Authors / CoAuthors
Lymburner, L. | Botha, E. | Hestir, E. | Anstee, J. | Dekker, A.G.
Abstract
The water clarity of many inland water bodies is under threat due to intensifying land use pressures in conjunction with changes water levels that result from increasing demand and climate variability. The recent launch of Landsat 8 coupled with Geoscience Australia's recent reprocessing of the Landsat TM and ETM+ archives over the whole of Australia to a consistent surface reflectance product enables large scale spatio-temporal analysis of freshwater optical water quality in support of monitoring and decision making for water management agencies. In this research, we present an objective assessment of the potential of Landsat 5 TM, Landsat 7 ETM+ and Landsat 8 OLI data for monitoring inland water quality dynamics over a number of lakes and reservoirs with a range of optical water types in New South Wales, Australia. We used bio-optical modelling to develop sensor-specific TSS retrieval algorithms that account for the difference in relative spectral response between Landsat 7 ETM+ and Landsat 8 OLI. We were able to compare the suitability of the different sensors for optical water quality measurements using water bodies that fell within Landsat path overlaps where surface reflectance measurements were acquired within 24 hours between Landsat 5 TM and Landsat 7 ETM+ or Landsat 7 ETM+ and Landsat 8 OLI. These water bodies represent a range of hydrological and limnological conditions, and enabled us to assess 1) comparability of TSS measurements retrieved from each sensor, and 2) the surface reflectance to image noise characteristics of Landsat 7 ETM+ and Landsat 8 OLI. Comparisons of lake surface reflectance and noise equivalent reflectance difference show that the improved radiometric resolution and increased quantization of Landsat 8 OLI relative to Landsat 7 ETM+ significantly reduce image noise and spectral heterogeneity, indicating that Landsat 8 OLI data are likely to provide more precise water quality retrievals relative to Landsat 7 ETM+. Despite differences in retrieval precision, the relative retrieval error between different sensors was not significantly different. We found that the TSS retrievals from the different sensors are highly comparable, Landsat 5 TM overestimated TSS relative to Landsat 7 ETM+ by 6.4 %, and Landsat 7 ETM+ overestimated TSS relative to Landsat 8 OLI by only 1.4%. The results demonstrate that time series analysis of a total suspended matter algorithm can be used to characterise the multi-decadal dynamics of TSS for a wide range of lakes.
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nonGeographicDataset
eCat Id
83852
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
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- External Publication
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
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2015-01-01T00:00:00
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