The GFM product provides a continuous, systematic monitoring of all major global flood events in near real-time, based on the latest Sentinel-1 SAR images, generating the ten output layers of flood information described in Table 1. The GFM product also provides a Sentinel-1 SAR-based processed archive of worldwide observed floods and water bodies, from 1st January 2015 until 2023. Central to the GFM product are three individual, state-of-the-art SAR-based flood mapping algorithms (i.e. LIST, DLR, and TUW), which are applied independently to the input Sentinel-1 SAR and ancillary datasets described in Section 2. The final flood maps (and likelihood values) that are provided by the GFM product are generated by combining the results of the three individual GFM flood mapping algorithms, using an Ensemble flood mapping algorithm.
The LIST, DLR and TUW flood mapping algorithms were originally described by Chini et al. (2017), Martinis et al. (2015), and Bauer-Marschallinger et al. (2022), respectively. The technical characteristics and main steps of the three algorithms, as implemented in the GFM product, are summarized in Table 7. Detailed descriptions of the LIST, DLR, TUW, and Ensemble algorithms, and how they are implemented in the GFM product, are provided in the remainder of this section.
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STEP |
LIST ALGORITHM |
DLR ALGORITHM |
TUW ALGORITHM |
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1. |
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2. |
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3. |
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4. |
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Table 7: Summary of the technical characteristics and main steps of the LIST, DLR, and TUW flood mapping algorithms, as implemented in the GFM product.
Further details on each flood mapping algortihm are provided in the following sections