Water Technology is proud to be sending 4 delegates at the 7th Australian Stream Management (7ASM) conference next week in Townsville. This years conference, with the theme ‘catchments to coasts’ promises an excellent variety of presentations an field trips. Have a look below to see the abstracts for presentations to be given by Water Tech staff next week.
Do native fish need healthy riparian vegetation? An assessment of 1,000km of the Billabong, Yanco and Columbo Creeks, NSW
- Water Technology, Wangaratta, VIC, Australia
- CPS Environmental Research, Irymple, VIC, Australia
- Murray Catchment Management Authority, Albury, NSW, Australia
The Billabong-Yanco-Colombo Creek system is a key natural asset within the Murray Catchment Management Authority’s region, recognised for natural, economic, social and cultural heritage values. The Murray CMA needed better knowledge of the condition of riparian vegetation within this system to assist with identifying NRM investment priorities. The Murray CMA had a broad understanding of the vegetation condition of these waterways which generally declined as they flowed west into more arid environments with cumulatively more water extraction. To build on this knowledge, a number of vegetation and habitat condition assessment parameters were chosen that were repeatable and that could be rapidly applied across a wide geographic area. The methods applied assessed vegetation cover, structure, diversity, health and habitat quality from the instream environment back out through the riparian zone. The results confirmed a general trend of decline downstream; however the range of assessment parameters provided a number of interesting results that were unexpected. While the vegetation condition project was being undertaken, fish surveys were in progress to collect information on the distribution, relative abundance, diversity and condition of fish communities throughout the same system. This paper also compares the riparian and instream condition results with the fish survey results. These comparisons are informing managers of priority actions for vegetation and waterway management to improve habitat provision for native fish.
Salinity, Water Level, and Flow Considerations for Assessing Environmental Water Requirements of the Lower Latrobe River
Christine S Lauchlan-Arrowsmith 1 Sandra Brizga 2 Eleisha Keogh 3
- Water Technology, Melbourne, VICTO, Australia
- S. Brizga & Associates Pty Ltd, Melbourne, Victoria, Australia
- West Gippsland Catchment Management Authority, Traralgon, Victoria, Australia
The lower Latrobe River is an estuarine system which connects the catchments of the Thomson, Macalister and Latrobe Rivers with Lake Wellington and the Gippsland Lakes. The estuarine conditions of the river are unusual, as its distance from the ocean entrance of the Gippsland Lakes results in a micro-tidal water level range, with water levels in the Lake Wellington and lower Latrobe River dominated by winds, waves and atmospheric pressure as well as the effects of upstream river inflows. Salinity conditions are also highly variable, ranging from predominantly fresh to almost ocean salinity during the recent extended drought period. Salinity is a crucial factor with regard to the ecological condition of the system and an environmental flows study investigated how environmental water could be used to moderate the effects of increasing salinity regimes as well as meet the ecological objectives of the system as a whole. Hydrodynamic modelling was used to assess the flushing behaviour of freshwater inflows on the lower river and this behaviour was then linked back to the ecological requirements. Environmental flow recommendations were developed which focussed on freshwater inflows to manage salinity, along with more typical criteria around flow inundation in terms of water levels and frequency. Quantification of these recommendations was made possible through the detailed hydrodynamic modelling.
Implications for river management on the Loddon River at Newstead long after the cessation of mining activities
Julian C Martin 1 Angela Gladman 2 Kathy Russell 3 Christine Arrowsmith 3
- Water Technology, Wangaratta, VIC, Australia
- North Central Catchment Management Authority, Huntly, VIC, Australia
- Water Technology, Melbourne, VIC, Australia
The Loddon River at Newstead has been subject to considerable physical and ecological modifications due to extensive historic mining activities and other anthropogenic influences. Of recent years bank erosion has been an issue for both landholders adjacent to the Loddon River and the North Central CMA. Following an investigation, pile fields were constructed on several bends of the river in 2003.
The Loddon River at Newstead was subject to a series of flood events ranging from a 1 in 20 year ARI event to over a 1 in 100 year ARI event during late 2010 and early 2011. Resultantly, the majority of an existing pile field site was significantly damaged.
A study was undertaken to assess the original pile field sites and the hydrology and hydraulics of the Loddon River at Newstead in context to the recent flood events in 2010 – 2011. The purpose of this study was to develop a new suite of works, including detail designs with consideration to the knowledge gathered in the study.
This paper investigates the geomorphic and hydraulic behaviour of the Loddon River at Newstead with reference to existing pile field sites and the 2010 – 2011 flood events.
Waterways and Gully Stabilisation in vertisol Soils: Dry Creek, Condamine Catchment, QLD.
- Water Technology, West End, QLD, Australia
Australia has the highest diversity and distribution of cracking clays in the world. The overriding problems associated with vertosols in Australia are those of erosion and waterway instability. Vertosols, commonly referred to as black earths, are defined as “clay soils with shrink-swell properties that exhibit strong cracking when dry” (Isbell, 1996) Numerous studies into erosion and waterway stability in vertosol environments were undertaken in the 1980’s, however, most focused on artificial waterways for contour farming and none found any solution to waterway stabilisation. Through community consultation, it was largely agreed upon that typical stream stabilisation measures were inappropriate for these sediments as structures were usually out-flanked or undercut.
The Dry Creek Catchment is a headwater catchment of Oakey Creek, a tributary of the Condamine River. Dry Creek flows west of the Great Dividing Range, with a relatively small catchment covering 40 km2. Land use on the valley floor is a combination of cropping and grazing land. Much of the agricultural land is contoured. Prior to European settlement, it is likely that many of the present day creeks did not exist as a defined channel but more of a grassed discontinuous watercourse with very little surface expression. An increase in catchment discharge, due to clearing for agriculture, and development on the floodplain, has concentrated flow, which has initiated the incision of a defined channel. The floodplains of the lower reaches of the catchment are now being intensely developed for industry. Whereas this has led to an interest in the future behaviour of the incised streams, there is little interest, funding or even established methodology, for waterway stabilisation at this site.
With reduced political interest in waterway health in Australia, research into waterway stability in vertosol soils has all but ceased. More worryingly, those involved in research and implementation in decades past are now retired, and we are at risk of losing vast amounts of knowledge. Here we review previous research and attempts on waterway stabilisation in vertosol soils with reference to Dry Creek and vertosol soils landscapes in general.