School of Science & Engineering Report commissioned by: Corangamite Wetland Inventory December 2005 Centre for Environmental Management CORANGAMITE WETLAND INVENTORY Prepared for: By: Centre for Environmental Management University of Ballarat Project Team Mapping & Report Claire Harding Kate Callister Field Survey Teams Claire Harding Damien Cook Dylan Osler Craig Billows Tracey Baldwin Rebecca Sheldon December 2005 EXECUTIVE SUMMARY Background Wetlands within the Corangamite region have been identified as highly valuable elements of the region’s natural ecosystems. Significant loss of wetlands within this region has occurred since European settlement, and threatening processes resulting in further loss of wetlands currently remain. The Corangamite Catchment Management Authority (CCMA) covers an area totalling 1, 334, 000 ha. It comprises the Barwon River, Moorabool River, Lake Corangamite and Otway Coast basins. A total of 56 sub-catchments have been identified within these basins. The greater part of the study area is freehold land (70%) used almost entirely for agriculture. The majority of wetlands occur on the volcanic plain, which covers 46% of the study area. Lakes and wetlands have formed in volcanic craters, depressions due to lava collapse and where drainage patterns have been interrupted, usually by lava flows. Seasonal variation in hydrology, the type of basalt substrate, and the great variety of catchment-to- surface area ratios and throughflows, combine to produce lakes and wetlands with an unusually wide range of salinities. The region contains wetlands of national and international significance. A total of 1, 457 wetlands greater than 1 ha in size, covering approximately 65, 000 ha have been identified. Of these, 24 wetland complexes have been listed as nationally important in the Directory of Important Wetlands (Environment Australia 2001). Two sites of international significance also exist within the Corangamite region: Western District Lakes Ramsar site and a large proportion of Port Phillip Bay (Western Shoreline) and Bellarine Peninsula Ramsar site. Knowing the location, distribution and character of wetlands, their values, uses and threats, is essential for developing and implementing management strategies for their wise use. This is required at geographical scales ranging from local site management, to development of national policies and global priority setting. Wetland conservation needs and priorities in the Corangamite region are currently determined primarily through reference to anecdotal knowledge of condition, values and threatening processes. Consequently it is not possible to adequately or objectively determine management and rehabilitation needs or to quantify resource requirements in meeting these needs. The Wetland Inventory for the Corangamite region was a CCMA initiative. The Centre for Environmental Management (CEM), University of Ballarat was contracted to design and complete the wetland inventory for the region. Review of wetland inventory and research A review was undertaken of the extent and adequacy of wetland inventory information and associated past research on the character, condition, known threats, trends and management issues relevant to wetlands within the Corangamite region. Wetland inventories on regional, national and international scales were reviewed including classification systems used and the ability of the data to provide information on wetland condition. A total of nine inventories and databases with relevance to wetlands of the Corangamite region were analysed. A large proportion of research papers focused on saline lakes, biological values, and management of wetlands within the Corangamite region. A total of 40 research papers of various formats containing information directly relating to wetlands and lakes of the Corangamite region were reviewed. The most complete wetland inventory data existing for the Corangamite region is the Wetlands Database (DCNR 1995), originating from mapping work undertaken in the 1970’s CORANGAMITE WETLAND INVENTORY i EXECUTIVE SUMMARY by Corrick (1982). The Directory of Important Wetlands in Victoria and wetlands listed under the Ramsar Convention provided detailed information on a total of 93 significant wetland areas throughout the Corangamite region. Most wetlands identified as nationally or internationally significant are large, permanent and publicly owned. Present wetland inventory data within the Corangamite region was found to be limited in scope and classification accuracy. It also lacked information on values and threats for the majority of wetlands. This lack of detailed biological data for 98% of the wetlands reflects a number of factors. Firstly, many of the wetlands are small and non-permanent or drained, and have often been extensively modified so that they are now little more than flooded pasture. Many others are artificial (farm dams) and both professional biologists and amateur naturalists tend not to study such areas. This is compounded by the lack of public access to many of these wetlands, especially those on private land. Wetland Inventory – wetland mapping Wetland inventory is the process for determining and recording the location, number and specific characteristics of wetlands within a given area. Existing wetland geographic data for the Corangamite region was found to be lacking for wetland areas under 1 ha in size. The use of remote sensing data on a regional scale was considered the most cost- effective and efficient method for mapping the extent of inundated areas. Wetland mapping for the Corangamite region consisted of identifying, delineating and broadly classifying wetlands from remotely sensed images. A combination of supervised and unsupervised classification techniques were used. Aerial photographs, ancillary data, the Wetlands Database (DCNR 1995), and field data were used to identify training sites and label spectral clusters. Post-classification modelling was performed using ancillary data (Wetland_1994, Wetland_1788 and hydrology data) to further refine the classification of wetlands. Fine scale wetland mapping was completed for sample sub-catchments and comparisons with previous wetland mapping enabled changes in wetland areas to be assessed and wetland boundaries updated to reflect the current situation. Wetland areas were found to have significantly decreased across all sub-catchments, when compared with pre- settlement wetland mapping (Wetland_1788 layer). An increase in the total number of wetlands identified was achieved, largely through the identification of smaller wetlands (<1 ha). Wetland Inventory – field survey A total of 96 wetland field surveys were completed within the five sub-catchments sampled. The number and types of wetlands surveyed within each sub-catchment was distributed with respect to both the number and the area of wetlands within each sub- catchment. The Corangamite Wetland Inventory documents a representative portion of wetland habitats within selected sub-catchments and records their spatial, physical, chemical and biological attributes. Human activities and impacts, and wetland function and values for the Corangamite region were also recorded. From this information, wetlands containing high biodiversity and ecosystem values were highlighted, and threats documented. Data from the Wetland Inventory were entered into a Microsoft Access 2000® format database. This allows the Wetland Inventory data to be easily accessible and updated as further wetland inventories are undertaken. The mechanism for the wetland inventory outlined in this report provides an effective tool for collecting and storing information on wetlands within the CCMA. The mechanism uses a strategic approach to collect information and utilises technological advances in mapping, data storage and dissemination. The Corangamite Wetland Inventory provides CORANGAMITE WETLAND INVENTORY ii EXECUTIVE SUMMARY an improvement on past inventory effort within the sample areas, notably that undertaken in the 1980’s, and later developed into the Wetland Database (DCNR 1995). CORANGAMITE WETLAND INVENTORY iii ACKNOWLEDGEMENTS The project team would like to thank the Centre for Environmental Management staff – Matthew Gibson, Robert Milne, Janet Leversha, Jim O’May, Stacey Gowans and John Miller – for advice and assistance with data analysis, editing and report production. We gratefully acknowledge the expertise and assistance of the following people: • Craig Allen, Wetlands Officer, Corangamite Catchment Management Authority; • Rebecca Sheldon, Wetlands Officer, Corangamite Catchment Management Authority; • Brock Baker, Ecol-GIS; • Rhonda Butcher, Deakin University; • Tracey Baldwin, RMIT University; • George Appleby; • Andrew Bishop, Golden Plains Shire; • Paul Coverdale, Corangamite Shire; • Alex Shackleton, Geelong City Council; • Ashley Burns, Greening Australia Victoria; • Philip DuGuesclin, Department of Natural Resources and Environment, Colac; • Gavin Cerini, Field and Game, Ballarat; • Andrew Corrick, Arthur Rylah Institute, Heidelberg; and • Grant Hull, Department of Natural Resources and Environment, Ballarat. CORANGAMITE WETLAND INVENTORY iv TABLE OF CONTENTS 1. INTRODUCTION ......................................................................................................................1 1.1 Project scope ........................................................................................................................................2 1.2 Aims and Objectives............................................................................................................................2