Improving water extent monitoring of Swedish wetlands with open-source satellite data & Google Earth

Research presentation from Stockholm University Baltic Sea Day, October 7, 2021.

Farzad Vahidi Mayamey, Department of Physical Geography: 'Improving water extent monitoring of Swedish wetlands with open-source satellite data and Google Earth Engine'.

In Sweden, there are 68 sites recognized as wetlands with international importance with Baltic coastal wetlands accounting for roughly a fourth of them. In this condition, water delineation is vital to understand wetlands' water availability changes and strengthen their resilience to the effects of human activities and climate change. Recent advances in remote sensing have improved the monitoring of wetlands; however, mapping their water extent is still challenging. Water below vegetation is difficult to recognize, and its changes remain hidden. Here, we used different polarizations of SAR and optical data of 10 m ESA Sentinel-1&2 satellites. We processed this data in the cloud computing platform of Google Earth Engine (GEE) and took advantage of machine learning clustering methods to detect the increased backscatter due to the double-bounce of the radar signal on flooded vegetation. We also analyzed the interferometric coherence increase as a sign for inundated vegetation. Furthermore, we used the thresholding method in the SAR images to extract open water extent. Finally, we compared the results to high-resolution optical images and field data.

[abdurrahimsafi]

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