Two centuries of water-level records at Lake George, NSW

Abstract

The year 2020 marked the 200th anniversary of European settlers first encountering the ‘noble expanse of water’ of Lake George in New South Wales. Since 1820, unofficial observations and official measurements of the lake’s water-level have been recorded almost continuously by various individuals, research teams, government departments and private companies. The lake’s recent hydrographic history has been characterised by periods of flood and drought, which correspond with the prevailing climate conditions of SE Australia. This is the longest water-level record of its sort in the Southern Hemisphere and hence of great scientific and historic value. Here, we have compiled all available historic water-level data for Lake George, referenced them to common datums and presented a methodology for continuing the record using satellite imagery in lieu of on-site measurements.

KEY POINTS

1. The 200-year water-level record of Lake George, NSW has been compiled and referenced to a common datum.

2. This is the longest record of its type in the South Hemisphere, documenting the modern periods of flood and drought in southeastern Australia.

3. Water levels for the period 1986–2019 when no on-site measurements were recorded have been estimated using satellite imagery and the lake’s bathymetry.

Keywords:

• endorheic lake
• long record
• hydrological changes
• remote sensing
• Landsat
• Sentinel

Acknowledgements

We wish to acknowledge the First Nations people of the Ngunnawal, Ngambri and Ngarigo who have deep connections to the land upon which Lake George is situated. We also repeat the call of numerous people before us for the return of the lake’s original name—whether that be Weereewa or Ngungara. As people of non-indigenous descent, we are in no place to say, but either would be preferable to the name of a monarch who never stepped foot in Australia, let alone on the shore of the lake.

During the course of this work, Bear McPhail passed away. His academic guidance, passion for Lake George and friendship were pivotal for the production of this work. We miss him tremendously, and we dedicate this work to his memory.

For the early stages of this research, M. Short received financial support from the Australian Government in the form of an Australian Postgraduate Award, and from the Australian National University in the form of a research scholarship.

We thank Timothy Purves (Senior Analytics Engineer, Icon Water) for providing the Icon Water lake-level data during the years 2013–2015 and permission to publish those data.

The Keatley family, of the Luckdale property on the eastern shore of Lake George, graciously provided access to collect samples and install sensors at Rocky Point between 2013 and 2017. Peter Keatley was an especially valuable source of information and history because of his many years living on the edge of the lake.

Professor Ian Acworth provided useful review and comments that helped improve the context and reference list of the final article.

All figures and majority of analyses presented in this study were produced thanks to the developers and supporters of open source software such as QGIS (QGIS Development Team, 2019), Spyder (Spyder Project Contributors, 2019) and Jupyter Notebook (Project Jupyter, 2019).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data used in this paper are available online from the PANGAEA data repository (Short et al., 2020) at https://doi.pangaea.de/10.1594/PANGAEA.922463, and are available for use under a CC Attribution 4.0 International Licence. Michael Short will endeavour to update this dataset with the satellite-derived water levels on an annual basis.

Additional information

Funding

Research funding was partially provided by a Linkage Grant awarded by the Australian Research Council for the Lake George Project [LP140100911].