No offence, but I find it rather strange that the relative effects of dams and desalination plants and the like are being discussed here, while the impact of a rapidly growing population is the factor that is really generating the significant impact.

I think that this is basically the wrong sort of thing to be discussing with respect to the overall water-supply issue.

Let’s take the hint from this national water crisis, or what is developing into a crisis, and get ourselves off the continuous growth paradigm and onto the path towards genuine sustainability as quickly as possible.

Let’s not get tricked into discussing the best or most efficient ways of providing water for a continuously growing population and hence a progressively less sustainable society. Let’s not get tricked into believing that we have to have this sort of continuous growth or that it will happen whether we like it or not. We CAN directly address it and curtail it if we collectively put our minds to it. And this factor is by far the most important aspect of this whole subject.

One of the most significant half-truths or pieces of misinformation is that we have to have continuous economic growth, and continuous population growth in order to achieve it

Ludvig, the reason the merits of water supply systems are being discussed here is that that is essentially what the thread is about - the myth of water scarcity. The thread is not about the sustainability of population growth. If that's to be discussed it should be in a different thread created for that purpose. The forum rules require that responses be on topic.

However, I am of the view that Sydney has already outgrown its water supply, and that steps need to be take to provide an adequate supply for the population Sydney currently has. Preventing further population growth in Sydney might ammeliorate the future water supply problems, but would do nothing to solve the problem we now have.

Sylvia

It was not clear just what the parameters of this discussion were intended to be. But I think the issues that I have raised well and truly fit in with the subject matter.

Sustainability is of direct relevance to the myth, or reality, of water scarcity. I do find it odd that you would suggest that it is not appropriate stuff to discuss here.

“Preventing further population growth in Sydney might ameliorate the future water supply problems, but would do nothing to solve the problem we now have.”

But it would most clearly work diametrically against ANY measures made to improve supply. So it is of direct relevance to the concepts of building desalination plants, more dams, installing tanks, mining groundwater, etc.

Thus, population stabilisation MUST be a part of any plan to improve water-provision. We simply MUST address the demand side of the equation as well as the supply side.

ludwig, you're absolutely right.
sylvia, the elimination of periodic flooding & sediment etc. only happens when you dam flowing streams. catchment dams on the other hand get filled with rainwater and can be placed anywhere. you could even have stormwater catchment which is far more easily and cost effective to filter than desalination. i personally prefer ludwig's approach. control (gawd i hate that word) of the population (humans AND animals) growth IS THE ONLY ALTERNATIVE period ! you simply can not have population growth without a growth in environmental problems. it just doesn't work that way. it's nature's law.

Reservoirs are not about catching water, they are about storing it. If you catch stormwater, you need to be able to store it somewhere. So if you want to use stormwater catchment, you need to determine the costs of either pumping the water into an existing reservoir (though new pieplies, and requiring lifting the water a considerable distance), or the cost of constructing new reservoirs and pumping the water into them.

In the latter case, you need data that lets your determine how much water needs to be stored to provide the required sustainable yield.

It's far from obvious that using storm water ends up cheaper than desalination. So if you want to claim that storm water catchment is the more economic, then produce some data and analysis that supports that view. Don't just state it.

So if you want to claim that storm water catchment is the more economic, then produce some data and analysis that supports that view. Don't just state it.

ok sylvia, we actually have and operate catchment lagoons for small communities. call them reservoirs if you like. the actual running costs come from the injection of small dosages of chlorine to control bacteria. low pressure pump running costs are insignificant. the desal plants are running 24/7. quite a difference in operational costs.
i can't see why many new residences couldn't have their own water supply. an outlandish idea ? well maybe, but consider this. the foundation of a residence could easily double as a reservoir. (ok some xtra cost) a 2 m deep reservoir of say 15 x 10 m would supply a family of 4 for 10 months @ 200litres per person/day and even longer with water saving devices. of course it wouldn't be logical for every house but if as many as possible have it then water supply would surely be less of a problem plus land requirements for storage would be greatly reduced.