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Australian coastal observation network

Australia’s coastline is one of the country’s greatest natural, economic and cultural resources. The asset value of existing beach-front infrastructure is immeasurable. Climate change is driving sea level rise and changing regional wave climates, resulting in coastal erosion and increasing threats to coastal sustainability.

Big Swamp restoration project

A two year collaborative project has turned a large acidic landscape into a new tidal wetland. WRL, working with Greater Taree City Council and WetlandCare Australia, have undertaken a comprehensive scientific study to identify and remediate high priority acid farmlands on the Big Swamp floodplain, near Taree, NSW. For many years, the site has been listed as one of the three worst ASS hotspots in NSW.

Big Swamp is the local name for a series of drained agricultural floodplains located on the Manning River estuary on the mid-north coast of NSW. The Big Swamp floodplain was historically a large brackish backswamp known for its abundant bird populations. Over the past 110 years, the system has undergone major hydrologic modifications, due to the construction of an extensive floodplain drainage network system and floodgates.

Cars in floods: Vehicle stability testing for flood flows

The study noted that while flood fatality rates are generally falling per capita, the number of fatalities that occurred in vehicles, particularly four wheel drive (4WD) vehicles has increased in the last fifteen years.

The study noted that while flood fatality rates are generally falling per capita, the number of fatalities that occurred in vehicles, particularly four wheel drive (4WD) vehicles has increased in the last fifteen years.

It is clear from this brief overview that there is a need for an understanding of the mechanisms by which vehicles become unstable in floodwaters. In a world first, the flow vulnerability thresholds for two vehicles were tested at full scale in a specially configured tow tank at the UNSW Water Research Laboratory. We are pleased to make the results of this research available.

Caseys Beach seawall upgrade

Eurobodalla Shire Council��engaged WRL in partnership with��Aurecon��to prepare the design for the Caseys Beach seawall upgrade. Caseys Beach is located on the mid-south coast of NSW approximately 5 km south-east of the CBD of Batemans Bay. It is an 850 m long pocket beach situated between Observation Head (Corrigans Beach) in the north and Sunshine Bay in the south.

The beach faces east with a low gradient and is exposed to a low to medium wave climate which usually maintains a shallow continuous bar along the length of the beach. The beach is generally most narrow at its centre and widens to the north and south of this point. Reefs exist off the northern and southern ends of the beach providing some protection from wave attack.

Climate change in NSW estuaries

Assessing the impacts and effect of climate change in estuaries is complex. To��help estuarine managers and coastal communities navigate this complexity we have developed a multi-report guideline that details climate change, it’s role in estuaries, existing trends/pressures and the potential impacts. Titled “Climate change in estuaries: State of the science & guidelines for assessment” this report is freely available online.

Clybucca Wetlands management options study

The low-lying areas of Mayes Swamp and Doughboy Swamp on the Collombatti-Clybucca floodplain were historically natural backswamp wetlands. Significant drainage infrastructure constructed over the 20^th��century has promoted rapid drainage and lower surface and groundwater levels. This has resulted in exposure of acid sulfate soils that discharge acidic waters (pH ~ 3). Prolonged inundation after floods can also lead to ‘blackwater’ runoff which has very low dissolved oxygen. These processes degrade the wetland areas and impact downstream aquatic ecosystems in the wider Macleay River Estuary.

In recent years, the Department of Transport for NSW (previously NSW Roads and Maritime Services (RMS)) purchased a large area of low-lying land on the Collombatti-Clybucca floodplain for biodiversity offsets as part of the Pacific Highway upgrade project. This land includes the Mayes Swamp and Doughboy Swamp areas. These areas have been identified for rehabilitation to improve the wetland habitats of the floodplain and improve water quality.

Clybucca monitoring

The Water Research Laboratory has been commissioned by the NSW North Coast Local Lands Services for hydrological monitoring at Clybucca; where the 2,500 ha site has been effected by acid sulfate soils and is prone to generating low-oxygen blackwater. Monitoring at Clybucca is required to establish baseline pre-rehabilitation conditions, as well as measure changes to the site following on-ground rehabilitation works to guide adaptive management and to minimise impacts to private landowners.

The primary objectives of monitoring at Clybucca are to observe changes to the hydrology, water quality and ecology; to enable impacts (potential or actual) of rehabilitation works on the wider floodplain drainage to be assessed; and to provide ongoing data to inform adaptive management and optimise rehabilitation outcomes.

Coastal adaptation needs for extreme events and climate change, Avarua, Rarotonga, Cook Islands

Led by��Principal Coastal Engineer Matt Blacka, WRL undertook a project spanning 8 months in Avarua, the main town of Rarotonga, Cook Islands.��The project was undertaken for the Climate Change Cook Islands division within the Office of the Prime Minister, and was funded under the��Pacific Adaptation Strategy Assistance Program (PASAP)��by the Australian Government.

Avarua lies on the cyclone prone north coast of Rarotonga, and is the administrative, economic and tourism hub of the Cook Islands. Within the study area are most government offices, the international airport, the main fuel stores, and the Avatiu harbour which processes all incoming freight to Rarotonga and the other Cook Islands. Previous cyclones impacting the study area,��including the unprecedented five cyclones early in 2005, have caused significant damage to buildings and threatened infrastructure.

CoastSat

��is an open-source software toolkit that enables user to obtain time-series of shoreline position at any sandy coastline worldwide from ~38 years (and growing) of publicly available satellite imagery.����

Satellite remote sensing currently offers medium-resolution (10 to 15 m) images at high temporal frequency (~5 days between images) and can provide low-cost shoreline data to coastal engineers, managers and scientists. This is often the only source of information on past shoreline changes at locations where no field measurements are available.����

CoastSnap

��community beach monitoring��was created by WRL's����and Mike Kinsela from the��, originally partnering with����installing the first CoastSnap community beach monitoring stations around the Northern Beaches of Sydney in 2017.

The simple system provides a platform for community members to snap images of a beach from a fixed position using their smartphones and share the images via social media.

Cold water pollution: What is it, and how can we limit its environmental impacts?

Cold water pollution is a serious environmental issue that affects river systems downstream of large storage dams. Dams are often fitted with offtakes that withdraw water from the deeper parts of the reservoir. In summer, increased air temperatures warm the water in rivers and at the surface of dams; however, this warming does not extend down into deep sections. This can have a significant negative impact downstream of the reservoir, where unnatural temperature variations can lead to��ecological impacts, particularly on native fish.

Eurobodalla Shire Council coastal hazard assessment

Eurobodalla Shire Council, located on the NSW south coast, commissioned WRL to prepare a coastal hazard assessment for 17 of their most vulnerable beaches. This study area comprises Durras Beach (south) to Broulee Beach, including Batemans Bay.��This assessment forms Stage 2 of their Coastal Management Program, following a scoping study in Stage 1 (prepared by Umwelt), which prioritised those beaches with public and private assets potentially at high risk from coastal hazards.��

Hunter River water quality model

Estuaries in Australia support a diverse range of uses and functions, both environmental and social, in a delicate balance and the Hunter River estuary near Newcastle in NSW, Australia is no exception. The estuary has internationally recognised wetlands existing along-side the heavy industry of the city and Port of Newcastle and further upstream, farmlands with periodically irrigated pastures. The river itself also supports commercial and recreational fishing and boating. Both industry and the environment identify with, and respond to, the balance of the ebb and flow of the river tides and catchment runoff.

WRL recently supported a Hunter Water Corporation preliminary planning exercise looking at the sustainable effluent management and potential re-use of wastewater in the lower Hunter River catchment. Preparation of the plan was required to allow an informed discussion with planning authorities and regulators to enable Hunter Water to effectively manage the predicted increases in wastewater discharges as a result of expected population growth in the region in the medium term.

What is the Hunter River Estuary?

The Hunter Estuary includes all tidal waters of the Hunter River and its tributaries. This includes the banks and beds of the waterway from the Port of Newcastle to the tidal limits at Seaham Weir (on the Williams River), Gostwyck (on the Paterson River) and Oakhampton (on the main Hunter River).

The Hunter River Estuary is home to:

• A vast range of land tenures and management priorities from conservation to industry
• A Ramsar listed wetland of international significance
• The largest coal export port in Australia being of local and national economic significance
• A range of commercial activities including tourism, commercial and recreational fishing

Following storm erosion episodes between 2009 and 2012 which severely impacted the Kingscliff Beach Holiday Park and other public assets, Tweed Shire Council engaged WRL in partnership with Haskoning Australia to prepare the design for a long-term terminal seawall.

This seawall would extend along the foreshore between the existing rock seawall at the Kingscliff Beach Bowls Club and the existing secant pile seawall at the Cudgen Headland Surf Life Saving Club to protect built assets at immediate risk from coastal hazards. It would replace existing interim rock and sand-filled geotextile container structures along this stretch of coast.

The iconic Sydney suburb of Manly occupies the northern shores of Sydney Harbour. It includes low energy harbour-side beaches as well as the famous Manly Beach dominated by the swells of the Pacific Ocean. Manly beaches are susceptible to significant erosion during extreme storm events and have a long history of failure of their protection works. WRL was commissioned by Manly Council to undertake a comprehensive investigation to identify and quantify coastal risks on sandy beaches within the local government area.

This study provides floodplain and estuary managers with a better understanding of where poor water quality is originating from, as well as assessing the vulnerability of coastal floodplains to sea level rise over the next century.

Oceanlinx wave energy system physical modelling

Oceanlinx Australia engaged WRL to undertake two-dimensional physical modelling of its Wave Energy System. The Oceanlinx system converts the flow of air above an oscillating water column (OWC) into electrical energy via a mechanical turbine. Wave flume tests were undertaken independently on two different types of OWC designs in the 3 m wave flume at WRL.

Oyster reef restoration project

WRL has a track record of delivering large scale environmental restoration projects including, wetlands, rivers, estuaries and beaches. Recently, we have been working with OceanWatch Australia to support their vision of restoring oyster reefs to Sydney Harbour and elsewhere on the Australian coast. While many great ideas are being trialled in the ecological engineering discipline, our research links practical engineering solutions with innovative performance testing to inform designs.

Prior to European settlement, naturally occurring oysters reefs were widely found around Australia and within Sydney Harbour. Indeed, diaries of early settlers suggest that oyster reefs were so abundant that they were described as a shipping hazard. However, since the 1880s these reefs have largely disappeared due to over-exploitation (for consumption and cement production), pollution, increased estuarine siltation and the introduction of a parasitic mudworm. Government regulations were introduced in Queensland, NSW and SA in the 1850s and 1860s but came too late to preserve the natural oyster reefs.

Physical modelling of Bounty Bay breakwater, Pitcairn Island

The Pitcairn Islands are an extremely isolated south-eastern extension of the Tuamotus Archipelago of French Polynesia, and are accessible only via a 30 hour boat ride from the Tahitian Island of Mangareva. The Pitcairn Islands consist of four separate islands: Pitcairn, Oeno, Henderson and Ducie, with the main Pitcairn Island being the only permanently inhabited.

The British Government’s Foreign and Commonwealth Office (FCO) has commissioned Tonkin & Taylor International (T+TI) to prepare a concept design for a breakwater at Bounty Bay, on the north-eastern side of Pitcairn Island. Subsequently, T+TI commissioned WRL to undertake a physical modelling investigation of the proposed breakwater and Bounty Bay harbour.

Port Fairy coastal hazard assessment

WRL undertook a detailed sea level rise and coastal hazard assessment for Moyne Shire Council, Victoria. This project was jointly funded by Moyne Shire Council and the Victorian Department of Sustainability and Environment (DSE), and is part of the Future Coasts Program. The main purpose of the Future Coasts Program is to assist Victoria in better understanding and planning for the risks associated with sea level rise and storm surge. Port Fairy has been identified as one of the priority locations along the coast for more detailed local coastal hazards assessment.

WRL’s study main objective was to provide Moyne Shire Council and other land and asset managers, with information which will assist in planning for and managing the projected impacts of climate change, encompassing over 50 km of coastline from Cape Reamur to Cape Killarney. This coastal vulnerability assessment considered local coastal processes and sea level rise implications, resulting in an integrated assessment of climate change impacts on the foreshore.

Scrivener Dam physical model

Scrivener Dam is a critical piece of Canberra’s infrastructure, maintaining water levels of the iconic Lake Burley Griffin. Like all dams in Australia, it requires regular maintenance and assessment to ensure ongoing safe operation.��A recent inspection identified potential for undesirable uplift forces under the stilling basin slab, triggering a more detailed assessment of dam stability.��

UNSW Sydney’s Water Research Laboratory was commissioned by the����to construct and test a 1:40 scale physical model of the dam in WRL’s hydraulics laboratory at Manly Vale.

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Since 2004, WRL has been working in collaboration with the NSW National Parks and Wildlife Services (NPWS) and the Department of Primary Industries (NSW Fisheries) to transform the Tomago Wetlands site from a large acidic landscape into a restored productive tidal wetland. The wetland is being created to compensate for migratory wading bird habitat destroyed elsewhere in the lower Hunter River estuary.

The specific challenge faced by the Tomago Wetland Restoration��Project was to design and build a system that would naturally encourage saltmarsh regeneration, an ecological community in serious decline in NSW. Saltmarsh requires very specific hydrological and water quality conditions. The engineering challenge was to deliver the right volume of water, to the right place, at the right depth, at the right time and at the right salinity to allow nature to flourish and generate saltmarsh.

Tomago Wetland restoration project

Since 2004, WRL has been working in collaboration with the NSW National Parks and Wildlife Services (NPWS) and the Department of Primary Industries (NSW Fisheries) to transform the Tomago Wetlands site from a large acidic landscape into a restored productive tidal wetland. The wetland is being created to compensate for migratory wading bird habitat destroyed elsewhere in the lower Hunter River estuary.

The project has been joint-funded by NSW Fisheries, National Parks and Wildlife Service (NPWS) and the Hunter Region Local Land Services (formerly Hunter River Catchment Management Authority) with in-kind support provided by WRL. Advice and assistance from the Hunter Bird Observers Club (HBOC) has been provided throughout the project.��

Nature is complex. Endangered ecological communities embody this complexity, existing in a fine balance, though influenced by numerous factors including topography, geology and hydrology. Restoring this balance, to foster the genesis of an endangered ecological community, is a multi-disciplinary challenge.

Tube fishway project

Australian governments spend millions of dollars to conserve aquatic biodiversity and fisheries threatened by water-resource development, but outcomes are poor when dams or weirs block fish migrations. Migrations essential for fish biodiversity, productivity and viability are obstructed by tens of thousands of barriers. Existing high fishways are unsatisfactory.

Current approaches using fishways, locks and lifts vary in their success but all are costly. For example the fish lift on Tallowa Dam on the Shoalhaven River cost $48 million. The UNSW Tube Fishway Project is developing cost-effective techniques to provide fish passage over high (>8m) barriers, with considerable promise for more ambitious applications.

Tuckean Swamp is a 6,000 hectare low-lying floodplain located on the Richmond River, which has been extensively drained since the 1880’s. By 1971, the existing drainage works were completed with the installation of the Bagotville Barrage, a large one-way flow control structures that excludes tidal exchange and prevents backwater flooding from the estuary. These drainage works altered the hydrology of the Tuckean Swamp floodplain, lowering the water table and exposing highly acidic soils to oxygen.

The ongoing drainage of the floodplain sees the regular discharge of highly acidic waters (pH < 3) with extremely high concentrations of iron and aluminium. Due to the very low-lying elevation of Tuckean Swamp, prolonged inundation following wet weather results in the generation of low dissolved oxygen ‘blackwater’ runoff. As a result, the impacts to the Richmond River estuary and wetland ecology itself has been significant.��

The mystery of Thirlmere Lakes

During the past decade, water levels in the Thirlmere Lakes have varied from full in 2016 to completely dry between October 2018 and February 2020. These variations have raised concerns with the local community and left them wondering; "Where has all the water gone in Thirlmere Lakes?"

Thirlmere Lakes National Park, located south-west of Sydney in an ancient river meander, contains five lakes – Lake Gandangarra, Lake Werri Berri, Lake Couridjah, Lake Baraba, and Lake Nerrigorang

Yeramba Lagoon restoration

Yeramba Lagoon is located on the left bank of the Georges River estuary, approximately 20 km upstream from Botany Bay.��Historically, the lagoon was connected to the estuary, receiving tidal flows, and was populated by macrophytes including mangroves, saltmarsh, and freshwater swamp species. Following on from years of reclamation, construction and poor land management have led to an accumulation of contaminants and poor tidal flushing.

The lagoon is managed by NSW National Parks & Wildlife Service, who sought to restore tidal flushing and re-create the lost critical blue carbon coastal wetland ecosystem. WRL completed a detailed investigation of the lagoon condition and hydrology, to develop a restoration action plan.��