A part of BMT in Energy and Environment Woorim Beach Shoreline Erosion Management Plan

Transcription

1 A part of BMT in Energy and Environment Woorim Beach Shoreline Erosion Management Plan R.B doc September 2007

2 Woorim Beach Shoreline Erosion Management Plan Prepared For: Prepared By: Caboolture Shire Council BMT WBM Pty Ltd (Member of the BMT group of companies) Offices Brisbane Denver Karratha Melbourne Morwell Newcastle Perth Sydney Vancouver

3 DOCUMENT CONTROL SHEET BMT WBM Pty Ltd BMT WBM Pty Ltd Level 11, 490 Upper Edward Street Brisbane 4000 Queensland Australia PO Box 203 Spring Hill 4004 Tel: Fax: ABN Document : Project Manager : Client : R.B doc Malcolm Andrews Caboolture Shire Council Client Contact: Graham Burgdorf Client Reference PKS Title : Author : Synopsis : Woorim Beach Shoreline Erosion Management Plan Dean Patterson; Malcolm Andrews; Dr Ian Teakle, Lyn Raphael Report outlining the status of coastal processes and erosion of Woorim Beach and consideration of options and feasibility of engineering works and management action leading to a SEMP for dealing with the existing erosion problems. REVISION/CHECKING HISTORY REVISION NUMBER DATE OF ISSUE CHECKED BY ISSUED BY /6/07 31/7/07 Ian Teakle M J Andrews D C Patterson D C Patterson 2 08/08/07 M J Andrews D C Patterson 3 24/09/07 M J Andrews D C Patterson DISTRIBUTION DESTINATION Caboolture Shire Council EPA BMT WBM File BMT WBM Library REVISION pdf Pdf + 2 copies Pdf Pdf pdf Pdf pdf pdf

4 EXECUTIVE SUMMARY I EXECUTIVE SUMMARY This Shoreline Erosion Management Plan (SEMP) has been prepared on behalf of the Caboolture Shire Council by BMT WBM Pty Ltd following best management practice in line with the Coastal Protection Act, State Coastal Management Plan and SEQ Regional Coastal management Plan. The beach system along much of the Woorim shoreline is presently in poor condition due to persistent erosion and Council has used beach nourishment over several decades to maintain a minimum level of property protection and beach amenity. Council, EPA and community inputs to the study in response to the information presented on the erosion processes taking place and the effects of the possible solution options have provided policy direction on the SEMP objectives as follows:!" There is demand for restoration and sustainable maintenance of the beach and dune at Woorim. This expectation requires a substantial increase in the sand volume in the beach and dune system as well as appropriate dune management along the whole Woorim and adjacent Bribie Island east coast shoreline.!" There is a demand for protection of the public roads and facilities together with residential and surf club development located on the dune behind the beach and dune system. Based on the present understanding of the processes and behaviour of Woorim beach, it is considered most improbable that any improvement in the condition of the beach will occur naturally, although there will continue to be normal fluctuations in the level of the beach from time to time associated with storm erosion and subsequent beach recovery. To the contrary, further degradation will occur as progressive erosion continues and the impacts of climate change occur. As such, continuing with minimal ad-hoc action is considered not feasible as the beach and parts of the dune would erode and remain in poor condition such that:!" For substantial periods of time, beach levels will be low and high tides and waves will impinge on the base of the dune scarp, with no usable beach available for access and recreational use by the community. At such times, there is a safety risk particularly for young children;!" The shoreline will recede, threatening Rickman Parade and the adjacent developed properties with erosion;!" The aesthetic, recreational and environmental value of the beach will continue to be degraded, significantly reducing the economic and social values of the beach for the local and regional community; and!" The shape and function of the dune in trapping sand as a buffer against storm erosion events will be compromised. While it is not feasible to quantify the socio-economic value of these risk factors within the scope of this study, it is noted that:!" The value of the housing located along Woorim is approximately $40 million;!" Local residents have purchased their properties on the understanding that the land use controls and zoning are appropriate;

5 EXECUTIVE SUMMARY II!" Bribie Island is a popular tourism focus and Woorim is widely used by the local and regional community for recreation. Many of the houses along the Woorim beachfront are rented to people who holiday there because of the benefits offered by the beach and its amenity. Recommended Action The consequences of taking no comprehensive management action and the generic management options outlined in Chapter 4 clearly identify the need to introduce more sand to the beach for beach restoration and protection of the properties. As such, it is strongly recommended that the option to implement beach nourishment, with associated appropriate dune management and maintenance action, be adopted as the primary action to restore and maintain the beach. Provision may be needed also for additional action to provide back-up protection to the erosion prone development along the southern section of Rickman Parade, in either the immediate or longer term future, depending on the timing, extent and sustainability of the proposed nourishment. Beach Nourishment As a first assessment, the minimum quantity of sand required to restore the beach would be about 225,000 cubic metres. This may be considered in the context that this quantity may be available and within reasonable cost constraints of Council and it represents approximately 5-6 years life of improvement along the key 1km stretch of beach. It must be recognised that the sand placed on the beach will be integrated into the natural processes of erosion from the beach during storms and subsequent gradual return to the beach by the swell waves. Thus, the sand will be distributed both alongshore and across the profile out to water depths of at least 6-8 metres and the realistic initial benefit of a nourishment quantity of 225,000 m 3 in terms of beach width will probably be around metres. This will provide the predicted storm erosion buffer for this section of coastline. However, progressive loss of sand will occur due to the longshore transport gradient along the beach. Ongoing maintenance nourishment is required to maintain the beach at its improved level. This could be achieved either by annual placement of about 35,000 m 3 /yr or regular placements of equivalent volumes 2 or 3 years apart. The annual approach would provide a more consistent beach condition. Review of potential sand sources indicates feasible options from two sources. Firstly, sand from offshore in deep water (greater than 15m depth), in association with navigation channel dredging can be cost-effectively delivered by Port of Brisbane Corporation (PBC). Secondly, sand derived from onshore sources, particularly recycling from the accreted area at Skirmish Point, however this is more expensive and currently constrained due to its inclusion in a Fish Habitat Area. Cost-effective placement of the sand from the PBC dredge involves pumping out by rainbowing the sand into the nearshore zone and allowing the waves to move it onshore and alongshore. As the beach develops and the sand becomes dry, the wind will blow sand back into the foredunes where, with appropriate control management, primary vegetation species (Spinifex) will grow and trap the sand. The process of foredune development to provide the dunal buffer against storm erosion may be assisted by scraping the sand back towards the dune during the nourishment process, with the deepened area progressively filled by the pumped sand.

6 EXECUTIVE SUMMARY III Dune Management Parts of the dune system backing the beach are in poor condition with extensive areas eroded to a bare sand dune scarp and no space for foredune development. The native dune plants and dune ecology there are degraded and the dune is vulnerable to wind erosion. It is recommended that, in conjunction with the nourishment to supply sand into the beach and foredune areas, the dunes be rehabilitated and managed to ensure adequate vegetative cover and protection from excessive pedestrian interference. This will restore their function in trapping wind-blown sand in a manner consistent with the natural processes. Accordingly, it is recommended that the existing dune and vegetation status be assessed and action taken as part of the nourishment design and implementation to reshape the main dune and to establish and maintain suitable native plants in accordance with EPA guidelines. A range of generic beach and dune management guidelines for developed and undeveloped areas are also included in the SEMP recommendations, as set out in Chapter 5. Protective Seawall Future circumstances may see the need for a protective seawall construction along about 150m of the dune scarp at the southern end of Rickman Parade, most particularly the southernmost 50m. This may be required if the timing and/or extent of the nourishment are such that adequate immediate or future protection of the development from major cyclone erosion is not achieved. If required, any such seawall should be located as far landward within the dune as practicable such that it would be covered by the dune under most circumstances and exposed only during severe erosion. Any seawall construction should be considered only where and when necessary to protect Rickman Parade should the top of the scarp recede to within about 5m of the road after the nourishment works have been implemented. It is noted that funds are best directed towards beach nourishment to the maximum extent possible. For example, should a 150m section of seawall be considered, a cost of about $0.5 million could be involved, equivalent to a quantity of about 100,000 m 3 of nourishment sand. Careful consideration of the need for such a seawall should be undertaken in the context of the feasibility of directing those funds to nourishment for protection. However, it is realised that this may be affected potentially by (for example) ongoing availability of suitable nourishment sand at reasonable cost and in reasonable time. Beach Monitoring A program of ongoing beach surveys and low cost observations is recommended to monitor beach behaviour and response to works as a basis for future action planning. Some of the beach monitoring work to add to the available knowledge of how the beach behaves can be implemented immediately at low cost, while more comprehensive monitoring surveys and investigations to locate future sand sources will require allocation of significant funds. Implementation Program and Costs The broad implementation program over the next 5 years is set out in Table E1. Planning and works for initial beach restoration would cost about $1.48 million, on the basis that PBC can assist with the nourishment, programmed for following planning and approvals in This would then

7 EXECUTIVE SUMMARY IV need to be followed by ongoing maintenance expenditure of about $430,000 per year from onwards. Additionally, should circumstances evolve requiring a section of seawall along about 150m of Rickman Parade, a cost of about $0.5 million could be involved, equivalent to a quantity of about 100,000 m 3 of nourishment sand. Careful consideration of the need for such a seawall should be undertaken in the context of the feasibility of directing those funds to nourishment as indicated above. It is noted that non-action, or works inconsistent with the recommended SEMP strategy, may be inefficient and involve greater cost in the long run. As an example, construction of a protective seawall without sand nourishment would be detrimental to the beach and may involve considerably greater future socio-economic losses and expense on seawall maintenance than would be needed with the beach restored by effectively implemented nourishment.

8 EXECUTIVE SUMMARY Table E 1 Summary of recommended restoration and management actions The Problem Long term progressive beach erosion. Ongoing nourishment. Dune vegetation management Limited records of beach processes and behaviour. Project management to ensure satisfactory completion. Protective seawall (if required) Do Nothing Woorim would continue to be starved of sand; erosion would continue with reduced beach area and erosion threat to Rickman Parade and property. Sand volumes will not provide enough protection to withstand storm events or cater for sea level rise. Continued weed growth smothering and over growing struggling native plants. A collection of anecdotal observations of beach behaviour lacking quantified data. Responsible use of public funds must have milestones of achievement Rickman Parade threatened with erosion:!" South end immediate!" North end within 5-10 yrs Proposed Action Initial nourishment 225,000m 3. Maintenance renourishment 35,000m 3 /yr from Offshore and/or onshore sources Woorim dune rehabilitation and vegetation management Woorim monitoring Project Management Initial limited seawall construction south from 2 nd Ave. Any further construction only as needed The Outcome Sand dredged onto Woorim to provide sufficient sand to restore the beach, provide property protection and form an incipient dune. Provide sufficient sand to maintain the improved beach. Dune vegetated with native species to provide stability from wind erosion, sand trapping capacity and natural dune habitat Records of beach before and during accretion in correlation to the works being undertaken. Scheduled tasks completed on schedule and on budget to the satisfaction of the community, council and EPA.. Protection of southern end of Rickman Pde and property subject to immediate erosion threat Cost Estimates (based on 2007 costing, future years need to allow CPI increases) $0.2M design and approvals $1.25M works Ongoing program at $0.35M/yr Ongoing program at $10k/yr 5 year Monitoring program $0.25M at $50k/yr 5 year Project Management $0.1M at $20k/yr Initial works $0.5M Possible future works up to $2.0M if nourishment is inadequate Timing 2007/ / /10 - ongoing 2007/08 - ongoing 2007/ / / / / /10 Funding Sources Council allocation with EPA support Council allocation with EPA support Council allocation with EPA support Council allocation with EPA support Council allocation with EPA support Council allocation with EPA support 2007/08 $0.27 $0.2M $50k $20k 2008/09 $1.26M $1.13M $10k $50k $20k $ 50k 2009/10 $0.88M $0.35M $10k $50k $20k $ 0.45M 2010/11 $430k $0.35M $10k $50k $20k 2011/12 $430k $0.35M $10k $50k $20k

9 CONTENTS VI CONTENTS Executive Summary Contents List of Figures List of Tables i vi ix x 1 INTRODUCTION Background Coastal Management Requirements PLANNING AND LEGISLATIVE FRAMEWORK Coastal Act and Plans Coastal Management Plans State Coastal Management Plan South-east Queensland Regional Coastal Management Plan Other Legislation and Approvals Commonwealth EPBC Act Queensland Integrated Planning Act Land Act Marine Parks Act Nature Conservation Act Indigenous Legal Issues Other Considerations Regional Plans SEQ Regional Plan Shorebird Management Strategy Moreton Bay Local Government Caboolture ShirePlan COASTAL PROCESSES & CAUSES OF EROSION General Considerations Geological Framework 3-1

10 CONTENTS VII 3.3 Contemporary Coastal Processes at Woorim Sand Transport Mechanisms and Beach Dynamics Assessment of Historical Shoreline Erosion Analysis of Aerial Photography Shoreline and Dune System Changes Longshore Sand Transport from Aerial Photography Analysis of Wave-Induced Longshore Sand Transport COPE Data Analysis Longshore Transport from Directional Wave Climate Hydrodynamic Modelling of Tide-Related Processes Net Longshore Sand Budget Storm Erosion Present and Future Shoreline Erosion Historical Erosion Trend Climate Change Impacts COASTLINE MANAGEMENT OPTION CONSIDERATIONS Background Beach Erosion Problem General Considerations Generic Option Considerations Decision Matrix Options for Woorim General Considerations Undeveloped Areas Areas With Existing Development Under Long Term Erosion Threat Areas With Existing Development under Immediate or Short Term Erosion Threat Structural Protection Options Seawalls Groynes and Artificial Headlands Offshore Breakwaters and Submerged Reefs Beach Nourishment Options Nourishment Alone Nourishment with Control Structures Nourishment with Terminal Protection (Seawalls) Material Sources and Costing Considerations Coastal Structures Beach Nourishment 4-17

11 CONTENTS VIII Offshore Marine Sand Sources Land-based Sand Sources Specific SEMP Option Considerations Strategy and Objectives Impacts of Climate Change and Sea Level Rise Beach Restoration by Nourishment with No Retreat Beach Restoration by Nourishment Alone Beach Restoration by Nourishment with Control Structures Dune Management Monitoring and Review Program Planning and Regulatory Controls Woorim Beach Management and Beach Access Activities in Undeveloped Dune Areas WOORIM SEMP PROVISIONS Strategy and Objectives Option Feasibility Assessment Beach Restoration by Nourishment Overview Beach Nourishment Design Requirements Seawall Protection Dune Rehabilitation and Management Impacts of Climate Change and Sea Level Rise Beach Nourishment Works Program Beach Restoration Ongoing Maintenance Nourishment Investigation and Review Program Recommended Planning and Regulatory Controls Woorim Beach and Dune Management Activities in Undeveloped Dune Areas Recommended SEMP Program and Cost Estimate REFERENCES 6-1 APPENDIX A: BEACH PROFILE SURVEYS A-1

12 LIST OF FIGURES IX LIST OF FIGURES Figure 1-1 Woorim Beach 1-2 Figure 2-1 Coastal Management District 2-14 Figure 2-2 Erosion Prone Area 2-15 Figure 2-3 Moreton Bay Ramsar Site 2-16 Figure 2-4 Pumicestone Channel Fish Habitat Area 2-17 Figure 2-5 Moreton Bay Marine Park Zoning Map including the Bribie Island Ocean Beach Area 2-18 Figure 2-6 Caboolture Shire Plan Eastern Planning Area Woorim Beach 2-19 Figure 3-1 Moreton Island & Bribie Island Onshore Geology (from Stephens 1982) 3-2 Figure 3-2 Geology of Bribie Island from Jones (1992) 3-4 Figure 3-3 Holocene Evolution of Southern Bribie Island from Armstrong (1990)3-5 Figure 3-4 Wave Propagation to Bribie Island is affected by North Banks 3-8 Figure 3-5 Irregular Shoreline Alignment of Bribie Island 3-8 Figure 3-6 Recent Accretion of Skirmish Point, Southern Bribie Island 3-10 Figure 3-7 Erosion and Limited Beach Width at the Southern Area 3-11 Figure 3-8 Northern End of Woorim Presently in Good Condition 3-11 Figure 3-9 Figure 3-10 Figure 3-11 The Armstrong (1990) Interpretation of Sediment Movement and Shoreline Erosion/Accretion. (E = erosion; A = accretion) 3-12 Dune instability associated with vegetation loss evident near the surf club in Extensive clearing, vegetation loss and dune instability associated with wind erosion evident in Figure 3-12 Vegetation regrowth and improved dune stability evident in Figure 3-13 General dune vegetation stability evident in Figure 3-14 Stabilised dune vegetation along the whole coastal unit and accretion at Skirmish Point evident in Figure 3-15 Present status of Woorim Beach near the surf club (2004) 3-16 Figure 3-16 Assessed change in position of the vegetation line Figure 3-17 Measured Beach Width at Woorim COPE Station: Figure 3-18 Analysis of Longshore Sand Transport from COPE Data 3-20 Figure 3-19 Modelled Wave Patterns 3-22 Figure 3-20 Hydrodynamic Model Bathymetry and Computational Grid Mesh 3-23 Figure 3-21 Typical Tidal Current Patterns Left: Flood tide; Right: Ebb tide 3-24 Figure 3-22 Nearshore Tidal Patterns Left: Flood tide; Right: Ebb tide 3-24 Figure 3-23 Measured and Modelled Currents Off Woorim 3-25 Figure 3-24 Modelled Net Sand Transport Induced by Tidal Currents Alone Figure 3-25 Alongshore Distribution of Net Tidal Sand Transport Figure 3-26 Comparison of Upper and Lower Limit Longshore Transport Rate

13 LIST OF TABLES X Figure 3-27 Derived From Historical Shoreline Change With Model Predictions Cross-Shore Distribution of Wave and Tidal-Current Sand Transport at South Woorim Figure 3-28 Vellinga Storm Erosion Profile at ETA Figure 3-29 Vellinga Storm Erosion Profile at ETA Figure 3-30 Figure 3-31 Old gravel road base horizon exposed below wind blown sand and mature vegetation in the eroding dune scarp adjacent to the surf club area 3-30 Old bitumen surface exposed below wind blown sand and mature vegetation in the eroding dune scarp adjacent to the surf club area 3-30 Figure 4-1 Development located in EPA erosion prone area 4-4 Figure 4-2 Undeveloped dune buffer area north of Woorim development 4-5 Figure 4-3 Seawalls on eroding shorelines cause loss of usable beach 4-8 Figure 4-4 Typical Groyne Effects on Beach System 4-9 Figure 4-5 Typical Offshore Breakwater Effects on Beach System 4-10 Figure 4-6 Typical Beach Nourishment Profile 4-12 Figure 4-7 Figure 4-8 Conceptual beach nourishment dispersion along the shoreline without maintenance nourishment (top) and with maintenance (bottom) 4-13 Conceptual shoreline response to groyne with nourishment maintenance to reduce downdrift erosion 4-15 Figure 4-9 Shoreline response to nourishment with maintenance 4-22 Figure 4-10 Vellinga Storm Erosion Profile at ETA With Nourishment Figure 4-11 Vellinga Storm Erosion Profile at ETA With Nourishment Figure 4-12 Shoreline response to groynes with nourishment and maintenance 4-24 Figure 5-1 Section requiring short term seawall protection 5-5 Figure 5-2 Typical Seawall Design Section. Rock material may be replaced by sand filled geotextile units to suitable equivalent design 5-6 Figure 5-3 Dune Management Guidelines 5-8 Figure 5-4 Conceptual Design Placement of Sand 5-9 LIST OF TABLES Table 3-1 Beach Nourishment Quantities 3-17 Table 3-2 Longshore Sand Transport Rates from Recorded Wave & Wind Data 3-22 Table 3-3 Calculated Total Longshore Sand Transport Rates 3-27 Table 3-4 IPCC Estimates of Sea Level Rise (m) 3-32 Table 4-1 Matrix of Beach System Management Options 4-3 Table 5-1 SEMP Options Assessment 5-3 Table 5-2 Summary of recommended restoration and management actions 5-13

14 INTRODUCTION INTRODUCTION 1.1 Background Woorim Beach is located towards the southern end of the east coast of Bribie Island (Figure 1-1). The beach sweeps in a gentle smooth curve around the southeastern part of Bribie Island. It faces east and is exposed to east to northeast ocean waves, but receives considerable protection by Moreton Island from the predominant southeast swell waves. The beach is exposed to winds and locally generated wind waves from the southeast to north sectors. The beach is backed by a substantial dune typically 5-8 metres in height. Woorim Beach is a popular sandy beach used for surfing, swimming, walking and jogging. Because of the shelter offered by Moreton Island and the offshore North Banks, wave conditions are generally mild and safe for swimming. Surf club facilities are provided together with car parking and recreational park areas on the foreshore. At present the beach is typically particularly narrow with a steep eroding dune face in the vicinity of the surf club as a result of persistent coastal erosion. The beach varies substantially in height and width in response to both seasonal wave conditions and progressive shoreline recession. It is believed to have diminished progressively over many decades and is considered inadequate as a recreational asset. The high tides reach and impact on the base of the dune for significant periods of time during and after erosion events. There is a potential imminent threat of erosion into the development along the southern section of Rickman Parade. 1.2 Coastal Management Requirements Along the developed Woorim Beach area:!" Beach amenity, access and safety are significantly diminished by erosion. When the beach is eroded, waves reach the base of the dune on high tides and an unstable high steep dune scarp often forms. This is potentially dangerous, particularly for small children;!" Beach recovery following storm erosion is slow and natural redevelopment of a sustainable suitably wide recreational beach in front of the existing dune scarp alignment is unlikely;!" Erosion has extended close to the southern section of Rickman Parade and there is a threat of short term storm erosion of the road and adjacent development there;!" Wind erosion of the dune has been a problem in the past and requires careful management; and!" The natural character of the beach has been altered by some limited protective works (geotextile bag wall). These issues are likely to be exacerbated in the event of future sea level rise. In the undeveloped areas to the north and south, coastal processes involving longshore sand movement and erosion and accretion of the beach associated with storms and subsequent beach recovery are able to occur naturally. The beaches there are in good condition and the dune system is extensive.

15 INTRODUCTION 1-2 Figure 1-1 Woorim Beach

16 INTRODUCTION 1-3 The present study is aimed at developing a Shoreline Erosion Management Plan (SEMP) based on identifying and assessing engineering and management options for dealing with the erosion problem. Policy guidance for identifying and assessing issues, specific objectives and suitable options is provided through liaison with the Woorim SEMP Study Steering Committee

17 PLANNING AND LEGISLATIVE FRAMEWORK PLANNING AND LEGISLATIVE FRAMEWORK Proposed management options recommended within this SEMP must be consistent with the local government planning scheme of the Caboolture Shire, and comply with all relevant legislation (Commonwealth, State and local) and coastal and environmental policies. The basis and control of management of the coast of Queensland is governed by the Coastal Protection and Management Act 1995 (Qld). Statutory plans under the Act, the State Coastal Management Plan (SCMP) and South-East Queensland Regional Coastal Management Plan (SEQRCMP), set out more detailed provisions for the management of the coastal zone and recommendations in this SEMP. Legislation and policies considered in this SEMP require consideration of issues including, but not limited to:!" The use of coastal structures for property protection;!" The listing of Moreton Bay as a Ramsar site and hence an area of international significance;!" Protection of species listed as protected under State and Commonwealth legislation and conservation of their habitat;!" Consideration of the location of potential proposed areas for extraction for sand for beach nourishment; and!" The maintenance of biodiversity e.g. shorebird habitat. These legislative and policy considerations are described in more detail below. 2.1 Coastal Act and Plans The Coastal Protection and Management Act 1995 (Qld) (the Coastal Act) provides for management of the coastal zone. 1 The Coastal Act recognises the diverse range of resources and values of the coastal zone, and has the following objectives: 2!" To provide for the protection, conservation, rehabilitation and management of the coast, including its resources and biological diversity;!!" To have regard to the goal, core objectives and guiding principles of the National Strategy for Ecologically Sustainable Development in the use of the coastal zone;!" To provide, in conjunction with other legislation, a coordinated and integrated management and administrative framework for the ecologically sustainable development of the coastal zone;!" To encourage the enhancement of knowledge of coastal resources and the effect of human activities on the coastal zone. 1 Coastal waters and all areas to the landward side of coastal waters in which there are physical features, ecological or natural processes or human activities that affect, or potentially affect, the coast or coastal resources: s11 Coastal Act. 2 s3 Coastal Act.

18 PLANNING AND LEGISLATIVE FRAMEWORK 2-2 The SCMP and SEQRCMP have been developed under the requirements of the Coastal Act. 3 Both plans are statutory instruments under the Coastal Act, and have the effect of a State Planning Policy (SPP) under the Integrated Planning Act 1997 (IPA). The Plans are designed to operate with other instruments to fulfil the objectives of the Coastal Act. The Woorim Beach SEMP will be required to adhere to the objectives set in the SCMP and SEQRCMP, and regional priorities will be referred to in this document and elaborated on from a local perspective Coastal Management Plans State Coastal Management Plan The SCMP seeks to protect and manage Queensland s coastal resources and provides an overarching framework for coastal management in Queensland. It is based on ten (10) topics for management: 1 Coastal Use And Development Use and development of the coastal zone occurs in an ecologically sustainable manner. 2 Physical Coastal Processes The coast is managed to allow for natural fluctuations to occur, including any that occur as a result of climate change and sea level rise, and provide protection for life and property. 3 Public Access To The Coast Opportunities for public access to the coast are maintained and enhanced, consistent with the conservation of coastal resources and provision of public safety. 4 Water Quality Water quality in the coastal zone is maintained at a standard that protects and maintains coastal ecosystems and their ability to support human use. 5 Indigenous Traditional Owner Cultural Resources The living culture of Indigenous Traditional Owners and their connection with cultural resources within the coastal zone is valued and continues for future generations of Indigenous Traditional Owners. 6 Cultural Heritage Places, buildings and objects with important cultural heritage values located on the coast are appreciated, conserved, managed and passed on to future generations. 7 Coastal Landscapes The scenic and cultural values associated with coastal landscapes are protected. 8 Conserving Nature Coastal ecosystems, including their ecological processes, opportunities for survival, biological diversity and potential for continuing evolutionary adaptation, are maintained, enhanced and restored. 9 Coordinated Management Coastal management is coordinated and integrated across all levels of government and within the community. 10 Research And Information Research programs, and data and information collection and management focus on, support and enhance effective coastal management. In general, the State Coastal Plan requires that protection from erosion should not impact on coastal resources, their values or natural cycles, particularly in regard to protection of natural areas and 3 Chapter 2, Part 2, Coastal Act.

19 PLANNING AND LEGISLATIVE FRAMEWORK 2-3 biodiversity. It also requires that structures should only be used where nourishment or other nonpermanent measures are not viable South-east Queensland Regional Coastal Management Plan The application of the SEQRCMP extends to the coastal zone of the area between and including Maroochy Shire to Coolangatta, and operates in conjunction with the SCMP. It aims to achieve sustainable coastal management in SEQ, and to avoid or minimise future adverse impacts on coastal resources. The SEQRCMP addresses the above ten topics in a more detailed manner than the SCMP, identifying areas within the region requiring special management, and developing regionallyspecific outcomes. It defines the Woorim Beach area as a Priority Area for Shoreline Erosion Management (Map 6A, Policy Shoreline Erosion). The area specified by the plan covers the coast along the urban area at Woorim Beach, as well as approximately 2km to the north (Map 6B). Within the SEQRCMP, specific regional direction is provided on 17 State Coastal Plan policies, and in addition, includes two regionally specific policies 4 (EPA 2006). The SEQRCMP also identifies a Coastal Management District (Policy 2.9.5) 5 over the coastline of the entire study area (Sheet 13.9 Pumicestone South). Figure 2-1 identifies the area where the EPA has a statutory role (concurrence agency or assessment manager) when assessing certain development proposals. Note that the most relevant policies in relation to the recommendation of erosion management measures are Policy 2.2 Physical Coastal Processes, Policy Shoreline Erosion Management and Policy Beach Protection Structures. The applicable sections of these policies are specified below. The SEQRCMP also identifies other important considerations areas within the Woorim Beach areas that are important for erosion management planning. Policies on Physical Coastal Process Policy Erosion Prone Areas recognises the importance of the erosion prone area as a valuable feature for its function as a coastal buffer zone (refer to the erosion prone area for Woorim Beach) (Figure 2-2). For developed erosion prone areas, where existing development is threatened by erosion and a strategy of retreat is not achievable, the following matters must be considered in determining the most appropriate defensive action to protect land uses and infrastructure:!" The value (economic, social and environmental) of the existing development;!" The practicality and cost of any defensive action;!" The potential adverse impacts to coastal resources and values associated with any defensive action. The Plan notes that development within an erosion prone area may include the construction of property protection works such as rock or revetment walls. However, the Plan requires that defensive actions involving structural engineering and stabilisation works such as revetments and boulder walls are to be avoided in the SEQ region where possible. Such works will only be supported where: 4 Policy Non-tidal artificial waterways and Policy Algal Bloom Management. 5 Policy also identifies a coastal building line over the Woorim Beach area. This helps to manage development in erosion prone areas by limiting encroachment of permanent building works into these areas and minimising the need for potential protection works. EPA is the designated concurrence agency for certain building works seaward (wholly or partially) of the coastal building line.

20 PLANNING AND LEGISLATIVE FRAMEWORK 2-4!" There is an immediate or critical threat of loss or damage to existing development from erosion impacts;!" No viable alternatives such as revegetation or bank reconstruction have been demonstrated to provide a similar or adequate level of protection from erosion;!" Potential adverse impacts on coastal processes and scenic amenity are minimised through remedial actions, such as beach nourishment to restore the beach and minimise impact on adjacent coast. As mentioned above, Policy Shoreline Erosion Management (SEQRCMP) identifies Woorim Beach as a priority area for erosion management. The SEQRCMP requires, when preparing SEMPs, preference be given to options that maintain natural coastal processes and recreational amenity. It also requires that where structures are found to be necessary, beach nourishment, revegetation and other similar actions should be considered to mitigate potential impacts of the works. Policy Beach Protection Structures (State Coastal Plan) 6 requires that any shoreline defence actions are not to adversely impact on coastal resources and their values or the natural cycles of erosion and accretion of beaches. Where structures are considered as management options, the State policy requires that the construction of beach protection structures in coastal waters will only be approved where: a) There is a demonstrated need in the public interest; and b) Comprehensive investigation has been carried out and it can be demonstrated that:!" There would not be any significant adverse impact on longshore transport of sediments; and!" There would be no increase in coastal hazards for the neighbouring foreshore. Other Relevant Policies Additional policies may also be relevant dependent on the final works carried out (e.g. cultural resources, cultural heritage and coastal landscapes). The SEQRCMP specifically identifies policies relevant to the Woorim Beach area, and therefore requires consideration of these policies in development of the recommendations:!" Policy Tourism and Recreational Activities Intense tourism and recreational pressures are important community and economic assets. Areas that experience high visitation and contribute significantly to the state and regional economies include the Woorim Beach area. These high-use recreational coastal locations usually require additional management to maintain and protect the coastal resources and values. Main management methods include intensive physical management and/or long-term planning (such as shoreline erosion management plans).!" Policy Algal Blooms The Woorim area is categorised as having high or very high indicative nutrient export rating if the area is not managed properly. Areas identified are of concern due to particular land uses, vegetation and soil characteristics, and are close to tidal waterways. Activities identified in the SEQRCMP that may increase the risk of nutrients entering coastal waterways include dredging, which may be required for beach nourishment. 6 Note there is no regional policy for Policy

21 PLANNING AND LEGISLATIVE FRAMEWORK 2-5 The SEQRCMP requires that best practice water quality management be implemented in areas with a high to very high nutrient export rating. It also requires that development and activities in these areas can demonstrate: o no lowering of existing groundwater levels where potent or actual acid sulfate soils are present; o avoidance or minimisation of the export of nutrients of concern exiting the site through surface water or groundwater; o no disturbance of coastal wetlands; o the maintenance and enhancement of riparian vegetation; and o incorporation of best practice stormwater quality management!" Policy Areas of state significance (natural resources) includes significant coastal wetlands, Nature Conservation Act Protected Areas 7 and significant coastal dunes. Areas of state significance (natural resources) play a critical role in maintaining a healthy functioning coast and are key elements of coastal resources that the State government is seeking to protect and manage. These important coastal resources have associated economic (e.g. fisheries habitats) and social (e.g. recreational amenity) values, and must be protected from land uses and activities that may have adverse impacts on their continued integrity and functioning. Uses and activities adjacent to areas of state significance (natural resources); also have the potential to impact on their values (e.g. through degrading water quality).!" Policy Coastal Wetlands Applies to the conservation and management of Queensland s coastal wetlands, including land within 100m of a coastal wetland. Wetlands play a key role in supporting the diversity and abundance of plants and animals and provide important habitats and refuges for many migratory, rare or threatened species. Threats to wetlands arise from clearing, filling, draining and impeding water flows as well as cumulative impacts from separate off-site activities. This policy identifies Bribie Island as having examples of large and intact coastal wetland ecosystems with high ecological integrity and functioning. However, coastal wetlands in parts of Bribie Island are experiencing pressures from direct and cumulative impacts. Consideration should be given to the impacts of sand removal/placement on coastal wetland functions and habitat for rare, threatened and migratory species.!" Policy Biodiversity Contains areas of Coastal Biodiversity Significance (for wetlands (significant and coastal)). There are also areas of shorebird habitat in close proximity to Woorim Beach. The Supporting Document to the SEQRCMP also designates the Woorim Beach area as an area of terrestrial Coastal (State) Biodiversity Significance. Biodiversity is fundamental to the maintenance of sustainable ecosystems and other features and processes of the coastal zone. Threats to biodiversity can be broadly classified as habitat loss, decline in the habitat quality, changes in ecological processes and direct removal (including harvesting) of species. A key objective of this policy is to maintain the integrity of tidal flats and protect beaches that provide significant wildlife habitats. Further, the area surrounding the urban development at Woorim Beach is considered Significant Coastal Dunes, and is an area of Coastal Biodiversity Significance (marine). 7 As identified under the SEQRCMP.

22 PLANNING AND LEGISLATIVE FRAMEWORK 2-6!" Policy Rehabilitation of Coastal Resources The SEQRCMP requires rehabilitation and enhancement of coastal resources to improve values and functioning of the coastal zone. While there are no specific areas defined in this plan within the Woorim Beach area, general areas defined for priority rehabilitation and enhancement include coastal wetlands, endangered regional ecosystems and dunal systems (refer Policies and 2.8.2) and shorebird nesting, roosting and feeding sites (Policy 2.8.3).!" Policy State Land on the Coast Excludes freehold land or land subject to a lease for the purposes of this Plan, provides a key opportunity for the State Government to directly influence the use and management of land on the coast and achieve coastal management outcomes. Consultation with State agencies, particularly EPA, will be carried out during the development of recommendations within this SEMP. 2.2 Other Legislation and Approvals The following legislation may need to be considered in the development of the SEMP and where approvals are necessary to carry out potential management options for shoreline erosion management in the Woorim area. This section also outlines the current (July 2007) approvals process relevant for recommended works Commonwealth EPBC Act Referral to the Commonwealth Department of Environment and Water Resources (DEW) is required for actions that have or are likely to have a significant impact on a matter of national environmental significance (NES) under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). Matters of NES cover a range of issues such as Ramsar sites and migratory species listed under international treaties including Japan Australia Migratory Bird Agreement (JAMBA) or the China Australia Migratory Bird Agreement (CAMBA) and the Convention on Migratory Species (Bonn Convention). Matters of NES that may be significantly impacted by coastal protection works in the Woorim area include, but are not limited to:!" Ramsar sites (Moreton Bay Ramsar site 8 )!" Listed threatened species and ecological communities; and!" Migratory species. If coastal protection works are declared a controlled action, approval will be required from DEW before the works can commence. Queensland and the Commonwealth have an agreement (Bilateral agreement) pursuant to the EPBC Act, which allows any controlled action requiring environmental impact assessment (EIA) to be assessed according to the EIA processes under State law. 8 Note that Moreton Bay is also a site in the East Asian-Australian shorebird site network.

23 PLANNING AND LEGISLATIVE FRAMEWORK 2-7 Approvals Process Where Council determines that referral of an activity is required, the application is made in the prescribed form to DEW. If DEWR determines that the activity is not a controlled action and no approval is required, they will notify the proponent and publish the decision. On the basis of the referral and supporting information, the Minister (DEW) will determine what level of assessment is required. The Bilateral Agreement between the Australian Government and the State of Queensland only applies to situation where an EIA is required. For the recommendations required in this SEMP, it is unlikely that an EIS would be required. Therefore, the assessment process is likely to continue at Commonwealth level, based on referral documentation (previously provided to DEW) or preliminary documentation (where additional information is required by DEW). Once public comment is provided, the revised documentation is submitted for approval and reviewed by the Minister prior to a decision being made Queensland Integrated Planning Act 1997 Coastal erosion management works may require development approval under the Integrated Development Assessment System (IDAS) of the Integrated Planning Act 1997 (IPA). Assessment under IPA for potential shoreline erosion management recommendations may be required according to triggers including but not limited to:!" Operational works in a tidal area or coastal management district including, for example: o Removing or interfering with quarry material; o Removing or interfering with coastal dunes.!" Operational work below high water mark.!" Fisheries matters. These include removal, destruction or damage to marine plants, and works or related activities in a declared fish habitat area (FHA) (Fisheries Act 1994). Woorim Beach is within the Pumicestone Channel Fish Habitat Area (Management B) (refer Figure 2-4). Policies on the DPI website should be considered where marine plants or Fish Habitat Areas may be impacted:!" Environmentally relevant activities (ERA s) (under the Environmental Protection Act 1994). For example, ERA19 (dredging).!" Acid sulfate soils. The proposed works must be considered in accordance with the State Planning Policy 2/02 (SPP 2/02) Planning and managing development involving acid sulfate soils.!" Vegetation management: Clearing of vegetation to which the Vegetation Management Act 1999 (VMA) applies is operational work and requires development approval. Exceptions apply where vegetation is adequately protected and regulated under other legislation. Once triggers and relevant referral agencies are determined, Council can determine whether referral coordination is required. At the time of application, Council should also determine whether resource

24 PLANNING AND LEGISLATIVE FRAMEWORK 2-8 entitlement consent is required from State agencies, or owner s consent for land where management measures take place. Approvals Process Making an application under IDAS requires the proponent to ensure the correct IDAS forms are lodged with the assessment manager. Dependent on the type of works being approved, the assessment manager is likely to be Caboolture Shire Council or the Environmental Protection Agency. Applications may also be required to be lodged with any relevant concurrence agency. An information request from State agencies may require further information, surveys or gathering of data, and after public submissions (if required), and following provision of this information, a decision will be made on the application. Note that applications for owner s consent and resource entitlement consent should be lodged and approval received prior to lodgement of the application to the assessment manager Land Act 1994 Land tenure is granted pursuant to the Land Act Any effect of proposed protection works upon State land, in terms of direct or indirect implications (eg. impact on access) requires approval from the State. This is also covered through the IDAS process, where the State must provide resource entitlement or owner s consent for works on Unallocated State Land and other State Land Marine Parks Act 2004 Queensland State Marine Parks are designed to conserve the marine and intertidal area and other internal waters of Queensland, and they extend to the high water mark. 9 The main legislation and regulation governing state marine parks in Queensland are the Marine Parks Act 2004 (Act) and Marine Parks Regulation 2006 (Regulation). The Moreton Bay Marine Park Zoning Plan 1997 (Zoning Plan) includes the objectives for each zone and specifies the activities that are allowed and prohibited, and those that require a marine park permit. The area surrounding Woorim Beach is designated Habitat Zone (refer Figure 2-5). The Habitat Zone allows a wide range of uses and activities, with few activities being prohibited. Woorim Beach is within the Bribie Island ocean beach area (refer Figure 2-5). The Zoning Plan defines the purpose of a designated ocean beach area:!" To protect the natural and visual amenity and ecological integrity of the ocean beaches; and!" To provide for the operation of natural coastal processes; and!" To protect and rehabilitate natural beach plant and animal communities. The Zoning Plan requires a number of considerations are to be taken into account when issuing a permit for works in a marine park, including those from the Regulation and the Zoning Plan. It provides that a permit may be granted for the installation or construction of a structure within an ocean beach area only if the structure is consistent with the purpose of the area. A public authority 9 EPA guidance on high water is as follows: High water mark usually equates with the highest flotsam line on the beach. Within estuaries, high water mark usually corresponds with the furthest extent of marine vegetation such as mangroves, saltwater couch or bare salt flats (EPA website).

25 PLANNING AND LEGISLATIVE FRAMEWORK 2-9 exercising its statutory powers in an ocean beach area must have regard to the purpose of the area, and consult QPWS 10 about any proposal or action that may affect the visit the visual amenity, coastal processes or beach, plant or animal communities of the area. Approvals Process For the purposes of the SEMP, a Marine Parks permit would most likely be required for any development below high water. Approval would be required from EPA/QPWS. Applications for a Marine Park permit are made through the Ecoaccess Customer Service Unit of the EPA and should provide enough information for the assessor (QPWS) to understand the proposed activity, its location, and the impact on the Marine Park. Consideration of the criteria in the Regulations and Zoning Plan will be carried out. These include but are not limited to:!" the purpose of the zone;!" the conservation of the natural and cultural resources of the Marine Park;!" the maintenance of the biological diversity and ecological functioning of the Marine Park;!" the potential impact on the existing and future or desirable use and amenity of the marine park and adjacent areas, and the environment generally;!" any potential environmental impacts associated with the activity;!" any effect on the Marine Park s natural tidal flushing pattern or natural coastal process;!" the cumulative impact on the marine park of the proposed entry or use of the zone and any other entry or use of the marine park, particularly the cumulative impact of small-scale developments for which an environmental impact statement is not required; and!" the effect on shorebirds, particularly international migratory bird species, and their habitat and the need to protect shorebirds and their habitat. 11 A permit is issued for an activity/ies in particular zones/locations, and can be granted to a nominated person/s or company for a specified length of time. Conditions will be imposed to protect the values of the marine park Nature Conservation Act 1992 The object of the Nature Conservation Act 1992 (NC Act) is the conservation of nature. Principles of biological diversity and ecologically sustainable development, as well as criteria developed by the World Conservation Union (International Union for the Conservation of Nature and Natural Resources) are used to establish and manage areas protected under the NC Act. The Act also ensures the recognition of the interest, and involvement, of Aborigines and Torres Strait Islanders in conservation of nature. Regulations under the NC Act which may be relevant to the development of the SEMP include:!" Nature Conservation Regulation 1994; 10 Chief executive. 11 EPA, Information Sheet: Marine Park Permits for Moreton Bay Marine Park, Ecoaccess, 03/02.

26 PLANNING AND LEGISLATIVE FRAMEWORK 2-10!" Nature Conservation (Protected Areas) Regulation 1994 This Regulation lists declared protected areas, including national parks and conservation parks. Buckley s Hole Conservation Park occurs in close proximity to the study area, on the south-west corner of Bribie Island. 12!" Nature Conservation (Wildlife) Regulation 1994 The Regulation relates to the significance of certain species (listed as presumed extinct, endangered, vulnerable, rare, common, international, and prohibited), and the management intent and principles of these species. It may apply to the SEMP through the listing of animals and/or plants in the Woorim Beach area. For example, species protected under the Regulation include the six species of marine turtles, all of which occur in Moreton Bay, and three (loggerhead, hawksbill and green turtle) are year-round residents of Moreton Bay. Moreton Bay has the most significant loggerhead population in Australia. The loggerhead turtle is listed as endangered under both the NC (Wildlife) Regulation and the EPBC Act. 13 The green and hawksbill turtles are both listed as vulnerable under the NC (Wildlife) Regulation and the EPBC Act. 14 The NC (Wildlife) Regulation and the EPBC Act also list as protected many of Moreton Bay s shorebirds. Other listed species also occur within Moreton Bay and the study area Indigenous Legal Issues When undertaking coastal protection works, Council must take all reasonable and practicable measures to ensure their activities do not harm Aboriginal cultural heritage, pursuant to the Aboriginal Cultural Heritage Act Measures that Council may take to ensure compliance with this Act include:!" Following the statutory duty of care guidelines, which may require consultation with the relevant Aboriginal party; or!" Development and approval of a Cultural Heritage Management Plan. Compliance with the Aboriginal Cultural Heritage Act 2003 should be determined at the planning stage of any coastal protection works. Native title legislation in Australia provides for the recognition and protection of native title. The Commonwealth Native Title Act 1993 and Native Title (Queensland) Act 1993 should be considered prior to the commencement of coastal protection works. Note that it is a requirement under the Native Title Act for native title parties to be given notification and an opportunity to comment on a wide range of activities that could affect native title rights, and this includes most activities authorised by Marine Park permits. In these cases, it is usual that the EPA provides notification to registered claimants and the Native Title Representative Body, and takes their comments into account when deciding the application. However, Council should ensure that notification and consideration of comments is conducted from the beginning of the process. 12 Previously, the Bribie Island National Park existed to the north of the study area, however this is now the Bribie Island Recreation Area pursuant to the Recreation Areas Management Act In recreation areas, nature-based recreation is encouraged but carefully planned and managed to protect these places for conservation. 13 The loggerhead is listed by the IUCN as Endangered. 14 The green and hawksbill turtles are listed by the IUCN as Endangered and Critically Endangered respectively.

27 PLANNING AND LEGISLATIVE FRAMEWORK Other Considerations It may be necessary to liaise with, and obtain permission from the following agencies regarding the legislation and issues mentioned above:!" Environmental Protection Agency (e.g. dredging, nourishment, conservation values, and ecological issues) and Queensland Parks and Wildlife Service (Moreton Bay Marine Park issues);!" Department of Primary Industries and Fisheries (e.g. fish habitat areas and marine plants);!" Department of Natural Resources and Water (e.g. ownership of Unallocated State Land); and!" Queensland Transport / Regional Harbour Master (e.g. navigation and navigation channels). 2.3 Regional Plans The South East Queensland Regional Plan and the Shorebird Management Strategy Moreton Bay need to be considered in the SEMP in the context of recommending appropriate shoreline erosion management measures for the South East Queensland region. However, depending on the specific erosion management options recommended, there may be other relevant regional plans that need to be considered SEQ Regional Plan The South East Queensland Regional Plan (SEQ Regional Plan) aims to manage growth and associated change in SEQ in the most sustainable way and to protect and enhance the quality of life in the region. Policies of the SEQ Regional Plan that may be relevant to shoreline erosion management in the Woorim Beach area, and should be considered in the development of recommendations are:!" Policy 2.1 Biodiversity Conserve and manage the region s biodiversity values and maintain supporting ecological processes. This policy identifies the Woorim Beach areas as a state significant biodiversity area including habitat for rare and threatened species (Map 4).!" Policy 2.6 Natural Hazards Requires that risk and exposure of the community to adverse impacts of natural hazards such as flood, storm tide, bushfire and landslide should be reduced.!" Policy 3.2 Scenic Amenity Acknowledge, protect and manage significant scenic amenity areas and features. Other policies such as Traditional Owner engagement (Policy 7.1) and Community engagement (Policy 7.2) may also be relevant. Further policies may be of relevance dependent on the final shoreline erosion management measures Shorebird Management Strategy Moreton Bay As stated above, Moreton Bay is a declared Ramsar site, and is also host to 30 of the 43 migratory shorebird species found in Moreton Bay listed under the Japan Australia Migratory Bird Agreement (JAMBA) or the China Australia Migratory Bird Agreement (CAMBA). In response to the need to protect these important shorebird species, the EPA and QPWS have developed the Shorebird

28 PLANNING AND LEGISLATIVE FRAMEWORK 2-12 Management Strategy Moreton Bay (June 2005). Within Moreton Bay, five main approaches have been adopted for the conservation of shorebirds:!" Protecting shorebird habitat;!" Protecting shorebirds from disturbance;!" Protecting critical shorebird sites;!" Community education; and!" Research and monitoring. In particular, actions identified within the Strategy for the first three approaches are the most relevant actions to the SEMP. Some of these include:!" Maintenance and enhancement of shorebird habitats;!" Restricting coastal development to areas where its impact on shorebird habitat is minimal; and!" Minimise human disturbance of shorebirds. 2.4 Local Government An important issue relevant to jurisdiction over the coastline is the definition of the high water mark, which is the seaward extent of jurisdiction for local government under the Local Government Act The Act also enables local government to obtain specific jurisdiction from the State over the beach, between high and low water mark for special purposes, for example, beach protection works. Local government controls land use and activity under the local planning scheme (under the IPA) and Local Laws (under the Local Government Act 1993). Local government also has legislative responsibilities under the Environmental Protection Act responsibilities relevant to coastal management for, inter alia:!" Land use control;!" Recreational planning;!" Management of local reserves;!" Environmental protection and rehabilitation; and!" Monitoring. Local government generally has The most relevant local government planning document is the Caboolture ShirePlan, however, additional Council Policies 15 may be relevant depending on the specific shoreline erosion management measures implemented. Further, community group activities such as dune revegetation may also need to be considered and these groups have been consulted in the development of the SEMP. 15 For example: Council Policy No 710/03: Community Consultation; Council Policy No: 427/05, Planning Scheme Policy 3 Cultural Heritage; Council Policy No 425/05:Planning Scheme Policy 1, Acid Sulfate Soils.

29 PLANNING AND LEGISLATIVE FRAMEWORK Caboolture ShirePlan Caboolture ShirePlan, 16 the planning scheme for the Caboolture Shire Council area, provides the vision for the planning and management of the local government area. Aspects of the Plan are relevant to the development and implementation of the SEMP. Desired environmental outcomes and planning intents from Caboolture ShirePlan are considered generally in the development of the SEMP (refer Part 3 Caboolture ShirePlan). Other important aspects of the Caboolture ShirePlan that are considered include designated potential and actual acid sulfate soil areas (and impacts on Fish Habitat Areas), cultural heritage, nature conservation and scenic amenity. These are outlined in the overlay codes. More specifically, the applicable planning area for the SEMP is the Eastern Planning Area (Zoning Map EZ-14) Woorim Beach (refer Figure 2-6). The Map depicts an Open Space Zone directly adjacent to the beach, with Residential B in closest proximity to Open Space. Local Centre and Residential A Zones occur adjacent to Residential B. For the purposes of the SEMP, consideration is required of the Open Space Zone. The most relevant outcomes to the SEMP, as defined under the ShirePlan are:!" Open space areas are of sufficient size, dimension, quality and quantity to cater for the needs of the community they serve, having regard to the character and function of the open space area; and!" The cultural, environmental, recreational and scenic value of the open space is protected. 16 Effective from 12 December 2005; and subsequent versions of the Caboolture ShirePlan.

30 PLANNING AND LEGISLATIVE FRAMEWORK 2-14 Figure 2-1 Coastal Management District

31 PLANNING AND LEGISLATIVE FRAMEWORK 2-15 Figure 2-2 Erosion Prone Area

32 PLANNING AND LEGISLATIVE FRAMEWORK 2-16 Figure 2-3 Moreton Bay Ramsar Site

33 PLANNING AND LEGISLATIVE FRAMEWORK 2-17 Figure 2-4 Pumicestone Channel Fish Habitat Area

34 PLANNING AND LEGISLATIVE FRAMEWORK 2-18 Figure 2-5 Moreton Bay Marine Park Zoning Map including the Bribie Island Ocean Beach Area

35 PLANNING AND LEGISLATIVE FRAMEWORK 2-19 Figure 2-6 Caboolture Shire Plan Eastern Planning Area Woorim Beach

36 COASTAL PROCESSES & CAUSES OF EROSION COASTAL PROCESSES & CAUSES OF EROSION 3.1 General Considerations A good understanding of the fundamental coastal processes affecting Woorim Beach has been developed in order to determine and assess engineering and management options such that solution strategies may be adopted with confidence of success. Only limited detailed study of the coastal processes and beach/dune dynamics has been undertaken previously. Nevertheless, considerable knowledge is available from both:!" Practical and theoretical knowledge of the principles of beach behaviour now established in the fields of coastal and ocean engineering and geomorphology;!" Geological and geomorphological investigations undertaken specifically of Bribie Island and the surrounding coastal system; and!" Measurements and modelling assessments undertaken as part of both previous studies and the present investigation of the wave, current and sand transport processes occurring at Woorim Beach. A brief outline of this knowledge is presented in this Chapter. The key issues affecting the most appropriate management action are those of historical and future:!" supply of sand into the beach system;!" sand movements within and through the beach system; and!" possible progressive net loss of sand from the beach system. The natural beach system includes not only the beach itself but also:!" the dune that acts as a reservoir of sand for the beach during major erosion events and subsequently rebuilds gradually as the sand is moved onshore by wave and wind action; and!" the nearshore zone where sand movement is related to beach behaviour. While it is known that there has been a tendency for gradual erosion of Woorim Beach superimposed on short term fluctuations of the shoreline location, the nature and rate of progressive long-term erosion has been uncertain. A comprehensive investigation over some years and involving substantial cost would be needed to gain a full understanding of those processes. However, the review of existing knowledge and additional investigations undertaken as part of this study and outlined below have provided a level of understanding sufficient to identify the most suitable engineering and management options for dealing with the erosion, as set out in this report. Within that context, relevant uncertainties and their significance are identified and discussed. 3.2 Geological Framework The geological evolution of the Woorim coastline fits within the broader evolutionary development of Bribie Island as a whole and the adjacent areas (Figure 3-1) and needs to be considered in that regional context. Jones (1992) provides the most recent and comprehensive assessment of the

37 COASTAL PROCESSES & CAUSES OF EROSION 3-2 geology and geomorphology of Bribie Island and the region north to Point Cartwright. Armstrong (1990) describes the geological development of the southern tip of Bribie Island in particular. Lester et al (2000) describe the geomorphological processes affecting stability of the northern tip of Bribie Island. Key findings of those research and investigation publications are summarised below. Figure 3-1 Moreton Island & Bribie Island Onshore Geology (from Stephens 1982) Bribie Island has formed through transport and deposition of unconsolidated sand during the late Quaternary period, including several episodes of rising and falling sea level. The most recent postglacial sea level rise was about 120 metres from 18,000 to 6,000 years BP. The oldest sand deposits are of Pleistocene age and occur as stranded dunes, beaches and tidal deltas accumulated about

38 COASTAL PROCESSES & CAUSES OF EROSION ,000 years ago when the sea was previously at the present level. Holocene (last 10,000 years) sand bodies similar to but less extensive than those of the Pleistocene were formed over the past 6,000-7,000 years. Offshore from Bribie Island, large deposits of marine sand moved north along the coastal system mainly at times of lower sea level have formed the North Banks and Hamilton Patches (Figure 3-1), between Moreton Island and Caloundra. At present sea level, those banks are submerged and being remoulded by the tides and waves while the coastal sand supply is feeding into Moreton Bay in the NE Passage region near Combuyoro Point. A well-defined natural channel along the western side of the banks separates them from Bribie Island. Further south, the alternating channels and banks of a large tidal delta occupy the entire entrance to Moreton Bay between Bribie Island and Moreton Island. There, tidal currents produce a dynamic environment for the evolution of ebb and flood tide dominated channels. Along Bribie Island, both wave and tidal currents are active in transporting sand, with tides becoming progressively more dominant to the south. Offshore from Woorim, well developed tidal channels to depths of 22m are separated by banks shallowing to less than 5m, with bed forms characteristic of strong tidal flows and active sediment transport. The profiles and sediments there indicate:!" The seafloor sediments are predominantly clean quartzose sands;!" A major tidal channel directly abuts the Bribie Island shoreline at Woorim;!" Along the western margin of this channel, estuarine muds are exposed at depths of 8-14m, believed to have formed prior to 6,000 years ago during the post-glacial transgression and forming the substrate of Bribie Island. Their exposure suggests that erosion at Woorim may relate to westward migration of the channel;!" The surficial sediments of the nearshore zone form a veneer less than 1m thick overlying the transgression age deposits, evidenced also by tree stumps and peaty deposits exposed at times on the lower beach south of Freshwater Creek (between Woorim and Skirmish Point). Onshore (Figure 3-2), the Holocene deposits on Bribie Island lie mainly at the northern and southern ends of the Pleistocene core deposits. In the north, they represent the tidal delta, narrow barrier peninsula and superficial swamp environments greatly influenced by the mobile channels of the Caloundra Bar. In the south, the Holocene deposits are mainly foredune ridges and their net accumulation in episodes of accretion and erosion has extended the island to the south-southeast by up to 2.5km. The southern end of the older Pleistocene deposits is located just north of the Bongaree-Woorim Road. South from there, the island has evolved by extensive deposition of Holocene dune barriers in a sequence of units that can be distinguished by differences in alignment and truncation of crests as mapped by Armstrong (1990) (Figure 3-3). This deposition occurred initially at the southern end of the island (Units 1-6) and subsequently expanding the width of the southeastern part, including Woorim (Units 7-8), unconformably truncating the seaward edge of the earlier units, followed by more recent deposits at the southern end of the island (Units 10-11).

39 COASTAL PROCESSES & CAUSES OF EROSION 3-4 Figure 3-2 Geology of Bribie Island from Jones (1992)

40 COASTAL PROCESSES & CAUSES OF EROSION 3-5 Figure 3-3 Holocene Evolution of Southern Bribie Island from Armstrong (1990) Despite this accretionary pattern of the past 6,000 years, the shoreline at Woorim is believed to be eroding at present. Exposure of old soil horizons in the dune scarp at Woorim indicates continuing erosion. Radiocarbon dating of charcoal from a buried soil profile at Woorim shows that, during the past 750 years:!" the coastline prograded seawards and topsoil developed;!" subsequent erosion occurred with a younger fore-dune blown inland over the soil; and!" continued erosion has exposed the soil horizon in the dune scarp at Woorim. This behaviour pattern appears to be part of a complex cyclical process of accretion and erosion over time. Although accretion and erosion have alternated during the build up of southern Bribie Island, this does not preclude erosion occurring at one location simultaneous with accretion at another. Presently, the sand eroded from the shoreline at Woorim is mostly transported southwards enabling accretion at Skirmish Point. Further north, along the central part of Bribie Island, a residual old Pleistocene shoreline and dune barrier aligned towards the NW is evident across the island, with a continuation of that Pleistocene alignment occurring as the boundary between Pleistocene and Holocene deposits on the mainland at Golden Beach (Figure 3-1). The present Bribie Island shoreline thus cuts into this Pleistocene barrier. Thus, at the beginning of the sea level stillstand period around 6,000-7,000 years BP, the ocean shoreline most likely lay at the rear of Golden Beach, Caloundra. The northern tip of Bribie Island developed later in the Holocene and overlies a Pleistocene humic sandrock layer that is exposed in

41 COASTAL PROCESSES & CAUSES OF EROSION 3-6 the side of the channel on the mainland side of Bribie Island. Dating of shell deposits suggests that this humic sandrock layer may be much younger than the sandrock exposed in the nearshore zone to the east of Bribie Island. There is little evidence for any present day onshore supply of sand either from the tidal delta at the southern end of Bribie Island or in the northern area near Caloundra. While the northern part of Hamilton Patches is undergoing tidal and wave transport, resulting in a northwestward displacement of about 13m/yr, those deposits appear to be independent of the sediment budget of the beaches on the mainland and Bribie Island. Jones (1992) suggests that an onshore supply may have occurred during the sea level rise at lower sea level, but has subsequently ceased. As such, the late Holocene evolution of Bribie Island has occurred predominantly by re-cycling of the older Pleistocene and younger Holocene sand deposits forming the island itself. Lester et al note that the northern Bribie Island spit exhibits a number of features consistent with a receding barrier, particularly exposures of estuarine sediments and tidal flat deposits in the inter-tidal zone along the eastern shore of the spit. Further evidence is the encroachment of foredunes into Pumicestone Passage on the mainland side of the spit and their subsequent erosion by tidal currents there. 3.3 Contemporary Coastal Processes at Woorim Sand Transport Mechanisms and Beach Dynamics Sand is transported along Woorim Beach by the combined action of waves and currents there. The prevailing waves are both ocean swell and locally wind-generated sea. The swell waves are of long period (typically 7-12 seconds) and propagate to the shoreline from the deep ocean across North Banks. They experience significant modification by refraction, bed friction and shoaling. The sea waves are of relatively very short period (generally less than 4 seconds) and are not substantially affected by the offshore bathymetry prior to breaking nearshore. The waves have three key effects on sand transport, namely:!" They break and generate so-called radiation stresses, particularly within the wave breaker zone where wave-driven longshore currents may result;!" Their orbital motion impacts on the seabed causes bed shear stresses that mobilise and put into suspension the seabed sand. Their asymmetry in shallower water causes a significant differential in the forcing on the bed sediments, stronger towards the shoreline in the forward direction of wave travel leading to an onshore mass transport of sand; and!" They cause a bottom return current in the surfzone, strongest during storms when they typically dominate over the mass transport and move sand off the beach to the offshore area. Currents generated by the tide, waves and wind provide the primary mechanism for the transport of the sand that has been mobilised and put into suspension by the wave/current action. It has been noted in Section 3.2 (Jones, 1992) that both tide and wave forces strongly affect sand transport along Bribie Island, with the tidal influence on currents becoming relatively more significant towards the southern end. Thus, Woorim Beach is likely to be subject to a combination of those factors from time to time, with waves dominant near the beach face and tidal currents dominant further offshore, leading to complex sand transport behaviour. The longshore direction of sand movement by those

42 COASTAL PROCESSES & CAUSES OF EROSION 3-7 processes may be opposite at any given time. Comprehensive 2-dimensional modelling is required to investigate these processes. Generally, at a typical beach location, sand transport may be regarded in simple terms as involving longshore and cross-shore sand movement processes. These act concurrently and interact. Cross-shore sand transport involves:!" Erosion of sand from the upper beach and dune area during large storm wave events, with the sand being taken offshore where it is commonly deposited as one or more shore-parallel sand bars located in the vicinity of the wave break area;!" Subsequent slow transport of the eroded sand back to the beach, often over many months or several years; and!" Transport by the wind of the accreting beach sand back to the dune system where dune grasses act to trap it and build the dune back to its former condition. Thus, on dynamically stable beaches, there is a balance in the amount of sand that is taken offshore and is subsequently returned to the beach and dune. The wind plays an important role in the natural balance of sand movements and beach and dune stability. If the dune is poorly vegetated, the sand may be blown landward and lost from the active dune system. Longshore sand transport results predominantly from waves breaking at an angle to the shore with an alongshore component of their radiation stress that drives an alongshore current and carries the sand along the coast. The wind and tide may also contribute to generation of alongshore currents near the beach. This longshore sand transport is distributed across the surfzone and is greatest in the area near the wave break point where the wave height, longshore current and bed shear are greatest. That is, it occurs across a limited zone most probably in water depths less than about 5-8m along Bribie Island. Longshore sand movements at water depths greater than 8m are likely to be associated with tidal currents. The beach may remain stable (without net recession or accretion) where the longshore sand transport is uniform along the coast. However, where there are differentials in the rates of longshore transport, including any interruption of the sand supply to an area, the beach will erode or accrete in response. Wave effects on longshore transport are expected to be complex and variable because the dominant ocean swell waves propagate over the shallow North Banks in reaching the Bribie Island shoreline and thus are subject to variable refraction patterns associated with both varying tide level and changes in the shoal bathymetry of North Banks over time (Figure 3-4). This is reflected in a highly uneven shoreline alignment along the island (Figure 3-5).

43 COASTAL PROCESSES & CAUSES OF EROSION 3-8 Figure 3-4 Wave Propagation to Bribie Island is affected by North Banks Figure 3-5 Irregular Shoreline Alignment of Bribie Island Because longshore and cross-shore transport co-exist, a net sand loss of sand in the nearshore part of the beach profile caused by a negative longshore transport differential may not manifest immediately as erosion of the upper beach. However, more sand would be taken from the beach when storm erosion occurs and, to maintain the normal equilibrium profile shape within the active zone, less sand is subsequently returned to the beach/dune than was previously there. This leads to a recession of the shoreline. The only quantitative assessment of coastal processes and erosion along the ocean shoreline of Bribie Island has been for the northern peninsula spit area (EPA 1992). There, detailed assessment of shoreline change has been made based on both survey data since 1970 and photogrammetric analysis of aerial photography dating back to 1940, with the following conclusions:!" Photogrammetry indicates typical recession of the mean water line (RL 0.0m AHD) in the range 55m-75m over the 52 years covered, equivalent to shoreline recession at an average rate of about m/yr;

44 COASTAL PROCESSES & CAUSES OF EROSION 3-9!" Surveys indicate recession of the shoreline at a rate of about 2m/yr after 1970 This recession is consistent with the geological history in that it is considered likely that the spit, although a Holocene accretion feature, has been migrating landward for many years as a receding barrier. Lester et al (2000) calculated erosion of the eastern shore of the spit at approximately 144,000 m 3 /yr with about 80% of the sand deposited in the flood tide delta of Caloundra inlet and about 30,000 m 3 /yr lost by littoral drift towards the south. The geological evolution of the shoreline suggests that there is only a limited direct link between the processes occurring at the spit and those at Woorim, although it is likely that there is a net southward longshore sand transport along the island. The balance between wave and tidal forcing of sand transport varies significantly along the island with tidal currents increasingly dominant towards the south. BMT WBM has undertaken further investigations including analysis of available aerial photography, current measurements, assessment of wave climate, analysis of longshore sand transport rates from both the recorded directional wave climate and the Coastal Observation Program Engineering (COPE) data, together with 2-dimensional modelling of currents and tide-related sand transport as part of the present study. Details of those investigations are outlined in the ensuing sections of this report. They have confirmed the expected general processes of wave propagation, current patterns and longshore sand transport. However, they show that the processes are complex and difficult to quantify reliably on the basis of available information. Nevertheless, they provide a sound basis for considering the effects and feasibility of the various management options Assessment of Historical Shoreline Erosion The primary research and information drawn upon in this study includes: i. Geological research reports as referenced and discussed in Section 3.2; ii. Historical and site information derived from:!" Library and historical society sources;!" Local residents and Steering Committee members; and!" Analysis of aerial photography obtained from the Department of Natural Resources. At Woorim, the historical erosion is considered the result of a negative longshore transport differential in which:!" More sand is moved away along the beach towards the south than is supplied from the north or offshore;!" The deficit in sand transport is made up by permanent erosion of the beach and dune. These are the result of natural processes that are part of the long-term geological evolution of this section of coastline. However, it is noted in Figure 3-3 that this behaviour is not simple or consistent over the geological time-frame. Woorim is located at the junction of Units 8 and 9 (illustrated in that figure). Armstrong (1990) notes:

45 COASTAL PROCESSES & CAUSES OF EROSION 3-10!" There were at least three phases of accretion of beach ridges normal to the alignment of Units 1 to 6 (Units 7a, 7b and 8). The inner part of Unit 7 (7a) is significantly older than the outer part (Unit 7b), indicating a long hiatus in deposition between them, possibly accompanied by erosion of part of 7a.!" Units 7b and 8 are of similar age but there is a disconformity between them in their ridge alignments indicating a period of erosion and slight change in shoreline orientation between them.!" The eastern side of Units 7 and 8 was eroded before deposition of Unit 9.!" It is likely that erosion of Units 7, 8 and (possibly) 9 contributed to the sediment deposited in Unit 10 at the southern end of the island, but subsequently largely eroded.!" Sand has accreted in modern times in Unit 11 at Skirmish Point, Bald Point and South Point. Deposition is continuing with shoreline accretion of several hundred metres since the 1970s evident at some locations (Figure 3-6). Figure 3-6 Recent Accretion of Skirmish Point, Southern Bribie Island The indications from observations and Armstrong (1990) are that Woorim Beach is eroding predominantly at the southern end of the township but is relatively stable at the northern end (Figure 3-7, Figure 3-8 and Figure 3-9).

46 COASTAL PROCESSES & CAUSES OF EROSION 3-11 Figure 3-7 Erosion and Limited Beach Width at the Southern Area Figure 3-8 Northern End of Woorim Presently in Good Condition

47 COASTAL PROCESSES & CAUSES OF EROSION 3-12 Figure 3-9 The Armstrong (1990) Interpretation of Sediment Movement and Shoreline Erosion/Accretion. (E = erosion; A = accretion) Analysis of Aerial Photography Shoreline and Dune System Changes Aerial photography sourced for this study extends from 1940 to present. Analysis of this photography has involved:!" Qualitative assessment of the state of the beach and dune system along Woorim Beach to determine changes in use and stability of the dunes, as indicated by the dune vegetation; and!" Measurement of changes in the seaward extent of the dune vegetation at nine (9) locations along the beach for various dates. Dune edge movements were determined by reference to fixed features (eg. roads) common to successive dates of photography. An accuracy of about #2m was possible for each case. In that regard, rectified aerial photography for selected dates from 1961 to 2004 was provided by EPA, allowing accurate comparison of those photographs without image distortion. The analysis indicated:!" In 1961 (Figure 3-10), damage to the dune vegetation in the surf club area is evident along a section of about 250 metres where wind erosion was causing dune sand to blow landward across the carpark and roads;!" By 1967 (Figure 3-11), although the photography is unclear, considerable adverse impact on the dune vegetation was evident over a wide area, with extensive areas of disturbance and blowouts occurring, allowing loss of sand from the beach by wind erosion, with sand blowing inland over previously hind-dune areas particularly evident at the main surfing beach area;

48 COASTAL PROCESSES & CAUSES OF EROSION 3-13!" Considerable effort by Council in conjunction with the (then) Beach Protection Authority to stabilise the dunes with respect to wind erosion during the early 1970s led to significant improvement in dune vegetation and, by 1978 (Figure 3-12 and Figure 3-13), that problem was largely under control.!" Subsequent erosion issues to 2004 (Figure 3-14 and Figure 3-15) related predominantly to shifts in high water mark, erosion of the base of the dune and changes in beach width associated with wave/current action rather than wind erosion.!" The aerial photo analysis (Figure 3-10 to Figure 3-15) shows the broad-scale changes that indicate a long-term trend of shoreline recession, particularly towards the southern parts of Woorim, as follows: 1961 to 2004 The change in position of the vegetation line shown in Figure 3-16 indicates varying recession from essentially nil at the northern end of Woorim to about 1.7m/yr south of Freshwater Creek. Between Second to Third Avenue south to the southern end of the SLSC carpark the erosion distance is about 12m over the 43 years, a rate of 0.3m/yr. The former mouth of Freshwater Creek has been substantially eroded, the rate immediately south of the creek being about 0.9m/yr, leaving the present mouth some 150m north of its 1961 position, while further southward recession of about 75m (1.7m/yr) is evident to 2004 Assessment of changes in the interpreted base of the dune scarp between 1979 (fence line visible) and 2004 (dune base unclear) indicates: o general stability north from around Third Avenue; o localised slight accretion of the foredune in front of Fourth Avenue area; o erosion between Third Avenue and the surf club of up to about 5m, equivalent to 0.2m/yr; o erosion south of the surf club area to Freshwater Creek of about 8m (0.3m/yr); o relative stability at and immediately south of Freshwater Creek following considerable recession (about 40m at 2.2m/yr) there between 1961 and 1979; o erosion of the dune by up to about 45 metres (1.8m/yr) further south, along about 400m of the shoreline in the area immediately north from Skirmish Point; and o at Skirmish Point, a progressive accretion of the shoreline, extending the width of the dune ridge barrier towards the south by up to about 400 metres between 1979 and 2004, as evident in Figure The estimated growth of sand volume in that area is about million m 3, providing a basis for estimating the rate of net southward sand transport at Skirmish Point over that time, as discussed in Section

49 COASTAL PROCESSES & CAUSES OF EROSION 3-14 Figure 3-10 Dune instability associated with vegetation loss evident near the surf club in 1961 Figure 3-11 Extensive clearing, vegetation loss and dune instability associated with wind erosion evident in 1967

50 COASTAL PROCESSES & CAUSES OF EROSION 3-15 Figure 3-12 Vegetation regrowth and improved dune stability evident in 1973 Figure 3-13 General dune vegetation stability evident in 1978

51 COASTAL PROCESSES & CAUSES OF EROSION 3-16 Figure 3-14 Stabilised dune vegetation along the whole coastal unit and accretion at Skirmish Point evident in 2004 Figure 3-15 Present status of Woorim Beach near the surf club (2004)

52 COASTAL PROCESSES & CAUSES OF EROSION Longshore Sand Transport from Aerial Photography It is feasible to derive an indication of the total wave and tide induced longshore transport rates and gradient along the shoreline from the erosion pattern and rates identified from the aerial photography. This requires knowledge of the relationship between the linear distances of shoreline change and the volumetric change in across the whole active profile, from the dune crest to the offshore limit of the active profile. The Woorim region shoreline has been subject to both erosion and beneficial beach nourishment. The combined action of waves and tidal currents has affected profile change to different degrees along the shoreline. The survey data suggests a shallower water depth of profile change at the northern end (4-6m) than at the south (10-15m). This would suggest greater tidal influence towards the southern areas towards Skirmish Point. However, the accretion zone beyond Skirmish Point is likely to have deposited across a zone of water depth less than about 5-6m, based on the prevailing offshore depths there now. The area of accretion at Skirmish Point from 1979 to 2004 has been derived from the photography to be 300,000 m 2, corresponding to about million m 3. Thus, on the basis that there was no transport out of that area to the west, the average annual net longshore transport rate from the north to Skirmish Point would have been in the range 100,000 to 115,000 m 3 /yr. The rates of total wave and tide induced net longshore transport rates at various locations along the shoreline between Skirmish Point and Woorim for the period 1979 to 2004 may be estimated from the rate determined for Skirmish Point with appropriate allowance for both:!" The measured distances of shoreline change; and!" The beach nourishment quantities of sand added into the system over that period. The nourishment record is as listed in Table 3-1. It indicates that about 0.62 million m 3 sand has been placed on Woorim Beach since June 1988 at an average rate of about 32,700 m 3 /yr. Table 3-1 Beach Nourishment Quantities Date Dredge Quantity (m 3 Cumulative ) Quantity (m 3 ) June 1988 Sir Thomas Hiley 50,000 50,000 Sept 1988 Sir Thomas Hiley 150, ,000 Sept 1989 Sir Thomas Hiley 65, ,000 Feb 1991 Sir Thomas Hiley 40, ,000 Feb 1997 Sir Thomas Hiley 86, ,000 Nov 2000 Sir Thomas Hiley 60, ,000 May 2004 Brisbane 45, ,000 July 2006 Brisbane 65, ,000 Dec/Jan 2006/07 Brisbane 60, ,000 Analysis of the likely transport rate at Woorim on this basis indicates a southward total wave plus tide transport of about 75,000 to 90,000 m 3 /yr. This is about 10,000 to 25,000 higher than that calculated for waves alone, potentially representing the tidal current contribution there. This analysis also suggests that the tidal current contribution at Skirmish Point could be as high as 50,000 to 60,000 m 3 /yr. This is reasonably consistent with the modelling undertaken (Section 3.3.5).

53 COASTAL PROCESSES & CAUSES OF EROSION 3-18 Figure 3-16 Assessed change in position of the vegetation line

54 COASTAL PROCESSES & CAUSES OF EROSION Analysis of Wave-Induced Longshore Sand Transport COPE Data Analysis The Coastal Observation Program Engineering (COPE) of the former Beach Protection Authority (BPA) operated at a station at Woorim over the period 1986 to A range of beach, wave and current parameters were measured each day, providing a most useful database for analysis of coastal processes. In particular, the breaking significant wave heights, longshore currents and longshore sand transport rates have been determined from the data using the simple techniques developed by the BPA (Patterson & Blair, 1985). Patterns of beach erosion and accretion in terms of beach berm width have also been assessed (Figure 3-17), indicating increased width following commencement of regular nourishment in The calculation method determined by the BPA as described in Patterson (1985) was used. It involves a modified form of the CERC relationship that eliminates the wave angle and includes the direct measure of longshore current available from COPE. A time series of longshore transport has been determined for each location from which annual average net transport results have been derived. This is considered to be a relatively accurate approach, particularly for the reasonably small and accessible surfzone at Woorim. While the absolute results contain some uncertainty, the relative transport results should give a reliable indication of any significant gradients and differentials. COPE Reading of Longshore Current at Woorim (approx 1985) Erosion at stairs near COPE station in 1988

55 COASTAL PROCESSES & CAUSES OF EROSION 3-20 The COPE wave and current data together with the analysis of daily sand transport rates are illustrated in Figure 3-7. They yield an average annual net sand transport rate over the ten year period of 65,600 m 3 /yr, with clearly some variability from year to year. 50 Beach Width 40 Width (m) /01/86 1/01/87 1/01/88 31/12/88 1/01/90 1/01/91 1/01/92 31/12/92 1/01/94 1/01/95 1/01/96 31/12/96 Figure 3-17 Measured Beach Width at Woorim COPE Station: Breaking Significant Wave Height Hs (m) /01/86 1/01/87 1/01/88 31/12/88 1/01/90 1/01/91 1/01/92 31/12/92 1/01/94 1/01/95 1/01/96 31/12/ Current Current Speed (m/s) /01/86 1/01/87 1/01/88 31/12/88 1/01/90 1/01/91 1/01/92 31/12/92 1/01/94 1/01/95 1/01/96 31/12/ Sand Transport 2000 Transport (Cum/day) /01/86 1/01/87 1/01/88 31/12/88 1/01/90 1/01/91 1/01/92 31/12/92 1/01/94 1/01/95 1/01/96 31/12/96 Figure 3-18 Analysis of Longshore Sand Transport from COPE Data

56 COASTAL PROCESSES & CAUSES OF EROSION Longshore Transport from Directional Wave Climate Comprehensive wave propagation analyses and calculation of longshore sand transport rates associated with both the ocean waves and the local wind-generated waves have been carried out for several sites from north of Woorim to Skirmish Point using:!" the recorded Brisbane directional wave data; and!" recorded wind data from Spitfire Channel. The available directional ocean wave data covers the period 1997 to 2005, with no overlap with the COPE data. Wind data for the period August 2002 to July 2005 were used. A conventional calculation methodology has been followed, applied to each record in the wave time series, involving:!" For the ocean waves, analysis of spectral wave propagation from deep water using SWAN to provide refraction transformation relationships to various nearshore locations in 10m depth along the coast;!" For the wind waves, hindcasting of the nearshore wave heights and periods;!" For each wave record in the data time series: o Representation of wave conditions in terms of the significant wave height (H s ), spectral peak period (T p ) and direction at the spectral peak as routinely analysed by the respective agencies (no spectral resolution of sea and swell); o Further propagation to the break point to estimate breaker height and angle on the basis that the nearshore contours shallower than 10m are essentially straight and parallel; o Calculation of the longshore transport rate for that time increment; o Filling of gaps in the data with transport at rates equivalent to the average annual rate for that year over the gap duration. Typical wave patterns for ocean swell and local wind-generated sea are shown in Figure 3-8. Modelled wave propagation indicates that the longer period ocean swell is refracted and arrives essentially shore-normal along most of the Bribie Island shoreline, although subject to minor variations associated with the incident deep-water direction and the effects of North Banks. However, the swell reaches the southern part of the island, south from around Woorim, at an angle to the shoreline consistent with causing a southward longshore sand transport. For the locally generated sea waves that are of short period (generally less than 6 seconds), their direction and angle at the shoreline are determined predominantly by the wind direction. Northerly wind/waves cause a southward transport and east to southeast wind/waves cause an upcoast northerly sand transport.

57 COASTAL PROCESSES & CAUSES OF EROSION 3-22 Large East Ocean Swell ESE Ocean Swell SE Swell and Local Wind Waves NE Waves Figure 3-19 Modelled Wave Patterns Thus, sand is transported in both directions along the shoreline from time to time, at varying rates. The wave-induced transport near the beach may occur independently of the tide-induced transport further offshore. The results of the analyses are summarised in Table 3-2. in terms of average annual net longshore transport rates for both ocean waves and local wind waves. Table 3-2 Longshore Sand Transport Rates from Recorded Wave & Wind Data Net Transport (m 3 /yr) Location Ocean Wind waves waves Resultant North Woorim -61,400 7,000-54,400 Woorim Surf Club -77,900 13,000-64,900 South Woorim -113,000 21,000-92,000 Skirmish Point -75,000 26,000-49,000 Note: Transport to north is +ve; to south is ve The resultant southward net transport rate of about 64,900 m 3 /yr at the Woorim Surf Club site corresponds very closely to the value of 65,600 m 3 /yr derived from the COPE data. Further, a gradient in the net transport rates is identified, increasing towards the south through Woorim,

58 COASTAL PROCESSES & CAUSES OF EROSION 3-23 consistent with the observed pattern of progressive erosion, but with a reduction in the wave-related net transport in the southern area at Skirmish Point. There is an additional influence of the tide in transporting sand along the coast. This is discussed further in Section (modelling of tidal processes) and Section in which longshore transport rates are deduced also from the shoreline changes identified in the analysis of aerial photography Hydrodynamic Modelling of Tide-Related Processes Hydrodynamic modelling has been undertaken as part of the present study to gain a better understanding of the role that tidal currents play in the movement of sand along the coastline of Bribie Island and its interaction with wave-induced sand transport near the shoreline. The modelling has been based on the hydrodynamic and wave models established and validated by BMT WBM for a range of investigations over many years, most recently for the Moreton Bay Sand Extraction Study and Brisbane Airport Corporation New Parallel Runway impact assessments. The computational layout of the hydrodynamic model is shown in Figure This has been substantially refined specifically for this study along the coastline of Bribie Island, particularly around Woorim in order to provide a suitable level of detail with respect to the cross-shore distribution of the longshore tidal current and sand transport potential. Additional bathymetric data from BPA/EPA profile surveys and a hydrographic survey undertaken by Queensland Transport in 2001 was utilised for the model refinement. It is noted that large differences were found between bathymetric chart data (AUSCHARTS) and these data sources in the vicinity of Bribie Island. Inset b) a) b) Figure 3-20 Hydrodynamic Model Bathymetry and Computational Grid Mesh

59 COASTAL PROCESSES & CAUSES OF EROSION 3-24 It must be recognised that modelling of coastal processes remains an imperfect science and obtaining a high level of quantitative accuracy depends to a large degree on:!" Accurate representation of the area being modelled (bathymetry, seabed characteristics, computational grid mesh, etc)!" The accuracy and representativeness of the boundary conditions applied (wave conditions, winds, tides);!" Validation to ensure that all of the physics of the processes important in any particular area are being properly simulated in the model. The models applied to this study provide an invaluable tool for providing both qualitative insights and quantitative information about the processes taking place. The level of modelling and analysis undertaken is considered sufficient for the purposes of this study given that the wave, current and sand transport processes occurring at Woorim are understood sufficiently well for a reasonable assessment of the key processes and erosion mechanisms that occur. Typical model results in terms of regional and local nearshore tidal current patterns are shown in Figure 3-21 and Figure 3-22 respectively. Figure 3-21 Typical Tidal Current Patterns Left: Flood tide; Right: Ebb tide Figure 3-22 Nearshore Tidal Patterns Left: Flood tide; Right: Ebb tide

60 COASTAL PROCESSES & CAUSES OF EROSION 3-25 The model shows flood tide dominant tidal currents close to the shoreline at Woorim, consistent with the geological interpretation. Tidal currents have been measured by BMT WBM offshore from Woorim for this study. The data obtained is presented in Figure 3-23 and also confirms:!" Flood tide dominance; and!" Current speeds in excess of 0.5m/s, sufficient to transport sand, particularly in conjunction with wave action. The refined RMA hydrodynamic model has been validated against the S4 current meter data collected for this study, with the model predictions also shown in Figure In general the model does a good job of predicting the phasing and amplitude of the tidal currents offshore of Woorim. The model has been used to determine net tide-induced sand transport adjacent to the southern Bribie Island coastline. The van Rijn model for total sand transport has been used for this purpose, with net transport calculated by averaging over two neap spring tidal cycles. The pattern of net sand transport is illustrated in Figure 3-24 and Figure 3-25, indicating:!" Flood tide dominance;!" Increasing transport towards Skirmish Point consistent with a net deficit sand budget for Woorim;!" Skirmish Point and its offshore shoals is a convergence (deposition) zone for sand transported from the north and west. The alongshore distribution of the net tidal sand transport is shown in Figure 3-25 and illustrates the strong increase in transport potential between Woorim and Skirmish Point. 1.5 FLOOD 1.0 Current Speed (m/s) EBB /12 2/12 3/12 4/12 5/12 6/12 7/12 8/12 9/12 10/12 11/12 12/12 13/12 14/12 15/12 16/12 S4 Current Meter Model Figure 3-23 Measured and Modelled Currents Off Woorim

61 COASTAL PROCESSES & CAUSES OF EROSION 3-26 Figure 3-24 Modelled Net Sand Transport Induced by Tidal Currents Alone. 140, ,000 Transport between shoreline and -10 m LAT Transport between shoreline and 300 m offshore Tidal Sediment Transport (m 3 /year) 100,000 80,000 60,000 40,000 20, Distance South From Fifth Avenue (m) Figure 3-25 Alongshore Distribution of Net Tidal Sand Transport.

62 COASTAL PROCESSES & CAUSES OF EROSION Net Longshore Sand Budget As shown in Sections and both wave-induced and tidal-current-induced net sediment transport gradients are potentially contributing to the long-term progressive erosion at Woorim, which was analysed from aerial photography in Section A summary of the modelled transport due to both waves (ocean and local wind waves) and tidal currents is given below. These results show the dominance of wave induced transport to the north of Woorim and the increasingly significant contribution from tidal current induced transport to the south. Table 3-3 Calculated Total Longshore Sand Transport Rates Net Transport (m 3 /yr) Location Tidal Waves Currents Resultant North Woorim -54,400-9,600-64,000 Woorim Surf Club -64,900-12,600-77,500 South Woorim -92,000-43, ,000 Skirmish Point -49,000-89, ,500 Note: Transport to north is +ve; to south is ve In Figure 3-26 the sediment transport model predictions are compared with net alongshore transport rates derived from the analysis of historical aerial photography (and taking into account sand nourishment) that was discussed in Section The combined model results are in reasonably good agreement with the derived transport rates between 5 th Avenue and 800 m south at Woorim Surf Club. At the southern end of Woorim the combined model results are higher than the derived rates. This may be due to the tidal transport being only partially coupled with the upper beach sand budget (and hence shoreline change). 160, ,000 Sediment Transport (m 3 /year) 120, ,000 80,000 60,000 40,000 20, Distance South From Fifth Avenue (m) Lower limit Upper limit Wave transport Wave+Tide Transport Figure 3-26 Comparison of Upper and Lower Limit Longshore Transport Rate Derived From Historical Shoreline Change With Model Predictions.

63 COASTAL PROCESSES & CAUSES OF EROSION 3-28 In order to investigate this further the cross-shore distribution of the wave and tidal-current related sediment transport are shown in Figure This plot shows that at Woorim the wave transport is focussed in a narrow surfzone of less than 50 m width. On the other hand the magnitude of tidal transport is relatively insignificant in the nearshore region. This result indicates that the tidal-current induced sand transport is much less significant to shoreline erosion than the wave induced transport process. 0 2 Sediment transport (m 3 /year/m) -2,000-4,000-6,000-8,000-10, RL (m AHD) -12, Cross-Shore Chainage (m) Net wave transport Net tidal transport Bathymetry Figure 3-27 Cross-Shore Distribution of Wave and Tidal-Current Sand Transport at South Woorim Storm Erosion The potential for short-term erosion due to severe wave and ocean surge conditions has been modelled using simple cross-shore equilibrium profile models. The models of Kriebel and Dean (1993) and Vellinga (1983) have been applied for this purpose. These methods require an input initial beach profile as well as wave and storm surge conditions during the storm event. The models predict the volume of dune erosion and corresponding shoreline recession that will result from these conditions. A significant wave height of approximately 9 m at the Point Lookout waverider buoy has been transferred inshore to Woorim using the SWAN model discussed in Section A significant wave height at Woorim of 3 m, and peak period of 12 s has been used for the storm erosion modelling. A super-elevation of the mean shoreline water level of 1.6 m above the average equilibrium conditions has been derived for a corresponding storm event. It is considered that these conditions are conservatively representative of a single 100 year ARI erosion event at Woorim. The cross-shore equilibrium profile models predict that if such an event were to occur with the current beach profile that approximately 60 to 70 m 3 /m of short-term erosion would occur. This would translate to a short-term recession of the dune toe of m.

64 COASTAL PROCESSES & CAUSES OF EROSION 3-29 Vellinga model results for the profiles corresponding to the BPA survey line ETA 408.0, which is situated at the southern end of Rickman Parade, are shown in Figure The same model results for ETA 409.0, which is 400 m further north along Rickman Parade, are shown in Figure Level (m AHD) Distance from existing dune toe (m) Storm Water Level Wave envelope Erosion Profile Existing profile Figure 3-28 Vellinga Storm Erosion Profile at ETA Level (m AHD) Distance from existing dune toe (m) Storm Water Level Wave envelope Erosion Profile Existing profile Figure 3-29 Vellinga Storm Erosion Profile at ETA Present and Future Shoreline Erosion Historical Erosion Trend As is evident in Figure 3-30 and Figure 3-31, continuing shoreline erosion is occurring at Woorim. This has been evident for many years. The analysis of aerial photography undertaken for this study shows that the erosion is more acute further south, most probably because beach nourishment has helped to minimise the erosion along the northern areas. Nevertheless, it is apparent that the placement of over 30,000 m 3 /yr of nourishment sand on average since 1988 has not been sufficient to prevent the shoreline erosion, indicating that the potential erosion exceeds that quantity along the nourished area.

65 COASTAL PROCESSES & CAUSES OF EROSION 3-30 Figure 3-30 Old gravel road base horizon exposed below wind blown sand and mature vegetation in the eroding dune scarp adjacent to the surf club area Figure 3-31 Old bitumen surface exposed below wind blown sand and mature vegetation in the eroding dune scarp adjacent to the surf club area