Abstract
Monitoring urban surface waters requires methods that preserve spatial detail while capturing seasonal and interannual variability. Multispectral satellite remote sensing provides a scalable complement to conventional field and laboratory monitoring across rivers, wetlands, lakes and coastal receiving waters. This study used Sentinel-2 Level-2A imagery processed through the Pixxel Aurora workflow to map a model-based water quality index (WQI) for the Swan-Canning River system, adjacent urban lakes and nearby coastal waters around Perth, Western Australia, from 2018 to 2025. Of 150 candidate images, 96 monthly WQI maps were accepted after software-based cloud correction, area-of-interest coverage checks and visual quality review. Satellite-derived chlorophyll-a, turbidity/total suspended solids and coloured dissolved organic matter were converted into trophic, turbidity and absorption indices and integrated through a fuzzy inference systems. Each image was normalised, fuzzified using triangular membership functions, evaluated with expert IF-THEN rules and defuzzified to produce WQI rasters on a 0–100 scale. Satellite outputs were compared with matched DWER/DBCA field and laboratory monitoring records and Bureau of Meteorology hydroclimatic data. Poor optical WQI (40–60) occurred most persistently in low-flushing inland waters and upper or middle estuarine reaches, whereas locally higher values near the lower-estuary mouth and open coast were associated with greater depth, tidal exchange and marine flushing; this pattern does not imply uniformly good estuarine water quality. The completed 96-map atlas resolved the previous monthly gaps while retaining residual cloud uncertainty in the interpretation. The framework supports spatial screening and targeted monitoring, while laboratory measurements remain essential for regulatory assessment.
Keywords
fuzzy inference systems, multispectral imaging, remote sensing, sentinel-2, spatiotemporal analysis, water quality index
Document Type
Journal Article
Date of Publication
9-1-2026
Article Number
110560
Volume
91
Publication Title
Journal of Water Process Engineering
Publisher
Elsevier
School
School of Engineering
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Recommended Citation
Hassnain, M., Veal, C., & Azhar, M. R. (2026). Spatiotemporal assessment of water quality around Western Australian central business district using satellite multispectral imaging. Journal of Water Process Engineering, 91, Article 110560. https://doi.org/10.1016/j.jwpe.2026.110560