The Goulburn River is 570 km long flowing from the high ranges of the Great Dividing Range in the South to the Murray River Plain to the north. Major tributaries of the Goulburn River include the Broken River, Seven Creeks, Castle Creek, Rubicon River, Acheron River, Yea Riverland Sunday Creek. Over thousands of years, silt deposition from this system has created the rich and fertile soils of the Goulburn Floodplain.
Native vegetation has been retained over much of the upper reaches in the south. In the north however, clearing for agriculture in the flood plain has been extensive and only small pockets and corridors have been retained. These provide critical habitat for a range of threatened flora and fauna.
The river has a mean annual discharge of 3,040 GL which represents 13.7% of the total Victorian discharge. Flow along the river has been modified by two major features, Eildon Reservoir upstream of the Eildon Township and the Goulburn Weir near Nagambie.
The Goulburn River supports one of Australia's pre-eminent agricultural regions providing dairying, cropping, grazing , horticulture and viticulture.
Major rural towns along the river include Shepparton, Mooroopna, Seymour, Nagambie, Thornton, Eildon, Jamieson and Woods Point.
The lower Goulburn River floodplain and Deep Creek system have been the focus of numerous investigations as part of the Lower Goulburn floodplain rehabilitation scheme. The rehabilitation scheme considers reflooding the northern section of the Goulburn River floodplain through Loch Garry and channelling overflows through the existing floodplain waterways (i.e. the Deep Creek system). The geomorphology of this region has been well documented (e.g. Bowler, 1976; Cameron McNamara, 1987; Erskine et al., 1993; SKM, 1998) with the floodplain channels reported as relics of ancestral and prior streams that formed thousands of years ago.
Since European occupation, irrigation development and regulation of the Goulburn River has reduced the frequency and magnitude of flows over the lower floodplain. Consequently, the rate of adjustment of floodplain channels has altered. Reintroducing flows to the floodplain may have numerous consequences including altered erosion rates and possible avulsion (course change) of the Goulburn River.
This project investigates the likelihood of an avulsion occurring as a result of increasing flows to the floodplain channels. The study deals with the section of the lower Goulburn River floodplain from Loch Garry to the Murray River and focuses on the effluent channel systems of Deep, Sheepwash, Skeleton and Bunbartha Creeks along the north bank of the river.
Investigations into historic and present day morphology, the rates of geomorphologic change, soil types and critical shear stress of the soil in the Deep Creek system provide information on bed and bank stability. These results are compared with those from similar tests conducted on the Goulburn River. Based on the analysis of these results an assessment of possible avulsion from the Goulburn River to Deep Creek under the proposed Lower Goulburn Floodplain management scheme is made.
The rehabilitation needs to consider the restoration of the natural flow while maintaining the ability to limit damage due to excessive flooding at times of excessive rainfall.
From the results of the modelling undertaken to assess the scheme, an arrangement of spillways and bund alignments are proposed that are aimed at providing flood protection to the Lower Goulburn for floods up to a 35-year flood. For floods approximately larger than the 35-year flood, the levee system is likely to over top and fail, allowing flood flows to be distributed to both the northern and southern floodplains.
The main structural elements of the proposed scheme include:
• Ground level spillway at the existing Loch Garry Outlet
• Ground level spillway close to the existing Deep Creek Outlet
• Spillway at Delma Lagoon and associated earthen bund to Madowla Lagoon
• Earthen bunds along both sides of the northern floodplain
• Realignment of several existing levees to improve conveyance and/or to restore levee integrity.
Activities undertaken to improve the river include
- Revegetation with local native species
- Fencing to manage stock grazing and access to rivers
- Enhancement of stream habitat for native fish by reintroducing snags for refuge
- Removal of willows and other woody weeds
- Removal of barriers to fish migration
- Rubbish traps to stop river contamination
(Sourced from The Lower Goulburn Floodplain Study by The Goulburn Broken Catchment Authority)
Requirements to have your Find on this Earthcache confirmed.
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List two activities which farmers or other folk can undertake to assist with the rehabilitation project.
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Look at the river. Based on the river height and the flow rate, what comment would you make on the apparent success of the project.
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Now Compulsory
Please attach a photo of the river at this site, preferably with yourself or a personal item included, to your log.
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You can log your find immediately, but please send your answers to me at earthcaches@jamieson.id.au If you want a quick response it is important to use this email address as it goes to my phone and I can usually respond almost immediately. Email or messageto via geocaching.com account email address will of course be responded to eventually. If I don't get your answers within ten days, your find log may be deleted./