Tuesday, 8 July 2008

it comes from the tap...

Water

we all just think it comes from the tap, especially if you come from a town or a city.

A few years ago I'd say that you've probably either never given it a second thought, but in Australia at least it has become a hot topic (especially with the introduction of water restrictions). What, with media attentions, news paper articles, talkback discussions it seems that almost noone can have dinner with friends these days without the discussion turning to water issues (such as a rainwater tank).

If I may quote the first paragraph of that wikipedia page just up there, it says:
Water restrictions are currently in place in many regions and cities of Australia in response to chronic shortages resulting from drought. Depending upon the location, these can include restrictions on watering lawns, using sprinkler systems, washing vehicles, hosing in paved areas and refilling swimming pools, among others. Increasing population and evidence of drying climates, coupled with corresponding reductions in the supply of drinking water, have led various state governments to consider alternative water sources to supplement existing sources, and to implement "water inspectors" who can issue penalties to those who waste water.
well, that's what it said when I accessed it on Tuesday, 8 July 2008.

I've marked in red the points which pique my attention.

Drought: while everyone "knows" that we're in the grip of the worst drought known to mankind, the fashionable topic of Climate Change seems to be the first donkey to get the tail pinned to. Certainly there has been some depression in rains, but is it fair to lump it all at the feet of Climate Change? For example, here is the rainfall data for the Queensland coastal town of Southport from 1882 to 2006 (this is now part of the Gold Coast City). If you can see any remarkable trends towards less rain in there I'll be interested to hear where you think they are and why.



Btw, the period called the worst drought is from 2002 to 2006, this is when the water restrictions came into force.

Interestingly the term "drought" can be defined as things like "a protracted period of deficient precipitation" (makes sence to me) or "acute water shortage". This last definition is interesting, because if (say) population increases (but climate doesn't change) then with more people drinking the water there'll be less water.

So is this drought acute water shortage, rather than anything caused by climate? Lets see if the population has got anything to do with this ...


This graph is the change in population from 1961 till 2001 (and its grown a further 15% between 2001 and 2007).

Looking at the growth of population from 50 to 500 thousand between the 60's and now. Clearly all other things being equal (like how much water each person uses) we must be drawing at least 10 times more water now than then.

If then we say that drought is "acute water shortage" well, its no wonder to me that with 10 times more people wanting water that there is some kind of water shortage.

Rather than looking at this as being any significant change in the amount of water that the environment provides, lets look at it from the perspective of dividing a bucket of water among increasingly larger population.

If we think that the bucket was big enough for 200 thousand (there were less than 100 thousand when the system was designed), lets see how it goes as we successively divide this across more people. The chart below does just that:

Looking at the amount of water available to us (through our dam which puts that water into our taps) it would seem that (based on the calculated and measured ability of the dam to provide water to us and not become empty) the population in the area at around 2001 finally grew to exactly the limit of water availability.

No environmental drought here, just water shortage from too many people consuming water. So it seems that it is over consumption of the resources, not the commonly stated reasons of "not enough rain" being the most significant aspect here. As can be seen that we're not getting a statistically lower amount of rain than shown as normal in the above historical chart, but we are increasing the population significantly.

So it seems like its population increase rather than anything caused by climate change. That's a pity ... that means we can't blame the environment for our woes and we have to take responsibility for it ourselves. Wouldn't that be a change!

So, are we at some sort of limit?

Maybe ... The idea that there may be some limits to growth has been around since the black stump was a tree. It was perhaps popularized by Thomas Malthus who generally believed in growth of populations as over using the resources available and being the cause for famine. This limits to growth idea has not gone away, despite the many criticisms of it.

Some put forward that technology can come to the rescue (hasn't it always) and provide us with more water by such methods as membrane filtration to recycle water and provide desalination methods. While this is certainly a source of additional water it comes with an energy cost (and energy costs money too).

I thought I'd look into the additional energy costs if we follow this path, which I've called a Business As Usual use of water. The solid red line shows the increase of energy need created by sourcing our additional water with desalination methods. To provide some sort of contrast or comparison, I thought I'd add another where magically we just had more rain fall into our dams (marked with the red dotted line).

Now since the population of the Gold Coast is slated to rise by about 3 times in the next 50 years I plotted this energy requirement change over time with the expanding populations.

As you can see quite quiclky the energy needs are higher by using the technology to "make more water" available. By the end of 50 years the end points of the red lines are quite far apart, as population increases this becomes rather an enormous power demand. But what is that blue line in there?? Well, I'll come back to that in a moment...

Is this suggesting that Malthus was right? There are limits?? Well it depends, people used to prove that it was impossible for humans to fly, impossible for us to travel at faster than 35 miles per hour and impossible to escape earths orbit.

A problem is created by the way you look at something.

If we were to use canons to fire us into space then the maths proving that man could not escape earths gravity are indeed correct. Luckily for the astronauts they didn't follow that school of thought, and used rockets instead of canons.

So if we change the way we think things then perhaps what seems to be a limit is in fact not one at all. Ecological Modernisation is a school of thought which suggests that we can solve our equation through a combination of moving further into technology use and balancing supply and demand along ecological lines.

Now, lets go back to my chart and that blue line again. If we were to change our water use methods to reduce how much we drain from the tap, say by reusing water (eg using shower water to flush out toilets, or say the rinse part of our clothes washing), we can in fact reduce the amount of water we need to use without needing to change anything much.

Using a view point called Urban Metabolism to consider the city's water needs (like considering your own metabolic needs) its possible to consider the city as like a plant. This has roots in the ground drawing water (the pipes transporting water from the dam to our homes) and leaves where water is used and ultimately lost back into the environment. Some plants are more efficient with their water than others (like Cactus) and can do very well when there is plenty of water and cope when there is less. The blue line represents the energy needs of the metabolically efficient city. By consuming less from the environment and using it more efficiently not only is the city within the environmental limits, but the cost is also reduced!

So, if we were to plan our directions towards reducing consumption from the supply (without changing our need for water) then we can effectively cope with the lager population. If we do things like this, then Malthusian limits to growth are non existent.

But are we doing that?

Well, it doesn't look like it. Instead the South East Queensland government is mandating the construction of expensive desalination and water recycling plants. This in turn will mandate the construction of more and more power generation plants (to cope with the added power needs) as well as in all probability result in more generation of green house gases, making worse any climate change effects which are perhaps attributed to our use of energy.