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2014 | Book

Estuaries of Australia in 2050 and beyond

Editor: Eric Wolanski

Publisher: Springer Netherlands

Book Series : Estuaries of the World

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About this book

The book addresses the questions: Is Australia’s rapidly growing human population and economy environmentally sustainable for its estuaries and coasts? What is needed to enable sustainable development?

To answer these questions, this book reports detailed studies of 20 iconic Australian estuaries and bays by leading Australian estuarine scientists.

That knowledge is synthesised in time and space across Australia to suggest what Australian estuaries will look like in 2050 and beyond based on socio-economic decisions that are made now, and changes that are needed to ensure sustainability.

The book also has a Prologue by Mr Malcolm Fraser, former Prime Minister of Australia, which bridges environmental science, population policy and sustainability.

Table of Contents

Frontmatter
Estuaries of Australia in 2050 and Beyond – A Synthesis
Abstract
This book “Estuaries of Australia in 2050 and Beyond” in the series “Estuaries of the World” addresses the question: Is Australia’s growing human population and economy environmentally sustainable for its estuaries and coasts by 2050? To answer this question, this chapter summarises detailed studies of a number of iconic Australian estuaries and bays. They can be divided in three types based on the human impact, namely (1) estuaries that bore the full pressure of the historical developments, (2) estuaries being degraded, and (3) estuaries that are still relatively pristine. For type (1) the case studies focus on Sydney Estuary, the Coorong/Murray-Darling Estuary, Port Philip Bay, and the Tamar Estuary. For type (2) the case studies focus on the Gold Coast Broadwater, the Hawkesbury Estuary, the Burdekin flood plains, Moreton Bay, the Ord River estuary, Brisbane peri-urban estuaries, South Australia gulfs, Hervey Bay, and Darwin Harbour. For type (3) the case studies focus on the Mary River estuary and floodplains in the Northern Territory and Deluge Inlet in Queensland. In addition, summaries are also provided of the state of the environment and the management strategy for a number of other estuaries and coastal waters. Overall, this chapter synthesises multidisciplinary scientific knowledge in time and space across Australia to suggest what Australian estuaries may look like in 2050 based on socio-economic decisions that are made now, and the changes that are needed to ensure sustainability.
Eric Wolanski, Jean-Paul Ducrotoy

Estuaries that Bore the Full Pressure of the Historical Developments

Frontmatter
Sydney Estuary, Australia: Geology, Anthropogenic Development and Hydrodynamic Processes/Attributes
Abstract
The Sydney Estuary is the focal point of the intensely developed city of Sydney. Since European settlement in 1788 the waterway has undergone many changes, including reclamation, contamination, modified fresh-water flow regimes and altered rates of sedimentation. The various alterations and their impact on the system is the focus of this chapter. Research undertaken over the past thirty years identified the threat of contamination on estuary health. This issue came to a head in 2006 with the closure of the Sydney commercial fin fish and prawn industries due to high concentrations of dioxins detected in fish and prawn tissue. Improved understanding of the impact of different chemicals on estuarine species has led to changes in policy and practices within the waterway and adjacent catchment. Despite better practices contaminants continue to be supplied to the estuary via the complex stormwater network draining the surrounding highly urbanised catchment. Stormwater runoff represents the major contemporary source of estuary contamination. Recent field and numerical investigations show that in order to reduce contaminant concentrations stormwater runoff must treated before being discharged into the waterway. Due to the hydrodynamic behaviour of this geometrically complex waterway rather than rapidly flushing out of the estuary to the open ocean contaminants supplied via stormwater runoff become entrained down the water column and settle on the estuary bed. Whilst many improvements have been made to address processes affecting estuary health, continued monitoring of contaminant concentrations within estuary waters, bed sediments and species are required to determine the success of past management strategies and to better inform decisions about the future management of this highly prized waterway.
Serena B. Lee, Gavin F. Birch
The Murray/Coorong Estuary: Meeting of the Waters?
Abstract
This chapter gives an overview of natural and anthropogenic factors that have shaped the lower reaches of the River Murray – the Murray Estuary (nowadays called the Coorong Estuary) including the Lower LakesLake Alexandrina and Lake Albert. The reader will learn of the traditional owners, the Ngarrindjeri peoples, whose enduring stories recall the transformation of the landscape by their pioneering culture heroes whose deeds widened the River Murray and created the distinctive ecology of the Lower Lakes and the Coorong some 10–12,000years ago. The reader will also learn that the natural environment of the river has been severely degraded over the last 150years through extensive water extraction used for irrigation and the construction of barrages. It becomes obvious that modifications to the system have been so detrimental and far reaching that a return to natural conditions is an almost impossible task. It is uncertain whether current water management plans will prevent an irreversible collapse of the system. This chapter celebrates the ecological richness of the watershed that the Murray once was and pays respect to the wise stewardship of its traditional owners.
Jochen Kämpf, Diane Bell
Port Phillip Bay
Abstract
Port Phillip Bay (also commonly referred to as Port Phillip) is a large bay in Victoria, Australia. It is an urban waterway as it drains Melbourne. The bay has a narrow entrance, where tidal velocities are high. Port Phillip was formed about 6,000years ago. Aborigines had lived in the area for tens of thousands of years. Europeans first arrived in the area in 1802. The bay has a temperate climate.
The tides, due to the Moon and Sun, fluctuate vertically by about 2m at the entrance and less than 1m for the rest of the bay. Waves in the bay are mainly generated by the wind. The bay has 132 beaches, which are quite popular for swimming. The bay and its environs are home to a variety of flora and fauna. A substantial amount of shipping comes from and goes to the Port of Melbourne. Over four million people live around the bay. The population quite possibly could double in the next 40years, putting pressures on the environment. The Federal, State and Local governments involved with the bay will have to cope with the effects of global warming, which will likely intensify with time. It could cause flooding of bayside areas regularly. Substantial population growth in the future could cause pollution and put increased demands on the water supply to Melbourne. The Victorian Government has plans to deal with these matters.
Joe Sampson, Alan Easton, Manmohan Singh
Past, Present and Futures of the Tamar Estuary, Tasmania
Abstract
The Tamar Estuary is located on the Bass Strait coast of North Tasmania, a drowned river valley of some 71km in length. The vast majority of fluvial flow enters through two rivers that meet at the estuary head, the South and North Esk Rivers with a catchment area comprising over 20% of Tasmania (about 11,000km2). The Tamar valley is a down-faulted graben structure, giving a bedrock-confined long and narrow shape to the majority of the estuary, causing tidal amplification to give the head of the estuary the largest tidal range in Tasmania. At the time of first European discovery in the early 1800s the upper Tamar Estuary was found to feature extensive mud banks, with a channel that was difficult to navigate in the 1.7m draft Lady Nelson. With establishment of the city of Launceston, the channel was dredged starting in the late 1870s until the 1960s allowing ship passage, until the major port was moved to the lower estuary. During this period contamination of the upper estuary increased, from organic and inorganic wastes from industrial, mining and domestic sources, as well as heavy metals from mining industries in the catchments, combined with high sediment yield. The Tamar has a high conservation significance being the only mesotidal drowned river valley in Tasmania, along with recording a large number of species not found elsewhere. There are significant threats to native species habitats from introduced species in the estuary, including Australia’s largest area of introduced Rice grass. This has caused a dramatic change to the physiography of the intertidal zone, with previous beaches or rock shorelines converted to accreting mud banks under Spartina. Sedimentation and water quality issues have long been a concern to the community, and over the last 15 years Natural Resource Management of the estuary and its catchments has greatly improved, including introduction of systematic monitoring. Aspirations for the estuary’s future are based on community consensus to maintain and improve biophysical values of the estuary, although preference remains for an upper estuary that resembles its early twentieth century dredged state rather than how it was first described 200 years ago.
Joanna C. Ellison, Matthew R. Sheehan

Estuaries Being Degraded

Frontmatter
Gold Coast Broadwater: Southern Moreton Bay, Southeast Queensland (Australia)
Abstract
The Gold Coast Broadwater, a large shallow estuarine water body, is a central feature of the Gold Coast City in Southeast Queensland (Australia) and forms the southern part of Moreton Bay. The Broadwater has undergone dramatic changes over the past few decades, including the construction of an extensive number and network of artificial waterways that account for up to 90 % of Australia’s canal estates. Positioned in one of the fastest growing regions in the developed world, urbanisation surrounding the Broadwater will continue. The region has important biodiversity values that have led to areas of the Broadwater being listed as an international Ramsar site and inclusion to international migratory bird agreements. The Broadwater provides a vital function in the provision of feeding, spawning and nursery sites for recreationally and commercially important finfish species. Key to the protection of the Broadwater is a reduction of pollutant loads from urban and agricultural stormwater run-off, golf courses and industrial infrastructure/areas and replacement of natural habitats with urban development. Collectively, initiatives undertaken by regulatory authorities have been successful to date and demonstrate that future conservation requires the integration of multidisciplinary science and proactive management driven by the high ecological, economical and community values placed on the Broadwater and adjoining waterways.
Ryan J. K. Dunn, Nathan J. Waltham, Nathan P. Benfer, Brian A. King, Charles J. Lemckert, Sasha Zigic
Hydrodynamics and Sediment Transport in a Macro-tidal Estuary: Darwin Harbour, Australia
Abstract
Sediment dynamics studies were undertaken for Darwin Harbour (DH), which is a tidal dominated mangrove system in the Northern Territory of Australia. DH is located in a region with extensive mangrove and tidal flat areas, which function as trapping zones of fine cohesive sediment. Transport of sediment was estimated for the dry season, and thus river discharge was negligible. Numerical simulations were also made with two scenarios: (S1) where the numerical mesh included mangrove and tidal flats, and (S2) in which the mesh neglected these areas. For the first scenario, the formation of two Estuarine Turbidity Maxima zones (ETM) were verified, and located at the inner and outer harbour. In addition to the formation of ETM zones, for the second scenario increased tidal asymmetry was predicted, which resulted in landward sediment transport. The suspended sediment concentration within these ETM zones was modulated by spring and neap tidal conditions. From our simulations we demonstrated that the sediment transport of small particles, e.g. 2 μm particle size, in DH is driven by flood dominance, which is affected by wet/dry areas such as mangroves and tidal flats. Therefore, mangrove areas of DH may trap fine sediment for long periods, and if the trapped sediment carries pollutants one would expect conditions similar to many European estuaries, where pollutant sediment has been found to be buried for over tens to hundreds of years.
F. P. Andutta, X. H. Wang, Li Li, David Williams
The Ord River Estuary: A Regulated Wet-Dry Tropical River System
Abstract
The lower Ord River is a wet-dry tropical river functioning as a perennial dry tropical river as a result of regulation. It is currently one of the few heavily regulated rivers in Australia’s tropical north, providing water for hydroelectrical production and irrigation. Current plans call for an increase in the area of irrigated land surrounding the lower Ord River and its estuary. The estuary is highly turbid and subject to very strong tides. It can be conceptualised as five connected physical zones – the Riverine Zone, the Tidal Freshwater Zone, the Transitional (Maximum Turbidity) Zone, the Estuary Mouth, and the Tidal Creeks and Flats Zone – distinguished by geomorphology, flow and tidal influence. Each of these physical zones functions as a distinct biogeochemical and ecological functional zone. Here, we describe how these zones function, how they interact, and how the estuary as a whole may respond to the changes expected in the mid-term future.
Barbara J. Robson, Peter C. Gehrke, Michele A. Burford, Ian T. Webster, Andy T. Revill, Duncan W. Palmer
South Australia’s Large Inverse Estuaries: On the Road to Ruin
Abstract
This chapter provides an overview of the past, present and likely future of South Australian gulfs – Spencer Gulf and Gulf St. Vincent. It describes the distinct physical factors shaping these inverse estuaries, their unique ecology, past environmental degradation and future threats. Rather than direct climate-change impacts, the reader will learn that traditional industrialization poses the biggest threat to the gulfs’ ecosystem health, despite recent enhanced efforts of protection and conservation of natural habitat.
Jochen Kämpf
Turbulent Mixing and Sediment Processes in Peri-Urban Estuaries in South-East Queensland (Australia)
Abstract
An estuary is formed at the mouth of a river where the tides meet a freshwater flow and it may be classified as a function of the salinity distribution and density stratification. An overview of the broad characteristics of the estuaries of South-East Queensland (Australia) is presented herein, where the small peri-urban estuaries may provide an useful indicator of potential changes which might occur in larger systems with growing urbanisation. Small peri-urban estuaries exhibit many key hydrological features and associated ecosystem types of larger estuaries, albeit at smaller scales, often with a greater extent of urban development as a proportion of catchment area. We explore the potential for some smaller peri-urban estuaries to be used as ‘natural laboratories’ to gain some much needed information on the estuarine processes, although any dynamic similarity is presently limited by a critical absence of in-depth physical investigations in larger estuarine systems. The absence of detailed turbulence and sedimentary data hampers the understanding and modelling of the estuarine zones. The interactions between the various stakeholders are likely to define the vision for the future of South-East Queensland’s peri-urban estuaries. This will require a solid understanding of the bio-physical function and capacity of the peri-urban estuaries. Based upon the current knowledge gap, it is recommended that an adaptive trial and error approach be adopted for their future investigation and management strategies.
Hubert Chanson, Badin Gibbes, Richard J. Brown
Hervey Bay and Its Estuaries
Abstract
Hervey Bay and its estuaries are located along the east coast of Australia just to the south of the Great Barrier Reef Marine Park. The region has long been recognised as one of Australia’s most biodiverse marine environments and including the Great Sandy Strait in the south of the Bay, it is referred to as the Great Sandy Biosphere. The United Nations Educational, Scientific and Cultural Organisation (UNESCO) included the area in its list of 580 designated biospheres located in 114 countries.
Although widely recognised for its exceptional biodiversity, little is known about the physical processes and climate characteristics that shape its natural marine environment. Only recently, the Bay has been classified as a large low inflow and predominantly hypersaline system. River runoff and discharge from its many estuaries is very small. It has almost been absent during the Australian Millennium Drought lasting the first decade of the twenty-first century. During other times, freshwater inflow is only significant following flooding as a result of tropical/subtropical depressions, which often is amplified during La Nina events. A positive freshwater balance leads to a net loss of water establishing hypersaline conditions. This appears to prevail throughout the year and is re-established shortly after storm events. Hydrodynamic modelling suggests that predominant southeasterly to easterly trade winds establish a cyclonic water renewal pathway, with Hervey Bay water exiting along the western shoreline. Hypersalinity and the characteristics of an inverse estuarine circulation are evident from observations and modelling.
This chapter reviews our understanding of the environmental processes that shape Hervey Bay and its estuaries in the context of its climate. Future changes in the regional freshwater balance indicate a continued trend toward drier and warmer conditions. It leads to an intensification of hypersaline and possible inverse circulation states of the Bay. Insight into the environmental forces shaping Hervey Bay, its estuaries, and a unique and biodiverse environment, informs continued sustainable natural resource management and policy development. It is anticipated that over the next few decades physical processes associated with climatic trends and variability are likely to impact more dramatically upon the natural environment of the region than direct human activities such as fishing, aquaculture, tourism and continued local population and urbanisation trends.
Joachim Ribbe
Moreton Bay and Its Estuaries: A Sub-tropical System Under Pressure from Rapid Population Growth
Abstract
Moreton Bay and its associated estuaries are an example of a complex aquatic system that is under increasing pressure from rapid population growth and urbanisation. Although the extent of decline in ecosystem health within Moreton Bay and its associated estuaries is significant and well documented, a range of innovative management responses have been implemented to reverse current declines. An overview of the development of Moreton Bay is provided, highlighting the dynamic and resilient nature of the system over geological time. The ecological responses that occur at decadal timeframes are presented along with a summary of the current state of the Bay’s ecology. The future challenges that are posed by predicted population increases, urbanisation and changes to the region’s climate are also discussed. The highly variable nature of the system over relatively short timeframes (i.e. flood vs non-flood conditions) as well as the ability of the system to adapt to long term changes (i.e. past morphological and ecosystem shifts) suggests that Moreton Bay and its associated estuaries have significant capacity to adapt to change. Whether the current rate of anthropogenically induced change is too rapid for the system to adapt, or whether such adaptions will be undesirable, is unable to be ascertained in any detail at this stage. Notwithstanding the above, the combination of a science-based management framework and the collaborative decision making processes that have been implemented to halt the decline of Moreton Bay have shown remarkable progress in a relatively short period of time.
Badin Gibbes, Alistair Grinham, David Neil, Andrew Olds, Paul Maxwell, Rod Connolly, Tony Weber, Nicola Udy, James Udy
Water Resource Development and High Value Coastal Wetlands on the Lower Burdekin Floodplain, Australia
Abstract
The lower Burdekin floodplain in north Queensland houses the combination of northern Australia’s largest and most intensively developed agricultural floodplain with one of the largest concentrations of high value freshwater, estuarine and marine wetlands in Australia. The area has a long history of supporting one of Australia’s most economically important sugarcane growing districts, most of which is located upstream of this complex of internationally and nationally significant wetland environments. A unique management feature of agriculture in the region is the total reliance on supplemental flood irrigation to meet crop water demands. Agricultural developments in the catchment area, particularly the establishment of water resource schemes to support this extensive irrigated agriculture, pose significant threats to the integrity of the downstream receiving wetlands. Cumulative (and ongoing) changes to water regimes and the chemistry of both surface and subsurface waters now pose major threats to both the long-term viability of wetlands and large sections of the sugar industry itself. Substantial shifts in societal perceptions and expectations regarding the value of wetlands and water resources at national and global levels are reflected in the lower Burdekin region. The legacy of earlier perceptions and associated policy decision-making are, however, going to provide some of the most enduring management challenges for lower Burdekin coastal wetlands, and ultimately the viability of irrigation areas themselves.
Aaron M. Davis, Stephen E. Lewis, Dominique S. O’Brien, Zoë T. Bainbridge, Christie Bentley, Jochen F. Mueller, Jon E. Brodie
The Hawkesbury Estuary from 1950 to 2050
Abstract
This chapter describes the eutrophication of the Hawkesbury-Nepean River estuary that drains Sydney western suburbs. The project started in the 1950s by spot measurements of nutrient concentration and in the 1970s with a hydrodynamic and water quality study of the estuary. This was to gauge the effect of sewage treatment plants already proposed in the 1970s to deal with the growth of Sydney and their projected effects on the flow, chemistry and biology of the system by the year 2000. The study, using a mathematical model of proposed effluents, predicted an increase of nitrogen and phosphorus nutrients that was large enough to significantly degrade the water quality of the estuary. In particular it predicted a large increase in plankton, mainly blue/green algae, if planners did not make careful decisions concerning land use, urbanization and catchment development. A recent detailed study of water quality by Sydney Water has shown that the river system has indeed been degraded with the occasional occurrence of outbreaks of floating flowering plants (macrophytes) in the upper Nepean and blue/green algae in the saline/freshwater interface and “red tides” of toxic diatoms near the mouth of the estuary. This is despite upgrading of sewage treatment plants. More upgrades are needed especially in the area of South Creek. The biggest problem to address is ongoing urbanization and the resulting wet-weather inflow of degraded stormwater, sediment, nutrients and many other contaminants that reach the estuary. A public information program should be started and wet weather runoff should be treated preferably at the source of the runoff, somewhat mimicking the planned new developments at the Gold Coast Broadwater. An estuary, once urbanized will always be degraded, the extent of which however can be managed.
Peter Collis

Estuaries that Are Still Relatively Pristine

Frontmatter
Deluge Inlet, a Pristine Small Tropical Estuary in North-Eastern Australia
Abstract
Deluge Inlet is a small, tide-dominated estuary on Australia’s north-east tropical coast, located in the central part of the Hinchinbrook Island National Park, Australia’s largest island National Park. It is situated in Australia’s humid tropical zone, and experiences an intense summer wet season and regular impacts of tropical cyclones. Protection by National Parks, World Heritage and Wild Rivers legislation means it remains in near pristine condition. Deluge Inlet sports substantial biodiversity in the form of extensive mangrove forests, seagrass beds, and complex marine mammal, reptile, fish and invertebrate assemblages, all supported by a mosaic of highly interconnected habitat types. The mix of habitats and rich biodiversity makes Deluge Inlet an important nursery for many species, and supports complex food webs. Current threats are from increasing fishing and boating pressure, and effective governance will be needed to ensure Deluge Inlet remains in near-pristine condition into the future.
Marcus Sheaves, Kátya G. Abrantes, Ross Johnston
Recent, Rapid Evolution of the Lower Mary River Estuary and Flood Plains
Abstract
The Lower Mary River is located 90 km to the east of Darwin, the capital city of the Northern Territory of Australia. The wetlands of the Lower Mary are a valuable ecological and economic resource supporting tourism and primary industry. The wetlands have had minimal disruption by human interaction and form a large component of the Northern Territory’s coastal wetland systems. The top end of the Northern Territory is in the wet-dry tropics where the annual rainfall of 1,700 mm falls mainly between December and April. The region also experiences regular cyclonic activity during these periods. The wetlands and floodplains formed up to 5,000–8,000 years ago when sea levels stabilised. The coastal plains prograded rapidly and extensive mangrove forests and freshwater habitats formed. It has been evident that during the last 50 years the coast has receded, the estuarine channels have expanded and become deeper and wider and tributary channels have grown across the flood plains invading previous freshwater environments. The cut and no recover model of coastal retreat is proposed as the dominant process of coastal erosion allowing the tidal creeks to expand onto the floodplains and change the environment from dominantly freshwater to saltwater. It is forecast that over the next 40 years the Lower Mary River estuary may continue to grow and become similar to neighbouring estuaries and those of the north-facing coast of the Northern Territory.
David Williams
Backmatter
Metadata
Title
Estuaries of Australia in 2050 and beyond
Editor
Eric Wolanski
Copyright Year
2014
Publisher
Springer Netherlands
Electronic ISBN
978-94-007-7019-5
Print ISBN
978-94-007-7018-8
DOI
https://doi.org/10.1007/978-94-007-7019-5