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).

songbird wrote:
David Hare-Scott wrote:
Billy wrote:

In a few years, if you want a breath of fresh air, you'll be able to
buy it at a store.

We are hoping for a couple of hundredths of an inch more rain
tonight. Wish us luck.

Here we have a concept related to rainwater called 'harvestable
right' . It means that roughly 10% of the rain that falls on your
land is yours to do with as you wish, the rest must available for
the environment or be allowed to run down to the rivers for others
to use. In practice it limits the size of the dam you can build and
the kind of waterway you can build it on. If for example a
permanent river crosses your land you can't dam that.

that first part seems somewhat odd, as it would
likely help moderate and encourage ground water to
have a higher percentage available to be held back.
as it will eventually get into the creeks/rivers
eventually.

the second part i would agree with, because by
damming those sorts of waterways you would likely
be interfering with fish migrations or perhaps
raising the temperature of the water.


On top of that if you are on "permanent" fresh water, a river or
lake, you can pump from it (while it runs) without charge for 'bona
fide domestic purposes'. This includes stock watering, human
consumption and gardens. There is no specified limit to this in
terms of volume although if you were taking huge amounts somebody
might come around and ask exactly what you are doing with it. If
you were irrigating on a commercial scale or selling it you would be
fined. If you want to irrigate on a commercial scale you have to buy
a water license.

that makes sense, but those who get there first
in a situation where supply is declining would
be those who would get it. sounds like eventually
there will be rationing when enough people want
to draw on it.


Any attempt by government to take away any of these rights would
have dire consequences at the ballot box, as despite the fact that
Oz is very urban the cities have a romantic attachment to the 'bush'
and a well organised campaign by farmers would gather many votes.

For the small landholder and those running sheep or cattle this is a
good system. As for irrigators it seems they are never happy
regardless of government, policy, rainfall or anything else.

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.

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

- 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.

- 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.

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.


David

In article ,
"David Hare-Scott" 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).

David, you date yourself. Getting "laissez faire" and "capitalist" into
the same sentence is so "decades" ago. These days, capitalist leave very
little to chance ;O)

songbird wrote:
David Hare-Scott wrote:
Billy wrote:

In a few years, if you want a breath of fresh air, you'll be able to
buy it at a store.

We are hoping for a couple of hundredths of an inch more rain
tonight. Wish us luck.

Here we have a concept related to rainwater called 'harvestable
right' . It means that roughly 10% of the rain that falls on your
land is yours to do with as you wish, the rest must available for
the environment or be allowed to run down to the rivers for others
to use. In practice it limits the size of the dam you can build and
the kind of waterway you can build it on. If for example a
permanent river crosses your land you can't dam that.

that first part seems somewhat odd, as it would
likely help moderate and encourage ground water to
have a higher percentage available to be held back.
as it will eventually get into the creeks/rivers
eventually.

the second part i would agree with, because by
damming those sorts of waterways you would likely
be interfering with fish migrations or perhaps
raising the temperature of the water.


On top of that if you are on "permanent" fresh water, a river or
lake, you can pump from it (while it runs) without charge for 'bona
fide domestic purposes'. This includes stock watering, human
consumption and gardens. There is no specified limit to this in
terms of volume although if you were taking huge amounts somebody
might come around and ask exactly what you are doing with it. If
you were irrigating on a commercial scale or selling it you would be
fined. If you want to irrigate on a commercial scale you have to buy
a water license.

that makes sense, but those who get there first
in a situation where supply is declining would
be those who would get it. sounds like eventually
there will be rationing when enough people want
to draw on it.


Any attempt by government to take away any of these rights would
have dire consequences at the ballot box, as despite the fact that
Oz is very urban the cities have a romantic attachment to the 'bush'
and a well organised campaign by farmers would gather many votes.

For the small landholder and those running sheep or cattle this is a
good system. As for irrigators it seems they are never happy
regardless of government, policy, rainfall or anything else.

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.

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

- 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.

- 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.

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.


David

You don't fill cisterns?



"Gardening requires lots of water - most of it in the form of
perspiration."
- Lou Erickson
--
Remember Rachel Corrie
http://www.rachelcorrie.org/

Welcome to the New America.
http://www.youtube.com/watch?v=hA736oK9FPg

Billy wrote:
In article ,
"David Hare-Scott" 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).

David, you date yourself. Getting "laissez faire" and "capitalist"
into the same sentence is so "decades" ago. These days, capitalist
leave very little to chance ;O)

The term does not mean unplanned or left to run free by the owner it means
uncontrolled by the State. All countries limit private enterprise to a
degree, the extent varies quite a bit. It was a whimsical nonce remark, I
don't propose to get into economic or political theory as that is OT for the
most part.


songbird wrote:
David Hare-Scott wrote:
Billy wrote:

In a few years, if you want a breath of fresh air, you'll be able
to buy it at a store.

We are hoping for a couple of hundredths of an inch more rain
tonight. Wish us luck.

Here we have a concept related to rainwater called 'harvestable
right' . It means that roughly 10% of the rain that falls on your
land is yours to do with as you wish, the rest must available for
the environment or be allowed to run down to the rivers for others
to use. In practice it limits the size of the dam you can build
and the kind of waterway you can build it on. If for example a
permanent river crosses your land you can't dam that.

that first part seems somewhat odd, as it would
likely help moderate and encourage ground water to
have a higher percentage available to be held back.
as it will eventually get into the creeks/rivers
eventually.

the second part i would agree with, because by
damming those sorts of waterways you would likely
be interfering with fish migrations or perhaps
raising the temperature of the water.


On top of that if you are on "permanent" fresh water, a river or
lake, you can pump from it (while it runs) without charge for 'bona
fide domestic purposes'. This includes stock watering, human
consumption and gardens. There is no specified limit to this in
terms of volume although if you were taking huge amounts somebody
might come around and ask exactly what you are doing with it. If
you were irrigating on a commercial scale or selling it you would
be fined. If you want to irrigate on a commercial scale you have
to buy a water license.

that makes sense, but those who get there first
in a situation where supply is declining would
be those who would get it. sounds like eventually
there will be rationing when enough people want
to draw on it.


Any attempt by government to take away any of these rights would
have dire consequences at the ballot box, as despite the fact that
Oz is very urban the cities have a romantic attachment to the
'bush' and a well organised campaign by farmers would gather many
votes.

For the small landholder and those running sheep or cattle this is
a good system. As for irrigators it seems they are never happy
regardless of government, policy, rainfall or anything else.

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.

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

- 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.

- 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.

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.


David

You don't fill cisterns?



I fill above ground house tanks holding 50 kl from roof water for domestic
use but that volume would be useless for the garden and in any case must be
reserved. I have a small dam for stock watering holding 2.4 Ml that will
keep the garden alive in emergencies but that is uncovered and does lose
some due to evaporation.

As I understand it a cistern is used in very dry climates (eg north Africa)
and it is covered like the former but as large as the latter. This would be
extremely expensive, certainly out of my range.

D

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

songbird wrote:
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?


Yes. The limit is on the size of your dam. Also see below.


- 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?


Some of both. Where catchments are regulated with meters the water
authority checks and where it is also highly competitive and water licenses
are bought and sold everybody knows what the others are doing. In my case
it isn't so closely monitored.


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?

No. My area is failrly high rainfall about 1100 mm PA but can come at any
time of year. Nothing for three months and then 200mm in a week is not
uncommon. This is from normal variability. If we have el nino we can get
as little as 300m or in la nina 1800mm in a year.

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...



It is done in two ways, by having clay subsoil that acts as a big sponge and
ensuring the topsoil has high infiltration so that it collects all but heavy
falls. The first is from choosing the right block the second from good
management. I can have grass growing for up to two months after the last
rain.

David

David Hare-Scott wrote:
songbird wrote:
David Hare-Scott wrote:
....
would you be fined if you ripped your land deeply
to capture more rainfall and soak it in instead
of letting it run off?


Yes. The limit is on the size of your dam. Also see below.

ah...


....
- 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?


Some of both. Where catchments are regulated with meters the water
authority checks and where it is also highly competitive and water licenses
are bought and sold everybody knows what the others are doing. In my case
it isn't so closely monitored.

you're close to the top of the water catchment?


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?

No. My area is failrly high rainfall about 1100 mm PA but can come at any
time of year. Nothing for three months and then 200mm in a week is not
uncommon. This is from normal variability. If we have el nino we can get
as little as 300m or in la nina 1800mm in a year.

that seems to really cry out for swales and
catches...


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...

It is done in two ways, by having clay subsoil that acts as a big sponge and
ensuring the topsoil has high infiltration so that it collects all but heavy
falls. The first is from choosing the right block the second from good
management. I can have grass growing for up to two months after the last
rain.

right, and that second bit is kinda my point,
that you do manage your property well so that it
does capture the water that lands on it. i would be
surprised if you are losing 90% of it to run off.
i.e. those pastures are recharging the ground water
at some level and are contributing to a longer term
flow for the water shed. probably also suffer very
little erosion too.


songbird

songbird wrote:
David Hare-Scott wrote:
songbird wrote:
David Hare-Scott wrote:
...
would you be fined if you ripped your land deeply
to capture more rainfall and soak it in instead
of letting it run off?


Yes. The limit is on the size of your dam. Also see below.

ah...


...
- 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?


Some of both. Where catchments are regulated with meters the water
authority checks and where it is also highly competitive and water
licenses are bought and sold everybody knows what the others are
doing. In my case it isn't so closely monitored.

you're close to the top of the water catchment?


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?

No. My area is failrly high rainfall about 1100 mm PA but can come
at any time of year. Nothing for three months and then 200mm in a
week is not uncommon. This is from normal variability. If we have
el nino we can get as little as 300m or in la nina 1800mm in a year.

that seems to really cry out for swales and
catches...

No the fainfall is too high, in a wet spell with clay soil it would remain
waterlogged for too long. As it is I have to plant all my fruit trees on
mounds and build up the vege garden so water doesn't sit in it. The heart
of the problem is that you must have a compromise between the design that
suits very wet and very dry conditions because you will get both at
different times.

The same applies to house design. You have to deal with a temperature range
from -7C to 44C and very low to very high humidity which is not the same as
a cool temperate area where you get (say) -20C to 25C where you want to get
the sun into the house all year round or tropical where you want to keep it
out all year round. As I said its a hard land.



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...

It is done in two ways, by having clay subsoil that acts as a big
sponge and ensuring the topsoil has high infiltration so that it
collects all but heavy falls. The first is from choosing the right
block the second from good management. I can have grass growing
for up to two months after the last rain.

right, and that second bit is kinda my point,
that you do manage your property well so that it
does capture the water that lands on it. i would be
surprised if you are losing 90% of it to run off.
i.e. those pastures are recharging the ground water
at some level and are contributing to a longer term
flow for the water shed. probably also suffer very
little erosion too.


Perhaps I didn't explain clearly in an earlier post. You are allowed to
impound ~10% in practice this limits your dam size according to a formula
based on your land area and rainfall. It doesn't mean the other 90%
necessarily runs off.

D

David Hare-Scott wrote:
songbird wrote:
David Hare-Scott wrote:
songbird wrote:
David Hare-Scott wrote:
....
No. My area is failrly high rainfall about 1100 mm PA but can come
at any time of year. Nothing for three months and then 200mm in a
week is not uncommon. This is from normal variability. If we have
el nino we can get as little as 300m or in la nina 1800mm in a year.

that seems to really cry out for swales and
catches...

No the fainfall is too high, in a wet spell with clay soil it would remain
waterlogged for too long.

smaller and wider swales/catches then. you can
always adjust them as needed.


As it is I have to plant all my fruit trees on
mounds and build up the vege garden so water doesn't sit in it. The heart
of the problem is that you must have a compromise between the design that
suits very wet and very dry conditions because you will get both at
different times.

well true, but when someone says they have intermittent
rains with months in between then that tells me that they
want to capture every bit of it. how to do that is the
fun part.


The same applies to house design. You have to deal with a temperature range
from -7C to 44C and very low to very high humidity which is not the same as
a cool temperate area where you get (say) -20C to 25C where you want to get
the sun into the house all year round or tropical where you want to keep it
out all year round. As I said its a hard land.

here it rarely hits -29C or 41C, but those
are possible extremes. so we need a dual
design which works to both let in light in
the winter and to not let it in during the
summer.

we also have low to high humidity conditions
in almost every season.


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...

It is done in two ways, by having clay subsoil that acts as a big
sponge and ensuring the topsoil has high infiltration so that it
collects all but heavy falls. The first is from choosing the right
block the second from good management. I can have grass growing
for up to two months after the last rain.

right, and that second bit is kinda my point,
that you do manage your property well so that it
does capture the water that lands on it. i would be
surprised if you are losing 90% of it to run off.
i.e. those pastures are recharging the ground water
at some level and are contributing to a longer term
flow for the water shed. probably also suffer very
little erosion too.


Perhaps I didn't explain clearly in an earlier post. You are allowed to
impound ~10% in practice this limits your dam size according to a formula
based on your land area and rainfall. It doesn't mean the other 90%
necessarily runs off.

ah, yes, that's clearer.


songbird

In article ,
"David Hare-Scott" wrote:

Billy wrote:
In article ,
"David Hare-Scott" 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).

David, you date yourself. Getting "laissez faire" and "capitalist"
into the same sentence is so "decades" ago. These days, capitalist
leave very little to chance ;O)

The term does not mean unplanned or left to run free by the owner it means
uncontrolled by the State. All countries limit private enterprise to a
degree, the extent varies quite a bit. It was a whimsical nonce remark, I
don't propose to get into economic or political theory as that is OT for the
most part.

https://en.wikipedia.org/wiki/Trans-...omic_Partnersh
ip#Response



songbird wrote:
David Hare-Scott wrote:
Billy wrote:

In a few years, if you want a breath of fresh air, you'll be able
to buy it at a store.

We are hoping for a couple of hundredths of an inch more rain
tonight. Wish us luck.

Here we have a concept related to rainwater called 'harvestable
right' . It means that roughly 10% of the rain that falls on your
land is yours to do with as you wish, the rest must available for
the environment or be allowed to run down to the rivers for others
to use. In practice it limits the size of the dam you can build
and the kind of waterway you can build it on. If for example a
permanent river crosses your land you can't dam that.

that first part seems somewhat odd, as it would
likely help moderate and encourage ground water to
have a higher percentage available to be held back.
as it will eventually get into the creeks/rivers
eventually.

the second part i would agree with, because by
damming those sorts of waterways you would likely
be interfering with fish migrations or perhaps
raising the temperature of the water.


On top of that if you are on "permanent" fresh water, a river or
lake, you can pump from it (while it runs) without charge for 'bona
fide domestic purposes'. This includes stock watering, human
consumption and gardens. There is no specified limit to this in
terms of volume although if you were taking huge amounts somebody
might come around and ask exactly what you are doing with it. If
you were irrigating on a commercial scale or selling it you would
be fined. If you want to irrigate on a commercial scale you have
to buy a water license.

that makes sense, but those who get there first
in a situation where supply is declining would
be those who would get it. sounds like eventually
there will be rationing when enough people want
to draw on it.


Any attempt by government to take away any of these rights would
have dire consequences at the ballot box, as despite the fact that
Oz is very urban the cities have a romantic attachment to the
'bush' and a well organised campaign by farmers would gather many
votes.

For the small landholder and those running sheep or cattle this is
a good system. As for irrigators it seems they are never happy
regardless of government, policy, rainfall or anything else.

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.

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

- 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.

- 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.

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.


David

You don't fill cisterns?



I fill above ground house tanks holding 50 kl from roof water for domestic
use but that volume would be useless for the garden and in any case must be
reserved. I have a small dam for stock watering holding 2.4 Ml that will
keep the garden alive in emergencies but that is uncovered and does lose
some due to evaporation.

As I understand it a cistern is used in very dry climates (eg north Africa)
and it is covered like the former but as large as the latter. This would be
extremely expensive, certainly out of my range.

D

I saw them in France. Why they feel they need them is anybody's guess,
as they get at least 2 - 3 days of rain every month.

In any event, in a cistern there is little evaporative loss of water to
heat, and wind as you find in ponds. A 25' x 45' cistern would be
expensive, no doubt. It was just an idea.
--
Remember Rachel Corrie
http://www.rachelcorrie.org/

Welcome to the New America.
http://www.youtube.com/watch?v=hA736oK9FPg

You don't fill cisterns?



I fill above ground house tanks holding 50 kl from roof water for
domestic use but that volume would be useless for the garden and in
any case must be reserved. I have a small dam for stock watering
holding 2.4 Ml that will keep the garden alive in emergencies but
that is uncovered and does lose some due to evaporation.

As I understand it a cistern is used in very dry climates (eg north
Africa) and it is covered like the former but as large as the
latter. This would be extremely expensive, certainly out of my
range.

D

I saw them in France. Why they feel they need them is anybody's guess,
as they get at least 2 - 3 days of rain every month.

In any event, in a cistern there is little evaporative loss of water
to heat, and wind as you find in ponds. A 25' x 45' cistern would be
expensive, no doubt. It was just an idea.

And only hold a tenth of my dam or less.

D

In article ,
"David Hare-Scott" wrote:


You don't fill cisterns?



I fill above ground house tanks holding 50 kl from roof water for
domestic use but that volume would be useless for the garden and in
any case must be reserved. I have a small dam for stock watering
holding 2.4 Ml that will keep the garden alive in emergencies but
that is uncovered and does lose some due to evaporation.

As I understand it a cistern is used in very dry climates (eg north
Africa) and it is covered like the former but as large as the
latter. This would be extremely expensive, certainly out of my
range.

D

I saw them in France. Why they feel they need them is anybody's guess,
as they get at least 2 - 3 days of rain every month.

In any event, in a cistern there is little evaporative loss of water
to heat, and wind as you find in ponds. A 25' x 45' cistern would be
expensive, no doubt. It was just an idea.

And only hold a tenth of my dam or less.

D

Sorry, error, 25' is the radius.

By 2.4Ml, am I to understand 2.4 million liters (= 84,755 cu.ft.)
which would be contained in a tank 50' in diameter and approximately 45'
tall. V = (pi * r^2) * height = 1962.5 sq. ft. * 45' = 1962.5.

In any event, there is no reason for the perfect to become the enemy of
the good.
--
Remember Rachel Corrie
http://www.rachelcorrie.org/

Welcome to the New America.
http://www.youtube.com/watch?v=hA736oK9FPg