Shoreline Management Planning A Gold Coast Journey Queensland Coastal Conference 2011 Ancient Knowledge Contemporary Innovation Wednesday 19 Friday 21 October 2011 THE PULLMAN REEF HOTEL, CAIRNS Kim Bowra 1, Shannon Hunt 1, John McGrath 1, Rodger Tomlinson 2 and Darrell Strauss 2 1 Gold Coast City Council PO Box 5042 QLD 9729 2 Griffith Centre for Coastal Management, Griffith University Gold Coast QLD 4222 INTRODUCTION LEARN The City of the Gold Coast in Queensland, Australia is a popular tourist area with 52km of recreational sandy beaches and many world class surfing sites. In addition to the open coastline, the Gold Coast Local Government Area has over 600km of waterways and canals that are either developed, or face emerging development pressure. At June 2010, the population of the Gold Coast was estimated at 527,828 persons, being the second largest Local Government Area in Australia in terms of population. This population is expected to increase to 798,417 residents in the year 2031. The City has been developed upon an area that can be described as coastal plains, 800m to 5km in width, consisting of sand, mud, peat, old dune ridges and estuarine alluvium, with the western edge bounded by mountains (DHI, 1970). The coastal plains are built up on a west to east sloping base of pre-pleistocene bedrock. At several locations the bedrock protrudes into the ocean as headlands (at Point Danger, Coolangatta, Currumbin, Burleigh and South Nobby). Figure 1 further describes the regional context of the Gold Coast. Sandy beaches are the geographically dominant type of shore along the Gold Coast. The beaches of the Gold Coast are high energy and dynamic, and the predominance of southeast swells result in a net northward littoral drift of approximately 500,000m3/year. This net transport is estimated to comprise approximately 650,000m3/year northwards, and 150,000m3/year southwards (Turner, 2006). The tidal cycle for Gold Coast beaches is semidiurnal, varying from 0.2m to 2m, with a mean 1m. The area is exposed to energetic swells, which can be differentiated into three different swell regimes having important effects on coastal dynamics (GCCM 2007). The normal condition is a swell direction varying between northeast and southeast sectors with a mean significant wave height of approximately 1m. The area is, however, often exposed to energetic swells during the year. The three swell regimes that are considered dominant on the Gold Coast s dynamic shoreline include: SE [110 ]: South to Southeast swells in winter and spring, generated by intense low pressure systems off the New South Wales coast. These contribute the main component of the northerly littoral drift and are most common.
ENE [60 - shore perpendicular]: East Coast Lows. These are fairly common, often resulting in strong wind gusts, high waves and storm surges. NE [20 ]: Tropical cyclones. These are not responsible for the majority of the high wave events on the Gold Coast; however they have the highest potential for destruction, with significant wave heights up to 8m. One regime is for S- SE swells in winter and spring Historically, episodic storm erosion is an ever-present threat to property, infrastructure, and the loss of beach amenity. Castelle et al (2007) notes that the potential of a tropical cyclone approaching the Gold Coast and generating storm and wave surges causing widespread damage to the local community is high. Severe cyclones caused widespread erosion and damage to beachfront property in 1954, 1967, 1972 and 1974. During these events, widespread erosion occurred which resulted in the loss of public open space, damage to both private and public infrastructure, and a decline in the local economy due to a reduction in tourism. In contrast to more recent events in Northern and Central Queensland coastal areas (cyclone Hamish 2009 and Larry 2006), the Gold Coast is yet to experience any significant cyclonic events since 1974. However, a series of east coast low pressure systems in mid 2009 resulting in significant erosion along central Gold Coast beaches reaffirmed to the Gold Coast City Council how vulnerable our coastline is if not managed appropriately. Figure 2 showcases significant wave heights over the past 3 years. Furthermore, key climate parameters such as the cumulative Southern Oscillation Index (SOI) suggest that a higher frequency of cyclonic events can be expected within the next few years or decades (Allen and Callaghan 1999).
Fig. 1. Regional coastal perspective of the Gold Coast (Source: DHL, 1970)
Fig. 2. Significant wave heights for Gold Coast July 2008 - April 2011. PLAN In response to the devastation of Gold Coast beaches during the 70 s, the Queensland Government, whom has a long history of involvement in planning for and managing the Gold Coast littoral environment; invited the Delft Hydraulics Laboratory (DHL) to advise them on ways of minimising erosion problems through varied management practices and coastal protection works (Delft Hydraulics Laboratory, 1965; Gourlay, 1996). A number of recommendations were put forth and the Gold Coast City Council together with the Queensland Government implemented many of the recommendations provided. Since this period, the Gold Coast City Council has been at the forefront of coastal management; pioneering technology and techniques providing improved outcomes for local and coastal communities around the world. Relatively calm periods for the Gold Coast since 1974 have meant significant population growth, tourism and associated development on the sand dunes of Gold Coast beaches has limited the beach s ability to cope with natural storm erosion events. This has required active involvement in managing the beach system, and as such this system has been heavily modified. The methods and activities by which the Gold Coast City Council manage the beaches remain today, under continuous scrutiny by the community and as such require continual review and provision of current data sets. Ongoing effective coastal management activities undertaken by the Gold Coast City Council include: - Bypassing operations of the Tweed River and Gold Coast Seaway Entrance - Dredging of Currumbin Creek and nourishment of southern Palm Beach - Dredging of Tallebudgera Creek and nourishment of Burleigh Beach - Maintenance and construction of foreshore seawalls and rock walls / groynes - Beach scraping and profiling activities It has been some 40 years since the Delft Report was first received, and with new science suggesting sea level rise, increased storm activity and intensity as a result of what we would all know as climate change, as well as community opposition to proposed protection strategies, the Gold Coast City Council in conjunction with the
Griffith Centre for Coastal Management in 2005 initiated a program of review and plan development. The program was referred to as the Gold Coast Shoreline Management Plan (GCSMP). THE GOLD COAST SHORELINE MANAGEMENT PLAN The Gold Coast Shoreline Management Plan, a whole of coast strategy, is a review of the social, environmental and economic processes that impact on the way we manage our sandy beaches. The major outcome of the review is the development of a new shoreline management plan to guide coastal works for the next 50 years. The GCSMP focuses research and planning on how we manage our beaches and shoreline and provides a mechanism to review all available previous investigations, identify knowledge gaps, undertake new research and identify priority areas for capital works investment. In November 2010, the GCSMP was officially endorsed by the Gold Coast City Council, which requested an investment of $60M over the next 15 years. This movement earmarked a significant milestone for the future strategic management of the Gold Coast. In addition the GCSMP is also closely aligned with the requirements of the States Shoreline Erosion Management Plans (SEMP). The GCSMP focuses on the management of the sandy beach environments from Point Danger in the south, to Jumpinpin in the north, concentrating on the littoral zone, where in the case of Gold Coast beaches is the area from the rear of the dune fence or boulder wall alignment to the offshore zone where sand deposits for beach nourishment may be (Fig 3). Figure 3: Littoral Zone defined The purpose of the GCSMP is to: 1. Ensure that beaches continue to contribute to coastal lifestyles and the tourist economy into the future. 2. Sustainably manage our sandy beach environment; and 3. Develop coastal protection measures to deal with current erosion issues and forecast effects.
The GCSMP is structured around five major themes that complement the objectives (standard SEMP) of the Department of Environment and Resource Management (DERM), including: 1. Coastal physical processes 2. Coastal ecological processes 3. Economic values of Gold Coast beaches 4. Community values and stakeholder engagement, and 5. Beach management planning Centred around these themes are 77 recommendations that the GCSMP provides for including major capital works, operational works, policy, design and management guidelines, natural asset management, community engagement, resourcing and further studies. The priority of recommendations is largely based upon the physical state of individual beaches, or a beach volume index value; which is a quantitative measure of a beaches ability to withstand erosion. For a BVI greater than one, there is adequate sand in the profile (1 is = to the Delft profile of 400m3/m), and for BVI less than one, the beach is vulnerable to storm erosion back to the boulder wall. In the event where the BVI is zero, it would suggest that the whole profile seaward of the boulder wall has been eroded since the last survey and there is a need for immediate action. In the case of the Gold Coast, central beaches, from Currumbin to Broadbeach have been identified as the most vulnerable. (more current survey data is available for 2011, although it is yet to be reduced) Since 2009 the same beaches from Currumbin to Broadbeach remain our most vulnerable. Some examples of key capital works identified through the GCSMP have been included here. Again these examples take into account the BVI assessment discussed. MANAGE Our Shore Future Utilising the GCSMP as the foundation for implementing future beach protection strategies; the recently developed Our Shore Future is an overarching community engagement program that will see effective communication of project components and role out of individual beach protection works. Our Shore Future consists of a number of stages and is at present only within its infant stages of development with the Corporate Communication branch of GCCC. Preliminary stages have largely involved the development of stakeholder inventory as well as the collection of various data sets that can be used in the engagement process. It is only through effective education and communication that the community can realise the vulnerable condition that some of our much loved beaches are in. Conclusion GCCC has a long history of involvement in planning for, and managing Gold Coast beaches. While the Gold Coast has been fortunate to have enjoyed relatively mild conditions for the past 30 years, this has brought about new challenges of ensuring that the intensity of shoreline development and the lifestyles we are accustomed to be protected now and into the future.
Whilst the recommendations put forth by Delft Hydraulics in 1967 remain instrumental in the way our beaches are currently managed; our changing climate experienced through increasing storm severity and sea level rise are fundamental factors in determining the direction and execution of a strategic structure of capital works and management activities for the next 15 years. Through GCCC s Our Shore Future engagement program, it is hoped community wide acceptance for the recommendations of the GCSMP will ensue. TAKE HOME MESSAGES - Proactive strategic planning by the Gold Coast City Council will ensure its coastal lifestyle and economic viability as a tourist hub remain sustainable for the long term. - It is only through effective education and communication with the community that the true state of our beaches can be realised and thus acceptance and support can be achieved, and more importantly, maintained. REFERENCES Allen, M., and Callaghan, J. (1999). Extreme wave conditions for the South Queensland coastal region. EPA Queensland Rep. Boak, L., Jackson, L.A., McGrath, J., Brosnan, M. (2001) An Overview of Gold Coast Coastal Management 1960-2001. Proc. Coasts and Ports 2001, 15th Australasian Coastal and Ocean Engineering Conf. (Gold Coast, Australia), September 25-28, 2001. Castelle, B., Le Corre, Y., and Tomlinson, T. (2007). Can the Gold Coast Beaches Withstand Extreme Events?, Geo-Marine Letters 10.1007/s00367-007-0086-y. DHL (1970). Gold Coast, Queensland, Australia Coastal Erosion and Related Problems. Delft Hydraulics Laboratory, The Netherlands, Rep R257. Gold Coast City Council (2007). Gold Coast Planning Scheme Our Living City v1.1. GCCM (2007). Gold Coast Shoreline Management Plan - Update on recommendations for Palm Beach Protection strategy. Griffith Centre for Coastal Management Report No. 69. Hunt, S., Stuart, G., McGrath, J. and Hossain, S., (2007). Improvements to Integrated Coastal Zone Management on Australia s Gold Coast. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), pg.25-28. Gold Coast, Australia, ISBN Maitra, A. K., and Walker, K. E. (1972). An Economic Appraisal of the Restoration of Gold Coast Beaches, prepared by Sharp and Shrapnel, report to Gold Coast City Council and Queensland State Government. Mirfenderesk, H. (2007). Strategic Plan, Development of Decision Support System for Flood Emergency Management on the Gold Coast. Gold Coast City Council. Report No. FS 757. Stuart, G. and Tomlinson, R., (2004). A way forward in managing the Gold Coast littoral environment. Griffith Centre for Coastal Management Research Report No. 39, 198p.
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