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Old Man Creek Old Man Creek is a flow through system, receiving water from the Murrumbidgee River downstream of Wagga Wagga (at Beavers Creek Weir) and returning to the Murrumbidgee River upstream of Narrandera. The creek bypasses Berembed Weir; the main supply to MIA. The creek supplies irrigation and environmental flows to areas west of Wagga Wagga and south of the river. Water is regulated into Old Man Creek via a fixed crest weir on Beavers Creek, designed prior to the higher flows now in the river following the commissioning of Blowering Dam, the Snowy Scheme and increased size of Burrinjuck Dam. Because of its design age, the weir only regulates water into Old Man Creek at flows less than 8,000ML/day at Wagga Wagga. In most irrigation years this flow is exceeded for many days, resulting in inefficient transmission of water to the lower river. By regulating the flows into Old Man Creek with a new weir, efficiency gains are potentially available, by reducing evaporation and evapotranspiration of flows along the creek. There are significant environmental and social issues associated with this management action that will require investigation. Hydraulic modeling of the flows in the creek has commenced using a digital elevation model built from Lidar survey data received in January 2009. This modelling is nearing completion and the results will enable plans for further studies to identify the potential water savings. Full regulation of all irrigation flows into Old Man Creek, will enable water to be conveyed via the more efficient Murrumbidgee River and will reduce evaporative losses in the creek. Tenders to complete a preliminary design for a regulating structure at the Beavers Creek Weir will be called for in the near future, to coincide with the completion of modelling work to estimate the existing water losses. A study on the relationship between flow rate and the abundance, distribution and habitat use of native fish in Old Man Creek has been underway since 2006. Funded in part by Water for Rivers in conjunction with Charles Sturt University, the study has surveyed the fish in Old Man Creek and has identified the critical threshold velocities (maximum velocity) at which larvae fish can swim. This information is being used to develop a model that will predict how changes to the current flow regime will affect fish populations in Old Man Creek. This research will be used to plan the flow rate and timing of environmental and regulated flows into Old Man Creek. The photos below show the existing weir into Old Man Creek and Old Man Creek flowing near Berry Jerry State Forest. |
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URL: http://www.waterforrivers.org.au/projects/current/20102812994.asp |
