Speaker
Description
In May 2023 the northern Italian region of Emilia-Romagna was hit by a series of floods. The first one occurred on 2-3 May after several months of drought. More severe floods hit Emilia-Romagna starting from 16–17 May 2023. During the latter event, more than 20 rivers burst their banks, about 15 people were killed, thousands people were displaced, and public transportation was stopped.
A daily monitoring of the flood, starting from 16 May 2023, was requested by the Italian Department of Civil Protection (DPC). Synthetic Aperture Radar (SAR) systems are particularly useful for flood mapping because of the synoptic view and the capability to provide data both day and night and in any meteorological conditions. Moreover, calm water is easily detected in SAR images because it has a distinguishable radar signature characterized by a low radar return. However the majority of SAR systems has a revisit time that does not comply with a daily monitoring. Moreover, a complete monitoring of the Emilia-Romagna flood required to observe different areas on the same day, especially during the first days of the flood. It was therefore necessary to rely on a SAR system offering both an on demand capability and the possibility to simultaneously observe different areas. The COSMO-SkyMed (CSK) constellation, hosting an X-band SAR, can operate as an on-demand system to ensure a timely provision of data. Presently, also the COSMO-SkyMed Second Generation (CSG) is deployed. It provides service continuity for the first generation while improving performance, functionality, and system services for the user community.
The satellite daily monitoring of the Emilia-Romagna flood was performed in the period 17 May – 3 July 2023 using data provided from both CSK and CSG. The activity included: 1) the tasking of the satellite (at least 36 h before the acquisition time) to observe the areas mostly affected by the flood according to the information daily gathered by DPC; 2) the calibration and the geocoding of the SAR data; 3) the generation of the flood maps.
To generate the flood maps, a change detection algorithm was applied. Note that only for a subset of the images of the flood it was possible to find in the archive a pre-event image acquired with the same geometry (interferometric pair). To apply change detection for the other post-event images too, a set of pre-flood images covering whole area hit by the flood was gathered. Among these images the most suitable one was selected based on the orbit (ascending or descending), the overlap with the considered post-event image, and the incidence angle.
The main outcomes of the satellite monitoring of the Email-Romagna flood will be presented at the conference.
