is an incredibly complicated field of study. I've only done a
tiny bit of reading and that a long time ago. But I do know a few of the
reasons why tampering with streams, damming injudiciously and
interfering with naturals systems can cause untold and often irreparable
damage. Look at the Snowy River! Who'd have thought such a 'beneficial'
scheme would cause such mayhem?

My personal soapbox is a dreary little local stream in my area. Forty
years ago, powers that be thought to dam it off and prevent the seasonal
flooding that interfered with roads, grazing, transport and so on. Now,
all these years later, the stream is dead, having been dammed and
contained in an artificial concrete bed for so long. When the stream
does run, the water is emerald green and serves only to move a massive
payload of orphan shopping trolleys a few metres closer to the Big Drain
in the middle of town.

This stream, in my living memory, was a paradise of wildlife back when
it lived! We caught tadpoles and penny turtles from its banks, climbed
the sheoaks in its meadows and counted the numerous species of birds
that lived off the fish in its waters. AND the commercial concerns the
original damming was supposed to have helped are all gone! All of them!
When the big Newcastle Flood occurred just recently, the water had
nowhere to go because the natural waterways in and around town have been
so stuffed up. Instead of following the natural drainage patterns, the
excess water backed up in eutrophied, clogged drains and took the line
of least resistance. THAT'S what happens when you bugger up waterways
without fully understanding what you're doing.

My opinion (and you, of course, have a perfect right to your own) is
that water is so scarce in this country, we can no longer afford to make
disastrous mistakes like those made on the Snowy and the Darling. We
need study, conservation of *all* resources and cooperation between all
interested parties.

Oh, and PS. A desalination plant is a good idea! It makes use of water
that has been tainted by the surface salts that wouldn't be there if so
many trees hadn't been removed from your catchment!

--
Trish {|:-} Newcastle, NSW, Australia