Reticulate Australia

[Julia]

Re: Reticulate Australia .....

I'm certainly not concerned about Brisbanes drinking water.
This place gets over a metre a year rain average.
It's got 500 mills this year. Including 20 mills just last week.
There is hundreds of thousands of litres of the best water running off every ones roof tops every year.
If people can't help themselves in such a wet climate, then that's their problem.

So are you suggesting every property must have a rainwater tank?
I've recently installed 3 x 5000 litre tanks (in June) and there is no way they have received enough inflow to run the household plus the garden and pool.
And I'm not in Brisbane but further north with a higher rainfall on average.
How are you going to organise rainwater tanks for high rise apartments?
I'd be genuinely interested in how you would ensure Brisbane has plenty of water. Ditto Adelaide.

And you simply can't say "then that's their problem". No it's not. It is the job of State governments and local water authorities to provide a reliable water supply to the population. That is why we pay taxes.

 

[Smurf1976]

Re: Reticulate Australia .....

A bit of technical info about dams and their operation for anyone who is interested.

The purpose of dams is not only for storage as commonly assumed. If you build a dam that has natural inflow (ie put the dam on a river - contrary to popular belief not all dams are built on rivers) then it will have an annual yield of x with variation +/- x%.

Using the storage capacity (larger the better within reason) the inflow is effectively averaged out thus providing a sustainable yield of x. A reliability factor (which is a matter of decision making) is then applied which will result in a "firm supply" value somewhat less than the gross yield.

I'm using Tasmanian figures here simply because I have the data. The same principles apply to any large scale water storage system.

For example, applying a 2% annual probability of failure (ie forced reduction in output to below 100% of normal for any period of time) to the Hydro Tas system results in a net yield of 91% of gross regulated flow (regulated flow means outflows excluding spill).

If that is changed to allow up to 20% output reduction as part of "normal" operations (that is, only a fall below 80% of normal is counted as "restricted") then that increases the annual yield to about 94.5% of gross regulated flow.

So if you decrease the minimum "firm" value that is acceptable then you increase the average yield. Accepting a maximum 30% production drop takes the system up to 96% utilisation of regulated flows, for example.

The only way to get to 100% is to have very large storage capacity such that spill never occurs even in a major flood. This is difficult to do in practice for a network of dams since it isn't always possible to build the dam high enough to create enough storage. For example, storage capacity in Tas ranges from 5 years at Great Lake (which has never been full) to about 48 hours of the natural inflow at Trevallyn (which spills quite regularly). Travallyn could not in practice be built much higher than it already is (would flood too much land for too little benefit) so the spill there is unavoidable. The same situation exists elsewhere in the system too.

Lake Margaret storage, for example, loses 2% of total inflows to spill. It holds about 3 months worth of inflows when full. That is a pure hydro-electric storage (no other use of the water) so can be run at least partly according to rainfall. More storage is needed for an irrigation or urban water supply storage since it isn't useful to be having maximum water release during a flood - you want maximum release when it's dry.

As for how a network of dams should be operated, basically what you want is to minimise spill but never run any storage completely dry. So that generally means running the small storages to seasonal "target" levels and adjusting outflows from the lager storages in order to attain those targets.

For example, the northern headwater storages (which are small relative to inflow - a few months worth) in Tas are now almost full but were very low at the start of Winter. That outcome is entirely intentional and is achieved in a very calculated, scientific manner by adjusting production rates to achieve the desired fill / depletion rates whenever possible. Those target levels are a means of balancing the risk of high inflows (ie heavy rain) and minimising spill versus the risk of high outflows being required at a time of low rainfall (due to unexpected major storage plant breakdown or high demand for export power, for example).

So in the context of Brisbane etc yes buildiing more dams will increase the supply of water on the condition that (1) they are built in a scale and location that gives a firm annual yield that is not zero and (2) they are operated collectively as an INTEGRATED system.

Integrated operation produces far higher output than independent operation. That is, if you have numerous dams then operating them collectively as one integrated system will produce far more water / power on a firm basis than stand alone operation. Quite a few of the dams in Tas for example have close to zero firm capacity as a stand alone operation but they make a significant contribution as part of an integrated system.

About 60% of the system in Tas wouldn't be much use at all as a stand alone operation - it can't achieve a decent firm supply level by itself. It only works due to integration (a point resonably well understood by the general public) through which it can achieve a very high level of reliability of output at a level far higher than stand alone operation could produce.

New Zealand loses about 10% of total production directly due to "competition" despite only having a small number of competitors. I'm not sure of the extent of losses but having Snowy Hydro and the Murray-Darling Basin Commission as separate operators certainly doesn't improve the management of the resource (MDBC treats Snowy outflows as unpredictable and intermittent just like the rain).

 

[kitehigh]

Re: Reticulate Australia .....

Completely agree.

Withdraw the troops from Iraq and Afghanistan, reduce the level of pay rises for politicians, just stop spending money on any other number of wasteful programmes and just build the pipelines.

I think you will find if Labor gets in they intend to withdraw troops from Iraq which I think is sensible as they are doing very little there anyways. But they have stated that they intend to keep troops in Afganistan, which I agree with as there is alot more hope for success there than there is in Iraq.

I don't think the pay rate of politicians is a concern but rather we have too many of them. Too much government at every level, I think. If you actually look at what Politicians get paid it isn't spectacular for the amount of time spent away from home and putting up with the intrusions into your private life. I for one wouldn't want the job at that lousy rate.

Prime Minster's Salary as of September 2006: $309,270
Base salaries for politicians: $118,950

I agree with you that there needs to be better oversite of money spent on projects. Government projects are some of the most wasteful, due mainly to poor project managment (due to not having the right people in the job) and poor advice.

I have to agree with The Once-ler, just because something is possible to do, doesn't mean it should be done.

We should instead look more at water conservation. People waste far too much water at the moment, due mainly to it being artificially cheap. Alot of gardens in Australia use far too much water because they are gardens designed on a European model not an Australian one.

"Australia's rainfall is the lowest of the continents (excluding Antarctica). This low rainfall combined with very high evaporation leads to low river flows. Despite this, Australia has one of the highest per capita water consumption rates in the world."
http://conservewater.melbournewater.com.au/content/driest.asp

Wake up Australians!!!

Growing cotton seems like another waste of water in my mind but maybe someone can convince me otherwise.....

 

[The Once-ler]

Re: Reticulate Australia .....

I've recently installed 3 x 5000 litre tanks (in June) and there is no way they have received enough inflow to run the household plus the garden and pool.
And I'm not in Brisbane but further north with a higher rainfall on average.
How are you going to organise rainwater tanks for high rise apartments?
I'd be genuinely interested in how you would ensure Brisbane has plenty of water. Ditto Adelaide.
.

Hang on a minute! I was refering to drinking water. Go back and have a look. Now your infering I'm talking about water in general. There is no way rain water will be enough for a garden and pool, especially if the pool is uncovered. Is your pool uncovered? I notice very few pools are covered, and this is one simple way to stop heaps of water loss. Covered pools have almost no water loss, and infact, water generally has to be pumped out regularly, as well as much less chemical use do to the softness of rain water. My pool hasn't needed topping up for years.

I happen to live in a community where everyone collects their rainwater, have done for 100 years, and uses it for drinking and showers. Most people have 50 000 litres or so storage and very rarely run out. No where near as much rain as Brisbane gets either.

Collecting rain water would be a simple solution to a lot of our water problems, but once again, until the water actually runs out, I don't think many will use their common sense.

I suspect it's a vanity thing with city people. No one wants big decent sized tanks in their yards, whereas in the bush, people are proud of their big tanks and they look good. It's something to brag about.

 

[MeekTrader]

I'd say the availability of space/land for tanks plays a large part in those attitudes