Swan and Canning Rivers Foreshore Assessment and Management Strategy10.04 MB
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Swan and Canning Rivers Foreshore Assessment and Management Strategy March 2008 Table of Contents Preface.......................................................................................................................................1 1.1 The Swan River Trust...................................................................................................1 1.2 About this Document ....................................................................................................1 2 Executive Summary............................................................................................................3 2.1 Riverbanks and Shoreline Issues .................................................................................3 2.2 Vegetation Issues.........................................................................................................7 2.3 Strategies for Management ........................................................................................10 2.4 Management Priorities................................................................................................12 3 Foreshore Assessment .....................................................................................................17 3.1 Overall Approach........................................................................................................17 3.2 Riverbank and Shoreline Assessment ........................................................................17 3.3 Vegetation Assessment..............................................................................................50 4 Foreshore Strategy ...........................................................................................................81 4.1 Approach....................................................................................................................81 4.2 Riverbanks and Shoreline Issues and Management...................................................82 4.3 Priorities for Action - Riverbanks and Shorelines ........................................................86 4.4 Vegetation Issues and Management ........................................................................110 4.5 Priorities for Action–Vegetation.................................................................................113 4.6 Summary: Priority Sites for Management .................................................................148 5 References .....................................................................................................................152 6 Appendices.....................................................................................................................154 Preface 1.1 The Swan River Trust The Swan River Trust works in collaboration with the Commonwealth and various State, and local government agencies, community and industry organisations to deliver two important outcomes: 1. The long-term community benefit of the Swan Canning river system is protected and enhanced; and 2. The ecological health of the Swan Canning river system is protected and enhanced. The replacement of the Swan River Trust Act 1988 and the Environmental Protection (Swan and Canning Rivers) Policy 1997 with the Swan and Canning Rivers Management Act (proclaimed September 2006) improves the State's ability to manage activities that may affect the Swan and Canning rivers. This will enable management issues such as maintaining biodiversity, facilitating commercial and recreational use of the waterways, and conserving indigenous and European heritage to be more effectively addressed. The new legislation recognises the importance of the rivers as an icon of Perth by establishing the Swan Canning Riverpark. Riverpark consists of the waterways and adjacent Crown land reserves of the Swan, Canning, Helena and Southern rivers (private property is not included in Riverpark). The legislation makes the Trust responsible for the waterways, establishes joint management arrangements for shorelines, and requires preparation of a Riverpark Management Program to integrate management of the waterways and the adjacent reserves along the foreshore. Since January 2002, the Trust, through its Riverbank Program, has worked with local and State government land managers to initiate foreshore protection and rehabilitation projects within its management area. The Trust will contine to work in partnership with local and State government to maintain and improve Riverpark foreshore areas. 1.2 About this Document The Swan River Trust has long recognised that to effectively manage the Swan Canning foreshores and allocate investments, a good understanding of the foreshore condition and threatening processes is required. In 2002, the Trust successfully sought funding through the Natural Heritage Trust to undertake an ecological and physical assessment of the Swan Canning foreshores and subsequently established a ‘Foreshore Assessment’ project in partnership with the Swan Catchment Council. That project was aimed at: • identifying condition and pressures; • making recommendations for management; • identifying priorities for investment; and • providing a benchmark for future evaluation. This document represents a culmination of that project and is divided into two major parts. The first part summarises the findings of the Foreshore Assessment, describing foreshores, their pressures and condition. The second part of this document is a management strategy which summarises the foreshore issues, defines management responses and identifies priorities for action. 1 Throughout this document, the riverbanks and shorelines are considered separately from the foreshore vegetation. This is deliberate and consistent with the two objectives of the Swan River Trust’s Riverbank Program: • To protect and enhance riverbanks and shorelines to mitigate threats to foreshore values; and • To protect, enhance and manage fringing indigenous vegetation and habitat. The Foreshore Strategy is intended as a guide for investment. It is neither an investment plan, nor a strategic plan for the Trust as a whole. Recommendations of the Foreshore Strategy will be considered and implemented through the Trust Riverbank Program under the Healthy Rivers Action Plan, and also through the Swan Catchment Council investment plans for the NHT3. Implementation is also through existing State and local government plans and community action plans. The Foreshore Assessment accounts for the current condition and pressures on riverbanks and shorelines and their associated vegetation. Management strategies are focussed on addressing these. The Foreshore Assessment, and thereby the Strategy, does not account for the potential impacts of climate change. It is too early to reliably anticipate the pace of any systemic change that will be forced by climate. However, it is expected that climate change will result in increased sea levels and storm surges within the Swan and Canning rivers. Therefore, the risk of erosion or inundation in some areas would be expected to increase beyond that identified in this document. In areas where that risk is high, it will become increasingly important to ensure that infrastructure is adequately protected, and to improve the stability of shorelines using appropriate techniques where necessary. It will also be important to ensure that adequate setbacks are in place to enable the shorelines and associated vegetation to adapt to the physical changes that they will encounter. Climate change is also likely to exacerbate sedimentation where streamflows decline, thereby increasing pressure on areas where this problem already exists. In addition, climate change is likely to change the distribution and abundance of fringing vegetation from which is recorded here. An important recommendation of the recent report on climate change in the Swan and Canning rivers (Technical Advisory Panel 2007) was the need for an assessment of the vulnerablility of foreshore areas to provide the basis for determining future planning setbacks, managing foreshore vegetation and erosion, and designing erosion control measures. This document and the associated database provide the benchmark against which future change can be measured and vulnerability under different scenarios evaluated. 2 2 Executive Summary The Swan and Canning Rivers Foreshore Assessment divided the river into three zones (Figure 2.1). The zones are: 1. Estuary: Perth and Melville Waters downstream of the Causeway and Mount Henry Bridges (Zone 1); 2. Swan: Swan, Helena and Lower Avon rivers upstream of the Causeway and within the Swan River Trust Management Area (Zone 2); and 3. Canning: Canning and Southern rivers upstream of Mount Henry Bridge within the Swan River Trust Development Control Area (Zone 3). In each zone, the condition and pressures of the shoreline (both built and non-built) and vegetation were documented. Information compiled as part of the Foreshore Assessment was then used as the basis for developing a management strategy. The strategy makes recommendations for management response within two overarching objectives, which are: • To protect and enhance riverbanks and shorelines to mitigate threats to foreshore values; and • To protect, enhance and manage fringing indigenous vegetation and habitat. Within the first objective the term ‘shoreline’ is defined as the area two metres either side of the high water mark (Swan Canning Rivers Management Act 2006). This is used in combination with the term ‘riverbank’ to acknowledge the spatial extent of foreshores and their