MDB Catchment Area >1Mil km2 SE Australia[/caption]
Lake Albert Study Area Methodology – Changes in Water Volumes
To begin our study, the team located data from 2008 - the point in time when the drought was at its worst and the lake volume was at its lowest. We found Digital Elevation Model (DEM) data from 2008 and then retrieved imagery from 2008, 2014 and 2018 to derive water masks using the Normalised Difference Vegetation Index (NDVI). The intersection of the DEM and each water mask provided a way to calculate the change in water volume on a pixel by pixel basis, relative to 2008.
The figures below show the 2008, 2014 and 2018 water masks that delineate Lake Albert.
The volume change results are shown in the graph below, reflecting a significant 15 gigalitres (GL) increase in Lake Albert’s water volume between 2008 and 2014 and indicating significant recovery following the end of the drought in 2011. Between 2014 and 2018, there has been only a minor 0.7GL increase in volume, reflecting a more stable period of in and outflow.
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Lake Albert Study Area – Change in Water Volumes 2008 - 2018[/caption]
Lake Albert Study Area Methodology – Water Quality (Turbidity)
Suspended material within bodies of water can have a detrimental impact on aquatic life. Measuring levels of this material, in addition to water volume, provides a more robust indication of the health of the basin.
In this study, we derived several different indices over Lake Albert using imagery captured between October 2017 and February 2018 (a period spanning the ‘wet season’ in central and northern Australia when heavy rains flow from the rivers southward). The figures below illustrate the amount of suspended material, demarked by a more prominent yellowish discolouration in the channel leading from the larger Lake Alexandrina (top left corner of the image) into Lake Albert. The extent of the plume extends further into the body of the lake as the wet season progresses.
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Images above: Amount of suspended material in Lake Albert between Dec. 2017 – Feb. 2018, with February reflecting the heaviest presence.[/caption]
Successful Proof of Concept Warrants Further Analysis of the MDB
While our study focused on a relatively small area of the MDB, the results show potential for informing authorities of the health of the entire basin. Supplemented with other datasets such as rainfall, climate, groundwater, land use and water allocation, GBDX and high-resolution imagery can be used to build a model that provides real insight for scientists, environmental managers, farmers and policy makers alike.
A Winning Team Effort – Geoimage and DigitalGlobe’s GBDX
The study proved that the winning combination of Geoimage’s geospatial analytical skills and DigitalGlobe’s satellite Imagery and GBDX can deliver an effective, high-value solution to one of Australia’s most significant environmental, economical and social challenges.