## 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 c} \hline \hline
**No** & **Date** & **No** & **Date** & **No** & **Date** & **No** & **Date** \\ \hline
1 & October 19, & 11 & February & 21 & July 10, & 31 & November \\  & 2016 & & 16, 2017 & & 2017 & & 19, 2017 \\
2 & October 31, & 12 & February & 22 & July 22, & 32 & December \\  & 2016 & & 28, 2017 & & 2017 & & 1, 2017 \\
3 & November & 13 & March 12, & 23 & August 3, & 33 & December \\  & 12, 2016 & & 2017 & & 2017 & & 13, 2017 \\
4 & November & 14 & March 24, & 24 & August 15, & 34 & December \\  & 24, 2016 & & 2017 & & 2017 & & 25, 2017 \\
5 & December & 15 & April 5, & 25 & August 27, & 35 & January 6, \\  & 6, 2016 & & 2017 & & 2017 & & 2018 \\
6 & December & 16 & April 17, & 26 & September & 36 & January 30, \\  & 18, 2016 & & 2017 & & 8, 2017 & & 2018 \\
7 & December & 17 & April 29, & 27 & October 2, & 37 & February \\  & 30, 2016 & & 2017 & & 2017 & & 11, 2018 \\
8 & January 11, & 18 & June 11, & 28 & October 14, & 38 & February \\  & 2017 & & 2017 & & 2017 & & 23, 2018 \\
9 & January 23, & 19 & June 4, & 29 & October 26, & & \\  & 2017 & & 2017 & & 2017 & & \\
10 & February 4, & 20 & June 28, & & 30 & November \\  & 2017 & & 2017 & & 7, 2017 & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Acquisitions dates of the S-1 satellite data used for China. The scene acquired on June 28, 2017 (highlighted with blue background) was used within this study as a flood event image. Figure 4: Overview map with the location of the study area (red rectangle) in China (**a**), study area in China (**b**). The red rectangle represents the reference mask extent (**c**), which was derived from S-2 data (June 27, 2017). According to the ESA (European Space Agency) acquisition plan for S-1 constellation, dual-polarized images of the S-1A with an interval of 12 days were available for the study areas and the analyzed acquisition period. These data sets are processed and provided by ESA as Ground Range Detected High Resolution (GRDH) products. According to [8], an automated preprocessing of the time series data for both areas and both polarizations VV and VH (vertical/horizontal) was carried out in several steps. The characteristics of all used S-1 data are listed in Table 3.  
In addition to the satellite data, ancillary information was used to avoid misclassification of the desired flood-related classes [8] in both study areas. Initially, permanent open water (POW) surfaces were identified by the 30 m SRTM Water Body Data (SWBD) [53]. Besides POW, information regarding urban areas and topography was integrated by using the Global Urban Footprint (GUF) and Height Above Nearest Drainage (HAND) index. Urban areas, as well as TFV, are characterized by strong double- and multiple-bounce backscattering effects. Therefore, the GUF [54] mask is used to identify and exclude urban areas. In order to prevent misclassifications in elevated areas, the HAND index [55] was used to identify and exclude areas with an elevation of greater than 20 m above the nearest water network [56]. Figure 5: High-resolution false-color (NIR, green, blue) Sentinel-2 image (June 27, 2017) for southern Greece/Turkey containing DL (**a**), TFV (**b**) and TOW (**c**). \begin{table}
\begin{tabular}{c c} \hline \hline
**Sensor Properties** & **Values** \\ \hline Wavelength Mode & Interferometric Wide Swath (IW) \\ Polarization & VV \(-\) VH \\ Frequency & C-band (GHz) \\ Resolution & 20 \(\times\) 22 m (az. \(\times\) gr. range) \\ Pixel spacing & 10 \(\times\) 10 m (az. \(\times\) gr. range) \\ Inc. angle & 30.5\({}^{\circ}\)\(-\)46.3\({}^{\circ}\) \\ Orbit & Ascending \\ Product-level & Level-1 (Ground Range Detected High Resolution (GRDH)) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Characteristics of the S-1 data used.