This product delivers a monthly timeseries of estimated water volume for On-Farm Storages (OFS) across the five valleys of the northern Murray-Darling Basin (Border River, Gwydir, Namoi, Macquarie-Castlereagh, and Barwon-Darling). OFS are critical for agricultural water supply, enabling farmers to store water for irrigation and supporting effective water resource management in the face of water scarcity, regulatory requirements, climate variability, and the need for sustainable agricultural practices.
Estimated OFS water volume is derived through a two-step remote sensing approach. First, water surface area is calculated from multispectral satellite imagery (Landsat and Sentinel-2) using a geospatial model [1][2]. Second, LiDAR-derived storage capacity curves are applied to relate the observed surface area to water height above the Australian Height Datum (AHD), enabling calculation of the estimated water volume for each storage [3].
The dataset is updated monthly using the latest available cloud-free satellite imagery, and historical volume are computed from archived images. The timeseries spans from 1987 to the present, providing a consistent monthly record of estimated OFS water volume across the region.
References
[1] https://datasets.seed.nsw.gov.au/dataset/remote-sensing-earth-observation-water-toolkit.
[2] https://www.tandfonline.com/doi/full/10.1080/01431160600589179
[3] HydroSpatial Pty Ltd (2018) Storage Bathymetry Model update and application (Gwydir Valley) - Report prepared for Department of Industry, Office of Water.
Format
ArcGIS Rest Map Service
ArcGIS Feature Service
WFS (Web Feature Service)
Information about output/files
The methodology for estimating monthly water volume in On-Farm Storages (OFS) combines satellite remote sensing and geospatial modelling. Water surface area timeseries are first extracted from medium-resolution optical satellite imagery, specifically Landsat (30 m) and Sentinel-2 (10 m). These estimated surface areas are then converted to water volume using storage-specific curves derived from elevation data, such as LiDAR or in situ surveys. Storage curves are generated with a Storage Bathymetry Model that establishes geometric relationships between storage wall height, wall width, and borrow pit geometry, based on analysis of storages observed empty during LiDAR acquisition. This relationship is then applied to other storages not empty at the time of LiDAR capture, enabling the derivation of storage volume curves across the dataset. The estimated water volume for each OFS is calculated by combining the satellite-derived surface area with its corresponding storage curve, resulting in a modelled estimate of water volume for each month in the timeseries.
Output
Polygon features defining On Farm Storages with a relationship class linked table of monthly mean volume totals.
1. ArcGIS REST MAP SERVICE - Earth Observation - On Farm Storage (OFS) Water Volume Monthly
What is a ESRI map service?
https://enterprise.arcgis.com/en/server/10.5/publish-services/windows/what-is-a-map-service.htm
2. ArcGIS REST FEATURE SERVICE - Earth Observation - On Farm Storage (OFS) Water Volume Monthly
What is a ESRI feature service?
https://enterprise.arcgis.com/en/server/10.5/publish-services/windows/what-is-a-feature-service-.htm
3. ArcGIS REST WFS - Earth Observation - On Farm Storage (OFS) Water Volume Monthly
What is a WFS ?
https://enterprise.arcgis.com/en/server/latest/publish-services/windows/wfs-services.htm
Dataset Attributes
POLYGON ID: Unique Identifier that links the OFS Polygon to the monthly volume mean totals.
FSL VOLUME: The operational Full Supply Level (FSL) volume in megalitres (ML). Note: often considered lower than the storage crest height.
MAX VOLUME: The estimated maximum observed monthly volume (ie highest level observed) held in storage over the identified month. The calculation is based upon surface area measurements applied to a storage capacity curve, and is subject to uncertainties as detailed in the Accuracy and Error section.
YEAR MONTH: Year and Month of the observation
