• Skip to main content
  • Skip to site footer
img MENU MEMBERSHIP img
  • Home
  • Donate
  • Join
  • Login
img
  • About Us
    • Mission
    • History
    • Values
    • Advocacy
    • Partners
    • People
  • Get Involved
    • What You Can Do
    • State Chapters
    • Become a Member
    • Donate
  • Resources
    • Photo Gallery
    • Conferences
    • Courses
  • Latest News
    • 2023
    • 2022
    • 2021
    • 2020
    • 2019
    • 2018
  • Blog
    • 2023
    • 2022
    • 2021
    • 2020
    • 2019
    • 2018
  • Podcast
  • Contact Us
Australian Coastal Society

Australian Coastal Society

We are the voice of the Australian coast

MOUTH OF THE RIVER MURRAY

October 3, 2015
Main Image

MOUTH OF THE RIVER MURRAY

Main Image

Our esteemed Vice-President of ACS, Emeritus Professor Nick Harvey, has recently co-authored a paper with Kristine James and Bob Bourman on the flood-tidal delta in the River Murray estuary (Journal of Coastal Research, 2015, 31, 1103-1119). This paper refers to a range of work by these three writers going back to the late 70s on the changes that have occurred at the mouth of our greatest river. Observations of sediment accumulation over many decades are used to tell a very powerful story which they quite significantly refer to in the title of this latest paper as “A Canary in the Cage of River Management”.

Flood tidal sediments are formed by wave/tide deposition inside the mouths of estuaries. They show that such sandy sediments existed in the vicinity of the Murray Mouth prior to the installation of the barrage system in the late 1930s. The mouth is a dynamic coastal inlet involving forces of river flow, micro-tidal exchange, and wave processes moving sand along the barriers that block the majestic Coorong Lagoon. The barrages reduced the tidal prism by 90%. Their study showed that over the 100 year period 1839 to 1938 even with low river flows, the ebb tidal current assisted in maintaining an open river mouth. The flood tidal flats were not vegetated during this time. However, since the barrages have been built the former tidal delta has become a stabilised island, Bird Island, colonised by more than 80 plant species. It took only 5 years for vegetation colonisation to commence indicating permanent alteration to the inlet/river mouth biophysical system. With decline in river flows as well as tidal exchange, longshore sand transport tends to choke the mouth. This leads to periods of mouth closure and the necessity of government intervention to dredge the entrance to  ensure as far as possible that Coorong’s water quality is maintained by tidal exchange to a level that according to the Murray Darling Basin Plan (MDBP) 2012 ‘’does not compromise the ecosystem”. At the moment a new dredging program is underway following a recent decline in river flows.

>

It is important to reflect on the initiative of federal and state governments in the development of the MDBP in 2012. The plan was finally accepted after much debate. One section (8, c to e) specifically relates to the environmental objectives of the Lower Lakes and the Coorong. Here the Plan refers to the mouth remaining open at frequencies, for durations and with passing flows, sufficient to enable the conveyance of salt, nutrients and sediment from the MDB to the ocean. In clause 8 (e) reference is made to maintaining levels in the Lower Lakes above 0.4m AHD for 95% of time and 0.0m AHD all of the time. This is said to avoid acidification and allow connection between Lakes Alexandrina and Albert. The Plan thus requires sufficient environmental flow into Lake Alexandrina to meet these targets despite variation in runoff within the catchments of the MDB and extraction for agricultural and urban uses.

In 2008, the Wentworth Group of Concerned Scientists prepared a submission to a Senate Inquiry into provision of water to the Coorong and Lower Lakes (copy available online at Wentworthgroup.org). We had been alerted by David Paton and others to the parlous state of the lakes and Coorong during the drought period then in full swing. During this period lake levels had dropped below 0.0m AHD exposing sand and mud flats. We were aware of changes in the chemistry of lake waters with some parts very alkaline but others reflecting local inputs of acid waters; it seemed that a toxic mess was emerging. We visited Goolwa in February, 2009, to see for ourselves how far the water had receded from the lake shore leaving piers high and dry. I was fascinated by the calcareous mounds of worm casts on the exposed floor reflecting high alkalinity. This state of affairs attracted considerable adverse publicity and community concern. The South Australian Government was spending millions dredging but with no flow from the river and lake level below mean sea level little could be done until a flood came; and it did in 2011 so that the salts, acids and nutrients could be flushed out to sea through an open mouth.

The Wentworth Group and others remain concerned that the MDBP does not adequately address the environmental needs of the Lower Lakes and Coorong. Like most coast and estuary areas impacted adversely by human demands, solutions are not easy to come by. Minster Burke indicated at the time of the release of the MDBP that the mouth would stay open 90% of the time. We argued that this underestimated the power of the sea to bring sand to the entrance and block the inlet as described by James, Bourman and Harvey. It did not take long to close! Extraction of water in the basin for agriculture may continue to get preference over a healthy estuary. The barrages will remain a problem as they age and encounter rising sea levels. Then there is the question of the impact of water availability in the southern half of the Basin under a warmer and drier climate as noted in Schedule 1 of the MDBP. We see in the paper by James, Bourman and Harvey some clear indications of just what has occurred in the past leaving a legacy of difficult issues that must be addressed in the broader context of managing environmental assets in the basin all the way to the mouth; the Lower lakes, the Coorong and the Murray Mouth are clearly canaries in a Basin cage that may suffer more in the future.

– words by Prof Bruce Thom

By

ACS Communications Officer |

Saturday, October 3, 2015 |

  • Uncategorised
Category: Blog
Previous Post:Main ImageTrip to the Southwest Coast of WA
Next Post:Caring for our coasts?Main Image

Sidebar

2022 (24)
  • Thursday, December 22 Protecting Nature: Art of the Impossible?
  • Tuesday, December 13 Drainage Window Concept
  • Thursday, November 24 Cootamundra Shoals Survey 1982
  • Thursday, November 10 US Coastal Zone Management Act 1972: A Model for Australia?
  • Wednesday, October 26 Great Barrier Reef—More or Less Gloom
  • Wednesday, October 12 Bondi Pavilion Reopened and Rejuvenated
  • Wednesday, September 28 Coastal Journey Begins: September 1962
  • Monday, September 12 Protection For Sydney Harbour: Berrys Bay Case
  • Thursday, August 25 Coastal Inundation: A Hazard Not to be Underestimated
  • Tuesday, August 9 Beach Access – An International Perspective
  • Wednesday, July 27 SoE 2021 and Coasts
  • Tuesday, July 19 Human Rights and Beaches
  • Wednesday, July 6 Coastal Walks and Local Councils
  • Thursday, June 23 EPBC Act and Regional Landscape and Resilience Plans
  • Wednesday, June 15 29th NSW Coastal Conference
  • Thursday, May 19 Lament for Estuaries? (0)
  • Wednesday, April 27 East Coast Floods 2022 (0)
  • Monday, April 11 East Coast Weather ‘Traffic Jam’ (0)
  • Tuesday, March 29 VALE: PAUL BISHOP (0)
  • Thursday, March 24 IPCC Throws Down the Gauntlet on Australian Institutional Deficiencies
  • Friday, February 25 Recent federal coastal initiatives – February 2022
  • Tuesday, February 8 Resourceful ‘lucky’ country
  • Friday, January 28 FUTURE EARTH AUSTRALIA: SUSTAINABLE OCEANS AND COASTS NATIONAL STRATEGY 2021-2030
  • Monday, January 10 Sunflowers and hope
2021 (27)
  • Wednesday, December 22 DISCOVERING MORUYA 1971-2021
  • Sunday, December 12 PROTECTING A BIG CITY: NEW YORK DECISION MAKING
  • Wednesday, December 1 ICA REPORT: CLIMATE CHANGE IMPACT “ACTIONS OF THE SEA” AND FUTURE RISKS
  • Friday, November 12 NATIONAL CLIMATE RESILIENCE AND ADAPTATION STRATEGY (NCRAS)
  • Thursday, October 28 COASTAL FAMILY—THE ELIOTS
  • Sunday, October 10 COASTAL CLIMATE CHANGE ADAPTATION: ROLES FOR THE AUSTRALIAN GOVERNMENT
  • Monday, September 27 Sydney Harbour: Impact of contamination studies
  • Friday, September 17 Geological indicators of seabed mobility – Narrabeen Beach (Sydney, Australia)
  • Monday, August 30 LAST INTERGLACIAL SEA LEVELS: RECENT RESEARCH AND MEET “STROMBUS BUBONIUS”
  • Wednesday, August 18   COASTAL NEWS – AUGUST 2021
  • Monday, July 19 Reflections on past coastal recommendations by the Australian Government
  • Monday, July 5 LARGS: A GEOHERITAGE SITE?
  • Thursday, June 24 PROPERTY RIGHTS: WHAT CONDITIONS PREVAIL IN A CIVIL SOCIETY?
  • Monday, June 14 UNIVERSITY RESEARCH—PERSONAL SADNESS
  • Saturday, May 29 SEAHORSE MONITORING BY WOOLLAHRA COUNCIL, NSW
  • Tuesday, May 18 US Climate Indicators
  • Saturday, May 8 AUSTRALIAN GOVERNMENT MARINE AND COAST INITIATIVES 2021
  • Sunday, April 25 Travelling west of the sandstone curtain – to Orange (NSW) and back
  • Tuesday, April 20 Big surf at Port Fairy (Victoria) – April 2021
  • Thursday, April 8 LAND: OWNERSHIP AND RIGHTS
  • Sunday, March 14 ESTUARY WETLANDS AND SEA-LEVEL RISE
  • Saturday, February 20 COASTAL ZONE AND CATCHMENT BOUNDARIES
  • Sunday, February 14 Coastal Archaeology Revisited
  • Saturday, January 30 JUDITH WRIGHT – POET, COASTAL CONSERVATIONIST AND MUCH MORE
  • Monday, January 18 COASTAL STORIES FROM THE FIELD,1970-2020
  • Monday, January 11 US COASTAL MANAGEMENT UNDER TRUMP
  • Monday, January 4 2020: A COASTAL PERSPECTIVE
2020 (26)
  • Wednesday, December 23 EPBC ACT CHANGES –WILL THEY BE WORTH THE EFFORT?
  • Monday, December 14 TWO JIMS—BOWLER AND COLEMAN
  • Thursday, November 26 AUSTRALIA UNDER THREAT—WHAT TO DO NEXT?
  • Saturday, November 7 SHORELINE RESPONSES TO SEA-LEVEL RISE
  • Sunday, October 25 Port Stephens-Myall Lakes 1960 – Research Opportunities
  • Wednesday, October 14 Port Stephens – Myall Lakes 1960 – the journey.
  • Monday, September 28 LEGACY ISSUES AND COASTAL MANAGEMENT
  • Friday, September 11 TYPHOONS AND HAINAN ISLAND, CHINA
  • Tuesday, September 1 Impact of sea-level rise on coastal natural values in Tasmania
  • Saturday, August 29 ENVIRONMENTAL VALUES REMAIN THREATENED
  • Thursday, August 6 HAMELIN POOL (Shark Bay, Western Australia) —AN ESTUARY?
  • Thursday, July 16 Estuary Health
  • Friday, July 3 UNIVERSITY RESEARCH AND TEACHING—THE NEXUS IS IT BROKEN?
  • Sunday, June 21 Sandy beach morphodynamics – a new book
  • Sunday, June 7 Cliffs in the Narrabeen Group, Sydney
  • Thursday, May 21 PROGNOSIS FOR A CHOKING MOUTH: THE RIVER MURRAY
  • Wednesday, May 6 Geomorphologic Mapping
  • Wednesday, April 22 DOVER HEIGHTS CLIFFS, SYDNEY
  • Sunday, April 12 Recent Coastal Legal Cases
  • Tuesday, March 24 CHALLENGE AND RESPONSE—THE CURRENT CRISIS
  • Wednesday, March 18 Recent papers in the journal Nature
  • Thursday, February 27 HOLOCENE SEA LEVELS AND COASTAL EVOLUTION
  • Monday, February 17 Brian Caton ‘a coastal legend’- RIP 9 February 2020
  • Tuesday, February 4 NATIONAL COASTAL ADAPTATION AGENDA 2010: A RETROSPECTIVE
  • Wednesday, January 22 TIME FOR ADAPTATION ACTION
  • Friday, January 10 EAST COAST FLOODS 2022 (0)
2019 (29)
  • Monday, December 30 Parsley Bay in the Summer
  • Monday, November 25 Australian Coastal Systems: A New Book from Andy Short
  • Tuesday, November 19 South Australian 2019 Coastal Conference and the ACS AGM
  • Wednesday, November 6 28th Annual NSW Coastal Conference – Terrigal, 2019
  • Sunday, October 27 Coastal Incidents
  • Tuesday, October 8 Coastal morphostratigraphy: two papers from Denmark
  • Friday, September 27 Climate Change Attribution
  • Tuesday, September 10 Vale Jack Davies at age 97 – leader, teacher and mentor
  • Wednesday, September 4 Coastal erosion and accretion beyond the historical timescale in NSW
  • Monday, August 19 Rethinking Landscape in Aotearoa
  • Friday, August 2 Collaborative Science and Coastal Adaptation
  • Saturday, July 20 CLIMATE CHANGE AND RELATIVITY – SOME PARALLELS
  • Sunday, July 14 DOUGLAS W. JOHNSON 1919 AND BEYOND
  • Tuesday, July 2 The Sandiford Line
  • Saturday, June 22 A Curiosity of Cusps
  • Monday, June 3 Federal Election 2019 and Coasts
  • Monday, May 13 Mangrove Generations
  • Sunday, May 5 John Sinclair of K’Gari (Fraser Island) 1939 – 2019
  • Monday, April 22 The Mighty Ord
  • Thursday, March 28 Climate change adaptation: perspectives from Canada and England
  • Monday, March 18 Foreshore land grants in eastern Sydney
  • Friday, March 15 The right to bath on the beach
  • Wednesday, March 6 Victorian Coastal Monitoring Program
  • Thursday, February 21 Future national need for a healthy environment
  • Wednesday, February 13 ANZGG CONFERENCE AT INVERLOCH, VICTORIA
  • Wednesday, February 6 Coastal science and the Murray River mouth
  • Saturday, February 2 INDIA COASTAL MANAGEMENT
  • Tuesday, January 15 Sydney Harbour Sea Fog – Summer of 2018/2019
  • Saturday, January 5 COASTAL RESILIENCE AND ADAPTATION
2018 (31)
  • Monday, December 17 CLIFF-TOP DUNES
  • Saturday, December 15 The whereabouts of climate change adaptation
  • Sunday, December 2 Observations from a long time marine debris collector.
  • Sunday, December 2 Backbarrier flats – a relic coastal landform
  • Monday, November 19 King Tides in Venice
  • Wednesday, November 14 27TH NSW COASTAL CONFERENCE 2018
  • Monday, November 12 Is the coast losing out with NRM? Proposed changes for South Australia
  • Saturday, November 3 Slicks (Part 2)
  • Tuesday, October 16 Twofold Bay – A Great Coastal Laboratory
  • Sunday, October 7 VALE: Professor John Chappell FAA (1940-2018)
  • Thursday, September 27 Coasts and Legal Systems
  • Sunday, September 16 Moods of Sydney Harbour
  • Sunday, August 26 Community Consultation
  • Saturday, August 18 Managing water quality through regenerative agriculture
  • Friday, August 3 Tomorrow’s Coasts – Complex and Impermanent
  • Thursday, July 12 Murray-Darling Basin Royal Commission
  • Monday, July 2 New South Wales Coastal Reforms – NSW Coastal Council’s first meeting
  • Tuesday, June 26 Victoria’s Coastal Reforms – ‘fit for purpose’ or an opportunity lost?
  • Wednesday, June 20 New SA Government promises improved coastal management
  • Thursday, June 14 OCCUPATION OF THE AUSTRALIAN CONTINENTAL SHELF
  • Wednesday, May 30 National Budgets – Some Thoughts
  • Wednesday, May 16 Guiding Principles for Marine and Coastal Management
  • Friday, May 4 Last Interglacial Marine Deposits at Mary Ann Bay, Tasmania
  • Sunday, April 29 Coast to Coast Hobart 2018
  • Thursday, April 5 Coastal Reforms in New South Wales – The Next Stage
  • Monday, March 26 Coastal Archaeology
  • Monday, March 12 Barrier Islands – An American Obsession?
  • Monday, February 26 Climate Change Adaptation in Australia – A Loss of Momentum
  • Thursday, February 15 Bruce Thom Blog – SUMMERAMA
  • Wednesday, January 31 King tides and extreme events
  • Sunday, January 14 Coastal Geomorphology 101
2017 (39)
  • Friday, December 29 Bruce Thom Blog – Speaking Truth to Power
  • Wednesday, December 20 National Surfing Reserves
  • Thursday, December 14 Beachrock
  • Saturday, December 9 Higher Tides
  • Monday, December 4 Keeping the Murray Mouth open
  • Monday, November 27 Victorian Coastal Management in 2017
  • Thursday, November 16 26th NSW Coastal Conference at Port Stephens
  • Thursday, October 26 Ancestral rivers and terraces
  • Monday, October 16 Murray Valley: a recent visit
  • Wednesday, October 11 The National Construction Code and coastal planning
  • Tuesday, September 19 Geomorphic evolution of Coorong, Lower Lakes and Murray Mouth
  • Wednesday, September 13 Queensland Coastal Conference 2017 – Ten years in the making
  • Tuesday, September 5 Hurricane Harvey and its implications
  • Friday, September 1 Gippsland (Victoria) and relative sea level rise
  • Sunday, August 27 US Office of Naval Research and the Australian Coast
  • Monday, August 21 Managing the unique wetlands of Gippsland Lakes
  • Thursday, August 10 Lifecycle of coastal environmental law
  • Friday, July 28 Charlie Veron – A Life Underwater
  • Sunday, July 23 Coastal Sediment Management
  • Friday, July 7 Coastal walks -Malabar Headland National Park, Sydney
  • Friday, June 30 Honeycomb Weathering
  • Friday, June 23 Disaster preparedness
  • Wednesday, May 31 Sept-Iles: Managing a migrating foreland
  • Wednesday, May 24 Achievements of the National Climate Change Adaptation Research Facility
  • Saturday, May 13 Coastal Shacks
  • Wednesday, April 26 Empress Augusta Bay, Bougainville
  • Thursday, April 20 The Blue Mud Bay case – Aboriginal property rights in the Northern Territory
  • Tuesday, April 4 Botany Bay Sands
  • Saturday, March 25 Wave Energy Resource
  • Wednesday, March 15 Clustering of Storms
  • Wednesday, March 15 Cape to Cape: A voyage around Botany Bay
  • Tuesday, March 7 The “Venice Effect”
  • Monday, February 27 Port Stephens Bioherms
  • Thursday, February 9 Coast Ambassadors
  • Friday, February 3 Coastal Graphics
  • Tuesday, January 31 Irukandji on the move
  • Tuesday, January 24 Acceleration in mean sea level
  • Wednesday, January 11 Concerns of an American coastal scientist under a Trump presidency
  • Sunday, January 8 EXTREME STORM EVENTS IN THE USA, AUGUST-SEPTEMBER 2021
  • About us
  • Get involved
  • News and events
  • Resources
  • Blog
  • Contact us

Banner Photography by Pixabay

© 2023 Australian Coastal Society. All Rights Reserved.

  • Facebook
  • Twitter
  • Mail
  • LinkedIn