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The effects of storm clustering on storm demand and dune recession at Old Bar, NSW.

Created 16/10/2025

Updated 16/10/2025

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Old Bar Beach on the NSW mid-coast is an erosion hotspot with chronic dune recession rates exceeding 0.5 m/yr combined with extreme storm demand events upwards of 200 m3/m. With resultant property loss, Old Bar is a focus for active shoreline management by Midcoast Council. Here we demonstrate a new approach to distinguish the erosional effects of individual storms versus clusters of storms. We modelled the observed sediment transport inside the Old Bar coastal compartment and used probabilistic modelling to quantify both shoreline recession and storm demand. The hybrid cross shore (equilibrium type) longshore morphodynamic Shoreline Evolution (EVO) model developed by WBM BMT was setup for the Old Bar coastal compartment. A suite of probabilistic synthetic time series of waves and tides were used to force the model allowing us to make robust statistical assessments of the modelled erosion. In the subsequent analysis, erosion caused by individual storms are merged into “clustered” events if accretionary beach recovery between storms was less than 50 percent. Modelling results were in line with previous studies indicating continued recessions of 0.5m/yr and 50 year storm demands that exceed 200m3/m. Preliminary analysis of storm clustering suggests that recession and storm demand for clustered events are greater than for individual storms. These findings suggest that traditional “design storm” methods based solely on the most severe individual storm event will underestimate recession and storm demand return periods. Results will aid ongoing management and planning supported by NSW Office of Environment and Heritage and Midcoast Council to better understand the nature of the coastal hazards that continue to place some beachfront properties at risk.
The Old Bar study was undertaken for the Bushfire and Natural Hazards CRC project ‘Resilience to clustered disaster events on the coast - storm surge’.]

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Field Value
Title The effects of storm clustering on storm demand and dune recession at Old Bar, NSW.
Language English
Licence Not Specified
Landing Page https://data.gov.au/data/dataset/d9a2d090-35a8-4861-9e6c-e333a2531c9f
Contact Point
Geoscience Australia Data
clientservices@ga.gov.au
Reference Period 14/06/2018
Geospatial Coverage
Map data © OpenStreetMap contributors
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  "coordinates": [
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      ],
      [
        154.0,
        -44.0
      ],
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        -9.0
      ],
      [
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      ],
      [
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      ]
    ]
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  "type": "Polygon"
}
Data Portal Geoscience Australia

Data Source

This dataset was originally found on Geoscience Australia "The effects of storm clustering on storm demand and dune recession at Old Bar, NSW.". Please visit the source to access the original metadata of the dataset:
https://ecat.ga.gov.au/geonetwork/srv/eng/csw/dataset/the-effects-of-storm-clustering-on-storm-demand-and-dune-recession-at-old-bar-nsw