Data

DEA Water Observations Statistics (Landsat) Version 2.0.0

Geoscience Australia
Mueller, N. ; Lewis, A. ; Roberts, D. ; Ring, S. ; Melrose, R. ; Sixsmith, J. ; Lymburner, L. ; McIntyre, A. ; Tan, P. ; Curnow, S. ; Ip, A. ; Lewis, B. ; Tissott, B.
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ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rfr_id=info%3Asid%2FANDS&rft_id=info:doi10.26186/150573&rft.title=DEA Water Observations Statistics (Landsat) Version 2.0.0&rft.identifier=10.26186/150573&rft.publisher=Commonwealth of Australia (Geoscience Australia)&rft.description=These are the statistics generated from the DEA Water Observations (Water Observations from Space) suite of products, which gives summaries of how often surface water was observed by the Landsat satellites for various periods (per year, per season and for the period from 1986 to 2025).The spatial extent is all Australia and the spatial resolution is 30 m x 30 m.DEA Water Observations Statistics is available in multiple forms, depending on the length of time over which the statistics are calculated. At present the following are available:- DEA WO Multi-Year: ga_ls_wo_fq_myear_3: statistics calculated from the full depth of time series (1986 to 2025) unfiltered- DEA WO Calendar Year: ga_ls_wo_fq_cyear_3: statistics calculated from each calendar year (1986 to 2025)- DEA WO November to March: ga_ls_wo_fq_nov_mar_3: statistics calculated yearly from November to March (1986 to March 2025)- DEA WO April to October: ga_ls_wo_fq_apr_oct_3: statistics calculated yearly from April to October (1986 to October 2025)Each dataset in this product contains the following information:- Clear Count: how many times an area could be clearly seen (i.e. not affected by clouds, shadows or other satellite observation problems)- Wet Count: how many times water was detected in observations that were clear- Water Summary: what percentage of clear observations were detected as wet (i.e. the ratio of wet to clear as a percentage)As no confidence filtering is applied to this product, it is affected by noise where misclassifications have occurred in the input water classifications, and can be difficult to interpret on its own. The confidence layer and filtered summary are contained in the Water Observations Filtered Statistics product, which provides a noise-reduced view of the all-of-time water summary.Band names:- count_wet: how many times water was detected in observations that were clear.- count_clear: how many times an area could be clearly seen.- frequency: what ratio of clear observations were detected as wet (represented as a number between 0 and 1 corresponding to 0 to 100% of observations)Maintenance and Update Frequency: asNeededStatement: This product is created from the WO water classification (Water Observations (Landsat)). Every pixel location is analysed statistically to derive the count of clear observations, the count of clear-wet observations and then to calculate the percentage of clear observations that were also wet. This provides a ‘normalised’ water frequency product for all of Australia.Each product within the WO-STATS set is derived from the available Landsat observations within the respective period: calendar years; Apr-Oct each year; Nov-Mar each year; all-of-time (first available Landsat observation in the DEA archive to 2023).To create the confidence layer required for the filtered product, a logistic regression is created between the unfiltered product and information about terrain, built-up areas, and coarse national water observations. In this way the confidence reflects the likelihood that the observed water is scientifically feasible at every pixel.Processing stepsCalculation of clear count, wet count and water summary (percentage of clear observations that are wet).For each WO pixel through time:- count the number of clear observations (ie observations not masked by pixel quality for cloud, shadows or sensor issues) to produce clear count dataset;- count the number of clear observations that are wet to produce wet count dataset;- create the ratio of wet to clear from the wet and clear count datasets and produce as a percentage dataset.Changelog Version 2.0.0Breaking change: Shift in grid origin point — The south-west origin point of the DEA Summary Product Grid has been shifted 18 tiles west and 15 tiles south. Therefore, all tile grid references have been changed. For instance, a tile reference of x10y10 has changed to x28y25. The tile grid references of all derivative products generated from 2024 onwards will also be changed; however, Analysis Ready Data products will not be affected.Enhanced cloud masking to reduce noise — An enhancement to cloud masking has reduced cloud and shadow noise. This enhancement (known as ‘cloud buffering’) involved cleaning cloud masks using a 6-pixel dilation on cloud and shadows. Note that some areas of very high surface reflectance (e.g. sand dunes and ocean areas) may exhibit worsened noise or data gaps, but these are infrequent occurrences with low impact.Landsat 9 product — Landsat 9 is processed from 2022 onwards.&rft.creator=Mueller, N. &rft.creator=Lewis, A. &rft.creator=Roberts, D. &rft.creator=Ring, S. &rft.creator=Melrose, R. &rft.creator=Sixsmith, J. &rft.creator=Lymburner, L. &rft.creator=McIntyre, A. &rft.creator=Tan, P. &rft.creator=Curnow, S. &rft.creator=Ip, A. &rft.creator=Lewis, B. &rft.creator=Tissott, B. &rft.date=2026&rft.coverage=westlimit=112.00; southlimit=-44.00; eastlimit=154.00; northlimit=-9.00&rft.coverage=westlimit=112.00; southlimit=-44.00; eastlimit=154.00; northlimit=-9.00&rft_rights=Creative Commons Attribution 4.0 International Licence https://creativecommons.org/licenses/by/4.0/&rft_rights=(c) Commonwealth of Australia (Geoscience Australia) 2025&rft_rights=Australian Government Security Classification System https://www.protectivesecurity.gov.au/publications-library/policy-8-classification-system&rft_subject=geoscientificInformation&rft_subject=Water Observations Statistics - WO-STATS&rft_subject=Water Observations from Space - WOFS&rft_subject=Surface Water&rft_subject=Landsat satellites&rft_subject=Clear count&rft_subject=Wet count&rft_subject=Water summary&rft_subject=DEA – Digital Earth Australia&rft_subject=EARTH SCIENCES&rft_subject=Published_External&rft.type=dataset&rft.language=English Access the data
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Creative Commons Attribution 4.0 International Licence
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(c) Commonwealth of Australia (Geoscience Australia) 2025

Australian Government Security Classification System
https://www.protectivesecurity.gov.au/publications-library/policy-8-classification-system

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Full description

These are the statistics generated from the DEA Water Observations (Water Observations from Space) suite of products, which gives summaries of how often surface water was observed by the Landsat satellites for various periods (per year, per season and for the period from 1986 to 2025).

The spatial extent is all Australia and the spatial resolution is 30 m x 30 m.

DEA Water Observations Statistics is available in multiple forms, depending on the length of time over which the statistics are calculated. At present the following are available:
- DEA WO Multi-Year: ga_ls_wo_fq_myear_3: statistics calculated from the full depth of time series (1986 to 2025) unfiltered
- DEA WO Calendar Year: ga_ls_wo_fq_cyear_3: statistics calculated from each calendar year (1986 to 2025)
- DEA WO November to March: ga_ls_wo_fq_nov_mar_3: statistics calculated yearly from November to March (1986 to March 2025)
- DEA WO April to October: ga_ls_wo_fq_apr_oct_3: statistics calculated yearly from April to October (1986 to October 2025)

Each dataset in this product contains the following information:
- Clear Count: how many times an area could be clearly seen (i.e. not affected by clouds, shadows or other satellite observation problems)
- Wet Count: how many times water was detected in observations that were clear
- Water Summary: what percentage of clear observations were detected as wet (i.e. the ratio of wet to clear as a percentage)

As no confidence filtering is applied to this product, it is affected by noise where misclassifications have occurred in the input water classifications, and can be difficult to interpret on its own. The confidence layer and filtered summary are contained in the Water Observations Filtered Statistics product, which provides a noise-reduced view of the all-of-time water summary.

Band names:
- count_wet: how many times water was detected in observations that were clear.
- count_clear: how many times an area could be clearly seen.
- frequency: what ratio of clear observations were detected as wet (represented as a number between 0 and 1 corresponding to 0 to 100% of observations)

Lineage

Maintenance and Update Frequency: asNeeded
Statement:
This product is created from the WO water classification (Water Observations (Landsat)). Every pixel location is analysed statistically to derive the count of clear observations, the count of clear-wet observations and then to calculate the percentage of clear observations that were also wet. This provides a ‘normalised’ water frequency product for all of Australia.
Each product within the WO-STATS set is derived from the available Landsat observations within the respective period: calendar years; Apr-Oct each year; Nov-Mar each year; all-of-time (first available Landsat observation in the DEA archive to 2023).
To create the confidence layer required for the filtered product, a logistic regression is created between the unfiltered product and information about terrain, built-up areas, and coarse national water observations. In this way the confidence reflects the likelihood that the observed water is scientifically feasible at every pixel.

Processing steps
Calculation of clear count, wet count and water summary (percentage of clear observations that are wet).
For each WO pixel through time:
- count the number of clear observations (ie observations not masked by pixel quality for cloud, shadows or sensor issues) to produce clear count dataset;
- count the number of clear observations that are wet to produce wet count dataset;
- create the ratio of wet to clear from the wet and clear count datasets and produce as a percentage dataset.

Changelog Version 2.0.0
Breaking change: Shift in grid origin point — The south-west origin point of the DEA Summary Product Grid has been shifted 18 tiles west and 15 tiles south. Therefore, all tile grid references have been changed. For instance, a tile reference of x10y10 has changed to x28y25. The tile grid references of all derivative products generated from 2024 onwards will also be changed; however, Analysis Ready Data products will not be affected.
Enhanced cloud masking to reduce noise — An enhancement to cloud masking has reduced cloud and shadow noise. This enhancement (known as ‘cloud buffering’) involved cleaning cloud masks using a 6-pixel dilation on cloud and shadows. Note that some areas of very high surface reflectance (e.g. sand dunes and ocean areas) may exhibit worsened noise or data gaps, but these are infrequent occurrences with low impact.
Landsat 9 product — Landsat 9 is processed from 2022 onwards.


Notes

Purpose
Water Observations Statistics provides information on how many times the Landsat satellites were able to clearly see an area, how many times those observations were wet, and what that means for the percentage of time that water was observed in the landscape.

Issued: 23 09 2025

Data time period: 1986-01-01

This dataset is part of a larger collection

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154,-9 154,-44 112,-44 112,-9 154,-9

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text: westlimit=112.00; southlimit=-44.00; eastlimit=154.00; northlimit=-9.00

Subjects
Clear count | DEA – Digital Earth Australia | EARTH SCIENCES | Landsat satellites | Published_External | Surface Water | Water Observations Statistics - WO-STATS | Water Observations from Space - WOFS | Water summary | Wet count | geoscientificInformation |

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Other Information
ga_ls_wo_fq_myear_3/2-0-0 (Link to Data)

url : https://data.dea.ga.gov.au/?prefix=derivative/ga_ls_wo_fq_myear_3/2-0-0/

ga_ls_wo_fq_apr_oct_3/2-0-0 (Link to Data)

url : https://data.dea.ga.gov.au/?prefix=derivative/ga_ls_wo_fq_apr_oct_3/2-0-0/

ga_ls_wo_fq_cyear_3/2-0-0 (Link to Data)

url : https://data.dea.ga.gov.au/?prefix=derivative/ga_ls_wo_fq_cyear_3/2-0-0/

ga_ls_wo_fq_nov_mar_3/2-0-0 (Link to Data)

url : https://data.dea.ga.gov.au/?prefix=derivative/ga_ls_wo_fq_nov_mar_3/2-0-0/

Link to DEA Knowledge Hub

url : https://knowledge.dea.ga.gov.au/data/product/dea-water-observations-statistics-landsat/

Identifiers