eWater CRC is working on local water-management issues in partnership projects with organisations in northern Victoria.
Focusing on the Goulburn and Ovens river catchments, the project teams are exploring the ecological value and benefits (or disbenefits) if offchannel habitats were to be deliberately rewetted.
About the Focus Catchment
The Ovens and Goulburn rivers contribute significantly to the water resources of the Murray-Darling Basin. These two rivers are similar in many ways in terms of their geomorphology, land-use, and vegetation communities, but their hydrology is vastly different. The Ovens River is largely unregulated while the Goulburn is highly regulated.
With a population of over 200,000 spread over 25,000 km2, these two catchments occupy much of the area known as the food bowl of the Murray-Darling Basin.
Irrigated and dryland agriculture are very important, and the region contributes signifi cantly to the Victorian and national economies.
Both rivers also have high environmental values and natural biodiversity. For example, the region includes the Barmah Forest — an internationally recognised wetland system and part of the largest river red gum forest in the world.
In their natural state, both rivers’ off-channel floodplain wetlands, redgum forests, and other ecosystems would be strongly influenced by seasonal flooding. Although the Ovens River still floods frequently, the Goulburn River, regulated by Eildon Dam, does not. Reduction in seasonal flooding affects the long-term condition of the
rivers’ important riparian ecosystems.
This eWater application is helping identify how potential flow scenarios could affect the river and floodplain ecology of the area.
Besides its strong research component, eWater’s work in this focus catchment involves applying a range of the CRC’s next-generation software tools, in:
(i) hydraulic and flow modelling of streamflow in the Goulburn River and its tributaries, in relation to its floodplain;
(ii) building up information about ecological responses in these catchments; for example, how floodplain vegetation responds to changes in flow conditions through time;
(iii) developing and evaluating models of ecological response.
Rewetting of dry floodplains
Flooding of dry floodplains can be benefi cial or pose risks for the floodplain ecosystems. River red gums and other floodplain and wetland vegetation, as well as waterbirds, resident fish and water bugs, may be rejuvenated by the watering. In refuge pools, rewetting can be the difference between surviving or succumbing to the pressures of water quality and quantity, predation and habitat loss that often accompany drought.
But the duration of wetting is very important. Unless the water stays for a suitable length of time the natural cycles it triggers may not be completed. And the timing of watering matters as well: for instance, delivering water during very hot summer weather carries a risk of blackwater’ events that can lead to fish deaths.
In the Goulburn and Ovens rivers, eWater’s research is helping identify the ecological assets, including key ecological communities, indicators of condition, and important habitats. The team is also identifying groundwater dependent wetlands and refuges.
The application is integrating ecological and hydrological modelling expertise to review existing information on the role of overbank fl ows in maintaining riparian ecosystems.
The team can then evaluate the likely ecological effects of restoring such fl ows in the Goulburn river system.
By combining rainfall-runoff, flow routing and hydraulic models, the project team is also exploring scenarios of potential climatic conditions (based on historical and predicted events) in relation to rewetting off-channel habitats.
This will give insight into the influence of tributary inflows
on flood heights. The team is also investigating options for piggybacking of flow releases onto natural flow events.
See Related Technical Reports
Barlow K, Weeks A, Githui F, Christy B. (2010) Northern Victoria Application Project: Parameterisation tools (PEST and RRL) and Source Catchments base model of the Goulburn River between Lake Eildon and the Goulburn Weir.
This research and accompanying trial of eWater software in northern Victoria is exploring and summarising how key ecological indicators are likely to respond to alternative future-fl ow scenarios, including floodplain wetting events, along the lower Goulburn and Ovens rivers.
It will also result in a management database identifying high priority areas for refuge management along the Goulburn River, based on the dynamics of groundwater-surfacewater interactions.
The models will be developed in such a way that the general approach and information requirements may be applied to similar river situations elsewhere.
These eWater partner organisations are involved in this project: