Saturday, 18 August 2007

When the water is all gone...

This past week took me to the headwaters of Australia's largest river, the River Murray, and the source of much of Adelaide's water supply. Critical, then, for us gardeners!

A thousand kilometres from Adelaide, the Hume Weir is the largest dam on the River Murray, and holds 3,038 Gigalitres of water when full. It's now down to less than 2% of capacity.

Back in February 2007, it looked like the top photo. I drove around it, and it looked much like the bottom photo - lots of dead trees standing in mud. And this at the end of winter...

On the drive back to Adelaide, I gave some thought to how this will affect all of us here in Adelaide, especially if Spring rains in the Snowy Mountains result in anything less than major floods (normal rains won't see us recover from a drought-ravaged catchment).

This past winter, I've collected 60,000 litres of rainwater off my house roof; how best to use it?

So far I've spent $300 buying pea-straw (50 bales, now at $6 per bale, and soon to be unavailable because of the drought). I'll lay this in thick sheets of mulch over the vegetable garden, on top of T-Tapes, which are a form of sub-surface dripper that lays down wet lines in the soil along which I will grow my summer vegetables. With so little rainwater (no more than 6 weeks worth in my normal garden), I will need to stretch this out by not using overhead sprinklers, where so much is lost to evaporation.

I will also have to plan my crops, and grow only essential stuff. We must expect that the food bill will go through the roof following the drought; ours is already costing us about $100 per week for fruit alone.

We had a taste of water restrictions last year. I believe that was a mere prelude to harsher restrictions yet to come. All along my travels this past week, I came across signs in townships advising of Level 4 and 5 water restrictions applying; and this towards the end of winter.

When the going gets tough, the tough get going! Now's the time to be planning your Spring plantings, with mulch and water saving techniques uppermost in your mind.


Kate said...

What are T tapes and why did you choose them over other dripper lines?

Andrew said...

T-Tape is a surface or sub-surface drip-line that applies water to the plants, without one having to screw 'drippers' into pipes. As the name suggests, it's a form of plastic flat hose-tape with in-built drippers.
It also works at low pressures over short-runs, which is ideal for backyard veggie patches running on rainwater (c.f. T-300 model)
One can see an animation of how it works at
My plan is to lay it under a thick layer of (dry) mulch, and plant the veggies as seedlings in rows along the tape lines.
The whole idea is to minimise water use.

Kate said...

Thanks but it seems like all the other dripper lines I have. Why did you choose this one - is it cheaper ?