HUON ESTUARY STUDY Environmental Research for Integrated Catchment Management and Aquaculture CSIRO Huon Estuary Study Team Project No 96/284 HUON ESTUARY STUDY Environmental Research for Integrated Catchment Management and Aquaculture CSIRO Huon Estuary Study Team Edward Butler, John Parslow, John Volkman, Susan Blackburn, Phillip Morgan, John Hunter, Lesley Clementson, Naomi Parker, Rosemary Bailey, Kate Berry, Pru Bonham, Alison Featherstone, David Griffin, Harry Higgins, Danny Holdsworth, Val Latham, Rhys Leeming, Tony McGhie, Don McKenzie, Ron Plaschke, Andrew Revill, Matt Sherlock, Louise Trenerry, Alison Turnbull, Ros Watson, Leanne Wilkes Project No. 96/284 CSIRO Marine Research GPO Box 1538 Hobart, Tas. 7001 Tel: (03) 6232 5222 Fax (03) 6232 5000 Cover design and layout: Gina Donnelly Printer: Information Solution Works Pty Ltd, Hobart National Library of A ustralia Catalog uing -in -p ublication entry CSIRO. Division of Marine Research. Huon Estuary Study Team. Huon estuary study: environmental research for integrated catchment management and aquaculture. Bibliography. ISBN 0 643 06225 4. 1. Watershed management – Huon River Region (Tas.). 2. Estuaries – Environmental aspects – Tasmania. 3. Water resources development – Environmental aspects – Tasmania. 4. Salmon industry – Tasmania. I. Butler, Edward, 1954- . II. Fisheries Research and Development Corporation (Australia). III. Title. 333.91640909946 For bibliographic purposes, this document may be cited as: CSIRO Huon Estuary Study Team. (2000) Huon Estuary Study — environmental research for integrated catchment management and aquaculture. Final report to Fisheries Research and Development Corporation. Project number 96/284, June 2000. CSIRO Division of Marine Research. Marine Laboratories, Hobart. Disclaimer: CSIRO Marine Research does not warrant that the information contained in this document is free from errors or omissions. CSIRO Marine Research shall not be in any way liable for any loss, damage or injury suffered by the User consequent upon, or incidental to, the existence of errors or omissions in the information. Huon Estuary Study iii Table of Contents Table of Contents............................................................................................................................iii Summary.........................................................................................................................................ix Chapter 1 1 INTRODUCTION.................................................................................................................... 1 1.1 Background to Study ........................................................................................................ 1 1.1.1 Previous environmental research on marine fish farming........................................ 2 1.1.2 Associated studies active in the Huon region........................................................... 3 1.2 Need .................................................................................................................................. 5 1.3 Scope of This Study..........................................................................................................5 1.4 Project Objectives ............................................................................................................. 7 1.5 References......................................................................................................................... 8 Chapter 2 2 STUDY CONTEXT AND DESIGN ..................................................................................... 11 2.1 Introduction..................................................................................................................... 11 2.2 Study Area....................................................................................................................... 12 2.2.1 The natural environment ......................................................................................... 12 2.2.2 Human activities in the catchment.......................................................................... 17 2.2.3 Other factors influencing the estuary...................................................................... 18 Winds.................................................................................................................................. 18 Run-off................................................................................................................................ 19 Groundwater ....................................................................................................................... 19 Tides.................................................................................................................................... 19 Bathymetry ......................................................................................................................... 21 2.3 Previous Investigations of the Huon Estuary................................................................. 21 2.4 Development of a Survey Strategy for the Huon Estuary Study................................... 21 2.4.1 Geographic coverage — spatial surveys................................................................. 24 Estuarine bounds ................................................................................................................ 24 Disposition of stations........................................................................................................ 26 Types of stations................................................................................................................. 26 Vertical resolution .............................................................................................................. 26 Zonation of estuary.............................................................................................................27 Survey frequency................................................................................................................27 2.4.2 Short time-scales — monitoring at key stations..................................................... 27 2.4.3 Shorter time-scales — autonomous continuous profilers ...................................... 28 2.4.4 Short time-scales and mapping of surface-water properties .................................. 30 2.4.5 Long time-scales — sediment sampling and analysis............................................ 30 Fallowing study .................................................................................................................. 31 2.4.6 Summary — covering relevant time and space scales ........................................... 33 2.5 References....................................................................................................................... 35 iv Table of Contents Chapter 3 3 PHYSICS OF THE ESTUARY .............................................................................................39 3.1 General Review ...............................................................................................................39 3.1.1 Introduction..............................................................................................................39 3.1.2 Classification of the Huon Estuary..........................................................................39 3.1.3 Dimensions of the Huon Estuary.............................................................................41 3.1.4 Tidal motions ...........................................................................................................43 3.1.5 Winds .......................................................................................................................44 3.1.6 River flow.................................................................................................................44 3.1.7 Currents ....................................................................................................................46 3.1.8 Other studies of the Huon Estuary ..........................................................................46 3.2 Background to Physical Surveys ....................................................................................48 3.2.1 River flows...............................................................................................................48 3.2.2 Winds .......................................................................................................................49 3.3 CTD Observations...........................................................................................................49 3.3.1 Vertical sections.......................................................................................................49 3.3.2 Surface salinity measured underway.......................................................................53 3.3.3 Comparison with the Derwent Estuary ...................................................................53 3.4 Inverse Modelling ...........................................................................................................56 3.4.1 Schematisation .........................................................................................................56 3.4.2 Processing of salinity data .......................................................................................57 3.4.3 Processing of bathymetric data................................................................................57 3.4.4 Processing of river flow data ...................................................................................58