Radar satellites, such as Sentinel-1, allow us to monitor the Earth's surface regardless of weather conditions, day or night. This generates an extensive time series of satellite images and enables numerous applications. The master thesis deals with the assessment of the quality of the detected water areas of the portal VodaKje.si.
Analyses were carried out in the karst area of the Ljubljanica River over longer periods of time. The collected data were compared with official water level and precipitation data. The correlation was highest in smaller regions with regular floods (Planina and Cerknica polje). Heat maps produced by summing all identified water areas show correspondence with the most frequently flooded areas. The maps indicate that detection is less good under dense vegetation (forest and related vegetation). Comparison of the heat maps with the integral flood hazard maps at discharge with 10 years return period shows the adequacy of the Vodakje.si water detection.
In the area of the lower Krka River, a flood event observed by Sentinel-1 satellites on two dates (17 and 22 September 2017) was studied. Comparison of the hydraulic model of this event and the detected areas from satellite images shows that the agreement is very good. The discrepancy between the areas identified by each approach can be largely explained by land use or flood edge analysis.
The VodaKje.si data are suitable for independent study of floodplains in areas with slower water dynamics. If the timing of the imaging fits well with the flood event, it is a good source of information also in the study of floods and useful for floodplain mapping.
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