Harvestable rights (was winters arrival)

[David Hare-Scott]

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

[Billy]

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)

You don't fill cisterns?

"Gardening requires lots of water - most of it in the form of perspiration." - Lou Erickson

[David Hare-Scott]

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.

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

[songbird]

maybe the long references line...

...

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?

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.

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).

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 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

[David Hare-Scott]

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

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.

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

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

[songbird]

...

ah...

...

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

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

:) 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

[David Hare-Scott]

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.

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

[songbird]

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

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. :)

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.

ah, yes, that's clearer. :)

songbird

[Billy]

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.

[David Hare-Scott]

And only hold a tenth of my dam or less.

D

[Billy]

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.