Lonsdale Bight Investigations Review and Options Overview

A general summary of the Lonsdale Bight Investigations Review and Options Overview

The Department of Environment, Land, Water and Planning (DELWP) has commissioned an independent review of reports on the Lonsdale Bight environment from the past 20 years.

A copy of the report can be downloaded from: www.engage.vic.gov.au/lonsdale-bight.

Study Area The Lonsdale Bight (see Figure 1) is a popular five- and-a-half kilometre stretch of coastline extending from Point Lonsdale at the south-west end, to Queenscliff in Figure 1. Lonsdale Bight, Pt Lonsdale to Shortland’s Bluff the east. A section of the study area lies within the Port Phillip Heads Marine National Park. Coastal Processes at a glance Coastal processes have caused coastal erosion, shifts in Sand is transported by waves and currents along the the shoreline and major fluctuations to sand volumes since th coast from the west and enters the Bay around the the area was first observed in the late 19 century. headland at Point Lonsdale. There is considerable Protection works since the 1900s have had varying variability in this process, depending on weather success in combatting the impacts of coastal erosion. conditions.

Objectives and Scope of the Review Sand moves in pulses in response to storms and, the Given the considerable knowledge already gained amount will vary within and between years. The sand is through previous investigations and reports, the then transported partly along the coastline close to the independent review considered 24 reports produced beach and partly across the seabed of the embayment since 1997 (see Section 2 of the Report) to: towards Shortland’s Bluff. These processes are also subject to variability across annual and decadal time  Identify common issues in the reports; scales and result in fluctuations of sand on the beach.  Identify knowledge gaps for considering short- and long-term sand management concepts and; Climate change projections show there is also the  Suggest short- and long-term sand management potential for sea level rise and increased wave energy, concepts which will further influence sand movement. Section 4 discusses these processes in more detail.

delwp.vic.gov.au

Lonsdale Bight Investigations Lonsdale

Bight Investigations Review and Options Overview

Knowledge Gaps Long Term: The reviewed reports provide some assessment of the  Do Nothing; let natural processes occur coastal processes although there are some limitations  No change; maintain existing structures. and gaps in knowledge. These knowledge gaps are  Construct more groynes; maintain exitsing and discussed in detail in Section 4.10. A summary of the modify/build more groynes key knowledge gaps are provided here.  Construct new offshore breakwater; deisgn and build large-scale defensive structure. Fluctuations in sand levels: Central Lonsdale Bight  We don’t have data on the amount and frequency of sand that travels around the headland in pulses. Short Term:  Limited monitoring data on past beach fluctuations and how this may have been influenced by natural  Do nothing; let natural processes occur. coastal processes and man-made structures.  No change; maintain exitsing rock wall and footpath

Climate Change Influences Long Term:  We haven’t projected the potential extent of beach  Do nothing; let natural processes occur. fluctuations and long term erosion associated with  No change; maintain existing rock wall and footpath climate change.  Build more groynes; maintain existing, modify/build  The implications of increased overtopping of the more groynes with ot without beach nourishment sea wall from sea level rise associated with \climate  Build new offshore breakwaters; design and build change has not been fully scrutinised. large-scale defensive structure.  Build artificial headland; create a protected new Sand Management concepts beach (pocket beach). Key considerations for sand management concepts are Dog Beach discussed in Section 5 of the Report. This includes discussion on a risk management approach.  Let natural processes occur; Continue to monitor shoreline fluctuations and existing dune Further investigation into any of the below management management concepts will also need to consider social, economic  Establish a trigger point for consideration of specific and environmental factors associated, including the actions related to future erosion threatening the values of the marine national park. More detail on each land behind. of the management concepts listed below can be found in Section 6 of the Report. Next Steps Point Lonsdale Front Beach Read the report and be a part of the conversation informing coastal zone management of Lonsdale Bight Short Term: by visiting www.engage.vic.gov.au/lonsdale-bight.

 Do Nothing; let natural processes occur  23 February 2017 - Consultation on report  No change; maintain existing structures. close  Move sand; maintain existing strcutures and  30 March 2017 – We will report back on what redistribute sand from nearby beaches we heard through the consultation.  Bring in sand; maintain existing structures and bring

in extra sand from elsewhere

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