5 thoughts on “Saving the Macquarie Marshes”

1. Several years ago, colleagues and I did a risk assessment of climate change on the Macquarie River system for 2030 and 2070. A paper describing it can be downloaded here:

   Click to access rjones.pdf

   We did this through assessing the likelihood of exceeding critical thresholds and chose two:
   1. Lack of waterbird breeding events in the Macquarie Marshes, taken as 10 consecutive years of inflows below 350 GL (chosen because of the lifespan of wild colonial waterbirds).
   2. Irrigation allocations falling below a level of 50% for five consecutive years (this was conservative – my gut feeling was three).

   Analysing the twentieth century climate as it would play out with 1996 infrastructure and river management rules, we found that the longest period that bird breeding would not have occurred was 8 years and the longest period with irrigation allocations

2. Several years ago, colleagues and I did a risk assessment of climate change on the Macquarie River system for 2030 and 2070. A paper describing it can be downloaded here:

   Click to access rjones.pdf

   We did this through assessing the likelihood of exceeding critical thresholds and chose two:
   1. Lack of waterbird breeding events in the Macquarie Marshes, taken as 10 consecutive years of inflows below 350 GL (chosen because of the lifespan of wild colonial waterbirds).
   2. Irrigation allocations falling below a level of 50% for five consecutive years (this was conservative – my gut feeling was three).

   Analysing the twentieth century climate as it would play out with 1996 infrastructure and river management rules, we found that the longest period that bird breeding would not have occurred was 8 years and the longest period with irrigation allocations less than 50% was 3 years. (Historically, the 1930s was the driest period to 1996 but the Marshes had more water back then because of the much lower volume extracted for irrigation)

   Now, in 2006, “There as been no successful ibis, egret or heron nesting for a decade and the last survey counted only 10 birds struggling to survive in a virtual wasteland.” The Macquarie system is classified as over-allocated in the National Land and Water Resources Audit.

   Anecdotal evidence suggests that some dairy farmers in the Goulburn Valley have closed down after receiving below 50% allocation after three years, as has happened recently.

   Whether current climate fluctuations can be called as natural variability or greenhouse (most likely a combination of both), a range of wetland systems in southern Australia are threatened by lack of water. Farmers are also highly stressed in a number of systems. There are a range of risks to water resources assessed for 2030 that are being realised now, due to the recent run of dry years and “business as usual” management.

   For the record, I have no interest in farmers vs wetlands scenarios, and am more interested in sustainable, integrated catchment management. Public discussion of these matters is warranted.

   (Sorry – post was truncated by a less than sign so is re-posted)

3. Victoria’s tried buying water back in a number of different ways. Every time, the howls of outrage from the farmers drown out any sensible discussion of the health of our waterways and economically efficient ways in which to restore them. Our new Water Act sets all the necessary rules for transfer and an environmental reserve, it’s just up to the politicians to take on a very loud and squeaky wheel in the reform-averse farm lobby.

4. Professor Quiggin & everyone, I implore you. Let’s campaign to drop the unit of volume, ‘gigalitre’. I’ve been conducting a long and lonely war against it for ages. It’s crap.

   I scribbled this to The Bulletin a few years ago:

   ‘Here’s a simple proposal that would improve public understanding of Australia’s water crisis: let’s stop using the unit “gigalitreâ€?. This measure of volume is ridiculously unwieldy for the quantities of water being discussed and should be jettisoned in favour of “cubic metresâ€? or “tonnesâ€? of water. A gigalitre is only a million cubic metres, a million tonnes of water, and Sydney Harbour – a tired old example – has about 500 million cubic metres. The Wentworth Group has estimated that the Murray needs new flows of about 1500 gigalitres. Let’s just say 1500 million cubic metres or 1.5 billion tonnes – simple.’

   Using the gigalitre is like describing Australia’s population as 20 billion millihumans.

5. Dear Will De Vere,

   and I get irritated by common measures for things when used in the wrong context.

   Why are ML and GL useful? It’s because they link back to the litre which can neatly translate energy, volume and depth of water. In fact the metric system is built around water. 1 calorie is the amount of energy required to heat 1 millilitre or 1 cubic centimetre of water.

   1 megalitre is 10 cm spread over 1 hectare or equal to 100 mm of rainfall over the same area. This is extremely useful to someone who has tramped a few irirgation paddocks in their time, or wants to know how far a river or reservoir might go if translated into irrigation porduction or wetland productivity. 1,200 mm depth irrigated over a summer crop is not unusual. The ability to use ML, GL and to scale up and down the metric system is terrific.

   It sounds to me like you want a more emotive measure of water. That’s ok if you are in the “Urgent! Let’s scare everyone phase”, but if you’re in the “alert not alarmed – let’s empower everyone stage”, then we need to get really smart and about water and energy. And part of that is knowing what a gigalitre of water actually is.

   “And here is the weather. Fifty million tonnes of water fell on Sydney last night.” Brilliant!