Department of Sustainability, Environment, Water, Population and Communities - July 2011
Dr Skye Wassens and her team from Charles Sturt University are monitoring ecosystesm responses to the release of more than 160 gigalitres of environmental water into the Murrumbidgee River.
The release included 109 gigalitres of Commonwealth environmental water.
In this interview, Dr Wassens explains the scientific monitoring.
Interviewee: Dr Skye Wassens
Interviewer: "Commonwealth Environmental water is flowing through the Murrumbidgee River and filling hundreds of wetlands along the way. More than 150 gigalitres of water, about 75,000 Olympic swimming pools' worth, was released from Burrinjuck and Blowering Dams in New South Wales in June, 2011.
It was the largest release of Commonwealth Environmental Water to have ever taken place, and is expected to improve river and wetland health all the way to the mouth of the connecting river Murray.
Dr Skye Wassens and her team from Charles Sturt University are monitoring eco-system responses to this man-made flow of water. Dr Wassens, what are the benefits of releasing so much water at once?"
Dr Wassens: "The biggest benefit is actually to do with connectivity, so when you release a large slug of water you are connecting the wetlands that border the river to the river, and you are creating this sort of pathway for animals, aquatic animals and nutrients and energy to move around the system and to sort of re-organise themselves.
So creating connectivity during a large flow is really critical to allow organisms back into wetlands that have been dry.
And also to allow the movement of nutrients and carbon that have been accumulating in wetlands during those dry periods to move back into river systems which feed some of those riverine food chains that many organisms depend on."
Interviewer: "And so we saw natural flooding last spring. Was it important that that flooding was then followed by this release, which was released from a dam as part of a watering program?"
Dr Wassens: "It is really important and I think the way to imagine these, particularly when you're working with wetlands that have been very stressed, and they have been dry for a very long time, you almost need to really jump-start these processes again.
Because a lot of the plants and animals that normally would, would sort of be driving the eco-system processes, cycling carbon, other plant growth that would normally support fish, and other animals.
It needs a real jump-start to get it going again. So last year's natural flood started off this process but we've still got wetlands that are almost in sort of critical care at the moment, and we need to keep trying to get those processes operating properly.
We need to get plants to, aquatic plants to start growing and putting down seed. So until we can get aquatic plants putting down seed then we're, we're not going to get a restoration of aquatic plant communities. And it's a little bit the same for, for things like frogs and fish. We actually need to give them the opportunity to, to have a couple of good years of breeding so that they can persist if we do go into another dry phase."
Interviewer: "This is a relatively new thing. How important is it that we understand what that water is doing and how it's benefiting the eco-systems downstream?"
Dr Wassens: "I think it's really important that, that we get a good handle on what's going on, and we do have to remember that environmental flooding is relatively new. It's only in the last few decades that we've really had to use this as a management tool rather than just relying on a natural flooding regime.
So it is these, the creation of dams, the utilisation of water for, for other purposes means that there's a lot less water available for the environment now than there was historically. And so what we're trying to do is maintain healthy wetlands, maintain healthy river red gum communities, maintain all that sort of biodiversity and all that, the important national heritage that we have using a very small amount of water.
And there's going to be a learning process from that. I mean, how we, how we get the very best outcome out of the, out of the water. So how do we extract every little bit of value out of the water that we have."
Interviewer:"So being really strategic about when that water's released and where it's released to, to save as many eco-systems as possible?"
Dr Wassens: "That's right. So the more information we can get on what's working during these flows, what happens when we run smaller flows more often, or whether we run a couple of big flows less frequently, so what's the best way to package up that water and use it to extract the most benefit for the environment.
Monitoring is really critical for that because that feeds back into the decision-making process. We know what worked, what hasn't worked, and how we can make it better in the future."
Interviewer: "And how are you going about monitoring this release?"
Dr Wassens: "We're managing a whole, monitoring a whole range of processes for this one. The time that that water leaves the dam, we're keeping an eye on what happens to it.
So we're looking at biofilm growth and we're also looking further down the system as we get to the wetlands at the movement of carbon and nutrients, because we know that's important and we need to understand how those processes occur.
And then we're looking sort of up the food chain, I guess, to tadpoles and frogs. Frogs are often quite a good indicator of what's going on in wetlands. But also vegetation, a whole range of factors."
Interviewer: "I guess there's a lot of local engagement that goes on as well as the scientific monitoring. How important is it to have anecdotes and observations from, from farmers and other locals in the area to help with the research?"
Dr Wassens: "It really is quite important and we can't put people into every wetland along the system, and quite a lot of our finds and a lot of our knowledge comes from people keeping their eyes and ears open and noticing maybe a frog that they haven't seen before has turned up, or noticing perhaps some different birds, or that some birds seem to be nesting on their property or around their wetlands.
So we always try to engage people as much as we can, because it helps us understand what's going on in the whole system, and the more people who are keeping an eye out for those changes or who have a lot of knowledge from before the drought or before regulation can be really useful."