## 2 Materials and Methods
### Study Areas and Available Data Sets: Greece/Turkey and China
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**No** & **Date** & **No** & **Date** & **No** & **Date** & **No** & **Date** \\ \hline
1 & October 19, & 16 & June 16, & 31 & January 6, & 46 & July 16, \\  & 2014 & & 2015 & & 2016 & & 2016 \\
2 & October 31, & 17 & June 28, & 32 & January 18, & 47 & July \\  & 2014 & & 2015 & & 2016 & & 28,2016 \\
3 & November & 18 & July 10, & 33 & January 30, & 48 & August 9, \\  & 24, 2014 & & 2015 & & 2016 & & 2016 \\
4 & December & 19 & July 22, & 34 & February & 49 & August 21, \\  & 6, 2014 & & 2015 & & 11, 2016 & & 2016 \\
5 & December & 20 & August 15, & 35 & February & 50 & September \\  & 18, 2014 & & 2015 & & 23, 2016 & & 2, 2016 \\
6 & December & 21 & August 27, & 36 & March 6, & 51 & September \\  & 30, 2014 & & 2015 & & 2016 & & 14, 2016 \\
7 & January 11, & 22 & September & 37 & March 18, & 52 & September \\  & 2015 & & 8, 2015 & & 2016 & & 26, 2016 \\
8 & February 4, & 23 & September & 38 & March 30, & 53 & October 2, \\  & 2015 & & 20, 2015 & & 2016 & & 2016 \\
9 & February & 24 & October 2, & 39 & April 11, & 54 & October 14, \\  & 16, 2015 & & 2015 & & 2016 & & 2016 \\
10 & March 12, & 25 & October 14, & 40 & April 23, & 55 & October 26, \\  & 2015 & & 2015 & & 2016 & & 2016 \\
11 & March 24, & 26 & October 26, & 41 & May 5, & 56 & November \\  & 2015 & & 2015 & & 2016 & & 7, 2016 \\
12 & April 5, & 27 & November & 42 & May 17, & 57 & November \\  & 2015 & & 19, 2015 & & 2016 & & 19, 2016 \\
13 & April 17, & 28 & December & 43 & May 29, & 58 & December \\  & 2015 & & 1, 2015 & & 2016 & & 1, 2016 \\
14 & May 11, & 29 & December & 44 & June & 59 & December \\  & 2015 & & 13, 2015 & & 10,2016 & & 13, 2016 \\
15 & June 4, & 30 & December & 45 & July 4, & 60 & December \\  & 2015 & & 25, 2015 & & 2016 & & 25, 2016 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Acquisition dates of the Sentinel (S-1) satellite data used for Greece/Turkey. The scenes acquired on March 12, 2015 and April 5, 2015 (highlighted with blue background) were used as flood event images for two different parts (northern and southern) of the Greece/Turkey study area. The second test case is the Dong Ting Lake, which is the second largest lake in China, located in the Hunan Province (Figure 4a). It is a flood-basin of the Yangtze River and thus varies seasonally in size. During the annual floods, it can expand to 2691 km\({}^{2}\) three times its size compared to the dry season. A flood event in summer 2017 (Figure 4b) was chosen. For this study, 38 dual-polarized S-1 scenes were used, which were acquired between October 2016 and February 2018 (Table 2). The scene acquired on June 28, 2017 is characterized by the largest flood extent. In addition, the selection of the analyzed flood image is carried out due to the temporal proximity to the reference data. Comparable to the study area in Greece/Turkey, the generation of the reference flood mask was carried out using a high-resolution optical Sentinel-2 (S-2) image (Figure 5), which was acquired on June 27, 2017 (Table 2). For the derivation of the reference mask, all bands with a resolution of 10 m and their combinations of the S-2 scene were used. The reference extent and the digitalized reference mask is shown in Figure 4c. No changes in flood extent were observed between the analyzed flood image and the optical scene. Figure 3: High-resolution false-color (NIR, green, blue) RapidEye image (April 04, 2015). (© Planet Labs Inc.) for southern Greece/Turkey containing TOW (**a**), DL (**b**), and TFV (**c**). Figure 2: High-resolution false-color (NIR (near infrared), green, blue) WorldView2 image (March 11, 2015) (© European Space Imaging/DigitalGlobe) for northern Greece/Turkey containing temporary flooded vegetation (TFV) (**a**), temporary open water (TOW) (**b**), and dry land (DL) (**c**).