Understanding the Effects of Flow Regime on the Snowy River Estuary — ASN Events

Understanding the Effects of Flow Regime on the Snowy River Estuary (#196)

Christine Arrowsmith 1 , Dan Stoessell 2 , Jon Hinwood 3
  1. Water technology , Victoria
  2. Arthur Rylah Institute, Department of Environment, Land, Water and Planning, Melbourne, Victoria, Australia
  3. Coastal Environmental Consultants, Melbourne, Victoria, Australia

Transfer of water out of the Snowy River system as a result of the Snowy Mountains Scheme in the 1970s has permanently altered the flow regime of the river, with large changes in the magnitude, and timing of flow events.  Concern over the declining health of the river system has led to the investigation of using environmental flow releases to improve river health.  In order to maximise the potential outcomes from any environmental flow releases as far downstream as the estuary it is necessary to understand the existing physical conditions within the estuary, particularly in terms of salinity and temperature, and how they are influenced by river inflows.  The Snowy River estuary is periodically open and closed and has experienced increasing periods of closure since the SMHS, exacerbated by a prolonged period of drought in the 2000s.  An extensive physical monitoring program coupled with the development of a detailed 3D hydrodynamic and water quality model has recently been undertaken to provide a tool for assessing the impacts of flow regime on the estuary system.  The physical monitoring included salinity, temperature and water level measurements throughout the estuary and adjacent connected lakes, along with bathymetric survey and aerial imagery capture of the entrance. This information was the used to update and extend an existing model of the system, which was then used to simulate a range of flow scenarios.  The results have so far have informed a study of the relationship between flows and recruitment and growth of Australian bass.

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